We planned for this from day one
Drilling for geothermal water in Iceland is well-founded — the geology around Hvalfjörður is exceptional and nearby wells prove the potential. But geothermal exploration always carries uncertainty. Fractures can be missed. A well can come up dry. Investors can lose patience.

We designed Hugarró so that this scenario, however unlikely (see this post), does not stop us.

Our answer is a purpose-built alternative heating system that delivers the same pools, the same warmth, the same experience — drawing heat not from the ground below, but from the river and the earth around us.

Why our heating needs are surprisingly modest
Most facilities of this kind would be in serious trouble without a geothermal source. Ours is not — because of how efficiently we use energy in the first place.

Our closed-loop pool system recirculates water rather than constantly replacing it, recovering 33% more heat than the traditional Icelandic approach. Our cascade design runs geothermal water through pools, then buildings, then roads — extracting every usable degree before returning it. Floating insulation covers eliminate heat loss overnight.

The result: our total heating demand — seven pools at 38°C, full hotel and cabin heating, road de-icing — requires the equivalent of just 1,185 kW of continuous thermal output. For a facility of this scale, that is a lean number. And it is exactly what our backup system is sized to deliver.

The alternative: CO₂ heat pumps

If no geothermal source is found, we install three Fenagy (or other reliable brand) H-600 CO₂ heat pump units, each delivering 600 kW of thermal output. Together they provide 1,800 kW of installed capacity — comfortably above our 1,185 kW peak demand, with full redundancy built in.

CO₂ (R744) is the ideal refrigerant for this application:

• GWP of 1 — the most climate-neutral refrigerant available
• No chemicals — fully aligned with Iceland’s environmental standards
• Highest efficiency in the 38–70°C output range — exactly our operating window
• Proven technology — widely used in Scandinavian district heating systems

The heat pumps run as water-to-water units, extracting heat from a local water source and delivering it at the temperatures our cascade system requires. The full cascade — pools, buildings, roads — operates identically to the geothermal design. From a guest perspective, nothing changes.

Where the heat comes from: a two-tier water source
Instead of one geothermal well, we use two complementary water sources that together provide year-round reliability.

Tier 1 — The Brunná river (primary, spring through autumn)
The Brunná flows just 200 metres from our plant room, crossing land whose owner has no objection to our intake (in fact, we are co-owner). A short insulated HDPE pipe draws water at ~6°C, passes it through a heat exchanger, and returns it a few degrees cooler. The river provides more than enough flow for our needs during the eight warmest months of the year.

Tier 2 — Two drilled groundwater wells (winter backup)
For the winter months, when surface water flow can drop and ice becomes a risk, we rely on two drilled wells at 80–150 metres depth. At that depth, groundwater in the Botnsdalur valley maintains a stable 4–6°C year-round — completely unaffected by surface weather, frost, or seasonal variation. No river. No tidal influence. No moving parts except a submersible pump in each well.

Crucially, these wells are drilled while the geothermal exploration rig is already on site — a modest incremental cost on an already-mobilised programme, and one that simultaneously provides valuable geological data to guide the deep geothermal drill.

The system switches automatically between sources based on flow sensors and temperature readings. No manual intervention required.

The buffer tank — smoothing out demand peaks
Between the heat pumps and the distribution system sits a 35 m3 insulated thermal buffer tank, maintained at 45–50°C. It acts as a reservoir of stored heat, absorbing demand peaks and allowing the heat pumps to run at steady, optimal load rather than cycling up and down.

The effect is meaningful: peak source water demand drops by around 20%, the heat pumps run more efficiently, and the system becomes more resilient to short interruptions in either water source. It is the thermal equivalent of a battery — simple, passive, and highly effective.

What it costs to run
Iceland’s electricity is among the cleanest and most affordable in Europe, generated almost entirely from hydro and geothermal sources. At current industrial tariffs:

For every unit of electricity the heat pumps consume, they deliver 3.8 units of heat — the rest comes free from the river or the wells. Compared to direct electric heating, the CO₂ heat pump system saves approximately €750,000 per year in energy costs.

How the two systems compare

The bottom line
Finding geothermal water is our ambition and our expectation. The geology strongly supports it. But if exploration falls short, Hugarró does not fall with it.

Our backup system — three CO₂ heat pumps, two groundwater wells, a river intake, and a thermal buffer — delivers the same warmth, the same pools, and the same guest experience at a known, manageable operating cost. It was engineered in parallel with the geothermal design, not as an afterthought.

We are not betting everything on a single drill result. That is how Hugarró was designed.

Hugarró: a facility powered by nature — with a plan B ready from day one
Hugarró will be a seven-pool geothermal wellness complex on the shores of Hvalfjörður, one of Iceland’s most striking fjords. From the water temperature in our pools to the warmth in our cabins and the heat under our roads in winter, every degree of energy in this facility comes from renewable natural sources.

We did not design this system around hope. We designed it around certainty — with a primary strategy backed by Iceland’s exceptional geology, and a fully engineered alternative ready to deploy if exploration falls short.

Either way, Hugarró will operate as planned!

The primary strategy — geothermal heat
Iceland sits on one of the most geothermally active zones on the planet. The geology around Hvalfjörður reflects this: temperature gradients of 120°C per 1,000 metres have been recorded nearby, and the Hvalur station a few kilometres away produces over 20 litres per second at 140°C. The natural resource is well-established.

Our target is modest by Icelandic standards: a production well yielding 7–10 litres per second at 70–90°C. A typical productive Icelandic well delivers 15–50 litres per second. We are not asking for much.

Finding that water is the ambition. The three-phase exploration programme — shallow pre-drills, drone magnetic survey to map fracture zones, then a targeted production well at 900–1,500 metres — is designed to maximise the probability of a productive strike while managing exploration risk.

One source. Four uses. Nothing wasted
If geothermal water is found, it flows through a cascade that extracts every usable degree before returning the water underground:

1. Pools — water enters at 70–90°C and heats all seven pools to a perfect 38°C
2. Buildings — the same water, still warm, then heats the hotel and all cabins
3. Hot water — covered in the same circuit, at no additional energy cost
4. Roads — remaining warmth keeps paths and access roads clear in winter

The water returns underground at 30°C. Zero discharge. Zero waste.

This cascade design and our closed-loop pool heating recirculation system recovers 33% more thermal energy than the approach used by traditional Icelandic pools, which continuously replace pool water and discharge thousands of cubic metres of hot water to nature every year. We do not do that.

Pool water — clean without chemicals
Our pools recirculate water in a closed loop rather than replacing it. Water is kept clean through UV disinfection, ultrafiltration membranes and biologica filters — the same technology used in drinking water treatment — monitored continuously by real-time microbiological sensors across all seven pools.

No chemicals are used or permitted. The result: 91% less water consumed than a traditional Icelandic pool operation, and measurably cleaner water for guests.

Beyond the facility — a district heating opportunity
A geothermal well of this scale does more than serve Hugarró. Should the Botnsdalur valley develop into a wider community, the same well — with capacity to spare — could supply heat to an estimated 200–250 neighbouring vacation homes, each with a hot tub, through a district heating network.

At a metered tariff, this transforms a facility operating cost into a recurring revenue stream. A geothermal well becomes a utility asset.

If no geothermal water is found
Drilling always carries geological uncertainty. A well can miss a fracture. Pre-drills can show unfavourable results (see this related FAQ). 

But we are planning for this before we break ground.

Our alternative is a purpose-built system of three Fenagy H-600 CO₂ heat pump units, each delivering 600 kW of thermal output. Together they provide 1,800 kW of installed capacity against a peak demand of 1,185 kW — full redundancy is built in. Two units alone cover peak load; the third is available for future expansion.

CO₂ (R744) is the most climate-neutral refrigerant available — a global warming potential of just 1, compared to 1,400+ for conventional refrigerants. It is also the most efficient refrigerant in the 38–70°C output range, which is exactly where we operate. For every unit of electricity these heat pumps consume, they deliver 3.8 units of heat — the rest comes free from the water sources below.

The cascade — pools, buildings, roads — operates identically to the geothermal design. From a guest perspective, absolutely nothing changes.

Where the heat comes from — two tiers, no single point of failure
The heat pumps draw their source heat from water. We use two complementary sources that together guarantee year-round reliability without dependence on rivers with fishing rights disputes, tidal complications, or expensive sea inlets.

Tier 1 — The Brunná river (spring through autumn)
The Brunná flows 200 metres from our plant room, crossing land whose owner raises no objection. A short insulated pipe draws river water at ~6°C, passes it through a heat exchanger, and returns it cooled by a few degrees. During the eight warmer months of the year, the Brunná provides everything we need.

Tier 2 — Two drilled groundwater wells (winter)
At 80–150 metres depth, groundwater in the Botnsdalur valley sits at a stable 4–6°C year-round — completely unaffected by surface frost, ice, or seasonal variation. Two drilled wells provide our winter heat source: reliable, permit-straightforward, and with no fishing rights complications.

Critically, these wells are drilled while the geothermal exploration rig is already on site — a modest incremental cost on an already-mobilised programme. The same activity that seeks geothermal water simultaneously secures our backup water source. The shallow geology data gathered also helps refine the deep drill target.

The system switches automatically between river and wells based on flow and temperature sensors. No manual intervention. No single point of failure.

The buffer tank
Between the heat pumps and the distribution system sits a 35,000-litre insulated thermal buffer tank at 45–50°C. It absorbs demand peaks, allows the heat pumps to run at steady optimal load, and reduces peak source water demand by around 20%. Think of it as a thermal battery — passive, simple, and highly effective.

The hydropower multiplier
The same river (Brunná)  that provide our backup heat source offer a second opportunity: small-scale run-of-river hydropower.

A €300,000 investment in a small hydropower plant on the Brunná or Botnsá delivers:

• 150 kW for eight months of the year (spring through autumn)
• 50 kW through the four winter months

That is enough to offset 50% of the heat pump system’s annual electricity consumption — effectively halving the grid electricity bill.

When river flow is high and heat pump demand is low, surplus hydro power heats the buffer tank directly through resistance elements — free thermal energy that further reduces the load on the heat pumps.

A 3.1-year payback on renewable infrastructure is exceptional by any standard. After that, the plant runs free for its remaining 30–40 year lifespan.

The numbers — what each path costs

The geothermal well is the cheapest long-term solution by a wide margin — €3.5M cheaper than heat pumps alone over 20 years. But the heat pump system combined with hydropower is a fully viable, lower-risk alternative that closes that gap significantly.

The capital costs of all three paths are remarkably similar. What separates them is operating cost — and operating cost is where geothermal wins decisively. Every year of successful geothermal operation saves €200,000 in electricity that the heat pump alternative would otherwise purchase from the grid.

Resilience by design
Most geothermal wellness projects are built around a single assumption: that the well succeeds. Ours is not.

Our engineering team designed the geothermal cascade and the CO₂ heat pump alternative in parallel — same output temperatures, same cascade architecture, same pool experience, same environmental standards. Switching between the two strategies requires no redesign of the facility. The plant room, pipework, heat exchangers, and distribution circuits serve both.

The exploration programme is thorough and data-driven. We expect to find water. But if we do not, a fully costed, fully engineered alternative is ready — one that combines proven industrial heat pump technology with local renewable water and hydropower sources, and delivers the same Hugarró experience at a known, manageable operating cost.

That is not a fallback. It is a feature.

The foundation of everything
Hugarró runs on the heat of the earth. Our geothermal pools, building heating, hot water, and road de-icing all draw from a single underground source. Finding that source — and doing so reliably and cost-effectively — is one of the most important investments we make.

Click to enlargeIceland’s geological advantage
The area around Hvalfjörður sits on one of the most geothermally active zones on the planet. Exploratory data from previous drillings in the area shows a temperature gradient of 120°C per 1,000 metres — well above the global average. The nearby Hvalur station, just a few kilometres away, produces over 20 litres per second at 140°C. Nature has already proven the potential here.

How we find the water?
Geothermal water typically flows along fractures and fault lines in the rock. Hitting those fractures is the real challenge — which is why we do not simply drill and hope.

Our approach, developed with one of Iceland’s leading geothermal specialists, follows a structured three-phase methodology:

1. Shallow exploratory drilling — 3 to 4 boreholes to 80 metres, mapping the subsurface geology
2. Drone magnetic survey — a non-invasive aerial survey pinpointing fault lines and fracture zones below ground
3. Production well — a single deep well of 900–1,500 metres, drilled with the best possible information, maximising the chance of a productive strike

On drilling method, we will choose between vertical, angled, or directional drilling based on what the survey data reveals. Directional drilling offers the greatest flexibility and the highest probability of intersecting a productive fracture — at a 40–60% premium over straight drilling. A worthwhile investment if the geology calls for it.

How much water do we actually need?
Surprisingly little, thanks to our closed-loop pool system. Our engineering calculations show that 7–10 litres per second at 70°C is sufficient to heat all seven pools to 38°C, supply all buildings and cabins with heat, and de-ice roads in winter — with capacity to spare.

Should the Botnsdalur valley ever develop into a wider community, that same well could realistically supply up to 50 holiday homes with heat at no additional extraction cost.  If water temperature would be 90°C and the flow 12 litres per second , 250 modern, well-insulated homes could benefit.  With their hot tubs of course: a must in Iceland! 

Needless to say the additional potential revenue stream of this option is considerable which is why the design of our geothermal water distribution system will be designed for this opportunity.

 What it costs
The table below shows our drilling budget, based on actual quotes from Icelandic contractors. Geothermal drilling in Iceland is one of the few things that costs significantly less here than in mainland Europe — geological conditions and a mature local industry make it so.

Click to enlarge

Our drinking water infrastructure — borehole, creek intake, filtration, UV disinfection, a 58 m³ storage tank and remote monitoring — is included in the budget above.

You may wonder why drilling a geothermal source in Iceland is considerably cheaper than in mainland Europe.

Icelandic groundwater is extremely hot (often 80°C to well over 150°C). The temperature gradient our our location suggests a temperature of 120 °C at 1.000 m. depth.    So if we hit an aquafier at 800 m. with 90 °C water we’re avoid extra drilling cost.  Moreover, the water there is often under natural pressure and rises on its own as an artesian spring, or with only a light pump. As a result, the costs for a heavy, expensive deep-well pump in the production well are often eliminated where a well depth of 2.500 m. is not uncommon.

The map below shows the distance to nearby wells.

The Hugarró development’s anchor are the geothermal pools.  Needless to say we need hot water.  We have already discussed the alternative if we don’t find (enough) geothermal water: C02 heat pumps.

But what are the actually chances of failure and which factors play a role?  We dove deeper into this subject.  Below the results of our research.

The most important distinction first
Almost every published statistic on geothermal well failure is based on power generation wells — where “success” means enough steam to drive a turbine, typically requiring 200°C+ at high flow rates. Our target is fundamentally different:

Our needs:  7–10 L/s at 70°C — a bar so low that many wells classified as “failures” in academic studies would comfortably pass for our purposes.

The IFC’s global study — the largest geothermal drilling database ever compiled — makes this explicit: “a dry well is a rarity — almost all wells flow to some extent” and “a well was only considered successful if the capacity was above a certain threshold.” ¹ That threshold is set for power production — not for our modest direct-use application.

What the numbers actually say

Global baseline (IFC database)

¹

Iceland high-enthalpy – over 200 °C (213 wells studied)

⁵

Low-temperature Iceland — our actual peer group
Iceland has drilled approximately 900 low-temperature wells since 1928, successfully supplying ~90% of the country’s space heating. ⁴ The track record of the low-temperature programme is exceptional precisely because the bar is lower — 70°C water is found across a much wider geographical area and shallower depth range than the 200°C+ needed for power generation.

Real examples near analogous settings:

• Thelamörk, N-Iceland: productive fracture intersected at just 450m depth, yielding 17 L/s at 91°C — more than double our target, at less than half our planned depth ²
• Hjalteyri, Eyjafjörður: well HJ-19 to 1,450m following ground magnetic survey yielded 200 L/s at 90°C — the most productive low-temperature well in that region ³

What the magnetic survey does — and doesn’t — do

This is where honesty matters for investors:

The research is direct on this: “pre-drill derisking techniques have not greatly mitigated the risk factors — there is a relatively small improvement in success rates between exploration and development wells.” ¹ What surveys do is eliminate the worst outcomes — drilling in completely the wrong location. What they cannot do is guarantee fracture intersection at the exact drill point. That residual uncertainty is irreducible with current technology.

The IFC study describes this remaining risk as simply “bad luck — local absence of fractures, difficult to predict even with surveys.” ¹

Our specific probability — After survey and pre-drills
Combining all factors — Iceland’s geological advantage, our low target, our pre-drill programme, the Hvalfjörður geological context, and proven nearby production at Hvalur:

The honest summary

In plain terms: after a thorough magnetic survey, shallow pre-drills, and with the geological context of Hvalfjörður behind us, the probability of finding sufficient water for our modest needs is approximately 85–90%. The remaining 10–15% is not ignorance or poor planning — it is the irreducible geological uncertainty that every geothermal project carries, regardless of how much exploration is done first.

