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

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 space.

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

Over the course of last year we’re proud to have participated in both new-build and retrofit projects, helping promote the development of sustainable and low-carbon architecture.

We’ve been able to contribute to the creation of comfortable, healthy and energy efficient spaces, fostering a more conscious and responsible lifestyle.

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.


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:

Terrassahaus: multi-residential block of 14 homes in Terrassa

Terrassahaus: multi-residential block of 14 homes in Terrassa

We delivered the Passivhaus design and consultancy, on-site supervision and Blower Door air tightness tests for this pioneering project in Terrassa city center that has achieved Passivhaus Classic Certification. This is the first multi-residential building with Passivhaus certification from the real estate developer Camoblico, and marks a before and after in the company’s trajectory.

ICONIC: high performance sports center in Andorra

ICONIC: high performance sports center in Andorra

Praxis carried out the design and Passivhaus consultancy for this ambitious project, together with thermodynamic simulation with Design Builder, to assess thermal comfort in critical areas. Designed by Engitec, the project is located at 2.500 meters above sea level and combines retrofit and new construction with prefabricated building enclosures that can be rapidly assembled during the window of summer months when construction is possible. It’s been by far one of the most complex projects we’ve taken part in, with extreme climate conditions and extensive facilities, including restaurants, industrial kitchens, sports spaces, heated technical pools and a residential area for athletes

Mirador de Gràcia: a nursing home in Barcelona

Mirador de Gràcia: a nursing home in Barcelona

This is a large and complex 5000 m2 new-build nursing home, nestled in the hills above Barcelona. The project was designed by Genars and developed by FIATC, and is set to become their first elderly people’s residence to obtain Passivhaus Classic certification. We delivered Passivhaus design and consultancy, Blower Door air tightness tests and the site supervision.

 


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.

Passivhaus Premium certification in a single-family home in the Barcelona province

Passivhaus Premium certification in a single-family home in the Barcelona province

This beautiful home in Sant Pere de Ribes was designed by SgArq, a design and build practice based in Sitges that is firmly committed to delivering all projects to Passivhaus standard. The home achieved Passivhaus premium certification, the most demanding class of certification, generating around 5 times more energy than it consumes.

Passivhaus Classic social housing multi-residential building in Andorra

Passivhaus Classic social housing multi-residential building in Andorra

Over the course of 2023 we completed the Passivhaus project audit for this 3,500 m2 high-rise residential building, designed by architects Pau Iglesias and Jacint Gil, which includes commercial spaces on the ground floors and social housing above. The project is being developed by the Government of Andorra and is aiming for Passivhaus Classic certification, with completion set for late 2024. 

EnerPHit Certification at the Aldabe community and sports center in the Basque Country

EnerPHit Certification at the Aldabe community and sports center in the Basque Country

This retrofit project, designed by Energiehaus Arquitectos, includes offices, a theater, libraries, playroom, training classrooms and a sports center with an indoor heated pool and multi-sports hall. The project presents significant challenges due to the complexity of the building and the variety of uses. EnerPHit is the Passivhaus certification seal for the deep energy retrofitting of existing buildings.


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.

Praxis takes part in the 15th Spanish Passivhaus Conference in Valencia

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!

Spanish Passivhaus Conference in Valencia

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?

Passivhaus Conference Valencia | Praxis Resilient Buildings

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

Modeling of refrigeration systems | Praxis Resilient Buildings

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

Eco Hub. Passivhaus educational modules for hot climates. Passivhaus Conference

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.

 

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

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

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.

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.

compressed wheat straw panels for the floor and wall panels at Casa Aya

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.

Passivhaus and thermal excellence at Casa Aya

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.

The walls of Casa AYA were plastered with clay sourced directly from the site
Casa AYA stands as a testament to innovation, combining straw bale construction with the rigorous Passivhaus standard

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.

Photod: Martín Comas

The academic year kicks off in Praxis! We interviewed two of our students to find out how they got along.

The academic year kicks off in Praxis! We interviewed two of our students to find out how they got along. The academic year has also started in Praxis. For this autumn we’ve prepared two Passivhaus courses we’re very excited about We want to share with you the experiences of two of our students, who are …

The academic year kicks off in Praxis! We interviewed two of our students to find out how they got along.

The academic year has also started in Praxis. For this autumn we’ve prepared two Passivhaus courses we’re very excited about

We want to share with you the experiences of two of our students, who are successfully skilling-up in Passivhaus construction.

Casa Sg Costa

Photo: Joan Giribet

The academic year has also started in Praxis. For this autumn we’ve prepared two Passivhaus courses that we’re very excited about. On October 24th, we start our Construction Verifier course, and on November 7th we’ll begin our Site Supervisor course. Both courses (currently in Spanish only, but soon available in English!) will help you gain advanced skills to successfully meet the on-site challenges of large-scale Passivhaus builds.

