Praxis will participate in 3 sessions at the Spanish Passivhaus Conference. We would love to see you and in Valencia!
Praxis is delivering three presentations at the Spanish Passivhaus Conference in Valencia
The 15th Spanish Passivhaus Conference takes place between November 29th and December 1st.
Don’t miss the one of the key conferences in energy efficient construction, which includes 2 hours of master classes, 11 hours of technical presentations, and 5 hours of practical sessions!
From November 29th to December 1st, the fifteenth Passivhaus Conference will take place at the Valencia Conference Center. Organized by the Spanish Passivhaus Building Platform (PEP), this event has become a reference meeting point in the sector and one of the main forums for innovation in Passivhaus on the Iberian peninsula.
At Praxis we are very happy to be able to participate as speakers in three presentations. Oliver Style and Bega Clavero will make their interventions on November 29th and 30th. We’d love to see you in Valencia!
Surfing the (heat) wave: can I use the PHPP to size cooling equipment?
Speaker: Oliver Sytle, CEO of Praxis. Passivhaus Certifier and Consultant
Date:November 29th, from 19:00h to 20:00h
It is estimated that by 2050, there will be 6 billion air conditioning units installed in the world. Global warming is causing ever more frequent heat waves, and with rising energy costs, it is crucial to optimize passive cooling strategies and correctly size cooling equipment. In this session, we will look at how to modify the boundary conditions of the Passive House Planning Package (PHPP) to correctly size cooling equipment and achieve environmental comfort with minimal energy consumption.
Modelling of air-to-air heat pumps in the new PHPP version 10
Speaker: Oliver Sytle, CEO of Praxis. Passivhaus Certifier and Consultant
Date: November 30th, from 12:00h to 14:00h
The latest version of the Passive House Planning Package (PHPP) program incorporates new functionalities and the possibility of modelling cooling equipment with far greater precision than in PHPP 9.
In this technical session, Oliver will explain the data entry requirements for modelling inverter air-air cooling equipment in the PHPP10, looking at the different operating modes (“normal mode”, “silent mode”, and “dehumidification mode”) and the Energy Efficiency Ratio at maximum and minimum power.
Eco Hub #Learnlife. Passivhaus educational modules for hot climates
Speaker: Bega Clavero, Chief Project Officer at Praxis. Passivhaus Tradesperson
Date: November 30th, from 15:45 to 17:20h
In a context where climatic conditions and air quality in Spanish educational centers are inadequate in 84% of the time, the creation of comfortable, adaptable, and healthy learning environments with good air quality and very high energy efficiency, suitable for warm climates, is a priority.
In this session, Bega Clavero will present Eco Hub, an educational module with Passivhaus Classic certification designed for warm climates with ex-situ construction techniques, designed and developed by Learnlife. The building is a learning centre, based on a scalable construction system that is adaptable to the needs of each institution, prefabricated and modular, removable and transportable to any other location, and built with low-emission and low embodied energy materials.
In the department of Canelones, Uruguay, a modest but groundbreaking architectural gem has emerged. Casa AYA stands as a testament to innovation, combining straw bale construction with the rigorous Passivhaus standard
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 stands as a testament to innovation, combining straw bale construction with the rigorous Passivhaus 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.
Straw bale innovation
The core innovation of Casa AYA lies in its use of prefabricated, compressed wheat straw panels for the floor and wall panels. These modules, crafted by a local company called BioFraming, provide a sustainable alternative to traditional construction systems, reducing the home’s environmental footprint and contributing to superior energy efficiency.
Passivhaus and thermal excellence
One of the standout features is its Passivhaus compliant, thermal bridge-free envelope. With a minimum of 20 cm of thermal insulation meticulously integrated into the floor, walls, and roof, the house is optimized for energy efficiency. Such attention to detail ensures that the home maintains a comfortable and consistent indoor temperature throughout the year.
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.
Casa Idonia is a detached single-family home that has achieved Passivhaus Plus certification: the first timber home in Catalonia to achieve this certification.
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.