That is precisely why our CO₂ heat pump backup system exists, and why it was engineered in full detail rather than treated as a footnote.

and how Hugarró goes far beyond them
What makes geothermal pools in Iceland unique — and what does it take to keep them safe, sustainable, and natural at the same time?

  translation below

What makes Icelandic geothermal pools so special?
Iceland’s geothermal pools are a product of the country’s unique geology. Water heated deep underground is mixed with cold water to set temperatures between 36–42°C — perfect for soaking, but also a warm, nutrient-rich environment in which bacteria can multiply quickly. Unlike outdoor seawater beaches or cold freshwater lakes, a warm pool with dozens of bathers needs active water quality management.

In most countries around the world, this is solved with chlorine and other chemical disinfectants. In Iceland, chemicals are explicitly prohibited in natural bathing facilities under Regulation No. 460/2015 (Reglugerð um baðstaði í náttúrunni). That is what makes Icelandic geothermal bathing culture genuinely different — and what makes the engineering challenge so interesting.

What does Icelandic law require instead?
The traditional solution used across Iceland is straightforward and effective, but also very resource-intensive: replace 30–40% of the pool’s total water volume every single day. Fresh cold water and geothermal hot water are continuously mixed in and the “old” water is flushed out — millions of litres of heated water discharged daily into drainage ditches.

The relevant law, Regulation No. 460/2015, classifies natural bathing facilities and sets bacterial count limits (e.g. E. coli < 500/100 ml; Enterococci < 200/100 ml for Class 1 facilities). The regulation requires:

• A minimum of 10 water samples per year for Class 1 facilities (like ours)
• An internal control system with risk assessments, incident logs, and staff training
• A documented emergency and contingency plan
• Strict bather number controls
• Mandatory signage, changing rooms, showers, and first aid on site

The regulation is outcome-based, not technology-prescriptive — meaning it sets the results you must achieve, not the method you must use. This is the regulatory opening that Hugarró’s engineering approach is built on.

What category does Hugarró fall under?
Hugarró is classified as a Recreation Pool (Afþreyingarlaug) — Class 1 — under Regulation 460/2015. This is the highest level of oversight, applying to facilities that operate regularly and year-round. It requires a full operating licence (starfsleyfi) from the local Health Committee, comprehensive internal controls, and continuous compliance with bacterial quality standards.

We welcome this level of scrutiny. Our systems are designed to far exceed Class 1 requirements, not merely meet them.

Why are chemicals not used — and why is that actually fine?
Chemicals such as chlorine kill bacteria effectively, but they have a serious downside: they react with organic matter introduced by bathers (sweat, skin cells, urine) to produce disinfection by-products (DBPs) — compounds that are themselves potentially harmful and are responsible for the characteristic “pool smell” most people associate with indoor public pools. In Iceland, the law simply prohibits them in natural bathing facilities.

The good news is that, as research has demonstrated, chemicals are not actually necessary if you control the source of contamination and treat the water effectively through physical methods.

What does the science say? The Keuten/Delft Study
Researcher M.C. Keuten at Delft University of Technology published a landmark study on bacterial pollution in swimming pools and how to reduce it — *Alternative Pool Water Treatment and the Influence of Swimmers on Water Quality*.

The study used a specially instrumented shower cabin to precisely measure the pollutants released by bathers before and during swimming. The key findings are striking:

This means that up to 60% of the bacterial input into a pool is directly controllable through bather behaviour — before any filtration or treatment technology is even needed. This is something Icelanders know well, which is why the country has a very strict pre-bath showering culture.

Keuten also demonstrated that UV disinfection combined with ultrafiltration — with no chemicals — can achieve microbial water quality comparable to chlorinated pools. Biological filtration further improved the removal of dissolved substances such as urea, reducing the formation of unwanted by-products.

What does Hugarró do to reduce bacterial input at the source?
Based directly on Keuten’s research, Hugarró has designed a two-step pre-entry protocol backed by technology, not just signage:

1. Mandatory pre-swim shower — Our facilities use sensor-based nudging technology that confirms a minimum 1.5 minutes of showering before entry is unlocked. This alone eliminates approximately 30% of the bacterial load that would otherwise enter the pool. A visible timer shows the bather how much time is left.
2. Toilet-first culture — Clear prompts, facility design, and staff communication encourage guests to use the toilet before bathing — targeting the remaining 30% of avoidable bacterial input.

Across our 7 pools, strict bather number limits are enforced in real time, both to comply with the regulatory requirement for access control and to ensure that the filtration system is never overwhelmed.

How does Hugarró manage water quality without chemicals and without massive water waste?
Instead of continuously flushing out large volumes of water, Hugarró’s pools are equipped with continuous ultrafiltration — a physical membrane-based process that removes bacteria, particles, and micro-organisms from pool water in a closed loop. This is combined with continuous water quality monitoring using systems such as those developed by bNovate, which allows near-real-time measurement of bacterial counts.

The result:

• • Water savings of over 90% compared to the traditional daily-replacement model used elsewhere in Iceland
  • Energy savings of over 30% in heating, as far less cold replacement water needs to be heated
  • Pool water that can be cycled to within safe bacteriological limits within one hour if needed — compared to the days it would take under a simple dilution/replacement model

Why ultrafiltration alone is not enough — the role of the active carbon biofilter
Ultrafiltration is highly effective at removing bacteria, viruses, and suspended particles from pool water. However, it has one fundamental limitation: its membranes work by physical size exclusion, and the pores are far too large to capture dissolved molecules. Urea — the primary dissolved contaminant in sweat and urine — is a small molecule (~0.4 nm) that passes straight through a UF membrane unimpeded.

This matters particularly in a geothermal pool at 38°C. At that temperature, the water is warmer than the human body’s cooling threshold, meaning that bathers sweat continuously and passively, even while sitting still. Research has measured sweat secretion of over 500 ml per person per hour during passive immersion at this temperature. Urea accumulates in the water with every bather, every session, every day — and UF does nothing to stop it.

To address this, Hugarró’s filtration system includes a biological active carbon filter. Granular activated carbon (GAC) offers an extraordinarily large internal surface area — hundreds of square metres per gram — on which both physical adsorption and biological degradation take place simultaneously:

• Adsorption: urea and other dissolved organic compounds bind chemically to the carbon surface and are removed from the water
• Biodegradation: beneficial micro-organisms colonise the carbon medium and break down the adsorbed organic matter into harmless compounds

This dual mechanism makes active carbon significantly more effective than alternative biological media such as MBBR carriers (moving bed biofilm reactors), which rely on biological action alone and offer no adsorption capacity. In a chemical-free system with clean fill water, active carbon can dedicate its full adsorption capacity exclusively to the dissolved substances introduced by bathers — making it the ideal complement to ultrafiltration.

Together, UF and the active carbon biofilter cover what neither can achieve alone: UF handles pathogens and particles; the biofilter handles dissolved organics. The result is pool water that is clean in every meaningful sense of the word.

Does Hugarró have any water replacement at all?

Yes — a small amount. Natural evaporation from the pool surface means that water is slowly lost and must be topped up. This amounts to less than 10% of pool volume per day — a fraction of the 30–40% daily replacement that is standard practice at comparable Icelandic geothermal pools. This replacement water is part of the natural water cycle, not a deliberate “flush-and-refill” approach.and-refill” approach.

How does Hugarró monitor water quality — and how does this compare to the law?
The law requires a minimum of 10 water quality checks per year for Class 1 facilities — roughly once per month. At Hugarró, we check every pool every 2 hours, using continuous real-time monitoring technology. This means:

Any exceedance of our internal quality thresholds triggers an automated filtration response. Our systems are designed to restore water to within safe parameters within one hour — even under peak load. In fact, the moment bacterial quality moves from the ‘green’ to the ‘yellow’ zone, we increase filtration on the pool in question to prevent it from ever reaching the ‘red’ zone.

Moreover, our system can be remotely monitored via online dashboards by the health authorities — providing real-time oversight rather than after-the-fact sampling during a site visit.

Other measures to assure water quality
An important part of our quality control system is pool design. By creating overflow around all pool edges, the formation of a bacterial biofilm on the water surface is minimised. Pool surfaces are smoother than standard concrete pool surfaces, which greatly reduces the build-up of deposits that are a breeding ground for bacterial growth, and allows easy cleaning.

Water flow through the pools — comprising evaporation replacement water as well as heated water inflow — is carefully engineered to avoid stagnant areas, which can lead to bacterial development. This is the principle behind the ‘islands’ in our pools: filtered water enters via the bottom of the pool and rises upward, flowing over the edges and carrying any contamination with it. This creates a continuously circulating cycle, carefully monitored by automation.

Are there any rules in Iceland that prohibit ultrafiltration?
No. Regulation 460/2015 contains no prohibition on ultrafiltration. The regulation is outcome-based — it sets bacterial limits and requires that a documented internal control system is in place. It does not prescribe which technology must be used to achieve those limits.

The regulation does describe the standard model for recreation pools as relying on “frequent water renewal and bather number control” — which is how the traditional approach is framed. However, since the law is outcome-focused, an alternative method that demonstrably achieves the same (or better) bacteriological outcomes is legally defensible.

Hugarró engages proactively with the local Health Committee to ensure our approach is fully documented, understood, and approved as part of our operating licence conditions. This regulatory dialogue will be an ongoing part of our operations and we hope to set an example for bacterial water control in Iceland.

What does the local Health Committee inspect?
The local Health Committee (heilbrigðisnefnd) holds broad powers under Regulation 460/2015 and the underlying Public Health Act No. 7/1998:

• Unrestricted access for inspections and water sampling at any time
• Power to issue public warnings and erect warning signs if bacterial limits are repeatedly exceeded
• Power to cap the number of bathers in a recreation pool
• Power to order additional sampling beyond the minimum (at the operator’s cost)
• Power to authorise or order disinfection — only by radiation or other non-chemical means — if quality standards are repeatedly not met

All of Hugarró’s water quality results — as required — are forwarded to the Environment Agency of Iceland (Umhverfisstofnun), where they are published publicly. We are confident in our results and welcome public transparency.

The bottom line
Hugarró operates at the intersection of Icelandic bathing culture, environmental responsibility, and evidence-based water science. We comply fully with Regulation No. 460/2015 as a Class 1 Recreation Pool — and go significantly further in every measurable dimension of water safety, resource efficiency, and monitoring rigour.

Our approach is not a workaround. It is what responsible geothermal bathing looks like when engineering and science are applied seriously to an age-old challenge

Click to enlarge

 

Íslenskar reglugerðir um böðun í náttúrunni

 

Flokkar: Spurningar stjórnar Umhverfi Jarðhiti Jarðböð

og hvernig Hugarró fer langt fram úr þeim
Hvað gerir íslenskar jarðhitalaugar einstakar — og hvað þarf til að halda þeim öruggum, sjálfbærum og náttúrulegum á sama tíma?

 

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Hvað gerir íslenskar jarðhitalaugar svona sérstakar?
Íslenskar jarðhitalaugar eru afurð einstakrar jarðfræði landsins. Vatni sem hitnar djúpt í jörðu er blandað við kalt vatn til að ná 36–42°C hita — fullkomið til að láta fara vel um sig, en jafnframt hlýtt og næringarríkt umhverfi þar sem bakteríur geta fjölgað sér hratt. Ólíkt sjávarströndum eða köldum ferskvatnsstöðum þarf hlý laug með tugum gesta virka stjórnun á vatnsgæðum.

Í flestum löndum heims er þetta leyst með klór og öðrum sótthreinsiefnum. Á Íslandi eru kemísk efni beinlínis bönnuð á náttúrulegum baðstöðum samkvæmt Reglugerð nr. 460/2015 (Reglugerð um baðstaði í náttúrunni). Það er það sem gerir íslenska baðmenningu sannarlega frábrugðna — og gerir verkfræðilegu áskorunina svo áhugaverða.

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Hvað krefjast íslensk lög í staðinn?
Hefðbundna lausnin sem notuð er um allt Ísland er einföld og áhrifarík, en jafnframt mjög auðlindafrek: skipta út 30–40% af heildarvatnsmagni laugarinnar á hverjum einasta degi. Fersku köldu vatni og heitu jarðhitavatni er stöðugt blandað saman og „gamla“ vatninu skolað út — milljónir lítra af hituðu vatni renna daglega í frárennslisskurði.

Viðeigandi lög, Reglugerð nr. 460/2015, flokka náttúruleg baðsvæði og setja mörk fyrir gerlafjölda (t.d. E. coli < 500/100 ml; Enterokokkar < 200/100 ml fyrir flokk 1). Reglugerðin krefst:

• Að lágmarki 10 vatnssýni á ári fyrir mannvirki í flokki 1 (eins og okkar)
• Innra eftirlitskerfi með áhættumati, atvikaskráningu og þjálfun starfsfólks
• Skráð neyðar- og viðbragðsáætlun
• Strangt eftirlit með fjölda baðgesta
• Skyldubundnar merkingar, búningsklefar, sturtur og skyndihjálp á staðnum

Reglugerðin er árangursmiðuð, ekki tækniforskrift — sem þýðir að hún setur fram þá niðurstöðu sem þarf að ná, en ekki hvaða aðferð þarf að nota. Þetta er reglugerðaropnunin sem verkfræðileg nálgun Hugarró byggir á.

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Undir hvaða flokk fellur Hugarró?
Hugarró er flokkað sem Afþreyingarlaug (Afþreyingarlaug) — Flokkur 1 — samkvæmt reglugerð 460/2015. Þetta er hæsta stig eftirlits og á við um mannvirki sem starfrækt eru reglulega og allt árið um kring. Það krefst fulls starfsleyfis frá heilbrigðisnefnd sveitarfélagsins, yfirgripsmikils innra eftirlits og stöðugrar fylgni við gæðastaðla fyrir gerla.starfsleyfistarfsleyfi

Við fögnum þessu eftirliti. Kerfin okkar eru hönnuð til að fara langt fram úr kröfur í flokki 1 ríflega, en ekki bara uppfylla þær.

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Af hverju eru engin kemísk efni notuð — og af hverju er það í raun í lagi?
Efni eins og klór drepa bakteríur á áhrifaríkan hátt, en þeim fylgir alvarlegur galli: þau hvarfast við lífræn efni sem berast með sundgestum (svita, húðfrumum, þvagi) og mynda aukaafurðir sótthreinsunar (DBP) — efnasambönd sem geta sjálf verið skaðleg og bera ábyrgð á hinni dæmigerðu „sundlaugalykt“ sem flestir tengja við almenningslaugar innanhúss. Á Íslandi banna lög þessi efni einfaldlega í náttúrulegum baðstöðum.

Góðu fréttirnar eru þær að rannsóknir hafa sýnt að kemísk efni eru í raun óþörf ef stjórnað er upptökum mengunar og vatnið meðhöndlað á áhrifaríkan hátt með eðlisfræðilegum aðferðum.

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Hvað segja vísindin? Keuten/Delft rannsóknin
Rannsakandinn M.C. Keuten við Tækniháskólann í Delft birti tímamótarannsókn á bakteríumengun í sundlaugum og hvernig megi draga úr henni — *Alternative Pool Water Treatment and the Influence of Swimmers on Water Quality*.

Í rannsókninni var notaður sérútbúinn sturtuklefi til að mæla nákvæmlega þau mengunarefni sem losna frá sundgestum fyrir og á meðan þeir synda. Helstu niðurstöður eru sláandi:

Upptök bakteríu- og mengunarálags	Hlutfall af heild
Svitamyndun í kafi á meðan sundi	~40%
Að fara ekki í sturtu áður en farið er í laugina	~30%
Að nota ekki salernið áður en farið er í laugina	~30%

Þetta þýðir að hægt er að stjórna allt að 60% af bakteríumagni sem berst í laug beint með hegðun gesta — áður en nokkur síunar- eða hreinsitækni er yfirhöfuð nauðsynleg. Þetta er eitthvað sem Íslendingar þekkja vel, og þess vegna ríkir hér á landi mjög ströng menning varðandi sturtuferðir fyrir sund.

Keuten sýndi einnig fram á að UV-sótthreinsun ásamt ofursíun (ultrafiltration) — án nokkurra íðefna — getur náð fram örverufræðilegum vatnsgæðum sem eru sambærileg við klóraðar laugar. Líffræðileg síun bætti enn frekar fjarlægingu uppleystra efna eins og þvagefnis, sem dregur úr myndun óæskilegra aukaafurða.