We want to share with you the experiences of two of our students, who are successfully skilling-up in Passivhaus construction. We’re really happy to see how more and more professionals are working towards creating sustainable and energy efficient architecture. We spoke with Toni Picó, CEO of Growing Buildings and Passivhaus Tradesperson, and Álvaro Martínez, CEO of Martinez Gil, technical architect and Passivhaus Designer.

I feel very satisfied. It’s everything I hoped for and more!

“The course has an eminently practical tone, without skimping on the theoretical concepts. I’ve learnt a lot from the different teachers, talking about real projects.”

Toni Picó

CEO at Growing Buildings

Passivhaus Tradesperson

I’ve taken a step further as an expert in Passivhaus

“I’m really happy to have taken the course. I highly recommend it to professionals who want to prepare for getting on-site with high-performance building projects.”

Álvaro Martinez

Technical Architect

Passivhaus Designer


Praxis: Which course have you taken with us?

Toni P: I did the Passivhaus Site Supervisor course and passed the exam, so now I have the additional qualification of “Site Supervisor”, the add-on to my Passivhaus Tradesperson qualification, which I already had. When I heard that Praxis was giving this course, I didn’t hesitate for a moment to sign up, so that I could become the first professional in Spain to achieve this qualification!

Álvaro M: I took the Construction Verifier course. I managed to pass the exam, so I’ve got the additional qualification of Construction Verifier, the add-on to my Passivhaus Designer qualification. I’m the 1st certified Construction Verifier in Spain so I’m excited about that!


Praxis: What was your work like, before doing our course?

Toni P: I’ve been working for more than 25 years in the real estate and construction sector and 6 years in the Passivhaus sector. I work as Project Manager or Main Contractor, for the construction of single-family Passive Houses. From now on, I’ll also offer the Site Supervisor service for developers, homebuilders, contractors, and architectural and Project Management practices, who are building high-performance buildings to Passivhaus standard.

Álvaro M: I have been working in Ibiza for about 10 years, and lucky enough to have participated in several Passivhaus projects.


Praxis: What led you to sign up for the course?

Toni P: I’ve built several passive houses and I have been working with Praxis for many years, so I was confident going into the course, and excited to learn new skills to help me improve the Passivhaus building projects that I’m working on. Above all, I’m keen to apply what I’ve learnt and do the Passivhaus Site Supervision on other projects now!

Álvaro M: : I’ve known the Praxis team for a while now, both in the teaching and professional fields, so that gave me a lot of confidence.

Praxis: How do you feel after doing our course and how has it helped you?

Toni P: Very happy to have done it, with the feeling of having learned and having taken another step forward as an expert in Passivhaus construction.

Álvaro M: I feel very satisfied, it’s everything I expected and even more. The course has had an eminently practical tone, without skimping on the theoretical concepts. The general level of the classes has been very high. The diversity of speakers talking about real projects has been very instructive. The course really fills the gap between theory and practice, by training technicians in the on-site challenges of Passivhaus buildings, as Site Supervisors and Construction Verifiers.


Praxis: Who would you recommend this course to?

Toni P: To any professional working on-site in high-performance and Passivhaus projects, whether designers, project or site managers.

Álvaro M: To any professional interested in Passivhaus, and more specifically to construction professionals who want to be specifically prepared for the on-site challenges of high-performance projects. Having previously trained as a Passivhaus Designer and Tradesperson and with on-site experience, I feel that the course has perfectly closed the loop between theory and practice.


Check out our next courses (currently in Spanish only, but soon available in English!)

Icono curso Supervisión

Supervisión de Obra en Edificios Passivhaus

Curso oficial Passivhaus, para obtener competencias avanzadas para la ejecución de obras Passivhaus. Si tienes la titulación Passivhaus Tradesperson, te prepara para el examen para la obtención del título “Supervisión de obra Passivhaus”.

¡Inscripciones abiertas!

Fecha inicio: 07/11/2023

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Curso Supervisión de Obra en edificios Passivhaus

Verificación de la Construcción en Edificios Passivhaus

Curso oficial Passivhaus, obtendrás competencias avanzadas de planificación, gestión, ejecución y entrega de obras Passivhaus. Si tienes la titulación Passivhaus Designer, te prepara para el examen de la obtención del título “Verificación de la construcción Passivhaus”.

¡Inscripciones abiertas!

