2023, a year of challenges and achievements: 6 flagship Passivhaus certification and consultancy projects

2023 was an exciting year at Praxis, full of challenges and achievements. We’re proud to have carried out projects in various countries, in both new-build and retrofit, promoting the development of sustainable construction and contributing to the creation of comfortable, healthy and energy efficient spaces. Below are a selection of some of the most challenging projects we took part in over the course of 2023.

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Passivhaus consultancy projects

At Praxis we are experts in applying passive and active design strategies that improve thermal comfort and reduce energy consumption in buildings. These are some of the projects we’ve taken part in during 2023:

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Passivhaus building certifications

At Praxis Resilient Buildings we are official certifiers accredited by the Passivhaus Institute in Germany. These are some of the projects in which we’ve participated in over the course of the last year.

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SIf you want to check out some of the other projects we’ve been working on, have a look at our projects section. At Praxis, we help our clients create healthy, efficient and comfortable buildings with excellent air quality and minimal energy consumption, prepared for extreme weather conditions and immune from rocketing energy prices.

Casa A, Somió, Gijón: single family home certified as PHI Low Energy Building by Praxis

This single-family home is located in Somió, Gijón, Asturias, Spain, and was designed by
Architect Juan Ignacio Corominas, and certified as a PHI Low Energy Building by Oliver Style
from Praxis. Patricia Borràs was the Passivhaus Designer on the project. Outer walls have 12cm
of external insulation fixed to 24cm honeycomb brick, U = 0.208 W/m2·K. The roof has 28cm of
XPS thermal insulation, U = 0.117 W/m2·K. The walls to ground of the heated basement have
8cm of insulation, U = 0.437 W/m2·K. The suspended floor slab has 15cm of insulation, U =
0.137 W/m2·K.

Window frames are Passivhaus certified Cortizo COR-80, Uf = 0.94 W/m2·K, with low-e argon
filled with triple glazing, Ug = 0.50 W/m2· K and g= 49%. Exterior roller blinds on all windows
control summer solar heat gains. A 9.2 kW Baxi PBM 10 air-source heat pump provides
underfloor space heating, as well as generating domestic hot water. A Passivhaus certified
ventilation unit, Aldes InspirAIR Side 240, provides controlled mechanical ventilation. The
Blower Door test result was N50 = 0.89 ren/h.

Pictures: Juan Ignacio Corominas

Link:

• iPHA de Proyectos Passivhaus Internacional database.
• Plataforma de Edificación Passivhaus PEP database.

Casa IDONIA: Passivhaus Plus timber home in Catalonia. 

Casa Idonia is a detached single-family home that has achieved Passivhaus Plus certification. A Passivhaus Plus building has a very high level of energy efficiency and generates more energy than it consumes in a typical year. The predicted total energy consumption for the house using the PHPP modelling tool is 7179 kWh/year, with a solar photovoltaic generation of 7815 kWh/year: approximately 8% more.

The house has a treated floor area of 201m² and has been built with CLT (cross laminated timber) boards, made by Egoin, using radiata pine from the Basque Country. Construction with CLT allows for fast assembly times, dry construction methods and less on-site waste, and a lower environmental impact compared to traditional reinforced concrete or metal structures.

Architect Emili Carrero Ramon oversaw the design, with construction carried out by Idonia Group. Oliver Style and Bega Clavero delivered the Passivhaus design, with Progetic installing the mechanical and electrical systems. The house has a compact shape and a good form factor (Aenvelope/ATFA = 2.8), with 8 cm of exterior insulation using Pavatex wood fibre boards on external walls, and an interior services cavity with 5 cm of Knauf Ultracoustic R mineral wool insulation, resulting in a U-value of 0.32 W/m²·K. The roof 18 cm of insulation (U-value = 0.20 W/m²·K) with the main objective of reducing transmission heat gains in the summer.

A dynamic vapour membrane, together with WERU Afino One PVC windows and top-notch airtightness detailing, provide the necessary airtightness to meet the strict requirements of the Passivhaus certification. In this case, a result of n50 = 0.45 air changes per hour was achieved in the Blower Door test. The airtightness was executed by Ecospai. The windows feature triple low-emissivity glazing and argon gas-filled cavities.