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Hvað gerir Hugarró til að draga úr bakteríumagni við upptökin?
Byggt beint á rannsóknum Keuten, hefur Hugarró hannað tveggja þrepa aðgangsferli sem studd er af tækni, ekki bara skiltum:

1. Skyldubundin sturta fyrir sund — Aðstaða okkar notar skynjaratækni sem hvetur gesti og staðfestir að lágmarki 1,5 mínútna sturtuferð áður en opnað er fyrir aðgang. Þetta eitt og sér eyðir um það bil 30% af því bakteríumagni sem annars myndi berast í laugina. Sýnilegur tímamælir sýnir gestinum hversu mikill tími er eftir.
2. Salernismenning í fyrirrúmi — Skýrar ábendingar, hönnun aðstöðunnar og samskipti starfsfólks hvetja gesti til að nota salernið fyrir sundferðina — sem beinist að þeim 30% af forðanlegu bakteríumagni sem eftir standa.

Í okkar 7 laugum, er ströngum takmörkunum á fjölda gesta fylgt eftir í rauntíma, bæði til að uppfylla reglugerðarkröfur um aðgangsstýringu og til að tryggja að síunarkerfið verði aldrei ofhlaðið.

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Hvernig stýrir Hugarró vatnsgæðum án íðefna og án gífurlegrar vatnssóunar?
Í stað þess að skola stöðugt út miklu magni af vatni, eru laugar Hugarró búnar samfelldri ofursíun — eðlisfræðilegu ferli byggðu á himnum sem fjarlægir bakteríur, agnir og örverur úr laugavatninu í lokaðri hringrás. Þessu er fylgt eftir með stöðugri vöktun á vatnsgæðum með kerfum eins og þeim sem þróuð eru af bNovate, sem gerir kleift að mæla bakteríufjölda nánast í rauntíma.

Niðurstaðan:

• • Yfir 90% vatnssparnaður miðað við hefðbundna líkanið þar sem vatni er skipt út daglega eins og annars staðar á Íslandi
  • Yfir 30% orkusparnaður í upphitun, þar sem hita þarf mun minna af köldu ferskvatni
  • Laugavatn sem hægt er að hreinsa upp að öruggum gerlamörkum innan klukkustundar ef þörf krefur — samanborið við þá marga daga sem það tæki með einfaldri útskiptingu vatns

Af hverju ofursíun ein og sér dugar ekki — hlutverk lífvirkrar kolsíu
Ofursíun er mjög áhrifarík við að fjarlægja bakteríur, vírusa og svifagnir úr sundlaugarvatni. Hún hefur þó eina grundvallartakmörkun: himnurnar virka með eðlisfræðilegri stærðarsíun og svitaholurnar eru allt of stórar til að fanga uppleystar sameindir.Þvagefni — helsta uppleysta mengunarefnið í svita og þvagi — er lítil sameind (~0,4 nm) sem fer óhindrað beint í gegnum ofursíunarhimnu.

Þetta skiptir sérstaklega miklu máli í jarðhitalaug sem er 38°C heit. Við það hitastig er vatnið heitara en kæliþröskuldur mannslíkamans, sem þýðir að baðgestir svitna stöðugt og ómeðvitað, jafnvel þótt þeir sitji kyrrir. Rannsóknir hafa mælt svitamyndun yfir 500 ml á mann á klukkustund við óvirka dvöl í vatni við þetta hitastig. Þvagefni safnast upp í vatninu með hverjum gesti, hverri baðferð, á hverjum degi — og ofursíun gerir ekkert til að stöðva það.

Til að bregðast við þessu inniheldur síunarkerfi Hugarró lífvirka kolsíu. Virkt kornakol (GAC) býður upp á óvenju stórt innra yfirborð — mörg hundruð fermetra á hvert gramm — þar sem bæði eðlisfræðileg ásog og líffræðileg niðurbrot eiga sér stað samtímis:

• Ásog: þvagefni og önnur uppleyst lífræn efnasambönd bindast efnafræðilega við yfirborð kolsins og eru fjarlægð úr vatninu
• Líffræðilegt niðurbrot: gagnlegar örverur setjast að í kolefninu og brjóta niður ásoguð lífræn efni í skaðlaus efnasambönd

Þetta tvíþætta ferli gerir virkt kol mun skilvirkara en önnur líffræðileg síuefni eins og MBBR-berar (skolpsíur með hreyfanlegu undirlagi), sem treysta eingöngu á líffræðilega virkni og hafa enga ásogsgetu. Í efnalausu kerfi með hreinu fyllivatni getur virka kolið nýtt alla ásogsgetu sína eingöngu fyrir þau uppleystu efni sem berast með baðgestum — sem gerir það að fullkominni viðbót við ofursíun.

Saman ná UF og virka kolefnis-lífsían því sem hvorugt getur áorkað eitt og sér: UF sér um sýkla og agnir; lífsían sér um uppleyst lífræn efni. Niðurstaðan er sundlaugarvatn sem er hreint í fyllsta skilningi þess orðs.

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Er einhver vatnsskipti yfirhöfuð hjá Hugarró?

Já — lítið magn. Náttúruleg uppgufun af yfirborði laugarinnar þýðir að vatn tapast hægt og rólega og þarf að fylla á hana. Þetta nemur minna en 10% af rúmmáli laugarinnar á dag — broti af þeim 30–40% daglegu vatnsskiptum sem eru venjubundin í sambærilegum íslenskum jarðhitalaugum. Þetta áfyllingarvatn er hluti af náttúrulegri hringrás vatnsins, ekki meðvituð „tæma-og-fylla“ nálgun.

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Hvernig vaktar Hugarró vatnsgæði — og hvernig er það í samanburði við lög?
Lögin krefjast að lágmarki 10 mælingar á vatnsgæðum á ári fyrir flokk 1 — u.þ.b. einu sinni í mánuði. Hjá Hugarró athugum við hverja laug á 2 klukkustunda fresti, með því að nota tækni sem vaktar vatnið stöðugt í rauntíma. Þetta þýðir:

Mælistærð	Lagalegt lágmark (Flokkur 1)	Hugarró staðall
Tíðni sýnatöku á vatnsgæðum	10× á ári (~mánaðarlega)	Á 2 klukkustunda fresti
Viðbragðstími við frávikum	Dagar (bið eftir rannsóknarstofu)	Innan 1 klukkustundar (sjálfvirkt viðbragð síunarkerfis)
Eftirlit með fjölda gesta	Skylt, aðferð ekki tilgreind	Rauntíma eftirlit með skynjurum í hverri laug

Öll frávik frá okkar innri gæðaviðmiðum ræsa sjálfvirkt viðbragð í síunarkerfinu. Kerfin okkar eru hönnuð til að koma vatninu aftur innan öruggra marka innan klukkustundar — jafnvel við hámarksálag. Í raun, um leið og bakteríugæði færast úr „græna“ svæðinu yfir í það „gula“, aukum við síun í viðkomandi laug til að koma í veg fyrir að hún nái nokkurn tímann í „rauða“ svæðið.

Auk þess geta heilbrigðisyfirvöld fylgst með kerfinu okkar í gegnum mælaborð á netinu — sem veitir rauntímaeftirlit í stað sýnatöku eftir á við vettvangsheimsókn.

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Aðrar ráðstafanir til að tryggja vatnsgæði
Mikilvægur hluti af gæðaeftirlitskerfi okkar er hönnun lauganna. Með því að hafa yfirfall meðfram öllum laugarköntum er myndun örveruskánar á yfirborði vatnsins lágmörkuð. Yfirborð lauganna er sléttara en á hefðbundnum steyptum laugum, sem dregur verulega úr útfellingum sem eru gróðrarstía fyrir bakteríuvöxt og auðveldar þrif.

Vatnsrennsli í gegnum laugarnar — sem samanstendur af vatni til að mæta uppgufun ásamt innrennsli á heitu vatni — er vandlega hannað til að forðast kyrrstöðusvæði þar sem bakteríur geta þrifist. Þetta er meginreglan á bak við „eyjarnar“ í laugunum okkar: síað vatn kemur inn um botn laugarinnar og stígur upp, flæðir yfir kanta og ber með sér hvers kyns óhreinindi. Þetta skapar stöðuga hringrás sem er vandlega vöktuð með sjálfvirkni.

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Eru einhverjar reglur á Íslandi sem banna ofursíun?
Nei. Reglugerð 460/2015 inniheldur ekkert bann við ofursíun. Reglugerðin er árangursmiðuð — hún setur mörk fyrir gerlafjölda og krefst þess að skjalfest innra eftirlitskerfi sé til staðar. Hún kveður ekki á um hvaða tækni skuli nota til að ná þeim mörkum.

Reglugerðin lýsir staðallíkani fyrir baðstaði sem byggir á „tíðri endurnýjun vatns og takmörkun á fjölda baðgesta“ — sem er hefðbundna nálgunin. Hins vegar, þar sem lögin einblína á niðurstöður, er önnur aðferð sem sýnanlega nær sömu (eða betri) niðurstöðum varðandi gerlafjölda lagalega verjanleg.

Hugarró á í virku samstarfi við Heilbrigðisnefnd til að tryggja að nálgun okkar sé fyllilega skjalfest, skilin og samþykkt sem hluti af starfsleyfisskilyrðum okkar. Þetta samtal við eftirlitsaðila verður áframhaldandi hluti af starfsemi okkar og við vonumst til að vera fyrirmynd í bakteríustjórnun vatns á Íslandi.

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Hvað skoðar heilbrigðisnefndin?
Heilbrigðisnefnd (heilbrigðisnefnd) hefur víðtækar heimildir samkvæmt reglugerð nr. 460/2015 og undirliggjandi lögum um hollustuhætti og mengunarvarnir nr. 7/1998:

• Ótakmarkaður aðgangur vegna eftirlits og sýnatöku hvenær sem er
• Heimild til að gefa út opinberar viðvaranir og setja upp viðvörunarskilti ef gerlamörk eru ítrekað yfir mörkum
• Heimild til að takmarka fjölda baðgesta á baðstað
• Heimild til að fyrirskipa aukna sýnatöku umfram lágmark (á kostnað rekstraraðila)
• Heimild til að heimila eða fyrirskipa sótthreinsun — eingöngu með geislun eða öðrum aðferðum án íblöndunarefna — ef gæðakröfur eru ítrekað ekki uppfylltar

Öllum niðurstöðum úr mælingum á vatnsgæðum Hugarró er — eins og krafist er — miðlað til Umhverfisstofnun (Umhverfisstofnun), þar sem þær eru birtar opinberlega. Við treystum okkar niðurstöðum og fögnum gagnsæi gagnvart almenningi.

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Kjarni málsins
Hugarró starfar á mótum íslenskrar baðmenningar, umhverfisábyrgðar og gagnreyndra vatnsvísinda. Við fylgjum reglugerð nr. 460/2015 að fullu sem flokkur 1 fyrir afþreyingarlaugar — og göngum mun lengra á öllum mælanlegum sviðum vatnsöryggis, auðlindanýtingar og eftirlits.

Nálgun okkar er ekki undanleið. Svona lítur ábyrg jarðhitabaðmenning út þegar verkfræði og vísindum er beitt af alvöru við forna áskorun

Birt þann 1. september 2026

Vacation home district heating — Iceland

Prepared: September 2026 | Confidential — For Discussion Purposes

Executive Summary
Our geothermal project will generate significantly more thermal capacity than the primary development requires. We propose to monetise this surplus by supplying hot water to a neighbouring planned vacation home community of 50 homes across two clusters. The developer of that community has indicated willingness to co-invest in the distribution infrastructure, which materially de-risks the project and compresses the payback period to approximately 10–11 years on a shared CAPEX basis — well within the operational lifespan of the asset (30–40 years).

This is a low-marginal-cost, recurring revenue stream built on zero-cost fuel.

Project overview

Capital expenditure

Build is phased: Phase 1 (Cluster A, ~€801k) triggers on Cluster A construction start; Phase 2 (Cluster B) triggers on Cluster B confirmation. No idle capital.

Revenue & Financial Projection

Why the developer co-invests
The developer’s motivation is straightforward. In Iceland, geothermal hot water access is a market baseline expectation — lots without it sell at a meaningful discount. Based on regional comparables, reliable hot water supply adds an estimated €15,000–€25,000 per lot in realised sale value. Across 50 lots, that represents a €750k–€1.25M uplift in gross development value — making a €800k infrastructure contribution not just reasonable, but commercially rational. We are effectively subsidising their product quality.

This alignment of interests is a structural strength of the deal.

Key strengths

• Zero fuel cost. The heat is a by-product of our existing geothermal investment. Marginal cost of production is effectively nil.
• Recurring, inflation-linked income. Subscription tariffs are typically indexed to energy price benchmarks. Utility revenues are sticky and predictable.
• Captive customer base. Once connected, switching costs are prohibitive. Customer churn is essentially zero.
• Developer co-investment halves our exposure and signals strong demand validation before a single pipe is laid.
• Phased build eliminates idle capital risk. Phase 2 is only committed when Cluster B development is confirmed.
• Enhances our own project’s social licence. Community benefit strengthens planning relationships and long-term operating position.
• Gateway asset. Once operational, additional projects in the area will find our infrastructure already in place, with extension economics improving per additional customer.

Risks & mitigants

Strategic upside (not in base case)
10 existing vacation homes in the wider area were judged too dispersed and few to connect at present. As our network grows and additional developments emerge, incremental connections become progressively cheaper per home.

• Future developments attracted by proven geothermal infrastructure can be connected on similar commercial terms — each new customer improves the network economics for all parties.
• Carbon credit potential. Displacing oil or electric boiler heating with geothermal may qualify under relevant Icelandic or European carbon mechanisms — upside not yet quantified.

Summary verdict
This is a long-duration, low-risk infrastructure asset generating clean recurring income from a zero-cost fuel source, with a co-investing partner whose financial interests are directly aligned with ours. The 10.6-year payback on net invested capital is conservative — and from year 11, the revenue stream runs largely unconstrained for a further 20–30 years.

The primary negotiation priority is the mandatory connection covenant in the developer’s lot sale contracts. That single clause converts a projected revenue stream into a contractual one — and that is the difference between a good investment and an excellent one.

This document is prepared for discussion purposes only and does not constitute a formal investment prospectus. All figures are estimates based on comparable Icelandic district heating projects and are subject to detailed engineering and commercial due diligence.

and how Hugarró goes far beyond them
What makes geothermal pools in Iceland unique — and what does it take to keep them safe, sustainable, and natural at the same time?

  translation below

What makes Icelandic geothermal pools so special?
Iceland’s geothermal pools are a product of the country’s unique geology. Water heated deep underground is mixed with cold water to set temperatures between 36–42°C — perfect for soaking, but also a warm, nutrient-rich environment in which bacteria can multiply quickly. Unlike outdoor seawater beaches or cold freshwater lakes, a warm pool with dozens of bathers needs active water quality management.

In most countries around the world, this is solved with chlorine and other chemical disinfectants. In Iceland, chemicals are explicitly prohibited in natural bathing facilities under Regulation No. 460/2015 (Reglugerð um baðstaði í náttúrunni). That is what makes Icelandic geothermal bathing culture genuinely different — and what makes the engineering challenge so interesting.

What does Icelandic law require instead?
The traditional solution used across Iceland is straightforward and effective, but also very resource-intensive: replace 30–40% of the pool’s total water volume every single day. Fresh cold water and geothermal hot water are continuously mixed in and the “old” water is flushed out — millions of litres of heated water discharged daily into drainage ditches.

The relevant law, Regulation No. 460/2015, classifies natural bathing facilities and sets bacterial count limits (e.g. E. coli < 500/100 ml; Enterococci < 200/100 ml for Class 1 facilities). The regulation requires:

• A minimum of 10 water samples per year for Class 1 facilities (like ours)
• An internal control system with risk assessments, incident logs, and staff training
• A documented emergency and contingency plan
• Strict bather number controls
• Mandatory signage, changing rooms, showers, and first aid on site

The regulation is outcome-based, not technology-prescriptive — meaning it sets the results you must achieve, not the method you must use. This is the regulatory opening that Hugarró’s engineering approach is built on.

What category does Hugarró fall under?
Hugarró is classified as a Recreation Pool (Afþreyingarlaug) — Class 1 — under Regulation 460/2015. This is the highest level of oversight, applying to facilities that operate regularly and year-round. It requires a full operating licence (starfsleyfi) from the local Health Committee, comprehensive internal controls, and continuous compliance with bacterial quality standards.

We welcome this level of scrutiny. Our systems are designed to far exceed Class 1 requirements, not merely meet them.

Why are chemicals not used — and why is that actually fine?
Chemicals such as chlorine kill bacteria effectively, but they have a serious downside: they react with organic matter introduced by bathers (sweat, skin cells, urine) to produce disinfection by-products (DBPs) — compounds that are themselves potentially harmful and are responsible for the characteristic “pool smell” most people associate with indoor public pools. In Iceland, the law simply prohibits them in natural bathing facilities.

