Can Naiades: first winter in our Passivhaus…warmth, comfort and tiny energy bills

By Oliver Style, Praxis CEO

I’ve lived in a few cool-temperate climates over the years – the UK, Switzerland, northern France – places where you’d expect winter to feel like winter. But, weirdly enough, I don’t think I’d ever really felt the cold at home as much as when I first moved to Barcelona in 2010 and installed myself in a flat in the historic city centre. Not because Barcelona is especially cold. It isn’t at all. But because many homes aren’t fit for the (thankfully!) short Mediterranean winter, and- in the case of the flat I moved in to- didn’t have the luxuries of central heating.

So, having got through our first summer in Can Naiades — our new Passivhaus — with flying colours, the next big question was: what would winter be like?

Would the house stay warm? Would the real energy consumption match the PHPP model? Would the solar PV and battery still pull their weight at the time of year when solar generation is at its lowest and energy demand is at its highest? Let’s have a look…

Nice and toasty

The short version is: it has been absolutely lovely.

The house has felt warm, calm and incredibly comfortable throughout the winter. Not “warm” in that slightly aggressive way you get when a radiator is blasting away in one corner of the room while your feet are still cold. Just evenly, quietly, consistently warm.

Temperatures have been stable and homogeneous throughout the house, with no noticeable cold spots, no draughts, and no cold air pouring in around windows, doors or junctions. That might sound like a small thing, but when you’ve lived in enough leaky buildings, the absence of discomfort becomes a kind of luxury.

There’s also something very particular about the quality of the air in a Passivhaus in winter. Because the house is airtight and ventilated continuously with heat recovery, we’re not relying on random infiltration through cracks and gaps to provide “fresh” air. The ventilation system just gets on with it: extracting stale, humid air from the kitchen and bathrooms, supplying filtered fresh air to the bedrooms, office and living spaces, and recovering heat from the outgoing air in the process.

The result is a house that feels fresh without feeling cold. That’s the magic trick. And then there’s the other great thing: no mould and no condensation. None. Zero.

This is the first home I’ve lived in, in Catalonia, where winter has not meant some combination of wet window frames, condensation on glass, suspiciously dark corners, or the occasional nasty surprise behind a wardrobe. In previous homes, condensation and mould felt like something you just had to manage: ventilate more, heat more, wipe it down, paint it over, move the furniture away from the wall, hope for the best.

Here, it just hasn’t happened. That’s not an accident. Warm internal surface temperatures, good insulation, reduced thermal bridges, airtightness, and continuous mechanical ventilation all work together. In practice, the experience is wonderfully uneventful: walls stay warm, indoor humidity is controlled, the air stays fresh, and nothing goes furry.

Fantastic!

The numbers

Of course, comfort is the most important thing. Buildings are for people, not spreadsheets. But the numbers matter too — especially if we want to show that low-energy, high-comfort buildings work not just in theory, but in real life, with real families, real weather, real cooking, real showers, real washing machines, and real life generally getting in the way.

So how did Can Naiades perform?

Really well. Over the winter period, the total measured energy consumption of the house was only 3% higher than the values predicted by the PHPP energy model. That’s a pretty remarkable result, given that PHPP is a design tool and real life is…well, real life, and consistently unpredictable.

There are always differences between modelling and measured performance: occupant behaviour, set-point temperatures, appliance use, hot water consumption, weather variations, commissioning, controls, and the million small things that happen once a building is occupied. So, to be within 3% of the predicted value is a very good sign that the design assumptions, construction quality and installed systems are all broadly doing what they were supposed to do.

Even better, despite winter being the worst time of year for solar generation — short days, lower sun angles, more cloud, and higher household demand — we were still 68% self-sufficient between November and February, using electricity generated by our solar PV panels and stored in the battery.

That really changes your relationship with energy. You become much more aware of when the sun is shining, when the battery is full, when it makes sense to run the washing machine, and how little energy the house actually needs to stay comfortable. It’s not about living with less comfort. It’s about getting more comfort from much less energy.

Compared with our previous flat, the difference is stark. This winter, we spent 79% less on energy bills and used 93% less energy.

Ninety-three percent less energy!