LILU’s House: the exception that should be the norm Two stories First story: a client calls me, the self-builder of a home with Passivhaus Plus certification and tells me: “Outside it’s – 4 ºC and inside we’re at 19.6 ºC, with no heating on.” Second story: a family calls me, recently installed in their newly …
LILU’s House: the exception that should be the norm
First story: a client calls me, the self-builder of a home with Passivhaus Plus certification and tells me: “Outside it’s – 4 ºC and inside we’re at 19.6 ºC, with no heating on.”
Second story: a family calls me, recently installed in their newly built home, and tells me: “We’re at our wits end… we’ve turned up the temperature of the underfloor heating to 51 ºC and we’re still cold! We have really high energy bills and we’re just not comfortable. Can you help us?”
Both homes have an energy performance certificate with an “A” rating. Why, in 2023, is the second story still happening? Why, after having made the biggest investment of their lives, with the expectation of living in a comfortable house with low energy bills, are there families going through what this family is experiencing? The second story is all too common. The first story is an exception, that should really be the norm.
LILU’s House: bioPassivhaus Plus
LILU’s House is the home referred to in the first story above, and it really works. It brings together, under one roof, an office, a home, and a research unit on timber construction. Developed by Pere Linares and Montserrat Lucas, the house has a treated floor area of 142 m2 distributed over two floors. Architect Oriol Martínez has created a modern and compact design with carefully designed and protected openings to maximize solar gain in winter and prevent overheating in summer.
The house has a mixed structure of light weight timber and CLT (cross laminated timber), where healthy materials with a low environmental impact have been prioritized. With a fully industrialized construction system that was prefabricated off-site, quality and precision have improved dramatically, with reduced on-site assembly times, less waste, less dust, less noise, and a lower carbon footprint.
LILU’s House aims to be a laboratory for the dissemination of knowledge about timber construction with biobased materials, certified to the Passivhaus standard.
The home is being monitored to evaluate it’s real-life performance, where data is being recorded on indoor CO2 concentration, air temperature, relative humidity, VOCs, energy consumption, and solar PV production. The house has a roof-integrated solar photovoltaic array with 126 photovoltaic tiles and a nominal power of 6 kWp. Each year, the building will produce, on average, 42% more energy than it consumes.
This is LILU’s House: an exception, which should really be the norm.
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 …
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?
Description Passivhaus design and consultancy for a high-performance sports centre located at 2600 metres above sea level in El Pas de la Casa, Andorra. This 9000 m2 building, designed by Engitec, is in the process of Passivhaus Classic certification. Praxis has done the PHPP energy modelling, design of the thermal envelope and airtight layer, advice …
Cramea, High performance sports centre
Passivhaus design and consultancy for a high-performance sports centre located at 2600 metres above sea level in El Pas de la Casa, Andorra. This 9000 m2 building, designed by Engitec, is in the process of Passivhaus Classic certification.
Praxis has done the PHPP energy modelling, design of the thermal envelope and airtight layer, advice on low-impact materials, and analysis and optimisation of thermal bridges and construction details.
We’ve undertaken thermodynamic analysis of the building, using Design Builder (EnergyPlus), to assess thermal comfort and analyse the risk of summer overheating in critical zones in the building.
We have also consulted on mechanical and electrical system design, with proposals for improvements and compliance with the Passivhaus standard, to ensure efficient operation and low maintenance costs. Finally, we have provided with on-site Passivhaus supervision and quality control.
Location: El Pas de la Casa, Andorra
Services Passivhaus design & consultancy, thermodynamic simulation, M & E consultancy, and site supervision
Radon gas is a naturally occurring radioactive gas that can enter buildings. It is currently the second most predominant cause of lung cancer after tobacco.
Radon gas: invisible and lethal. What is it and how to prevent it?
Radon gas is a naturally occurring radioactive gas that can enter buildings. It is currently the second most predominant cause of lung cancer after tobacco. It’s colorless, tasteless and has no smell, and is produced from the natural radioactive decay of uranium, present in many types of soils and rocks.
How is radon gas measured in a building?
Becquerels (Bq) is the measurement of radioactivity. A becquerel corresponds to the transformation or decay of 1 atomic nucleus per second. In the air, radon concentration is measured by the number of transformations per second in one cubic meter of air (Bq/m3).