The good news is that, as research has demonstrated, chemicals are not actually necessary if you control the source of contamination and treat the water effectively through physical methods.

What does the science say? The Keuten/Delft Study
Researcher M.C. Keuten at Delft University of Technology published a landmark study on bacterial pollution in swimming pools and how to reduce it — *Alternative Pool Water Treatment and the Influence of Swimmers on Water Quality*.

The study used a specially instrumented shower cabin to precisely measure the pollutants released by bathers before and during swimming. The key findings are striking:

This means that up to 60% of the bacterial input into a pool is directly controllable through bather behaviour — before any filtration or treatment technology is even needed. This is something Icelanders know well, which is why the country has a very strict pre-bath showering culture.

Keuten also demonstrated that UV disinfection combined with ultrafiltration — with no chemicals — can achieve microbial water quality comparable to chlorinated pools. Biological filtration further improved the removal of dissolved substances such as urea, reducing the formation of unwanted by-products.

What does Hugarró do to reduce bacterial input at the source?
Based directly on Keuten’s research, Hugarró has designed a two-step pre-entry protocol backed by technology, not just signage:

1. Mandatory pre-swim shower — Our facilities use sensor-based nudging technology that confirms a minimum 1.5 minutes of showering before entry is unlocked. This alone eliminates approximately 30% of the bacterial load that would otherwise enter the pool. A visible timer shows the bather how much time is left.
2. Toilet-first culture — Clear prompts, facility design, and staff communication encourage guests to use the toilet before bathing — targeting the remaining 30% of avoidable bacterial input.

Across our 7 pools, strict bather number limits are enforced in real time, both to comply with the regulatory requirement for access control and to ensure that the filtration system is never overwhelmed.

How does Hugarró manage water quality without chemicals and without massive water waste?
Instead of continuously flushing out large volumes of water, Hugarró’s pools are equipped with continuous ultrafiltration — a physical membrane-based process that removes bacteria, particles, and micro-organisms from pool water in a closed loop. This is combined with continuous water quality monitoring using systems such as those developed by bNovate, which allows near-real-time measurement of bacterial counts.

The result:

• • Water savings of over 90% compared to the traditional daily-replacement model used elsewhere in Iceland
  • Energy savings of over 30% in heating, as far less cold replacement water needs to be heated
  • Pool water that can be cycled to within safe bacteriological limits within one hour if needed — compared to the days it would take under a simple dilution/replacement model

Why ultrafiltration alone is not enough — the role of the active carbon biofilter
Ultrafiltration is highly effective at removing bacteria, viruses, and suspended particles from pool water. However, it has one fundamental limitation: its membranes work by physical size exclusion, and the pores are far too large to capture dissolved molecules. Urea — the primary dissolved contaminant in sweat and urine — is a small molecule (~0.4 nm) that passes straight through a UF membrane unimpeded.

This matters particularly in a geothermal pool at 38°C. At that temperature, the water is warmer than the human body’s cooling threshold, meaning that bathers sweat continuously and passively, even while sitting still. Research has measured sweat secretion of over 500 ml per person per hour during passive immersion at this temperature. Urea accumulates in the water with every bather, every session, every day — and UF does nothing to stop it.

To address this, Hugarró’s filtration system includes a biological active carbon filter. Granular activated carbon (GAC) offers an extraordinarily large internal surface area — hundreds of square metres per gram — on which both physical adsorption and biological degradation take place simultaneously:

• Adsorption: urea and other dissolved organic compounds bind chemically to the carbon surface and are removed from the water
• Biodegradation: beneficial micro-organisms colonise the carbon medium and break down the adsorbed organic matter into harmless compounds

This dual mechanism makes active carbon significantly more effective than alternative biological media such as MBBR carriers (moving bed biofilm reactors), which rely on biological action alone and offer no adsorption capacity. In a chemical-free system with clean fill water, active carbon can dedicate its full adsorption capacity exclusively to the dissolved substances introduced by bathers — making it the ideal complement to ultrafiltration.

Together, UF and the active carbon biofilter cover what neither can achieve alone: UF handles pathogens and particles; the biofilter handles dissolved organics. The result is pool water that is clean in every meaningful sense of the word.

Does Hugarró have any water replacement at all?

Yes — a small amount. Natural evaporation from the pool surface means that water is slowly lost and must be topped up. This amounts to less than 10% of pool volume per day — a fraction of the 30–40% daily replacement that is standard practice at comparable Icelandic geothermal pools. This replacement water is part of the natural water cycle, not a deliberate “flush-and-refill” approach.and-refill” approach.

How does Hugarró monitor water quality — and how does this compare to the law?
The law requires a minimum of 10 water quality checks per year for Class 1 facilities — roughly once per month. At Hugarró, we check every pool every 2 hours, using continuous real-time monitoring technology. This means:

Any exceedance of our internal quality thresholds triggers an automated filtration response. Our systems are designed to restore water to within safe parameters within one hour — even under peak load. In fact, the moment bacterial quality moves from the ‘green’ to the ‘yellow’ zone, we increase filtration on the pool in question to prevent it from ever reaching the ‘red’ zone.

Moreover, our system can be remotely monitored via online dashboards by the health authorities — providing real-time oversight rather than after-the-fact sampling during a site visit.

Other measures to assure water quality
An important part of our quality control system is pool design. By creating overflow around all pool edges, the formation of a bacterial biofilm on the water surface is minimised. Pool surfaces are smoother than standard concrete pool surfaces, which greatly reduces the build-up of deposits that are a breeding ground for bacterial growth, and allows easy cleaning.

Water flow through the pools — comprising evaporation replacement water as well as heated water inflow — is carefully engineered to avoid stagnant areas, which can lead to bacterial development. This is the principle behind the ‘islands’ in our pools: filtered water enters via the bottom of the pool and rises upward, flowing over the edges and carrying any contamination with it. This creates a continuously circulating cycle, carefully monitored by automation.

Are there any rules in Iceland that prohibit ultrafiltration?
No. Regulation 460/2015 contains no prohibition on ultrafiltration. The regulation is outcome-based — it sets bacterial limits and requires that a documented internal control system is in place. It does not prescribe which technology must be used to achieve those limits.

The regulation does describe the standard model for recreation pools as relying on “frequent water renewal and bather number control” — which is how the traditional approach is framed. However, since the law is outcome-focused, an alternative method that demonstrably achieves the same (or better) bacteriological outcomes is legally defensible.

Hugarró engages proactively with the local Health Committee to ensure our approach is fully documented, understood, and approved as part of our operating licence conditions. This regulatory dialogue will be an ongoing part of our operations and we hope to set an example for bacterial water control in Iceland.

What does the local Health Committee inspect?
The local Health Committee (heilbrigðisnefnd) holds broad powers under Regulation 460/2015 and the underlying Public Health Act No. 7/1998:

• Unrestricted access for inspections and water sampling at any time
• Power to issue public warnings and erect warning signs if bacterial limits are repeatedly exceeded
• Power to cap the number of bathers in a recreation pool
• Power to order additional sampling beyond the minimum (at the operator’s cost)
• Power to authorise or order disinfection — only by radiation or other non-chemical means — if quality standards are repeatedly not met

All of Hugarró’s water quality results — as required — are forwarded to the Environment Agency of Iceland (Umhverfisstofnun), where they are published publicly. We are confident in our results and welcome public transparency.

The bottom line
Hugarró operates at the intersection of Icelandic bathing culture, environmental responsibility, and evidence-based water science. We comply fully with Regulation No. 460/2015 as a Class 1 Recreation Pool — and go significantly further in every measurable dimension of water safety, resource efficiency, and monitoring rigour.

Our approach is not a workaround. It is what responsible geothermal bathing looks like when engineering and science are applied seriously to an age-old challenge

Click to enlarge

 

Íslenskar reglugerðir um böðun í náttúrunni

 

Flokkar: Spurningar stjórnar Umhverfi Jarðhiti Jarðböð

og hvernig Hugarró fer langt fram úr þeim
Hvað gerir íslenskar jarðhitalaugar einstakar — og hvað þarf til að halda þeim öruggum, sjálfbærum og náttúrulegum á sama tíma?

 

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Hvað gerir íslenskar jarðhitalaugar svona sérstakar?
Íslenskar jarðhitalaugar eru afurð einstakrar jarðfræði landsins. Vatni sem hitnar djúpt í jörðu er blandað við kalt vatn til að ná 36–42°C hita — fullkomið til að láta fara vel um sig, en jafnframt hlýtt og næringarríkt umhverfi þar sem bakteríur geta fjölgað sér hratt. Ólíkt sjávarströndum eða köldum ferskvatnsstöðum þarf hlý laug með tugum gesta virka stjórnun á vatnsgæðum.

Í flestum löndum heims er þetta leyst með klór og öðrum sótthreinsiefnum. Á Íslandi eru kemísk efni beinlínis bönnuð á náttúrulegum baðstöðum samkvæmt Reglugerð nr. 460/2015 (Reglugerð um baðstaði í náttúrunni). Það er það sem gerir íslenska baðmenningu sannarlega frábrugðna — og gerir verkfræðilegu áskorunina svo áhugaverða.

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Hvað krefjast íslensk lög í staðinn?
Hefðbundna lausnin sem notuð er um allt Ísland er einföld og áhrifarík, en jafnframt mjög auðlindafrek: skipta út 30–40% af heildarvatnsmagni laugarinnar á hverjum einasta degi. Fersku köldu vatni og heitu jarðhitavatni er stöðugt blandað saman og „gamla“ vatninu skolað út — milljónir lítra af hituðu vatni renna daglega í frárennslisskurði.

Viðeigandi lög, Reglugerð nr. 460/2015, flokka náttúruleg baðsvæði og setja mörk fyrir gerlafjölda (t.d. E. coli < 500/100 ml; Enterokokkar < 200/100 ml fyrir flokk 1). Reglugerðin krefst:

• Að lágmarki 10 vatnssýni á ári fyrir mannvirki í flokki 1 (eins og okkar)
• Innra eftirlitskerfi með áhættumati, atvikaskráningu og þjálfun starfsfólks
• Skráð neyðar- og viðbragðsáætlun
• Strangt eftirlit með fjölda baðgesta
• Skyldubundnar merkingar, búningsklefar, sturtur og skyndihjálp á staðnum

Reglugerðin er árangursmiðuð, ekki tækniforskrift — sem þýðir að hún setur fram þá niðurstöðu sem þarf að ná, en ekki hvaða aðferð þarf að nota. Þetta er reglugerðaropnunin sem verkfræðileg nálgun Hugarró byggir á.

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Undir hvaða flokk fellur Hugarró?
Hugarró er flokkað sem Afþreyingarlaug (Afþreyingarlaug) — Flokkur 1 — samkvæmt reglugerð 460/2015. Þetta er hæsta stig eftirlits og á við um mannvirki sem starfrækt eru reglulega og allt árið um kring. Það krefst fulls starfsleyfis frá heilbrigðisnefnd sveitarfélagsins, yfirgripsmikils innra eftirlits og stöðugrar fylgni við gæðastaðla fyrir gerla.starfsleyfistarfsleyfi

Við fögnum þessu eftirliti. Kerfin okkar eru hönnuð til að fara langt fram úr kröfur í flokki 1 ríflega, en ekki bara uppfylla þær.

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Af hverju eru engin kemísk efni notuð — og af hverju er það í raun í lagi?
Efni eins og klór drepa bakteríur á áhrifaríkan hátt, en þeim fylgir alvarlegur galli: þau hvarfast við lífræn efni sem berast með sundgestum (svita, húðfrumum, þvagi) og mynda aukaafurðir sótthreinsunar (DBP) — efnasambönd sem geta sjálf verið skaðleg og bera ábyrgð á hinni dæmigerðu „sundlaugalykt“ sem flestir tengja við almenningslaugar innanhúss. Á Íslandi banna lög þessi efni einfaldlega í náttúrulegum baðstöðum.

Góðu fréttirnar eru þær að rannsóknir hafa sýnt að kemísk efni eru í raun óþörf ef stjórnað er upptökum mengunar og vatnið meðhöndlað á áhrifaríkan hátt með eðlisfræðilegum aðferðum.

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Hvað segja vísindin? Keuten/Delft rannsóknin
Rannsakandinn M.C. Keuten við Tækniháskólann í Delft birti tímamótarannsókn á bakteríumengun í sundlaugum og hvernig megi draga úr henni — *Alternative Pool Water Treatment and the Influence of Swimmers on Water Quality*.

Í rannsókninni var notaður sérútbúinn sturtuklefi til að mæla nákvæmlega þau mengunarefni sem losna frá sundgestum fyrir og á meðan þeir synda. Helstu niðurstöður eru sláandi:

Upptök bakteríu- og mengunarálags	Hlutfall af heild
Svitamyndun í kafi á meðan sundi	~40%
Að fara ekki í sturtu áður en farið er í laugina	~30%
Að nota ekki salernið áður en farið er í laugina	~30%

Þetta þýðir að hægt er að stjórna allt að 60% af bakteríumagni sem berst í laug beint með hegðun gesta — áður en nokkur síunar- eða hreinsitækni er yfirhöfuð nauðsynleg. Þetta er eitthvað sem Íslendingar þekkja vel, og þess vegna ríkir hér á landi mjög ströng menning varðandi sturtuferðir fyrir sund.

Keuten sýndi einnig fram á að UV-sótthreinsun ásamt ofursíun (ultrafiltration) — án nokkurra íðefna — getur náð fram örverufræðilegum vatnsgæðum sem eru sambærileg við klóraðar laugar. Líffræðileg síun bætti enn frekar fjarlægingu uppleystra efna eins og þvagefnis, sem dregur úr myndun óæskilegra aukaafurða.

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Hvað gerir Hugarró til að draga úr bakteríumagni við upptökin?
Byggt beint á rannsóknum Keuten, hefur Hugarró hannað tveggja þrepa aðgangsferli sem studd er af tækni, ekki bara skiltum:

1. Skyldubundin sturta fyrir sund — Aðstaða okkar notar skynjaratækni sem hvetur gesti og staðfestir að lágmarki 1,5 mínútna sturtuferð áður en opnað er fyrir aðgang. Þetta eitt og sér eyðir um það bil 30% af því bakteríumagni sem annars myndi berast í laugina. Sýnilegur tímamælir sýnir gestinum hversu mikill tími er eftir.
2. Salernismenning í fyrirrúmi — Skýrar ábendingar, hönnun aðstöðunnar og samskipti starfsfólks hvetja gesti til að nota salernið fyrir sundferðina — sem beinist að þeim 30% af forðanlegu bakteríumagni sem eftir standa.

Í okkar 7 laugum, er ströngum takmörkunum á fjölda gesta fylgt eftir í rauntíma, bæði til að uppfylla reglugerðarkröfur um aðgangsstýringu og til að tryggja að síunarkerfið verði aldrei ofhlaðið.

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Hvernig stýrir Hugarró vatnsgæðum án íðefna og án gífurlegrar vatnssóunar?
Í stað þess að skola stöðugt út miklu magni af vatni, eru laugar Hugarró búnar samfelldri ofursíun — eðlisfræðilegu ferli byggðu á himnum sem fjarlægir bakteríur, agnir og örverur úr laugavatninu í lokaðri hringrás. Þessu er fylgt eftir með stöðugri vöktun á vatnsgæðum með kerfum eins og þeim sem þróuð eru af bNovate, sem gerir kleift að mæla bakteríufjölda nánast í rauntíma.

Niðurstaðan:

• • Yfir 90% vatnssparnaður miðað við hefðbundna líkanið þar sem vatni er skipt út daglega eins og annars staðar á Íslandi
  • Yfir 30% orkusparnaður í upphitun, þar sem hita þarf mun minna af köldu ferskvatni
  • Laugavatn sem hægt er að hreinsa upp að öruggum gerlamörkum innan klukkustundar ef þörf krefur — samanborið við þá marga daga sem það tæki með einfaldri útskiptingu vatns

Af hverju ofursíun ein og sér dugar ekki — hlutverk lífvirkrar kolsíu
Ofursíun er mjög áhrifarík við að fjarlægja bakteríur, vírusa og svifagnir úr sundlaugarvatni. Hún hefur þó eina grundvallartakmörkun: himnurnar virka með eðlisfræðilegri stærðarsíun og svitaholurnar eru allt of stórar til að fanga uppleystar sameindir.Þvagefni — helsta uppleysta mengunarefnið í svita og þvagi — er lítil sameind (~0,4 nm) sem fer óhindrað beint í gegnum ofursíunarhimnu.