That number still makes me stop and look at it twice. Because this isn’t a smaller, colder, more miserable house. It’s the opposite: it’s bigger, warmer, healthier, quieter and more comfortable. We’re not saving energy by putting up with discomfort. We’re saving energy because the building fabric does most of the work before the mechanical systems even need to get involved.

That, for me, is the key point.

The house doesn’t need much heating because it doesn’t lose much heat and because the sun does most of the heating. The windows don’t feel cold because they’re high-performance and properly installed. The air doesn’t feel stale because the ventilation system is doing its job. The indoor temperature doesn’t swing all over the place because the envelope is insulated, airtight and carefully designed. The systems can be small because the demand is small.

It’s all very boring, really. And that’s exactly how it should be.

The best kWh…

After our first summer, I wrote that living in a Passivhaus in a Mediterranean heat wave felt like a dream come true. After our first winter, I’d say the same thing again — only with a jumper I didn’t really need.

Can Naiades has been warm, fresh, dry and comfortable, while using a tiny amount of energy. The PHPP model has proven to be very close to measured reality. The PV and battery have provided a surprisingly high level of self-sufficiency, even in winter. And our energy bills have dropped dramatically compared with our previous home.

But beyond the technical satisfaction, there’s a broader reflection.

We often talk about energy in terms of production: more renewables, more generation, more infrastructure, more supply. And of course, we need all of that. But living in this house is a daily reminder that the best kWh is still the one you don’t consume.

That truth resonates every time another war breaks out, another geopolitical crisis sends energy prices sky high, or another family has to choose between heating their home properly and paying the rest of the bills.

Reducing demand is not boring. It’s resilience. It’s comfort. It’s climate action. It’s protection against volatile energy prices. And, at the most basic level, it means living in a home that feels good.

After one summer and one winter in Can Naiades, I can confirm: Passivhaus works. And it works beautifully.

Check out our previous articles about the project:

• Can Naiades: 15 steps towards a comfortable, healthy, resilient, and efficient home
• Can Naiades: first summer in our Passivhaus…comfort, coolness and energy savings
• Can Naiades: real-life performance of a mechanical ventilation unit with heat and moisture recovery

Thank you to the following people and companies for their support:

Tigges Architekt

Aliaxis

Arquitectura Sana

Bequerel

Ecospai

EGOIN

Energiehaus Arquitectos

Fontalgar Instalaciones

FAKRO

Ventanas Gardea

Griesser

HEBHAUS

House Habitat

Iso Chemie

Knauf Insulation

Loxone

Pafile

Panasonic

Petwalk

Prot Energia

SIGA

Soudal

Zehnder

Can Naiades: real-life performance of a mechanical ventilation unit with heat and moisture recovery

Mechanical ventilation with heat recovery.

Mechanical ventilation with heat recovery (or MVHR) is a key component of passive houses. This type of system consists of a ventilation unit with a heat exchanger (and humidity exchanger if the unit is enthalpic), which transfers the energy from the air being taken out of the house, to the fresh air being supplied from outside (in summer this process operates in reverse). In this way, in winter, supply air is preheated, using only a small amount of electricity for the fans. In summer, when the indoor air is cooler than the outdoor air, the process is reversed: the air supplied to the interior is cooled.

The ventilation unit also allows the incoming air to be filtered, significantly improving air quality and reducing the amount of dust and other airborne particles.

The system operates continuously, at low airflow rates and without noise. Air is extracted from wet rooms such as bathrooms and the kitchen (eliminating the need to install separate extractor fans with roof ducts), and fresh air is supplied to dry rooms such as living rooms, dining rooms, and bedrooms.