The national annual average reference level, set out by WHO in its “WHO Handbook on Indoor Radon: A Public Health Perspective”, is 100 Bq/m3. If this level cannot be reached due to country-specific conditions, the level should not exceed 300 Bq/m3.
Radon measuring devices are divided between passive and active detectors, with an uncertainty range of between 8% and 25%, depending on the type of device. The most common devices are usually passive, logically cheaper than active ones, and incorporate trace sensors for alpha particles, or ion electret chambers, to measure radon concentration.
As the concentration of the gas in indoor air can increase significantly in the short term (hours), is recommended to take long-term measurements (for example, 3 months). If the building has a ventilation or HVAC system, it is convenient to take measurements with the system on and off, in both cases for a long period time.
There are low-cost types of equipment such as the RadonEye RD200, or Airthings Wave, shown in Figure 2 and Figure 3.
Radon gas and the Spanish building regulations
In 2019, and for the first time, Spanish building regulations established the scope and requirement of radon gas with a reference level for the average annual radon concentration inside habitable premises of 300 Bq/m3 (triple of what is recommended by the WHO).
Applicable to all new buildings, extensions, changes of use, or refurbishment of existing buildings, the regulations require the following measures, according to the risk area:
Radon barrier between living spaces and the ground
Ventilated air gap between the living spaces and the ground
Radon barrier between living spaces and the ground
Additional protection system:
Ventilated air gap between the living spaces and the ground
Ground depressurization system that allows the gas to dissipate from the ground.
The radon gas map of Spain according to the HS6 level 1 and 2 classification is shown in Figure 4.
How does radon gas enter a building and how to avoid it?
Radon enters a building through the fissures and openings in the envelope, especially in parts of the building in contact with the ground (slabs, basement walls, etc.), where the concentration of the gas is generally higher on the floors above (ground and first floor, etc). This is accentuated in the building during the heating period, where warm air rises, and the stack effect creates air infiltration of air on the lower floors (and exfiltration on the upper floors).
Radon gas entry is reduced and/or eliminated by a gas-resistant membranes, with a diffusion coefficient against radon less than 10-11 m2/s. An example is shown in Figure 5. The barrier must be continuous, taped and sealed at all joints and service penetrations. It is advisable to conduct a Blower Door test during the construction phase to detect leaks and repair them.
In Level 1 areas, as an alternative, it is possible to build a ventilated crawl space between the living areas and the ground, although it is a less safe solution than a radon barrier.
In Level 2 areas, the radon barrier is essential, along with a ventilated crawl space or a ground depressurization system.
The ground depressurization system consists of installing a network of perforated intake ducts, with mechanical extractors that conduct the air to the outside, above the building. This system has the same drawbacks as the ventilated crawl space and depends on a mechanical system.
Although few epidemiological studies have been conducted on the possible link between radon gas in drinking water and the incidence of stomach cancer, a study by Kyle P Messier and Marc L Serre of the University of North Carolina, USA indicates that increases the risk of stomach cancer. Therefore, water becomes a double entry route, by ingestion of contaminated water or by breathing radon gas evaporated from drinking water. Under normal circumstances, the amount of radon inhaled when breathing is greater than that ingested when drinking.
Radon in drinking water can be reduced and/or eliminated by employing granular activated carbon filters, but the filter itself can accumulate radioactivity and should be located outside the thermal envelope (in a garage, for example), taking care of its treatment as toxic waste at the end of its useful life.
Study of the incidence of radon gas in 122 homes in Ireland
Barry Mc Carron, Xianhai Meng, and Shane Colclough conducted a radon gas measurement study on 122 homes in Ireland, 97 Passivhaus-certified homes, and 25 conventional homes (reference). The results can be seen in Figure 6. The average level of radon gas inside the Passivhaus dwellings was below 40 Bq/m3, both on the ground and first floors. However, in conventional homes, the average level was 104 Bq/m3 on the lower floor, and 69 Bq/m3 on the first floor.
The differences clearly show the effectiveness of airtight construction to prevent the entry of radon gas: one of the requirements of the Passivhaus certification is to have a level of air infiltrations n50 ≤ 0.60, verified by an air-tightness test.