Þetta skiptir sérstaklega miklu máli í jarðhitalaug sem er 38°C heit. Við það hitastig er vatnið heitara en kæliþröskuldur mannslíkamans, sem þýðir að baðgestir svitna stöðugt og ómeðvitað, jafnvel þótt þeir sitji kyrrir. Rannsóknir hafa mælt svitamyndun yfir 500 ml á mann á klukkustund við óvirka dvöl í vatni við þetta hitastig. Þvagefni safnast upp í vatninu með hverjum gesti, hverri baðferð, á hverjum degi — og ofursíun gerir ekkert til að stöðva það.

Til að bregðast við þessu inniheldur síunarkerfi Hugarró lífvirka kolsíu. Virkt kornakol (GAC) býður upp á óvenju stórt innra yfirborð — mörg hundruð fermetra á hvert gramm — þar sem bæði eðlisfræðileg ásog og líffræðileg niðurbrot eiga sér stað samtímis:

• Ásog: þvagefni og önnur uppleyst lífræn efnasambönd bindast efnafræðilega við yfirborð kolsins og eru fjarlægð úr vatninu
• Líffræðilegt niðurbrot: gagnlegar örverur setjast að í kolefninu og brjóta niður ásoguð lífræn efni í skaðlaus efnasambönd

Þetta tvíþætta ferli gerir virkt kol mun skilvirkara en önnur líffræðileg síuefni eins og MBBR-berar (skolpsíur með hreyfanlegu undirlagi), sem treysta eingöngu á líffræðilega virkni og hafa enga ásogsgetu. Í efnalausu kerfi með hreinu fyllivatni getur virka kolið nýtt alla ásogsgetu sína eingöngu fyrir þau uppleystu efni sem berast með baðgestum — sem gerir það að fullkominni viðbót við ofursíun.

Saman ná UF og virka kolefnis-lífsían því sem hvorugt getur áorkað eitt og sér: UF sér um sýkla og agnir; lífsían sér um uppleyst lífræn efni. Niðurstaðan er sundlaugarvatn sem er hreint í fyllsta skilningi þess orðs.

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Er einhver vatnsskipti yfirhöfuð hjá Hugarró?

Já — lítið magn. Náttúruleg uppgufun af yfirborði laugarinnar þýðir að vatn tapast hægt og rólega og þarf að fylla á hana. Þetta nemur minna en 10% af rúmmáli laugarinnar á dag — broti af þeim 30–40% daglegu vatnsskiptum sem eru venjubundin í sambærilegum íslenskum jarðhitalaugum. Þetta áfyllingarvatn er hluti af náttúrulegri hringrás vatnsins, ekki meðvituð „tæma-og-fylla“ nálgun.

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Hvernig vaktar Hugarró vatnsgæði — og hvernig er það í samanburði við lög?
Lögin krefjast að lágmarki 10 mælingar á vatnsgæðum á ári fyrir flokk 1 — u.þ.b. einu sinni í mánuði. Hjá Hugarró athugum við hverja laug á 2 klukkustunda fresti, með því að nota tækni sem vaktar vatnið stöðugt í rauntíma. Þetta þýðir:

Mælistærð	Lagalegt lágmark (Flokkur 1)	Hugarró staðall
Tíðni sýnatöku á vatnsgæðum	10× á ári (~mánaðarlega)	Á 2 klukkustunda fresti
Viðbragðstími við frávikum	Dagar (bið eftir rannsóknarstofu)	Innan 1 klukkustundar (sjálfvirkt viðbragð síunarkerfis)
Eftirlit með fjölda gesta	Skylt, aðferð ekki tilgreind	Rauntíma eftirlit með skynjurum í hverri laug

Öll frávik frá okkar innri gæðaviðmiðum ræsa sjálfvirkt viðbragð í síunarkerfinu. Kerfin okkar eru hönnuð til að koma vatninu aftur innan öruggra marka innan klukkustundar — jafnvel við hámarksálag. Í raun, um leið og bakteríugæði færast úr „græna“ svæðinu yfir í það „gula“, aukum við síun í viðkomandi laug til að koma í veg fyrir að hún nái nokkurn tímann í „rauða“ svæðið.

Auk þess geta heilbrigðisyfirvöld fylgst með kerfinu okkar í gegnum mælaborð á netinu — sem veitir rauntímaeftirlit í stað sýnatöku eftir á við vettvangsheimsókn.

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Aðrar ráðstafanir til að tryggja vatnsgæði
Mikilvægur hluti af gæðaeftirlitskerfi okkar er hönnun lauganna. Með því að hafa yfirfall meðfram öllum laugarköntum er myndun örveruskánar á yfirborði vatnsins lágmörkuð. Yfirborð lauganna er sléttara en á hefðbundnum steyptum laugum, sem dregur verulega úr útfellingum sem eru gróðrarstía fyrir bakteríuvöxt og auðveldar þrif.

Vatnsrennsli í gegnum laugarnar — sem samanstendur af vatni til að mæta uppgufun ásamt innrennsli á heitu vatni — er vandlega hannað til að forðast kyrrstöðusvæði þar sem bakteríur geta þrifist. Þetta er meginreglan á bak við „eyjarnar“ í laugunum okkar: síað vatn kemur inn um botn laugarinnar og stígur upp, flæðir yfir kanta og ber með sér hvers kyns óhreinindi. Þetta skapar stöðuga hringrás sem er vandlega vöktuð með sjálfvirkni.

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Eru einhverjar reglur á Íslandi sem banna ofursíun?
Nei. Reglugerð 460/2015 inniheldur ekkert bann við ofursíun. Reglugerðin er árangursmiðuð — hún setur mörk fyrir gerlafjölda og krefst þess að skjalfest innra eftirlitskerfi sé til staðar. Hún kveður ekki á um hvaða tækni skuli nota til að ná þeim mörkum.

Reglugerðin lýsir staðallíkani fyrir baðstaði sem byggir á „tíðri endurnýjun vatns og takmörkun á fjölda baðgesta“ — sem er hefðbundna nálgunin. Hins vegar, þar sem lögin einblína á niðurstöður, er önnur aðferð sem sýnanlega nær sömu (eða betri) niðurstöðum varðandi gerlafjölda lagalega verjanleg.

Hugarró á í virku samstarfi við Heilbrigðisnefnd til að tryggja að nálgun okkar sé fyllilega skjalfest, skilin og samþykkt sem hluti af starfsleyfisskilyrðum okkar. Þetta samtal við eftirlitsaðila verður áframhaldandi hluti af starfsemi okkar og við vonumst til að vera fyrirmynd í bakteríustjórnun vatns á Íslandi.

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Hvað skoðar heilbrigðisnefndin?
Heilbrigðisnefnd (heilbrigðisnefnd) hefur víðtækar heimildir samkvæmt reglugerð nr. 460/2015 og undirliggjandi lögum um hollustuhætti og mengunarvarnir nr. 7/1998:

• Ótakmarkaður aðgangur vegna eftirlits og sýnatöku hvenær sem er
• Heimild til að gefa út opinberar viðvaranir og setja upp viðvörunarskilti ef gerlamörk eru ítrekað yfir mörkum
• Heimild til að takmarka fjölda baðgesta á baðstað
• Heimild til að fyrirskipa aukna sýnatöku umfram lágmark (á kostnað rekstraraðila)
• Heimild til að heimila eða fyrirskipa sótthreinsun — eingöngu með geislun eða öðrum aðferðum án íblöndunarefna — ef gæðakröfur eru ítrekað ekki uppfylltar

Öllum niðurstöðum úr mælingum á vatnsgæðum Hugarró er — eins og krafist er — miðlað til Umhverfisstofnun (Umhverfisstofnun), þar sem þær eru birtar opinberlega. Við treystum okkar niðurstöðum og fögnum gagnsæi gagnvart almenningi.

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Kjarni málsins
Hugarró starfar á mótum íslenskrar baðmenningar, umhverfisábyrgðar og gagnreyndra vatnsvísinda. Við fylgjum reglugerð nr. 460/2015 að fullu sem flokkur 1 fyrir afþreyingarlaugar — og göngum mun lengra á öllum mælanlegum sviðum vatnsöryggis, auðlindanýtingar og eftirlits.

Nálgun okkar er ekki undanleið. Svona lítur ábyrg jarðhitabaðmenning út þegar verkfræði og vísindum er beitt af alvöru við forna áskorun

Birt þann 1. september 2026

We planned for this from day one
Drilling for geothermal water in Iceland is well-founded — the geology around Hvalfjörður is exceptional and nearby wells prove the potential. But geothermal exploration always carries uncertainty. Fractures can be missed. A well can come up dry. Investors can lose patience.

We designed Hugarró so that this scenario, however unlikely (see this post), does not stop us.

Our answer is a purpose-built alternative heating system that delivers the same pools, the same warmth, the same experience — drawing heat not from the ground below, but from the river and the earth around us.

Why our heating needs are surprisingly modest
Most facilities of this kind would be in serious trouble without a geothermal source. Ours is not — because of how efficiently we use energy in the first place.

Our closed-loop pool system recirculates water rather than constantly replacing it, recovering 33% more heat than the traditional Icelandic approach. Our cascade design runs geothermal water through pools, then buildings, then roads — extracting every usable degree before returning it. Floating insulation covers eliminate heat loss overnight.

The result: our total heating demand — seven pools at 38°C, full hotel and cabin heating, road de-icing — requires the equivalent of just 1,185 kW of continuous thermal output. For a facility of this scale, that is a lean number. And it is exactly what our backup system is sized to deliver.

The alternative: CO₂ heat pumps

If no geothermal source is found, we install three Fenagy (or other reliable brand) H-600 CO₂ heat pump units, each delivering 600 kW of thermal output. Together they provide 1,800 kW of installed capacity — comfortably above our 1,185 kW peak demand, with full redundancy built in.

CO₂ (R744) is the ideal refrigerant for this application:

• GWP of 1 — the most climate-neutral refrigerant available
• No chemicals — fully aligned with Iceland’s environmental standards
• Highest efficiency in the 38–70°C output range — exactly our operating window
• Proven technology — widely used in Scandinavian district heating systems

The heat pumps run as water-to-water units, extracting heat from a local water source and delivering it at the temperatures our cascade system requires. The full cascade — pools, buildings, roads — operates identically to the geothermal design. From a guest perspective, nothing changes.

Where the heat comes from: a two-tier water source
Instead of one geothermal well, we use two complementary water sources that together provide year-round reliability.

Tier 1 — The Brunná river (primary, spring through autumn)
The Brunná flows just 200 metres from our plant room, crossing land whose owner has no objection to our intake (in fact, we are co-owner). A short insulated HDPE pipe draws water at ~6°C, passes it through a heat exchanger, and returns it a few degrees cooler. The river provides more than enough flow for our needs during the eight warmest months of the year.

Tier 2 — Two drilled groundwater wells (winter backup)
For the winter months, when surface water flow can drop and ice becomes a risk, we rely on two drilled wells at 80–150 metres depth. At that depth, groundwater in the Botnsdalur valley maintains a stable 4–6°C year-round — completely unaffected by surface weather, frost, or seasonal variation. No river. No tidal influence. No moving parts except a submersible pump in each well.

Crucially, these wells are drilled while the geothermal exploration rig is already on site — a modest incremental cost on an already-mobilised programme, and one that simultaneously provides valuable geological data to guide the deep geothermal drill.

The system switches automatically between sources based on flow sensors and temperature readings. No manual intervention required.

The buffer tank — smoothing out demand peaks
Between the heat pumps and the distribution system sits a 35 m3 insulated thermal buffer tank, maintained at 45–50°C. It acts as a reservoir of stored heat, absorbing demand peaks and allowing the heat pumps to run at steady, optimal load rather than cycling up and down.

The effect is meaningful: peak source water demand drops by around 20%, the heat pumps run more efficiently, and the system becomes more resilient to short interruptions in either water source. It is the thermal equivalent of a battery — simple, passive, and highly effective.

What it costs to run
Iceland’s electricity is among the cleanest and most affordable in Europe, generated almost entirely from hydro and geothermal sources. At current industrial tariffs:

For every unit of electricity the heat pumps consume, they deliver 3.8 units of heat — the rest comes free from the river or the wells. Compared to direct electric heating, the CO₂ heat pump system saves approximately €750,000 per year in energy costs.

How the two systems compare

The bottom line
Finding geothermal water is our ambition and our expectation. The geology strongly supports it. But if exploration falls short, Hugarró does not fall with it.

Our backup system — three CO₂ heat pumps, two groundwater wells, a river intake, and a thermal buffer — delivers the same warmth, the same pools, and the same guest experience at a known, manageable operating cost. It was engineered in parallel with the geothermal design, not as an afterthought.

We are not betting everything on a single drill result. That is how Hugarró was designed.

Hugarró: a facility powered by nature — with a plan B ready from day one
Hugarró will be a seven-pool geothermal wellness complex on the shores of Hvalfjörður, one of Iceland’s most striking fjords. From the water temperature in our pools to the warmth in our cabins and the heat under our roads in winter, every degree of energy in this facility comes from renewable natural sources.

We did not design this system around hope. We designed it around certainty — with a primary strategy backed by Iceland’s exceptional geology, and a fully engineered alternative ready to deploy if exploration falls short.

Either way, Hugarró will operate as planned!

The primary strategy — geothermal heat
Iceland sits on one of the most geothermally active zones on the planet. The geology around Hvalfjörður reflects this: temperature gradients of 120°C per 1,000 metres have been recorded nearby, and the Hvalur station a few kilometres away produces over 20 litres per second at 140°C. The natural resource is well-established.

Our target is modest by Icelandic standards: a production well yielding 7–10 litres per second at 70–90°C. A typical productive Icelandic well delivers 15–50 litres per second. We are not asking for much.

Finding that water is the ambition. The three-phase exploration programme — shallow pre-drills, drone magnetic survey to map fracture zones, then a targeted production well at 900–1,500 metres — is designed to maximise the probability of a productive strike while managing exploration risk.

One source. Four uses. Nothing wasted
If geothermal water is found, it flows through a cascade that extracts every usable degree before returning the water underground:

1. Pools — water enters at 70–90°C and heats all seven pools to a perfect 38°C
2. Buildings — the same water, still warm, then heats the hotel and all cabins
3. Hot water — covered in the same circuit, at no additional energy cost
4. Roads — remaining warmth keeps paths and access roads clear in winter

The water returns underground at 30°C. Zero discharge. Zero waste.

This cascade design and our closed-loop pool heating recirculation system recovers 33% more thermal energy than the approach used by traditional Icelandic pools, which continuously replace pool water and discharge thousands of cubic metres of hot water to nature every year. We do not do that.

Pool water — clean without chemicals
Our pools recirculate water in a closed loop rather than replacing it. Water is kept clean through UV disinfection, ultrafiltration membranes and biologica filters — the same technology used in drinking water treatment — monitored continuously by real-time microbiological sensors across all seven pools.

No chemicals are used or permitted. The result: 91% less water consumed than a traditional Icelandic pool operation, and measurably cleaner water for guests.

Beyond the facility — a district heating opportunity
A geothermal well of this scale does more than serve Hugarró. Should the Botnsdalur valley develop into a wider community, the same well — with capacity to spare — could supply heat to an estimated 200–250 neighbouring vacation homes, each with a hot tub, through a district heating network.

At a metered tariff, this transforms a facility operating cost into a recurring revenue stream. A geothermal well becomes a utility asset.

If no geothermal water is found
Drilling always carries geological uncertainty. A well can miss a fracture. Pre-drills can show unfavourable results (see this related FAQ). 

But we are planning for this before we break ground.

Our alternative is a purpose-built system of three Fenagy H-600 CO₂ heat pump units, each delivering 600 kW of thermal output. Together they provide 1,800 kW of installed capacity against a peak demand of 1,185 kW — full redundancy is built in. Two units alone cover peak load; the third is available for future expansion.

CO₂ (R744) is the most climate-neutral refrigerant available — a global warming potential of just 1, compared to 1,400+ for conventional refrigerants. It is also the most efficient refrigerant in the 38–70°C output range, which is exactly where we operate. For every unit of electricity these heat pumps consume, they deliver 3.8 units of heat — the rest comes free from the water sources below.

The cascade — pools, buildings, roads — operates identically to the geothermal design. From a guest perspective, absolutely nothing changes.

Where the heat comes from — two tiers, no single point of failure
The heat pumps draw their source heat from water. We use two complementary sources that together guarantee year-round reliability without dependence on rivers with fishing rights disputes, tidal complications, or expensive sea inlets.

Tier 1 — The Brunná river (spring through autumn)
The Brunná flows 200 metres from our plant room, crossing land whose owner raises no objection. A short insulated pipe draws river water at ~6°C, passes it through a heat exchanger, and returns it cooled by a few degrees. During the eight warmer months of the year, the Brunná provides everything we need.