Real‑life performance at Can Naiades

We have evaluated the real-life performance of a Zehnder ComfoAir Q450 ERV unit, installed by Fontalgar Instalaciones in the Can Naiades house, working at a flow rate of 200 m³/h. To calculate the actual performance of the machine, we’ve used the Passive House Institute’s efficiency equation:

Where:

The performance data of the Passivhaus Certificate is shown below (full data here). The heat recovery rate according to the certificate is 83%:

The Zehnder ComfoAir Q450 ERV model has not yet been certified for cooling performance. However, the ComfoAir Q350 ERV (being a very similar machine), has a cooling recovery certificate (complete data here). The cooling recovery rate in summer according to the certificate is 81%:

In both cases, the electrical consumption of the equipment is certified at 0.21 Wh/m3. In summary, the certified values are:

Field inputs and real-life performance

Temperature data were taken for a cold day in winter, and a hot day in summer. The temperatures in each case are as follows:

Winter

Summer

The electric term was calculated as follows:

The calculation of heat recovery efficiency in winter and summer is shown below:

Efficiency in winter:

Efficiency in summer:

Finally, electricity consumption, measured for 6 months of 2025 (the data available at the time of writing), was 150 kWh, shown below:

At a flow rate of 200 m³/h, for 4416 hours (June-December inclusive), that’s a total volume of 883,200 m³. The average specific fan energy consumption is therefore Wh/m³ = 883,200 ÷ 150,000​= 0.1698 Wh/m³.

In summary, the certified values compared to the measured values are as follows:

Conclusions

Regarding heat / cooling recovery, the comparison shows that the installed unit has a real-life performance very close to the certified values, both in winter and summer. As for electricity consumption, the measured value is lower than the value of the certificate.

For the moment analysed in winter, the MVHR unit pre-heats the supply air from -1.5ºC to 19.9 ºC, with a ΔT = 21.4 ºC and a COP = 42 (recovered heating power ÷ electrical power input). This translates into significant savings in space heating energy consumption.

We’d like to thank Fontalgar Instalaciones and Zehnder Group Ibérica for their support on this project.

Glaser vs WUFI: Comparative Hygrothermal Analysis of Interior Insulation on Solid Brick Walls in Two Climates

We know that a deep energy retrofits can be delicate, so the question often arises: what tools can I use for the hygrothermal analysis of potential moisture damage?

In this article, we present a comparison between the simplified Glaser calculation method, as specified in ISO 13788 [1], and dynamic hygrothermal simulation with WUFI Pro 1D [2], in accordance with EN 15026 [3], in two Spanish climates: Barcelona and Burgos. The case study looks at a historic solid brick wall, unrendered, with interior insulation, where we analyse the relative humidity on the interior face of the existing wall, and compare the results from each calculation method. Although ISO 13788 makes clear what the limitations of the Glaser method are, and that it should not be used in cases like this, in practice it is still widely used among building professionals. The results underline the limitations of the simplified method for analysing moisture transport in solid walls with interior insulation.

Introduction

A whole‑building deep energy retrofit radically changes the hygrothermal response of the building envelope. What if I can only install interior insulation on a solid brick wall, exposed to driving rain? Will there be condensation and moisture problems? What tools can I use to analyse the risk? One of the most common tools is the Glaser method, included in ISO 13788. But how reliable are its results?
Let’s look at the results of a comparative study between the Glaser method and a dynamic hygrothermal simulation with WUFI Pro 1D, for a solid brick wall with interior insulation, in the climates of Burgos and Barcelona, Spain.

What tools can I use for a hygrothermal risk analysis of moisture damage in retrofit projects?

The best‑known calculation method is Glaser, covered by ISO 13788 and developed in 1958 for analysing lightweight assemblies. It is a simplified calculation method, based on monthly average indoor and outdoor temperatures and relative humidity. It assumes:

• Steady‑state heat transfer
• Moisture transfer only by vapor diffusion
• Materials are completely dry at the start

The calculation determines whether there are critical points of condensation over one year, neglecting the following physical processes:

• Variation of hygrothermal properties of materials due to their moisture content
• Latent heat absorption and release
• Capillary suction and liquid transport within materials
• Airflow through the building element
• The hygroscopic capacity of materials

ISO 13788 states that the method is valid only for building elements where these effects are negligible. So it shouldn’t be used to analyse massive assemblies with interior or exterior insulation, or for elements exposed to rain or subject to freeze–thaw cycles. Spain’s CTE DB‑HE building regulations also explicitly states this premise. Nevertheless, the Glaser method is often used incorrectly in practice.