A Zehnder ComfoAir Q 450 HRV unit provides the home’s ventilation system, with high-efficiency heat recovery. The building has a Loxone home automation system. Heating and cooling is provided by an 8 kW Daikin air-to-water heat pump and fan coils for both heating and cooling. The same heat pump produces domestic hot water. A total of sisxtenn 440 Wp photovoltaic panels form a 7 kWp generator, generating the calculated 7,815 kWh/year according to the PHPP calculations.

At Praxis Resilient Buildings, we have extensive experience in Certification, Consulting, and Blower Door tests for all types of Passivhaus buildings. If you have a project you want to discuss, don’t hesitate to contact us.

https://passivehouse-database.org/index.php#d_6832

Casa IDONIA

Casa SG Costa: Passivhaus Plus in a warm climate

¿Can you imagine living in a super comfortable home, with great indoor air quality, that generates all the energy it needs with solar panels on the roof? Can you imagine a home so efficient that it can be heated with just 2 hair dryers on the coldest winter day? Can you imagine a home that stays cool in summer thanks to external blinds, natural ventilation, and a little bit of active cooling from the air conditioning system?

This is Casa SG Costa in Sitges, a single-family home that’s just received the Passivhaus Plus certification. Designed by Sergi Gargallo from SGarq, the home has been certified by Oliver Style from Praxis Resilient Buildings, an expert in Passivhaus buildings for warm climates.

With a treated floor area of 230 m2, across a basement, ground, and first floor, the exernal walls are made of “Honeycomb brick” with 10cm of high-performance EPS external thermal insulation “ETICS”. To protect the home from the scorching summer sun, the roof has a generous 20 cm of XPS thermal insulation. The windows are made by WERU, with Afino One Passivhaus certified frames (Uf = 1.04 W/m2 K) and low-emissivity triple-glazed argon filled glazing (Ug = 0.72 W/m2 K, and solar factor g = 49%). All bedroom windows have external blinds to control solar gains in summer, with large roof overhangs over the ground floor sitting room windows. The colour of the outer wall is white, like most traditional buildings in the historic centre of Sitges: this helps reflect the sun in summer and reduce indoor temperatures. Mechanical ventilation with heat recovery is provided by a Passivhaus certified Zehnder ComfoAir Q600 ERV unit, that recovers both heat (η sensible = 80%) and moisture (η latent = 68%), thus helping to reduce air conditioning loads in the humid Sitges summer.

A Daikin direct expansion or “air-to-air” heat pump provides heating and cooling, and a separate compact Panasonic PAW-DHW270F “air-to-water” heat pump for domestic hot water.

Finally, 16 solar PV modules make up a 5.7 kWp roof-mounted array. According to the PHPP energy model used for the certification, in an average year, the photovoltaic installation will generate more energy than the home consumes…can you imagine that?

https://passivehouse-database.org/index.php#d_7161

Casa SG Costa

DHW + PV: solar PV top-up for domestic hot water

Energy consumption from DHW use is often higher than heating and cooling requirements in a residential Passivhaus. This is mainly due to the large losses inherent in storing and recirculating hot water, and because heating and cooling demands are very low, thanks to an optimised fabric design that minimises thermal losses/gains. Reducing the net energy consumption of DHW in Passivhaus is therefore important.  

The article presents monitored data from a solar PV installation for a single-family certified Passivhaus in Girona, Spain, designed by Tigges Architekt and Energiehaus Arquitectos, with services installed by Progetic (Figure 1 & Figure 2). The system diverts surplus PV production to an electric immersion heater in the DHW tank, where the primary generator for hot water is an air-source heat pump.  

Monitoring data & conclusions

Monitoring data for 2018-2019 shows a total of 1211 kWh of PV production was diverted to the electrical resistance in the DHW tank, with a peak water temperature of 58 ºC. PHPP calculations projected that DHW consumption was 1764 kWh. Logically, not all of the PV energy diverted to the DHW tank is useful, as it depends on when DHW consumption takes place. Nonetheless, the system shows that solar PV top-up is effective for assisting in hot water generation, thereby reducing net energy consumption derived from hot water use, shown in (Figure 10) and (Figure 11) below.

Bibliography

[1] Feist W., Peper S., 2015, “Energy efficiency of the Passive House Standard: Expectations confirmed by measurements in practice”. Passive House Institute Dr. Wolfgang Feist, Rheinstraße 44/46, 64283 Darmstadt, Alemania.