Tier 2 — Two drilled groundwater wells (winter)
At 80–150 metres depth, groundwater in the Botnsdalur valley sits at a stable 4–6°C year-round — completely unaffected by surface frost, ice, or seasonal variation. Two drilled wells provide our winter heat source: reliable, permit-straightforward, and with no fishing rights complications.

Critically, these wells are drilled while the geothermal exploration rig is already on site — a modest incremental cost on an already-mobilised programme. The same activity that seeks geothermal water simultaneously secures our backup water source. The shallow geology data gathered also helps refine the deep drill target.

The system switches automatically between river and wells based on flow and temperature sensors. No manual intervention. No single point of failure.

The buffer tank
Between the heat pumps and the distribution system sits a 35,000-litre insulated thermal buffer tank at 45–50°C. It absorbs demand peaks, allows the heat pumps to run at steady optimal load, and reduces peak source water demand by around 20%. Think of it as a thermal battery — passive, simple, and highly effective.

The hydropower multiplier
The same river (Brunná)  that provide our backup heat source offer a second opportunity: small-scale run-of-river hydropower.

A €300,000 investment in a small hydropower plant on the Brunná or Botnsá delivers:

• 150 kW for eight months of the year (spring through autumn)
• 50 kW through the four winter months

That is enough to offset 50% of the heat pump system’s annual electricity consumption — effectively halving the grid electricity bill.

When river flow is high and heat pump demand is low, surplus hydro power heats the buffer tank directly through resistance elements — free thermal energy that further reduces the load on the heat pumps.

A 3.1-year payback on renewable infrastructure is exceptional by any standard. After that, the plant runs free for its remaining 30–40 year lifespan.

The numbers — what each path costs

The geothermal well is the cheapest long-term solution by a wide margin — €3.5M cheaper than heat pumps alone over 20 years. But the heat pump system combined with hydropower is a fully viable, lower-risk alternative that closes that gap significantly.

The capital costs of all three paths are remarkably similar. What separates them is operating cost — and operating cost is where geothermal wins decisively. Every year of successful geothermal operation saves €200,000 in electricity that the heat pump alternative would otherwise purchase from the grid.

Resilience by design
Most geothermal wellness projects are built around a single assumption: that the well succeeds. Ours is not.

Our engineering team designed the geothermal cascade and the CO₂ heat pump alternative in parallel — same output temperatures, same cascade architecture, same pool experience, same environmental standards. Switching between the two strategies requires no redesign of the facility. The plant room, pipework, heat exchangers, and distribution circuits serve both.

The exploration programme is thorough and data-driven. We expect to find water. But if we do not, a fully costed, fully engineered alternative is ready — one that combines proven industrial heat pump technology with local renewable water and hydropower sources, and delivers the same Hugarró experience at a known, manageable operating cost.

That is not a fallback. It is a feature.

The foundation of everything
Hugarró runs on the heat of the earth. Our geothermal pools, building heating, hot water, and road de-icing all draw from a single underground source. Finding that source — and doing so reliably and cost-effectively — is one of the most important investments we make.

Click to enlargeIceland’s geological advantage
The area around Hvalfjörður sits on one of the most geothermally active zones on the planet. Exploratory data from previous drillings in the area shows a temperature gradient of 120°C per 1,000 metres — well above the global average. The nearby Hvalur station, just a few kilometres away, produces over 20 litres per second at 140°C. Nature has already proven the potential here.

How we find the water?
Geothermal water typically flows along fractures and fault lines in the rock. Hitting those fractures is the real challenge — which is why we do not simply drill and hope.

Our approach, developed with one of Iceland’s leading geothermal specialists, follows a structured three-phase methodology:

1. Shallow exploratory drilling — 3 to 4 boreholes to 80 metres, mapping the subsurface geology
2. Drone magnetic survey — a non-invasive aerial survey pinpointing fault lines and fracture zones below ground
3. Production well — a single deep well of 900–1,500 metres, drilled with the best possible information, maximising the chance of a productive strike

On drilling method, we will choose between vertical, angled, or directional drilling based on what the survey data reveals. Directional drilling offers the greatest flexibility and the highest probability of intersecting a productive fracture — at a 40–60% premium over straight drilling. A worthwhile investment if the geology calls for it.

How much water do we actually need?
Surprisingly little, thanks to our closed-loop pool system. Our engineering calculations show that 7–10 litres per second at 70°C is sufficient to heat all seven pools to 38°C, supply all buildings and cabins with heat, and de-ice roads in winter — with capacity to spare.

Should the Botnsdalur valley ever develop into a wider community, that same well could realistically supply up to 50 holiday homes with heat at no additional extraction cost.  If water temperature would be 90°C and the flow 12 litres per second , 250 modern, well-insulated homes could benefit.  With their hot tubs of course: a must in Iceland! 

Needless to say the additional potential revenue stream of this option is considerable which is why the design of our geothermal water distribution system will be designed for this opportunity.

 What it costs
The table below shows our drilling budget, based on actual quotes from Icelandic contractors. Geothermal drilling in Iceland is one of the few things that costs significantly less here than in mainland Europe — geological conditions and a mature local industry make it so.

Click to enlarge

Our drinking water infrastructure — borehole, creek intake, filtration, UV disinfection, a 58 m³ storage tank and remote monitoring — is included in the budget above.

You may wonder why drilling a geothermal source in Iceland is considerably cheaper than in mainland Europe.

Icelandic groundwater is extremely hot (often 80°C to well over 150°C). The temperature gradient our our location suggests a temperature of 120 °C at 1.000 m. depth.    So if we hit an aquafier at 800 m. with 90 °C water we’re avoid extra drilling cost.  Moreover, the water there is often under natural pressure and rises on its own as an artesian spring, or with only a light pump. As a result, the costs for a heavy, expensive deep-well pump in the production well are often eliminated where a well depth of 2.500 m. is not uncommon.

The map below shows the distance to nearby wells.

The Hugarró development’s anchor are the geothermal pools.  Needless to say we need hot water.  We have already discussed the alternative if we don’t find (enough) geothermal water: C02 heat pumps.

But what are the actually chances of failure and which factors play a role?  We dove deeper into this subject.  Below the results of our research.

The most important distinction first
Almost every published statistic on geothermal well failure is based on power generation wells — where “success” means enough steam to drive a turbine, typically requiring 200°C+ at high flow rates. Our target is fundamentally different:

Our needs:  7–10 L/s at 70°C — a bar so low that many wells classified as “failures” in academic studies would comfortably pass for our purposes.

The IFC’s global study — the largest geothermal drilling database ever compiled — makes this explicit: “a dry well is a rarity — almost all wells flow to some extent” and “a well was only considered successful if the capacity was above a certain threshold.” ¹ That threshold is set for power production — not for our modest direct-use application.

What the numbers actually say

Global baseline (IFC database)

¹

Iceland high-enthalpy – over 200 °C (213 wells studied)

⁵

Low-temperature Iceland — our actual peer group
Iceland has drilled approximately 900 low-temperature wells since 1928, successfully supplying ~90% of the country’s space heating. ⁴ The track record of the low-temperature programme is exceptional precisely because the bar is lower — 70°C water is found across a much wider geographical area and shallower depth range than the 200°C+ needed for power generation.

Real examples near analogous settings:

• Thelamörk, N-Iceland: productive fracture intersected at just 450m depth, yielding 17 L/s at 91°C — more than double our target, at less than half our planned depth ²
• Hjalteyri, Eyjafjörður: well HJ-19 to 1,450m following ground magnetic survey yielded 200 L/s at 90°C — the most productive low-temperature well in that region ³

What the magnetic survey does — and doesn’t — do

This is where honesty matters for investors:

The research is direct on this: “pre-drill derisking techniques have not greatly mitigated the risk factors — there is a relatively small improvement in success rates between exploration and development wells.” ¹ What surveys do is eliminate the worst outcomes — drilling in completely the wrong location. What they cannot do is guarantee fracture intersection at the exact drill point. That residual uncertainty is irreducible with current technology.

The IFC study describes this remaining risk as simply “bad luck — local absence of fractures, difficult to predict even with surveys.” ¹

Our specific probability — After survey and pre-drills
Combining all factors — Iceland’s geological advantage, our low target, our pre-drill programme, the Hvalfjörður geological context, and proven nearby production at Hvalur:

The honest summary

In plain terms: after a thorough magnetic survey, shallow pre-drills, and with the geological context of Hvalfjörður behind us, the probability of finding sufficient water for our modest needs is approximately 85–90%. The remaining 10–15% is not ignorance or poor planning — it is the irreducible geological uncertainty that every geothermal project carries, regardless of how much exploration is done first.

That is precisely why our CO₂ heat pump backup system exists, and why it was engineered in full detail rather than treated as a footnote.

Our energy source: the earth itself

Hugarró is heated entirely by geothermal energy — natural heat drawn from deep underground. It powers our pools, our hot water, our buildings, and even our roads in winter. No fossil fuels. No emissions. No utility bills.

Smarter than the traditional approach

The standard practice in Iceland is to continuously replace pool water with fresh geothermal water — discarding around 230 m³ of hot water into nature every single day. We think that is wasteful, and we designed our way around it.

Our pools use a closed-loop recirculation system: water stays in the pools and is kept clean through UV disinfection and ultrafiltration membranes — the same technology used in drinking water treatment. No chemicals are used or permitted in Iceland. A real-time microbiological monitoring system continuously checks water quality across all seven pools, so you are always swimming in water that is measurably clean.

The result? We use 91% less water than a traditional Icelandic pool operation, and we recover 33% more heat energy by not throwing it away.

One source, four uses — in sequence

Rather than drawing separate energy for each need, we run our geothermal water through a cascade:

• Geothermal pools — water enters at 70°C and heats our pools to a perfect 38°C
• Hotel & cabin heating — the same water, still warm at 50°C, then heats all our buildings
• Hot tap water — covered in the same circuit
• Road de-icing — remaining warmth is used to keep paths and roads clear in winter

The water is then returned underground at 30°C — completing a fully closed, zero-discharge cycle.

A modest well is all we need

Because our system is so efficient, a geothermal well yielding just 7–10 litres per second at 70°C covers all our needs — pools, buildings, roads, and future expansion. For context, a typical productive well in Iceland delivers 15–50 litres per second. We are not greedy with the resource.

This also means we have realistic capacity to supply heating to neighbouring summer homes and future development in the area — turning a facility cost into a potential revenue stream.

The bottom line

and how Hugarró goes far beyond them
What makes geothermal pools in Iceland unique — and what does it take to keep them safe, sustainable, and natural at the same time?

  translation below

What makes Icelandic geothermal pools so special?
Iceland’s geothermal pools are a product of the country’s unique geology. Water heated deep underground is mixed with cold water to set temperatures between 36–42°C — perfect for soaking, but also a warm, nutrient-rich environment in which bacteria can multiply quickly. Unlike outdoor seawater beaches or cold freshwater lakes, a warm pool with dozens of bathers needs active water quality management.

In most countries around the world, this is solved with chlorine and other chemical disinfectants. In Iceland, chemicals are explicitly prohibited in natural bathing facilities under Regulation No. 460/2015 (Reglugerð um baðstaði í náttúrunni). That is what makes Icelandic geothermal bathing culture genuinely different — and what makes the engineering challenge so interesting.

What does Icelandic law require instead?
The traditional solution used across Iceland is straightforward and effective, but also very resource-intensive: replace 30–40% of the pool’s total water volume every single day. Fresh cold water and geothermal hot water are continuously mixed in and the “old” water is flushed out — millions of litres of heated water discharged daily into drainage ditches.

The relevant law, Regulation No. 460/2015, classifies natural bathing facilities and sets bacterial count limits (e.g. E. coli < 500/100 ml; Enterococci < 200/100 ml for Class 1 facilities). The regulation requires:

• A minimum of 10 water samples per year for Class 1 facilities (like ours)
• An internal control system with risk assessments, incident logs, and staff training
• A documented emergency and contingency plan
• Strict bather number controls
• Mandatory signage, changing rooms, showers, and first aid on site

The regulation is outcome-based, not technology-prescriptive — meaning it sets the results you must achieve, not the method you must use. This is the regulatory opening that Hugarró’s engineering approach is built on.

What category does Hugarró fall under?
Hugarró is classified as a Recreation Pool (Afþreyingarlaug) — Class 1 — under Regulation 460/2015. This is the highest level of oversight, applying to facilities that operate regularly and year-round. It requires a full operating licence (starfsleyfi) from the local Health Committee, comprehensive internal controls, and continuous compliance with bacterial quality standards.

We welcome this level of scrutiny. Our systems are designed to far exceed Class 1 requirements, not merely meet them.

Why are chemicals not used — and why is that actually fine?
Chemicals such as chlorine kill bacteria effectively, but they have a serious downside: they react with organic matter introduced by bathers (sweat, skin cells, urine) to produce disinfection by-products (DBPs) — compounds that are themselves potentially harmful and are responsible for the characteristic “pool smell” most people associate with indoor public pools. In Iceland, the law simply prohibits them in natural bathing facilities.

The good news is that, as research has demonstrated, chemicals are not actually necessary if you control the source of contamination and treat the water effectively through physical methods.

What does the science say? The Keuten/Delft Study
Researcher M.C. Keuten at Delft University of Technology published a landmark study on bacterial pollution in swimming pools and how to reduce it — *Alternative Pool Water Treatment and the Influence of Swimmers on Water Quality*.

The study used a specially instrumented shower cabin to precisely measure the pollutants released by bathers before and during swimming. The key findings are striking:

This means that up to 60% of the bacterial input into a pool is directly controllable through bather behaviour — before any filtration or treatment technology is even needed. This is something Icelanders know well, which is why the country has a very strict pre-bath showering culture.

Keuten also demonstrated that UV disinfection combined with ultrafiltration — with no chemicals — can achieve microbial water quality comparable to chlorinated pools. Biological filtration further improved the removal of dissolved substances such as urea, reducing the formation of unwanted by-products.

What does Hugarró do to reduce bacterial input at the source?
Based directly on Keuten’s research, Hugarró has designed a two-step pre-entry protocol backed by technology, not just signage:

1. Mandatory pre-swim shower — Our facilities use sensor-based nudging technology that confirms a minimum 1.5 minutes of showering before entry is unlocked. This alone eliminates approximately 30% of the bacterial load that would otherwise enter the pool. A visible timer shows the bather how much time is left.
2. Toilet-first culture — Clear prompts, facility design, and staff communication encourage guests to use the toilet before bathing — targeting the remaining 30% of avoidable bacterial input.

Across our 7 pools, strict bather number limits are enforced in real time, both to comply with the regulatory requirement for access control and to ensure that the filtration system is never overwhelmed.

How does Hugarró manage water quality without chemicals and without massive water waste?
Instead of continuously flushing out large volumes of water, Hugarró’s pools are equipped with continuous ultrafiltration — a physical membrane-based process that removes bacteria, particles, and micro-organisms from pool water in a closed loop. This is combined with continuous water quality monitoring using systems such as those developed by bNovate, which allows near-real-time measurement of bacterial counts.

The result:

• • Water savings of over 90% compared to the traditional daily-replacement model used elsewhere in Iceland
  • Energy savings of over 30% in heating, as far less cold replacement water needs to be heated
  • Pool water that can be cycled to within safe bacteriological limits within one hour if needed — compared to the days it would take under a simple dilution/replacement model

Why ultrafiltration alone is not enough — the role of the active carbon biofilter
Ultrafiltration is highly effective at removing bacteria, viruses, and suspended particles from pool water. However, it has one fundamental limitation: its membranes work by physical size exclusion, and the pores are far too large to capture dissolved molecules. Urea — the primary dissolved contaminant in sweat and urine — is a small molecule (~0.4 nm) that passes straight through a UF membrane unimpeded.

This matters particularly in a geothermal pool at 38°C. At that temperature, the water is warmer than the human body’s cooling threshold, meaning that bathers sweat continuously and passively, even while sitting still. Research has measured sweat secretion of over 500 ml per person per hour during passive immersion at this temperature. Urea accumulates in the water with every bather, every session, every day — and UF does nothing to stop it.

To address this, Hugarró’s filtration system includes a biological active carbon filter. Granular activated carbon (GAC) offers an extraordinarily large internal surface area — hundreds of square metres per gram — on which both physical adsorption and biological degradation take place simultaneously:

• Adsorption: urea and other dissolved organic compounds bind chemically to the carbon surface and are removed from the water
• Biodegradation: beneficial micro-organisms colonise the carbon medium and break down the adsorbed organic matter into harmless compounds

This dual mechanism makes active carbon significantly more effective than alternative biological media such as MBBR carriers (moving bed biofilm reactors), which rely on biological action alone and offer no adsorption capacity. In a chemical-free system with clean fill water, active carbon can dedicate its full adsorption capacity exclusively to the dissolved substances introduced by bathers — making it the ideal complement to ultrafiltration.