By contrast, dynamic hygrothermal calculation via numerical simulation—described in EN 15026 and implemented in tools like WUFI and Delphin—addresses Glaser’s limitations through an hourly numerical analysis that considers all the above physical processes, realistic boundary conditions, and initial moisture conditions in materials, reflecting real‑world scenarios in retrofit or new construction.

Comparison: Glaser vs. WUFI — Solid Brick Wall with Interior Insulation

Below are the results of a comparative study between Glaser and WUFI, for the climates of Barcelona and Burgos. A 5‑cm interior thermal insulation layer is applied. A second variant with a vapor barrier on the warm side of the insulation is also studied.

The brick wall is 29 cm thick. Of the 29 cm, 80% is brick and 20% is lime mortar. The one‑dimensional section is subdivided to reflect this brick‑mortar ratio, according to the data in Figure 2, following the methodology of Little et al. [4]. Simulations in WUFI were initialized with materials at a moisture content corresponding to 80% RH, at 20°C. Simulations were run for 10 years, starting in October. The WUFI results presented in the comparison with Glaser correspond to year 10. The wall orientation in the WUFI calculations is north, with a rainwater penetration coefficient of 70%. Basic hygrothermal properties of the sample materials are shown in Figure 2.

To compare WUFI results with the monthly Glaser method (whose results do not have an hourly resolution), monthly average values of temperature and relative humidity were extracted from the hourly WUFI outputs.

Results

Figure 3 shows the results for the Barcelona climate with 5 cm of interior insulation. In January, Glaser yields temperatures 16% higher than the dynamic calculation and relative humidity 14% lower.

Figure 4 shows the results for the Burgos climate. In January, Glaser yields temperatures 22% higher than the dynamic WUFI calculation and relative humidity 4% lower.

Figure 5 shows the results for Barcelona with a vapor barrier installed between the interior insulation and the gypsum plasterboard. In January, Glaser yields temperatures 16% higher than the dynamic WUFI calculation and relative humidity 81% lower. The Glaser method indicates no risk of moisture damage, with a maximum RH of 67%, whereas WUFI indicates a mean RH of 99%, implying risk of moisture‑related pathologies.

Figure 6 shows the results for the Burgos climate. The trend is identical: the Glaser results yield much lower relative humidity values than the dynamic calculation with WUFI.

Conclusions

In Barcelona without a vapor barrier, the relative humidity results on the interior face of the existing wall are 2% to 28% lower with the Glaser method than the dynamic WUFI results. In Burgos, the difference ranges between 2% higher and 26% lower.

For the wall with a vapor barrier, the difference is much more pronounced: from 48% to 81% lower in Barcelona, and from 62% to 116% in Burgos.

The results indicate that the Glaser method described in UNE‑ISO 13788 is not suitable for analysing moisture transfer in unrendered solid walls exposed to rain with interior insulation. The large discrepancy between the results may lead to incorrect hygrothermal design and potential interstitial moisture damage.

For situations like this, that are hygrothermally sensitive, we recommend carrying out a dynamic calculation and/or consulting a specialist. We also recommend extending the study to analyse the water content of materials and the effect of air infiltration/exfiltration (beyond an analysis of relative humidity on the interior face of the wall). In addition, we recommend in‑situ testing to determine the liquid transport coefficient of a historic solid brick wall, since its hygrothermal behaviour can vary widely.

References

[1] EN ISO 13788:2016. Hygrothermal performance of building components and building elements — Internal surface temperature to avoid critical surface humidity and interstitial condensation — Calculation methods (ISO 13788:2012).

[2] WUFI (Wärme Und Feuchte Instationär): dynamic hygrothermal simulation software for analysing heat and moisture transport in building components, developed by the Fraunhofer Institute, Germany.

[3] EN 15026:2007. Hygrothermal performance of building components and building elements — Assessment of moisture transfer by numerical simulation.

[4] Joseph Little, Carolina Ferraro & Beñat Arregi (2015). Assessing risks in insulation retrofits using hygrothermal software tools. Heat and moisture transport in internally insulated stone walls. Historic Environment Scotland Technical Paper 15, Second Edition, 2015, Edinburgh, Scotland.

