Can Naiades: first summer in our Passivhaus…comfort, coolness and energy savings
I’ve worked on Passivhaus projects for more than a decade now, based here in Catalonia, north-east Spain. I came across the standard when I was doing a Masters in Architecture, Energy and Environmental studies at Centre for Alternative Technology in Wales (UK).
Can Naiades: first summer in our Passivhaus…comfort, coolness and energy savings
By Oliver Style, Praxis CEO
I’ve worked on Passivhaus projects for more than a decade now, based here in Catalonia, north-east Spain. I came across the standard when I was doing a Masters in Architecture, Energy and Environmental studies at Centre for Alternative Technology in Wales (UK). Passivhaus resonated with me…it made sense: to design, build, and retrofit buildings that are super comfortable, need very little energy and radically reduce CO2 emissions. So choosing a passive house was a way of living more coherently, and a personal statement of intent to fight against the climate emergency…of living better, with less.
It wasn’t until last year that I was able to take part in the design and construction of my own Passivhaus, Can Naiades, a prefabricated lightweight timber frame house located about 40 kilometres northeast of Barcelona, with a useful floor area of 128m2. Having heard from many clients about how wonderful it is to live in a Passivhaus, it’s quite different to experience it first-hand. What does it feel like? It feels solid, comfortable, and quiet. It feels safe, airy and light. It is everything I’ve never had in any of the houses I’ve previously lived in and complained about. It really is, GREAT!
Surfing the heat waves
We moved in at the end of May 2025 and walked slap bang into the middle of a major heat wave, with average temperatures around 4 ºC higher than previous years and peaks of 37 ºC. Walking outside was like stepping into a furnace. We had no blinds for all of June and July (they were only installed in August), but despite that, it was wonderfully cool and comfortable. We did- of course- have our (one) air conditioning unit on quite a lot…but even so, our energy use from June-October was 3 % lower than predicted with the (calibrated) PHPP energy model. Fantastic!
The house has really worked a treat this first summer. Plenty of people complain that lots of insulation and airtightness means passive houses overheat in the summer. But, despite large amounts of glazing, Can Naiades has kept us nice and cool all summer, with 96% of our energy use coming directly from the solar PV panels and battery bank.
Temperature-wise, there is a noticeable difference between the ground floor (which has a big fat concrete floor slab with lots of thermal inertia), and the 1st floor (which has very little thermal mass). Heat rises of course, so to some degree that’s as expected…but a bit of thermal inertia really does help shave the peaks of those daily temperature swings.
Powered by the sun
Between June and October, we used only 137 kWh from the grid. We got our grid feed-in connection legalised at the end of September, so in October, 57% of the energy we generated with the PV panels we used in the house and pumped the remaining 43% into the grid…clean, fossil-fuel-free electricity.
And then we got our 1st energy bill: 19 € for the month of August, of which only 3€ was for the electricity we consumed from the grid (in total 18 kWh, or 0.15 €/m2). In the 80m2 flat we used to live in, we used 475 kWh the previous August and paid 95 € for a month of electricity (1.19 €/m2)…that’s 87% less (in €/m²). Bargain!
It’s a wrap!
I remember a friend telling me once, that the only problem with living in a Passivhaus is that you don’t sleep very well when you go and stay anywhere else! There are still a lot of jobs to finish in the house and we’re skint, so we’re not going very far for the foreseeable future…but I can confirm: living in a Passivhaus is a dream come true, especially in a Mediterranean summer!
But it shouldn’t be a luxury: it should be normal, and within everyone’s reach. In the context of a serious housing crisis in many European countries, decent, comfortable, and efficient homes should be accessible to the majority of the population- especially for low-income families, who often live in a situation of energy poverty. Both the public and private sector need to work to make this a reality.
For more tecnical information about the project, have a look at this article.
Can Naiades: professionals & contractors
- Architect: Daniel Tigges – Tigges Architekt
- Quantity Surveyor/Site Supervisor/H&S: Josep Maria Fosalba – Oftecnics
- Passivhaus design, MEP system design & Blower Door testing: Praxis Resilient Buildings
- Final Blower Door test: Timo Hoek – Air Test
- Passivhaus Certification: Micheel Wassouf – Energiehaus Arquitectos
- Health & geobiological analysis: Sonia Hernandez – Arquitectura Sana
- Contractor: House Habitat
- MEP installation: Fontalgar Instalaciones
- Monitoring & control system installation: John Kregel – Hebhaus
- Solar PV installation: Prot Energia
- Shading devices: Griesser España & Buohome
- Ventilation: Zehnder
Can Naiades: components and systems
- Insulation: Panel Plus TP138, Smart Wall FKD-N Thermal, Knauf Insulation
- Specialist insulation: Nanoboard Aerogel, Pafile
- Timber structure: EGOIN
- Windows: Smartwin Compact, Ventanas Gardea
- Window subframes: ISO-TOP construction sheets WF3, Iso Chemie
- Airtightness tapes & membranes: SIGA & Onhaus
- Liquid airtight membrane and radon gas barrier: Soudatight SP & LQ, Soudal
- Radon gas sensors: Bequerel
- Control & monitoring system: Loxone
- Rainwater catchment tank: Simop 6328
- Grey water treatment system: Intewa Aqualoop, Ecospai
- Shading devices: Solomatic II 80 FIX, Griesser España
- Rooflight: DEC-C U8 + AMZ/C Z-Wave awning blind, Fakro
- Heat pump (heating, cooling, hot water): Aquarea Ecoflex, Panasonic
- DHW heat recovery systems: Zypho iZi 30 & Zypho PiPe 65, Aliaxis
- MVHR unit: Zehnder ComfoAir Q450 ERV + ComfoClime Q, Zehnder
- Solar PV system: 21 TwinPeak5 410W PV panels; 1 Primo GEN24 8.0 Plus hybrid inverter; BYD B-Box Premium HVM 13.8kW battery bank, Prot Energia