Together, UF and the active carbon biofilter cover what neither can achieve alone: UF handles pathogens and particles; the biofilter handles dissolved organics. The result is pool water that is clean in every meaningful sense of the word.

Does Hugarró have any water replacement at all?

Yes — a small amount. Natural evaporation from the pool surface means that water is slowly lost and must be topped up. This amounts to less than 10% of pool volume per day — a fraction of the 30–40% daily replacement that is standard practice at comparable Icelandic geothermal pools. This replacement water is part of the natural water cycle, not a deliberate “flush-and-refill” approach.and-refill” approach.

How does Hugarró monitor water quality — and how does this compare to the law?
The law requires a minimum of 10 water quality checks per year for Class 1 facilities — roughly once per month. At Hugarró, we check every pool every 2 hours, using continuous real-time monitoring technology. This means:

Any exceedance of our internal quality thresholds triggers an automated filtration response. Our systems are designed to restore water to within safe parameters within one hour — even under peak load. In fact, the moment bacterial quality moves from the ‘green’ to the ‘yellow’ zone, we increase filtration on the pool in question to prevent it from ever reaching the ‘red’ zone.

Moreover, our system can be remotely monitored via online dashboards by the health authorities — providing real-time oversight rather than after-the-fact sampling during a site visit.

Other measures to assure water quality
An important part of our quality control system is pool design. By creating overflow around all pool edges, the formation of a bacterial biofilm on the water surface is minimised. Pool surfaces are smoother than standard concrete pool surfaces, which greatly reduces the build-up of deposits that are a breeding ground for bacterial growth, and allows easy cleaning.

Water flow through the pools — comprising evaporation replacement water as well as heated water inflow — is carefully engineered to avoid stagnant areas, which can lead to bacterial development. This is the principle behind the ‘islands’ in our pools: filtered water enters via the bottom of the pool and rises upward, flowing over the edges and carrying any contamination with it. This creates a continuously circulating cycle, carefully monitored by automation.

Are there any rules in Iceland that prohibit ultrafiltration?
No. Regulation 460/2015 contains no prohibition on ultrafiltration. The regulation is outcome-based — it sets bacterial limits and requires that a documented internal control system is in place. It does not prescribe which technology must be used to achieve those limits.

The regulation does describe the standard model for recreation pools as relying on “frequent water renewal and bather number control” — which is how the traditional approach is framed. However, since the law is outcome-focused, an alternative method that demonstrably achieves the same (or better) bacteriological outcomes is legally defensible.

Hugarró engages proactively with the local Health Committee to ensure our approach is fully documented, understood, and approved as part of our operating licence conditions. This regulatory dialogue will be an ongoing part of our operations and we hope to set an example for bacterial water control in Iceland.

What does the local Health Committee inspect?
The local Health Committee (heilbrigðisnefnd) holds broad powers under Regulation 460/2015 and the underlying Public Health Act No. 7/1998:

• Unrestricted access for inspections and water sampling at any time
• Power to issue public warnings and erect warning signs if bacterial limits are repeatedly exceeded
• Power to cap the number of bathers in a recreation pool
• Power to order additional sampling beyond the minimum (at the operator’s cost)
• Power to authorise or order disinfection — only by radiation or other non-chemical means — if quality standards are repeatedly not met

All of Hugarró’s water quality results — as required — are forwarded to the Environment Agency of Iceland (Umhverfisstofnun), where they are published publicly. We are confident in our results and welcome public transparency.

The bottom line
Hugarró operates at the intersection of Icelandic bathing culture, environmental responsibility, and evidence-based water science. We comply fully with Regulation No. 460/2015 as a Class 1 Recreation Pool — and go significantly further in every measurable dimension of water safety, resource efficiency, and monitoring rigour.

Our approach is not a workaround. It is what responsible geothermal bathing looks like when engineering and science are applied seriously to an age-old challenge

Click to enlarge

 

Íslenskar reglugerðir um böðun í náttúrunni

 

Flokkar: Spurningar stjórnar Umhverfi Jarðhiti Jarðböð

og hvernig Hugarró fer langt fram úr þeim
Hvað gerir íslenskar jarðhitalaugar einstakar — og hvað þarf til að halda þeim öruggum, sjálfbærum og náttúrulegum á sama tíma?

 

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Hvað gerir íslenskar jarðhitalaugar svona sérstakar?
Íslenskar jarðhitalaugar eru afurð einstakrar jarðfræði landsins. Vatni sem hitnar djúpt í jörðu er blandað við kalt vatn til að ná 36–42°C hita — fullkomið til að láta fara vel um sig, en jafnframt hlýtt og næringarríkt umhverfi þar sem bakteríur geta fjölgað sér hratt. Ólíkt sjávarströndum eða köldum ferskvatnsstöðum þarf hlý laug með tugum gesta virka stjórnun á vatnsgæðum.

Í flestum löndum heims er þetta leyst með klór og öðrum sótthreinsiefnum. Á Íslandi eru kemísk efni beinlínis bönnuð á náttúrulegum baðstöðum samkvæmt Reglugerð nr. 460/2015 (Reglugerð um baðstaði í náttúrunni). Það er það sem gerir íslenska baðmenningu sannarlega frábrugðna — og gerir verkfræðilegu áskorunina svo áhugaverða.

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Hvað krefjast íslensk lög í staðinn?
Hefðbundna lausnin sem notuð er um allt Ísland er einföld og áhrifarík, en jafnframt mjög auðlindafrek: skipta út 30–40% af heildarvatnsmagni laugarinnar á hverjum einasta degi. Fersku köldu vatni og heitu jarðhitavatni er stöðugt blandað saman og „gamla“ vatninu skolað út — milljónir lítra af hituðu vatni renna daglega í frárennslisskurði.

Viðeigandi lög, Reglugerð nr. 460/2015, flokka náttúruleg baðsvæði og setja mörk fyrir gerlafjölda (t.d. E. coli < 500/100 ml; Enterokokkar < 200/100 ml fyrir flokk 1). Reglugerðin krefst:

• Að lágmarki 10 vatnssýni á ári fyrir mannvirki í flokki 1 (eins og okkar)
• Innra eftirlitskerfi með áhættumati, atvikaskráningu og þjálfun starfsfólks
• Skráð neyðar- og viðbragðsáætlun
• Strangt eftirlit með fjölda baðgesta
• Skyldubundnar merkingar, búningsklefar, sturtur og skyndihjálp á staðnum

Reglugerðin er árangursmiðuð, ekki tækniforskrift — sem þýðir að hún setur fram þá niðurstöðu sem þarf að ná, en ekki hvaða aðferð þarf að nota. Þetta er reglugerðaropnunin sem verkfræðileg nálgun Hugarró byggir á.

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Undir hvaða flokk fellur Hugarró?
Hugarró er flokkað sem Afþreyingarlaug (Afþreyingarlaug) — Flokkur 1 — samkvæmt reglugerð 460/2015. Þetta er hæsta stig eftirlits og á við um mannvirki sem starfrækt eru reglulega og allt árið um kring. Það krefst fulls starfsleyfis frá heilbrigðisnefnd sveitarfélagsins, yfirgripsmikils innra eftirlits og stöðugrar fylgni við gæðastaðla fyrir gerla.starfsleyfistarfsleyfi

Við fögnum þessu eftirliti. Kerfin okkar eru hönnuð til að fara langt fram úr kröfur í flokki 1 ríflega, en ekki bara uppfylla þær.

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Af hverju eru engin kemísk efni notuð — og af hverju er það í raun í lagi?
Efni eins og klór drepa bakteríur á áhrifaríkan hátt, en þeim fylgir alvarlegur galli: þau hvarfast við lífræn efni sem berast með sundgestum (svita, húðfrumum, þvagi) og mynda aukaafurðir sótthreinsunar (DBP) — efnasambönd sem geta sjálf verið skaðleg og bera ábyrgð á hinni dæmigerðu „sundlaugalykt“ sem flestir tengja við almenningslaugar innanhúss. Á Íslandi banna lög þessi efni einfaldlega í náttúrulegum baðstöðum.

Góðu fréttirnar eru þær að rannsóknir hafa sýnt að kemísk efni eru í raun óþörf ef stjórnað er upptökum mengunar og vatnið meðhöndlað á áhrifaríkan hátt með eðlisfræðilegum aðferðum.

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Hvað segja vísindin? Keuten/Delft rannsóknin
Rannsakandinn M.C. Keuten við Tækniháskólann í Delft birti tímamótarannsókn á bakteríumengun í sundlaugum og hvernig megi draga úr henni — *Alternative Pool Water Treatment and the Influence of Swimmers on Water Quality*.

Í rannsókninni var notaður sérútbúinn sturtuklefi til að mæla nákvæmlega þau mengunarefni sem losna frá sundgestum fyrir og á meðan þeir synda. Helstu niðurstöður eru sláandi:

Upptök bakteríu- og mengunarálags	Hlutfall af heild
Svitamyndun í kafi á meðan sundi	~40%
Að fara ekki í sturtu áður en farið er í laugina	~30%
Að nota ekki salernið áður en farið er í laugina	~30%

Þetta þýðir að hægt er að stjórna allt að 60% af bakteríumagni sem berst í laug beint með hegðun gesta — áður en nokkur síunar- eða hreinsitækni er yfirhöfuð nauðsynleg. Þetta er eitthvað sem Íslendingar þekkja vel, og þess vegna ríkir hér á landi mjög ströng menning varðandi sturtuferðir fyrir sund.

Keuten sýndi einnig fram á að UV-sótthreinsun ásamt ofursíun (ultrafiltration) — án nokkurra íðefna — getur náð fram örverufræðilegum vatnsgæðum sem eru sambærileg við klóraðar laugar. Líffræðileg síun bætti enn frekar fjarlægingu uppleystra efna eins og þvagefnis, sem dregur úr myndun óæskilegra aukaafurða.

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Hvað gerir Hugarró til að draga úr bakteríumagni við upptökin?
Byggt beint á rannsóknum Keuten, hefur Hugarró hannað tveggja þrepa aðgangsferli sem studd er af tækni, ekki bara skiltum:

1. Skyldubundin sturta fyrir sund — Aðstaða okkar notar skynjaratækni sem hvetur gesti og staðfestir að lágmarki 1,5 mínútna sturtuferð áður en opnað er fyrir aðgang. Þetta eitt og sér eyðir um það bil 30% af því bakteríumagni sem annars myndi berast í laugina. Sýnilegur tímamælir sýnir gestinum hversu mikill tími er eftir.
2. Salernismenning í fyrirrúmi — Skýrar ábendingar, hönnun aðstöðunnar og samskipti starfsfólks hvetja gesti til að nota salernið fyrir sundferðina — sem beinist að þeim 30% af forðanlegu bakteríumagni sem eftir standa.

Í okkar 7 laugum, er ströngum takmörkunum á fjölda gesta fylgt eftir í rauntíma, bæði til að uppfylla reglugerðarkröfur um aðgangsstýringu og til að tryggja að síunarkerfið verði aldrei ofhlaðið.

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Hvernig stýrir Hugarró vatnsgæðum án íðefna og án gífurlegrar vatnssóunar?
Í stað þess að skola stöðugt út miklu magni af vatni, eru laugar Hugarró búnar samfelldri ofursíun — eðlisfræðilegu ferli byggðu á himnum sem fjarlægir bakteríur, agnir og örverur úr laugavatninu í lokaðri hringrás. Þessu er fylgt eftir með stöðugri vöktun á vatnsgæðum með kerfum eins og þeim sem þróuð eru af bNovate, sem gerir kleift að mæla bakteríufjölda nánast í rauntíma.

Niðurstaðan:

• • Yfir 90% vatnssparnaður miðað við hefðbundna líkanið þar sem vatni er skipt út daglega eins og annars staðar á Íslandi
  • Yfir 30% orkusparnaður í upphitun, þar sem hita þarf mun minna af köldu ferskvatni
  • Laugavatn sem hægt er að hreinsa upp að öruggum gerlamörkum innan klukkustundar ef þörf krefur — samanborið við þá marga daga sem það tæki með einfaldri útskiptingu vatns

Af hverju ofursíun ein og sér dugar ekki — hlutverk lífvirkrar kolsíu
Ofursíun er mjög áhrifarík við að fjarlægja bakteríur, vírusa og svifagnir úr sundlaugarvatni. Hún hefur þó eina grundvallartakmörkun: himnurnar virka með eðlisfræðilegri stærðarsíun og svitaholurnar eru allt of stórar til að fanga uppleystar sameindir.Þvagefni — helsta uppleysta mengunarefnið í svita og þvagi — er lítil sameind (~0,4 nm) sem fer óhindrað beint í gegnum ofursíunarhimnu.

Þetta skiptir sérstaklega miklu máli í jarðhitalaug sem er 38°C heit. Við það hitastig er vatnið heitara en kæliþröskuldur mannslíkamans, sem þýðir að baðgestir svitna stöðugt og ómeðvitað, jafnvel þótt þeir sitji kyrrir. Rannsóknir hafa mælt svitamyndun yfir 500 ml á mann á klukkustund við óvirka dvöl í vatni við þetta hitastig. Þvagefni safnast upp í vatninu með hverjum gesti, hverri baðferð, á hverjum degi — og ofursíun gerir ekkert til að stöðva það.

Til að bregðast við þessu inniheldur síunarkerfi Hugarró lífvirka kolsíu. Virkt kornakol (GAC) býður upp á óvenju stórt innra yfirborð — mörg hundruð fermetra á hvert gramm — þar sem bæði eðlisfræðileg ásog og líffræðileg niðurbrot eiga sér stað samtímis:

• Ásog: þvagefni og önnur uppleyst lífræn efnasambönd bindast efnafræðilega við yfirborð kolsins og eru fjarlægð úr vatninu
• Líffræðilegt niðurbrot: gagnlegar örverur setjast að í kolefninu og brjóta niður ásoguð lífræn efni í skaðlaus efnasambönd

Þetta tvíþætta ferli gerir virkt kol mun skilvirkara en önnur líffræðileg síuefni eins og MBBR-berar (skolpsíur með hreyfanlegu undirlagi), sem treysta eingöngu á líffræðilega virkni og hafa enga ásogsgetu. Í efnalausu kerfi með hreinu fyllivatni getur virka kolið nýtt alla ásogsgetu sína eingöngu fyrir þau uppleystu efni sem berast með baðgestum — sem gerir það að fullkominni viðbót við ofursíun.

Saman ná UF og virka kolefnis-lífsían því sem hvorugt getur áorkað eitt og sér: UF sér um sýkla og agnir; lífsían sér um uppleyst lífræn efni. Niðurstaðan er sundlaugarvatn sem er hreint í fyllsta skilningi þess orðs.

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Er einhver vatnsskipti yfirhöfuð hjá Hugarró?

Já — lítið magn. Náttúruleg uppgufun af yfirborði laugarinnar þýðir að vatn tapast hægt og rólega og þarf að fylla á hana. Þetta nemur minna en 10% af rúmmáli laugarinnar á dag — broti af þeim 30–40% daglegu vatnsskiptum sem eru venjubundin í sambærilegum íslenskum jarðhitalaugum. Þetta áfyllingarvatn er hluti af náttúrulegri hringrás vatnsins, ekki meðvituð „tæma-og-fylla“ nálgun.

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Hvernig vaktar Hugarró vatnsgæði — og hvernig er það í samanburði við lög?
Lögin krefjast að lágmarki 10 mælingar á vatnsgæðum á ári fyrir flokk 1 — u.þ.b. einu sinni í mánuði. Hjá Hugarró athugum við hverja laug á 2 klukkustunda fresti, með því að nota tækni sem vaktar vatnið stöðugt í rauntíma. Þetta þýðir:

Mælistærð	Lagalegt lágmark (Flokkur 1)	Hugarró staðall
Tíðni sýnatöku á vatnsgæðum	10× á ári (~mánaðarlega)	Á 2 klukkustunda fresti
Viðbragðstími við frávikum	Dagar (bið eftir rannsóknarstofu)	Innan 1 klukkustundar (sjálfvirkt viðbragð síunarkerfis)
Eftirlit með fjölda gesta	Skylt, aðferð ekki tilgreind	Rauntíma eftirlit með skynjurum í hverri laug

Öll frávik frá okkar innri gæðaviðmiðum ræsa sjálfvirkt viðbragð í síunarkerfinu. Kerfin okkar eru hönnuð til að koma vatninu aftur innan öruggra marka innan klukkustundar — jafnvel við hámarksálag. Í raun, um leið og bakteríugæði færast úr „græna“ svæðinu yfir í það „gula“, aukum við síun í viðkomandi laug til að koma í veg fyrir að hún nái nokkurn tímann í „rauða“ svæðið.