[5] ASHRAE 160‑2016. Standard 160‑2016 — Criteria for Moisture‑Control Design Analysis in Buildings (ANSI Approved).

Passivhaus EnerPHit certification for existing buildings: What is it and how to achieve it?

As the demand for energy-efficient buildings continues to grow, the retrofit of existing buildings to meet modern efficiency standards has become increasingly important.

Passivhaus EnerPHit certification provides a rigorous and effective framework for deep energy retrofits, ensuring optimal energy performance and comfort. This article outlines the pathways to achieving EnerPHit certification, its advantages, and considerations for partial renovations.

Pathways for achieving EnerPHit certification

There are two primary pathways to achieving EnerPHit certification: performance-based and prescriptive, together with common requirements that apply to both. Let’s take a look at each one.

1. EnerPHit Energy Demand Method

This performance-based approach is similar to Passivhaus certification for new builds but with slightly relaxed heating and cooling demand requirements, adjusted for the seven global climate zones defined by the Passivhaus Institute, shown in Figure 2.

2. EnerPHit Building Component Method

This prescriptive approach sets maximum thermal transmittance values (“U-values”) for each building element, requires control of solar gains, and establishes minimum performance requirements for mechanical ventilation with heat or moisture recovery, depending on the climate zone (Figure 4). The aim is to ensure that the retrofit is highly energy-efficient and safe with respect to moisture-related pathologies.

Common requirements (for both pathways)

For both pathways, there are common requirements. Regarding the level of air infiltration, the maximum allowed value in the airtightness (Blower Door) test is n50 = 1.0 air changes per hour (instead of n50 = 0.6 ach required by Passivhaus for new builds). Additionally, the total renewable primary energy consumption of the building is limited, depending on whether it is certified as EnerPHit Classic, Plus, or Premium (Plus and Premium include renewable energy generation), as shown in Figure 6. Each certification class has its respective seal, shown in Figure 7.

Figure 7: EnerPHit Classic, Plus y Premium seals

Advantages of EnerPHit certification

Pursuing EnerPHit certification provides numerous benefits:

• Holistic deep energy retrofit: Ensures comprehensive upgrades that prevent moisture damage associated with partial retrofits.
• Up to 90% energy savings: Significant reductions in space heating and cooling costs.
• Enhanced indoor air quality: Mechanical ventilation with heat recovery (MVHR) ensures a controlled, fresh, and comfortable air supply.
• Superior thermal comfort: High-performance insulation and airtightness eliminate cold spots and drafts.
• Efficient HVAC systems: Optimized heating, cooling, and hot water systems reduce energy consumption.
• Lower life-cycle carbon emissions: Avoids “lock-in” effects where partial renovations leave high CO2 emissions unaddressed for years.

Step-by-step retrofits and partial renovations

For phased retrofits, buildings can receive pre-certification for all steps up to the final complete retrofit, under an EnerPHit Retrofit Plan (ERP). This ensures that when all phases are complete, the building meets EnerPHit standard. Pre-certification offers reassurance to owners and planners that performance targets will be achieved and helps spread the investment over a longer period.

EnerPHit Unit certification is also available for individual apartments within multi-residential buildings. This requires:

• Airtightness verification: Either a pressure test (qe 50 ≤ 1.0 m³/(hm²)) or detailed documentation and photographic evidence of airtight construction.
• Connection to adjacent spaces: Measures to ensure the retrofit works don’t generate moisture damage in neighbouring units.

Conclusions

EnerPHit offers several pathways to achieve Passivhaus certification. When carrying out an energy retrofit, it’s especially important to implement improvements in a way that avoids moisture damage. EnerPHit certification provides reliable and safe methodologies to avoid this, ensuring that existing buildings meet modern standards of efficiency and comfort, while significantly reducing their environmental impact.

Delivering large Passivhaus buildings: Site Supervisor & Construction Verifier training

The article presents the experiences and lessons learned from our Passivhaus Site Supervisor and Construction Verifier training courses.

The courses provide architects and engineers with the tools they need for delivering large and complex Passivhaus buildings, achieving certification and reigning in cost overruns. 