[2] Grant N., Clarke A., 2010, “The importance of hot water system design in the Passivhaus”. Elemental Solutions, Withy Cottage, Little Hill, Orcop, Hereford, HR2 8SE, Reino Unido.

[3] Parlamento Europeo, 2010, “DIRECTIVA 2010/31/UE DEL PARLAMENTO EUROPEO Y DEL CONSEJO, de 19 de mayo de 2010 relativa a la eficiencia energética de los edificiosb(refundición)”.

Casa AYA: Latin America’s sustainable marvel combining straw bales and Passive House Standard

In the department of Canelones, Uruguay, a modest but groundbreaking architectural gem has emerged – Casa AYA. Designed by Martin Comas of Arquitectura Regenerativa, this eco-friendly dwelling redefines sustainable living in Latin America. Casa AYA stands as a testament to innovation, combining straw bale construction with the rigorous Passivhaus standard, marking a significant milestone in the region’s environmentally conscious architecture.

Redefining conventional construction

Casa AYA challenges conventional construction practices by achieving a remarkable 70% reduction in the use of concrete compared to traditional building methods. The design team achieved this impressive feat by using locally sourced timber on raised foundations and straw bale insulation, a design decision that reflects the essence of the project: reducing the environmental impact of the built environment while providing a super comfortable, healthy home with absurdly small energy bills.

Martin Comas, project architect, explains the path he’s trodden to get here and his recent immersion in the world of Passivhaus

“Before 2019, our constructions were made of concrete, brick and glass, without much real or conceptual technology. That was until I came across Passivhaus. It was a before and after thing…It’s something that opens your mind and gives you tools to take architecture to a much higher level.”

“At first, Passivhaus seemed very German to me…like, very far away. And I wondered…can this be done in Uruguay? Will I be able to find suppliers, labour, know-how and so on…and at reasonable cost? Basically, I was asking myself: is it possible?”

“With this project we not only showed that it was possible, but also, we added some layers of difficulty. For example, we set out to have the smallest possible carbon footprint (using compressed straw wherever possible). And we also set out to build it cheaper than local standard construction, with local labour and in a similar timeframe. In the end we were able to achieve all these goals. It was very challenging, but we are very proud to have managed to raise the bar for construction in Uruguay (which- to be honest- is very low).” 

Km zero and draught-free

To further celebrate its connection to the local environment, the walls of Casa AYA were plastered with clay sourced directly from the site, creating a harmonious union between the building and its surroundings. Furthermore, a mechanical ventilation system with heat recovery was installed, providing excellent indoor air quality with minimal heat loss. The Blower Door airtightness test yielded a result of n50=1.2 ach: not enough to achieve one of the project goals of PHI Low Energy Demand certification, but nonetheless, around 10 times more draught-free than standard construction in the area. When combined with controlled ventilation, reducing draughts and air leaks improves thermal comfort, reduces heat loss and energy bills, and minimizes the risk of moisture damage and unnecessary maintenance costs.

Casa AYA is more than just a home: it’s a symbol of sustainable innovation and a testament to what can be achieved when modern design meets an environmentally conscious mindset. This pioneering project in Carrasco, Uruguay, sets a new standard for environmentally friendly construction in Latin America, proving that we can live in harmony with nature while enjoying the comforts of contemporary living. Casa AYA’s successful integration of modular straw bale construction with the Passivhaus standard serves as an inspiration for architects, builders, and homeowners looking to embrace a more sustainable future.  

After handover, we have asked the architect: what would you recommend to someone when buying or renting a home?

“I would recommend that, if you can, go visit someone who already lives in a Passivhaus, so you can hear a person explain, in a real and non-technical way, what it’s like to live and feel a high-performance house, designed and built for the climate of the next 50 years. That- I think- is fundamental for anyone who is thinking of building a house.  When our clients, who’ve have already been living in these kinds of houses for a while, go to visit their parents or friends, they always comment on how different it is to live in a house with even temperatures in all spaces, damp-free, comfortable and with great air quality”.

Congratulations to Martin Comas and the team at Arquitectura Regenerativa, for designing and building one of the most sustainable homes, not only in the country, but also in the region. Do you want to build or retrofit a nearly-zero energy learning space with excellent air quality, great comfort, and absurdly low energy bills? Contact us and let’s talk through your project.

Images: Martín Comas

Project featured at Passive House Accelerator