But not only this, Passivhaus homes have a mechanical ventilation system with heat recovery, which constantly renews the air, eliminating stale and polluted air, and introducing fresh and filtered air. This can be seen in the graph in Figure 7, where Professor Walter Reinhold Uhlig of the HTW University of Dresden, measured radon gas in a Passivhaus dwelling with a mechanical ventilation system on and off. With the ventilation turned off, in certain rooms the radon level increased to 350 Bq/m3, having remained below 100 Bq/n3 with the ventilation working.
Considering how lethal it is, radon gas has- surprisingly- gone unnoticed among many professionals in the sector, public administrations, and health professionals. Thanks to increased awareness and the update of the Spanish building regulations, it’s an issue we clearly can’t ignore: we need to prevent radon from entering our buildings, and ensure correct ventilation! The empirical results shown above indicate that an air or radon gas barrier, together with a mechanical ventilation system, is a highly effective combination to reduce the entry of radon gas into a building and thus protect the health of users.
Description Passivhaus Component certification of the Hormipresa Arctic Wall construction system: a fully industrialized, high thermal inertia solution with an exterior white concrete finish. It has been certified as a Passivhaus component for the warm-temperate climate zone. To reach the Passivhaus Component certification Praxis undertook three-dimensional simulations of the wall to determine the thermal effect …
Passivhaus Component certification of the HormipresaArctic Wall construction system: a fully industrialized, high thermal inertia solution with an exterior white concrete finish. It has been certified as a Passivhaus component for the warm-temperate climate zone.
To reach the Passivhaus Component certification Praxis undertook three-dimensional simulations of the wall to determine the thermal effect of the steel connections penetrating the insulation layer using Dartwim Mold Pro 3D and Flixo Pro finite element simulation packages.
We calculated and optimised 10 standardised construction details, as required by the certification, associated with wall, roof, and floor connection details, and window installations. Praxis managed the certification process with the Passivhaus Institut.
The certification criteria for warm-temperate climate requires a Uwall ≤ 0.25 W/m2·K and all construction details must be thermal bridge free with Ψ ≤ 0.01 W/m·K.
Descripción Certificación PHI Baja Demanda Energética para una vivienda unifamiliar aislada en Gijón, Asturias, diseñada por el arquitecto Juan Ignacio Corominas. La vivienda consta de 184 m2 distribuidos en una planta baja y una planta semisótano. La construcción es mixta, combinando muros de termo arcilla rectificada con aislamiento SATE y cubierta de estructura de madera …
Casa Pasiva B en Gijón
Certificación PHI Baja Demanda Energética para una vivienda unifamiliar aislada en Gijón, Asturias, diseñada por el arquitecto Juan Ignacio Corominas.
La vivienda consta de 184 m2 distribuidos en una planta baja y una planta semisótano. La construcción es mixta, combinando muros de termo arcilla rectificada con aislamiento SATE y cubierta de estructura de madera con 28cm de aislamiento térmico. Las carpinterías son Cortizo COR 80 de aluminio con certificación de componente Passivhaus.
En la auditoría, Praxis verifica todos los documentos de cálculo y diseño presentados por la Consultora Passivhaus, que incluyen planos y memorias de arquitectura e instalaciones, cálculo PHPP, informe del test Blower Door, puesta en marcha de ventilación, seguimiento de la obra y fotografías.
Description PHI Low Energy Building certification for a single-family detached home in Gijón, Asturias, designed by architect Juan Ignacio Corominas. The house has a treated floor area of 285 m2 distributed over a ground floor and a semi-basement. The construction system is mixed, combining honeycomb brick walls with external insulation, and a timber roof structure …
The house has a treated floor area of 285 m2 distributed over a ground floor and a semi-basement. The construction system is mixed, combining honeycomb brick walls with external insulation, and a timber roof structure with 28cm of thermal insulation.
Window frames are aluminum, Passivhaus certified, Cortizo COR 80.
As part of the audit, Praxis audited the calculations and design documentation presented by the Passivhaus Consultant, which include architectural and M&E drawings and reports, the PHPP calculation, the Blower Door test report, ventilation commissioning documentation and photographs of the construction process and completed building.
Location: Gijón, Asturias
Services: Passivhaus certification
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