Large and complex Passivhaus buildings: reducing risk and reigning in cost overruns through practical online training

“Your course has saved me at least 20,000 € in construction costs”

This was the feedback we got from the developer of a small multi-residential building we consulted on, following the online Site Supervisor course we gave to his team. The building was developed, designed, and built by a team with no prior experience in Passivhaus and has now achieved Passivhaus Classic certification.

Lack of experience increases the risk of cost overruns during the construction phase- particularly in relation to the execution of the airtight layer and achieving the required result in the final Blower Door test. Our experience with Site Supervisor and Construction Verifier training is that the courses provide architects and engineers with the tools they need for successful site supervision and navigation of the certification process, and deliver important on-site savings for developers and contractors. 

Another client, FIATC Residencias, who are developing 7 elderly people’s residencies that are all aiming for Passivhaus certification, have made our Site Supervisor and Construction Verifier course obligatory for the contractors, installers, and design teams on each project, with 3 courses held to date. In the course satisfaction survey, one student reported:

“I particularly want to highlight how useful it was to get all of us who’ll be working on-site together on the course, including both civil works and mechanical and electrical contractors”. 

Bridging the gap between Passivhaus design and Passivhaus construction: online Site Supervisor & Construction Verifier training

According to the PHI database, as of 2023, there were over 700 certified Passivhaus Designers in Spain and over 1300 Passivhaus Tradesperson, compared with 195 and 25 respectively in Germany. This suggests that Passivhaus design and tradesperson training has got off to a good start in the construction sector.

However, despite extensive Passivhaus Designer and Tradesperson training, there is a clear knowledge gap when it comes to the construction and certification of large and complex Passivhaus buildings. This is where the official Passivhaus Site Supervisor and Construction Verifier courses come in: they are especially designed to fill that gap, helping contractors, installers, site managers and tradespeople in the successful execution of large and complex Passivhaus buildings, on time, on budget, and compliant with Passivhaus certification. 

While the courses can be taken by any construction professional, those with Tradesperson and Designer qualifications can acquire the Site Supervisor or Construction Verifier add-ons, if they take the course and pass the exam (shown in Figure 2). At the time of writing, we have held two exams, leading to the first qualified Site Supervisors and Construction Verifiers in Spain. 

The format used for the courses and for the exam is 100 % online, making an easier fit with on-site work and other commitments. Exam preparation includes an intensive on-line class, with review of the course content and question and answer time. The Site Supervisor exam must be completed in under 45 minutes, and the Construction Verifier exam in under 2 hours, both done online. 

Praxis uses proprietary course material, based on abundant practical examples of on-site situations using photographs and videos. During each course, there are always two trainers, one giving the content and another attending the live chat, launching surveys, and posting references to documentation on the online campus, where 77 technical articles, guides and how-to documents are available for reading and download. A forum in the online campus provides a space for participants to ask questions, exchange ideas, and generate debate. The participants on our courses are often from very different countries and technical backgrounds, providing a rich and diverse learning environment.The Site Supervisor course consists of 4 modules, while the Construction Verifier course includes 8 modules, with the courses held concurrently.

Summary of the modules for each course and their content

Every online session includes a guest speaker, presenting a specific technical issue relating to the module in question. Both during and at the end of each session, multiple choice questions are presented online to the students, to consolidate learning and generate debate and reflection. Each online session is also recorded and made available for watching offline, with attendees commenting that they found them to be a useful resource for reviewing and taking notes after the online classes. Additionally, and to provide networking opportunities, we offer site visits for all students, so they can see a Passivhaus building under construction in the month or two following the course.

Feedback

Each course includes on online student satisfaction survey. Some of the answers provide by students are shown below:

Filling the gap for a successful execution of large and complex Passivhaus buildings

Official Passivhaus Site Supervisor and Construction Verifier courses come in: they are especially designed to fill that gap, helping contractors, installers, site managers and tradespeople in the successful execution of large and complex Passivhaus buildings, on time, on budget, and compliant with Passivhaus certification. 