Auk þess geta heilbrigðisyfirvöld fylgst með kerfinu okkar í gegnum mælaborð á netinu — sem veitir rauntímaeftirlit í stað sýnatöku eftir á við vettvangsheimsókn.

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Aðrar ráðstafanir til að tryggja vatnsgæði
Mikilvægur hluti af gæðaeftirlitskerfi okkar er hönnun lauganna. Með því að hafa yfirfall meðfram öllum laugarköntum er myndun örveruskánar á yfirborði vatnsins lágmörkuð. Yfirborð lauganna er sléttara en á hefðbundnum steyptum laugum, sem dregur verulega úr útfellingum sem eru gróðrarstía fyrir bakteríuvöxt og auðveldar þrif.

Vatnsrennsli í gegnum laugarnar — sem samanstendur af vatni til að mæta uppgufun ásamt innrennsli á heitu vatni — er vandlega hannað til að forðast kyrrstöðusvæði þar sem bakteríur geta þrifist. Þetta er meginreglan á bak við „eyjarnar“ í laugunum okkar: síað vatn kemur inn um botn laugarinnar og stígur upp, flæðir yfir kanta og ber með sér hvers kyns óhreinindi. Þetta skapar stöðuga hringrás sem er vandlega vöktuð með sjálfvirkni.

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Eru einhverjar reglur á Íslandi sem banna ofursíun?
Nei. Reglugerð 460/2015 inniheldur ekkert bann við ofursíun. Reglugerðin er árangursmiðuð — hún setur mörk fyrir gerlafjölda og krefst þess að skjalfest innra eftirlitskerfi sé til staðar. Hún kveður ekki á um hvaða tækni skuli nota til að ná þeim mörkum.

Reglugerðin lýsir staðallíkani fyrir baðstaði sem byggir á „tíðri endurnýjun vatns og takmörkun á fjölda baðgesta“ — sem er hefðbundna nálgunin. Hins vegar, þar sem lögin einblína á niðurstöður, er önnur aðferð sem sýnanlega nær sömu (eða betri) niðurstöðum varðandi gerlafjölda lagalega verjanleg.

Hugarró á í virku samstarfi við Heilbrigðisnefnd til að tryggja að nálgun okkar sé fyllilega skjalfest, skilin og samþykkt sem hluti af starfsleyfisskilyrðum okkar. Þetta samtal við eftirlitsaðila verður áframhaldandi hluti af starfsemi okkar og við vonumst til að vera fyrirmynd í bakteríustjórnun vatns á Íslandi.

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Hvað skoðar heilbrigðisnefndin?
Heilbrigðisnefnd (heilbrigðisnefnd) hefur víðtækar heimildir samkvæmt reglugerð nr. 460/2015 og undirliggjandi lögum um hollustuhætti og mengunarvarnir nr. 7/1998:

• Ótakmarkaður aðgangur vegna eftirlits og sýnatöku hvenær sem er
• Heimild til að gefa út opinberar viðvaranir og setja upp viðvörunarskilti ef gerlamörk eru ítrekað yfir mörkum
• Heimild til að takmarka fjölda baðgesta á baðstað
• Heimild til að fyrirskipa aukna sýnatöku umfram lágmark (á kostnað rekstraraðila)
• Heimild til að heimila eða fyrirskipa sótthreinsun — eingöngu með geislun eða öðrum aðferðum án íblöndunarefna — ef gæðakröfur eru ítrekað ekki uppfylltar

Öllum niðurstöðum úr mælingum á vatnsgæðum Hugarró er — eins og krafist er — miðlað til Umhverfisstofnun (Umhverfisstofnun), þar sem þær eru birtar opinberlega. Við treystum okkar niðurstöðum og fögnum gagnsæi gagnvart almenningi.

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Kjarni málsins
Hugarró starfar á mótum íslenskrar baðmenningar, umhverfisábyrgðar og gagnreyndra vatnsvísinda. Við fylgjum reglugerð nr. 460/2015 að fullu sem flokkur 1 fyrir afþreyingarlaugar — og göngum mun lengra á öllum mælanlegum sviðum vatnsöryggis, auðlindanýtingar og eftirlits.

Nálgun okkar er ekki undanleið. Svona lítur ábyrg jarðhitabaðmenning út þegar verkfræði og vísindum er beitt af alvöru við forna áskorun

Birt þann 1. september 2026

Vacation home district heating — Iceland

Prepared: September 2026 | Confidential — For Discussion Purposes

Executive Summary
Our geothermal project will generate significantly more thermal capacity than the primary development requires. We propose to monetise this surplus by supplying hot water to a neighbouring planned vacation home community of 50 homes across two clusters. The developer of that community has indicated willingness to co-invest in the distribution infrastructure, which materially de-risks the project and compresses the payback period to approximately 10–11 years on a shared CAPEX basis — well within the operational lifespan of the asset (30–40 years).

This is a low-marginal-cost, recurring revenue stream built on zero-cost fuel.

Project overview

Capital expenditure

Build is phased: Phase 1 (Cluster A, ~€801k) triggers on Cluster A construction start; Phase 2 (Cluster B) triggers on Cluster B confirmation. No idle capital.

Revenue & Financial Projection

Why the developer co-invests
The developer’s motivation is straightforward. In Iceland, geothermal hot water access is a market baseline expectation — lots without it sell at a meaningful discount. Based on regional comparables, reliable hot water supply adds an estimated €15,000–€25,000 per lot in realised sale value. Across 50 lots, that represents a €750k–€1.25M uplift in gross development value — making a €800k infrastructure contribution not just reasonable, but commercially rational. We are effectively subsidising their product quality.

This alignment of interests is a structural strength of the deal.

Key strengths

• Zero fuel cost. The heat is a by-product of our existing geothermal investment. Marginal cost of production is effectively nil.
• Recurring, inflation-linked income. Subscription tariffs are typically indexed to energy price benchmarks. Utility revenues are sticky and predictable.
• Captive customer base. Once connected, switching costs are prohibitive. Customer churn is essentially zero.
• Developer co-investment halves our exposure and signals strong demand validation before a single pipe is laid.
• Phased build eliminates idle capital risk. Phase 2 is only committed when Cluster B development is confirmed.
• Enhances our own project’s social licence. Community benefit strengthens planning relationships and long-term operating position.
• Gateway asset. Once operational, additional projects in the area will find our infrastructure already in place, with extension economics improving per additional customer.

Risks & mitigants

Strategic upside (not in base case)
10 existing vacation homes in the wider area were judged too dispersed and few to connect at present. As our network grows and additional developments emerge, incremental connections become progressively cheaper per home.

• Future developments attracted by proven geothermal infrastructure can be connected on similar commercial terms — each new customer improves the network economics for all parties.
• Carbon credit potential. Displacing oil or electric boiler heating with geothermal may qualify under relevant Icelandic or European carbon mechanisms — upside not yet quantified.

Summary verdict
This is a long-duration, low-risk infrastructure asset generating clean recurring income from a zero-cost fuel source, with a co-investing partner whose financial interests are directly aligned with ours. The 10.6-year payback on net invested capital is conservative — and from year 11, the revenue stream runs largely unconstrained for a further 20–30 years.

The primary negotiation priority is the mandatory connection covenant in the developer’s lot sale contracts. That single clause converts a projected revenue stream into a contractual one — and that is the difference between a good investment and an excellent one.

This document is prepared for discussion purposes only and does not constitute a formal investment prospectus. All figures are estimates based on comparable Icelandic district heating projects and are subject to detailed engineering and commercial due diligence.

We planned for this from day one
Drilling for geothermal water in Iceland is well-founded — the geology around Hvalfjörður is exceptional and nearby wells prove the potential. But geothermal exploration always carries uncertainty. Fractures can be missed. A well can come up dry. Investors can lose patience.

We designed Hugarró so that this scenario, however unlikely (see this post), does not stop us.

Our answer is a purpose-built alternative heating system that delivers the same pools, the same warmth, the same experience — drawing heat not from the ground below, but from the river and the earth around us.

Why our heating needs are surprisingly modest
Most facilities of this kind would be in serious trouble without a geothermal source. Ours is not — because of how efficiently we use energy in the first place.

Our closed-loop pool system recirculates water rather than constantly replacing it, recovering 33% more heat than the traditional Icelandic approach. Our cascade design runs geothermal water through pools, then buildings, then roads — extracting every usable degree before returning it. Floating insulation covers eliminate heat loss overnight.

The result: our total heating demand — seven pools at 38°C, full hotel and cabin heating, road de-icing — requires the equivalent of just 1,185 kW of continuous thermal output. For a facility of this scale, that is a lean number. And it is exactly what our backup system is sized to deliver.

The alternative: CO₂ heat pumps

If no geothermal source is found, we install three Fenagy (or other reliable brand) H-600 CO₂ heat pump units, each delivering 600 kW of thermal output. Together they provide 1,800 kW of installed capacity — comfortably above our 1,185 kW peak demand, with full redundancy built in.

CO₂ (R744) is the ideal refrigerant for this application:

• GWP of 1 — the most climate-neutral refrigerant available
• No chemicals — fully aligned with Iceland’s environmental standards
• Highest efficiency in the 38–70°C output range — exactly our operating window
• Proven technology — widely used in Scandinavian district heating systems

The heat pumps run as water-to-water units, extracting heat from a local water source and delivering it at the temperatures our cascade system requires. The full cascade — pools, buildings, roads — operates identically to the geothermal design. From a guest perspective, nothing changes.

Where the heat comes from: a two-tier water source
Instead of one geothermal well, we use two complementary water sources that together provide year-round reliability.

Tier 1 — The Brunná river (primary, spring through autumn)
The Brunná flows just 200 metres from our plant room, crossing land whose owner has no objection to our intake (in fact, we are co-owner). A short insulated HDPE pipe draws water at ~6°C, passes it through a heat exchanger, and returns it a few degrees cooler. The river provides more than enough flow for our needs during the eight warmest months of the year.

Tier 2 — Two drilled groundwater wells (winter backup)
For the winter months, when surface water flow can drop and ice becomes a risk, we rely on two drilled wells at 80–150 metres depth. At that depth, groundwater in the Botnsdalur valley maintains a stable 4–6°C year-round — completely unaffected by surface weather, frost, or seasonal variation. No river. No tidal influence. No moving parts except a submersible pump in each well.

Crucially, these wells are drilled while the geothermal exploration rig is already on site — a modest incremental cost on an already-mobilised programme, and one that simultaneously provides valuable geological data to guide the deep geothermal drill.

The system switches automatically between sources based on flow sensors and temperature readings. No manual intervention required.

The buffer tank — smoothing out demand peaks
Between the heat pumps and the distribution system sits a 35 m3 insulated thermal buffer tank, maintained at 45–50°C. It acts as a reservoir of stored heat, absorbing demand peaks and allowing the heat pumps to run at steady, optimal load rather than cycling up and down.

The effect is meaningful: peak source water demand drops by around 20%, the heat pumps run more efficiently, and the system becomes more resilient to short interruptions in either water source. It is the thermal equivalent of a battery — simple, passive, and highly effective.

What it costs to run
Iceland’s electricity is among the cleanest and most affordable in Europe, generated almost entirely from hydro and geothermal sources. At current industrial tariffs:

For every unit of electricity the heat pumps consume, they deliver 3.8 units of heat — the rest comes free from the river or the wells. Compared to direct electric heating, the CO₂ heat pump system saves approximately €750,000 per year in energy costs.

How the two systems compare

The bottom line
Finding geothermal water is our ambition and our expectation. The geology strongly supports it. But if exploration falls short, Hugarró does not fall with it.

Our backup system — three CO₂ heat pumps, two groundwater wells, a river intake, and a thermal buffer — delivers the same warmth, the same pools, and the same guest experience at a known, manageable operating cost. It was engineered in parallel with the geothermal design, not as an afterthought.

We are not betting everything on a single drill result. That is how Hugarró was designed.

Our energy source: the earth itself

Hugarró is heated entirely by geothermal energy — natural heat drawn from deep underground. It powers our pools, our hot water, our buildings, and even our roads in winter. No fossil fuels. No emissions. No utility bills.

Smarter than the traditional approach

The standard practice in Iceland is to continuously replace pool water with fresh geothermal water — discarding around 230 m³ of hot water into nature every single day. We think that is wasteful, and we designed our way around it.

Our pools use a closed-loop recirculation system: water stays in the pools and is kept clean through UV disinfection and ultrafiltration membranes — the same technology used in drinking water treatment. No chemicals are used or permitted in Iceland. A real-time microbiological monitoring system continuously checks water quality across all seven pools, so you are always swimming in water that is measurably clean.

The result? We use 91% less water than a traditional Icelandic pool operation, and we recover 33% more heat energy by not throwing it away.

One source, four uses — in sequence

Rather than drawing separate energy for each need, we run our geothermal water through a cascade:

• Geothermal pools — water enters at 70°C and heats our pools to a perfect 38°C
• Hotel & cabin heating — the same water, still warm at 50°C, then heats all our buildings
• Hot tap water — covered in the same circuit
• Road de-icing — remaining warmth is used to keep paths and roads clear in winter

The water is then returned underground at 30°C — completing a fully closed, zero-discharge cycle.

A modest well is all we need

Because our system is so efficient, a geothermal well yielding just 7–10 litres per second at 70°C covers all our needs — pools, buildings, roads, and future expansion. For context, a typical productive well in Iceland delivers 15–50 litres per second. We are not greedy with the resource.

This also means we have realistic capacity to supply heating to neighbouring summer homes and future development in the area — turning a facility cost into a potential revenue stream.

The bottom line

Vacation home district heating — Iceland

Prepared: September 2026 | Confidential — For Discussion Purposes

Executive Summary
Our geothermal project will generate significantly more thermal capacity than the primary development requires. We propose to monetise this surplus by supplying hot water to a neighbouring planned vacation home community of 50 homes across two clusters. The developer of that community has indicated willingness to co-invest in the distribution infrastructure, which materially de-risks the project and compresses the payback period to approximately 10–11 years on a shared CAPEX basis — well within the operational lifespan of the asset (30–40 years).

This is a low-marginal-cost, recurring revenue stream built on zero-cost fuel.

Project overview

Capital expenditure

Build is phased: Phase 1 (Cluster A, ~€801k) triggers on Cluster A construction start; Phase 2 (Cluster B) triggers on Cluster B confirmation. No idle capital.

Revenue & Financial Projection

Why the developer co-invests
The developer’s motivation is straightforward. In Iceland, geothermal hot water access is a market baseline expectation — lots without it sell at a meaningful discount. Based on regional comparables, reliable hot water supply adds an estimated €15,000–€25,000 per lot in realised sale value. Across 50 lots, that represents a €750k–€1.25M uplift in gross development value — making a €800k infrastructure contribution not just reasonable, but commercially rational. We are effectively subsidising their product quality.

This alignment of interests is a structural strength of the deal.

Key strengths

• Zero fuel cost. The heat is a by-product of our existing geothermal investment. Marginal cost of production is effectively nil.
• Recurring, inflation-linked income. Subscription tariffs are typically indexed to energy price benchmarks. Utility revenues are sticky and predictable.
• Captive customer base. Once connected, switching costs are prohibitive. Customer churn is essentially zero.
• Developer co-investment halves our exposure and signals strong demand validation before a single pipe is laid.
• Phased build eliminates idle capital risk. Phase 2 is only committed when Cluster B development is confirmed.
• Enhances our own project’s social licence. Community benefit strengthens planning relationships and long-term operating position.
• Gateway asset. Once operational, additional projects in the area will find our infrastructure already in place, with extension economics improving per additional customer.

Risks & mitigants

Strategic upside (not in base case)
10 existing vacation homes in the wider area were judged too dispersed and few to connect at present. As our network grows and additional developments emerge, incremental connections become progressively cheaper per home.

• Future developments attracted by proven geothermal infrastructure can be connected on similar commercial terms — each new customer improves the network economics for all parties.
• Carbon credit potential. Displacing oil or electric boiler heating with geothermal may qualify under relevant Icelandic or European carbon mechanisms — upside not yet quantified.

Summary verdict
This is a long-duration, low-risk infrastructure asset generating clean recurring income from a zero-cost fuel source, with a co-investing partner whose financial interests are directly aligned with ours. The 10.6-year payback on net invested capital is conservative — and from year 11, the revenue stream runs largely unconstrained for a further 20–30 years.

The primary negotiation priority is the mandatory connection covenant in the developer’s lot sale contracts. That single clause converts a projected revenue stream into a contractual one — and that is the difference between a good investment and an excellent one.

This document is prepared for discussion purposes only and does not constitute a formal investment prospectus. All figures are estimates based on comparable Icelandic district heating projects and are subject to detailed engineering and commercial due diligence.