The growth in Passivhaus construction in Spain in recent years has been significant: in 2021, Spain was ranked 2^nd in the world after China, with the most square meters of floor space certified to the Passivhaus standard. Increasingly, larger, and more complex Passivhaus buildings are being designed or retrofitted, tendered and built by large “mainstream” contractors and installers who often have little experience in executing Passivhaus buildings. The Site Supervisor and Construction Verifier courses provide contractors, installers, site managers and tradespeople with the knowledge they need for the successful execution of large and complex Passivhaus buildings.

Praxis at the 27th International Passive House Conference

Held in Innsbruck, the International Passivhaus Conference combines technical presentations and visits to Passivhaus buildings.

Recent developments were presented, such as the new protocol to certify apartments within multi-family residential buildings.

The International Passive House Conference is a benchmark event in the construction sector, where professionals from all over the world get together to look at the latest trends in Passivhaus and high performance buildings. Held this year in the alpine city of Innsbruck in Austria, the event combined technical presentations, visits to passivhaus buildings and an exhibition of innovative materials and components for sustainable and energy efficient construction.

Recent developments were presented, such as the new protocol to certify apartments within multi-family residential buildings. This means it won’t be necessary to carry out a step-by-step retrofit plan to obtain EnerPHit certification, and will simplify the work for Passivhaus Designers and Certifiers, while offering a solution to owners who want to retrofit and certify their apartment. Also, a new simplified version of the PHPP was presented, for the certification of single-family homes. The idea is to streamline the design and certification process for this type of property.

Praxis CEO Oliver Style gave a presentation on the Site Supervisor and Construction Verifier training courses we provide at Praxis, which have helped developers, contractors and designers minimise risk and cost overruns. He explained how the seven editions of both courses have equipped more than 80 attendees with the tools and knowledge needed to bridge the gap between design and construction for large and complex Passivhaus projects.

It was exciting to be able to meet so many professionals from such a range of countries and share ideas on how to transform architecture and create more efficient, healthy and comfortable buildings. In these two videos, Bega Clavero and Macarena Rossetti, Passivhaus Designers at Praxis, share their experience at the 27th edition of the International Passive House Conference:

Can Naiades: 15 steps towards a comfortable, healthy, resilient, and efficient home

Can Naiades is a single-family, 4 bedroom, 2 storey Passivhaus Plus home, located in Sant Julia d’Alfou, in the province of Barcelona, Catalonia, Spain. Designed by Daniel Tigges from Tigges Architekt, with Oftecnics as Quantity Surveyor/Site Supervisor, the house is built by House Habitat, with Fontalgar Instalaciones installing electrical and mechanical services, and Praxis Resilient Buildings providing Passivhaus design, HVAC system design and Blower Door testing. The house is being certified to Passivhaus standard by Micheel Wassouf of Energiehaus Arquitectos.

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3. Timber structure

The house is built with a lightweight timber structure assembled off-site by EGOIN, in the Basque country (northern Spain), using local radiata pine timber. The wall modules consist of 140mm timber studs, filled with recycled glass wool insulation and enclosed internally with a 12mm particle board and externally with a 12mm OSB 3 board.

The roof modules consist of 200mm joists, filled with recycled glass wool insulation, enclosed internally with a dynamic vapour control membrane and externally with an 18mm OSB 3 board.

The intermediate floor and roof modules all came factory fitted with a SIGA Wetguard waterproof membrane, to protect them from rain during on-site assembly. Due the double height design in the sitting room area, a part of the structure on the northern façade consists of 150mm Cross Laminated Timber (CLT) panels, together with a steel frame structure.

The wall and roof modules were delivered to site and the house was erected and waterproofed in only 8 working days, bringing with it all the advantages of off-site prefabrication: rapid onsite assembly, greater precision and build quality, less waste, and optimization of materials.

The owners would like to thank all of the following people and companies for their support with the project:

Tigges Architekt

Aliaxis

Arquitectura Sana

Bequerel

Ecospai

EGOIN

Energiehaus Arquitectos

Fontalgar Instalaciones

FAKRO

Ventanas Gardea

Griesser

HEBHAUS

House Habitat

INBIOT

Iso Chemie

Knauf Insulation

Loxone

Pafile

Panasonic

Petwalk

Prot Energia

SIGA

Soudal

Zehnder