Fecha inicio: 24/10/2023

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Contacta con Praxis

Get in touch with us

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    Learnlife’s Eco Hub wins the Low-Tech Prize in the prestigious Green Solutions Awards 2022-2023

    Learnlife’s Eco Hub, the Passivhaus Classic certified pop-up learning space located in Castelldefels, Spain, has won the Low-Tech Prize in the Green Solutions Awards 2022-2023!

    Learnlife’s Eco Hub wins the Low-Tech Prize in the prestigious Green Solutions Awards 2022-2023

    El Eco Hub de Learnlife gana el Premio Low-Tech

    Learnlife’s Eco Hub, the Passivhaus Classic certified pop-up learning space located in Castelldefels, Spain, has won the Low-Tech Prize in the Green Solutions Awards 2022-2023!

    6 experts from the sector analysed the submissions and praised the Eco Hub for the social aspect of its spaces, as well as the non-permanent structure, which blends in with nature and reduces the environmental impact of the building.

    Designed by Sol Espoille, with Ramiro Chiaradia as collaborating architect, and Praxis Resilient Buildings delivering Passivhaus Consultancy and Blower Door testing, the Eco Hub is a pioneering learning space, sustainability, and innovation centre, built on the sea front in Castelldefels, near the city of Barcelona. The project provides a scalable, modular, prefabricated construction system for the rapid assembly of healthy learning spaces with good air quality and thermal comfort, fit for warm climates.

    Exterior Eco Hub de Learnlife
    Interior Eco Hub de Learnlife

    Learnlife is an organisation based in Barcelona whose goal is to build an open ecosystem for a new lifelong learning paradigm alongside existing education systems. Christopher Pommerening, Learnlife Founder, said: “We’re honoured to receive this prestigious award. The Eco Hub was designed to provide a learning environment that enables children to flourish, connects with nature and has a positive environmental impact.

    “The award recognises this and highlights the possibilities for change in developing purpose-inspired learning spaces that have wellbeing and the environment as pillars of their design.” 

    Certificado Casa Pasiva

    The Eco Hub is built from a series of prefabricated lightweight timber modules, built off-site, and assembled in-situ, installed on screw pile foundations, meaning it can be disassembled in the future, moved, and re-assembled elsewhere. The design team prioritised the use of healthy, low emission materials, with low embodied energy, including internal finishes with low-emission paints on fibreboard made from recycled gypsum and cellulose fibres from post-consumer waste. The module is equipped with a Passivhaus certified Zehnder mechanical ventilation system with heat recovery, and a 2.73 kWp solar PV array that generates around 90% of the building’s energy consumption.

    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 here and let’s talk through your project.

    Photos: Jordi Vila Marta – Argotphoto

    Links:

    Casa IDONIA: Passivhaus Plus timber home in Catalonia.

    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.

    Figure 1: Total consumption and generation, calculated with the PHPP

    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.

    Figure 2: CLT Timber structure from Egoin, Radiata pine

    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.

    Figure 3: View of the south facade with pergola and sunshades

    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.

    Figure 4: Photovoltaic generator on the roof of 7,04 kWp

    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

    LILU’s House: the exception that should be the norm

    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 

    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 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

    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?

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

    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.

    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.

    Diagrama

Descripción generada automáticamente
    Figure 1: Gas radon [Source Dreamstime]

    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.

    Figure 2: RadonEye RD200, low-cost radon gas meter [Source: Radonova]
    Figure 3: Airthings Wave, low-cost radon gas meter [Source: Airthings]

    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:

    Level 1:

    • Radon barrier between living spaces and the ground
    • Ventilated air gap between the living spaces and the ground

    Level 2:

    • 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.

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    Figure 4: Map of radon gas in Spain [Source: Institute for Geoenvironmental Health]

    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.

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    Figure 5: Radon gas resistant membrane, Ampack Sisalex 871

    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.

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    Figure 6: Radon gas measurement results in 122 homes in Ireland [Source: McCarron et al 2020]
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    Figure 7: Measurement of radon gas concentration in a Passivhaus dwelling, with and without controlled ventilation [Source: Prof. Walter Reinhold Uhlig]

    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.

    Freshen up: active cooling with radiant ceilings in a Passivhaus retrofit 

    The article presents an active cooling system using the supply air of the ventilation system with radiant ceiling panels, installed in a multi-residential building in the historic center of Girona, certified Passivhaus EnerPHit – Demand method.

    Freshen up: active cooling with radiant ceilings in a Passivhaus retrofit

    The article presents an active cooling system using the supply air of the ventilation system with radiant ceiling panels, installed in a multi-residential building in the historic center of Girona, certified Passivhaus EnerPHit – Demand method. For each apartment, the system consists of an air-source heat pump, a mechanical ventilation unit with heat and moisture recovery (MVHR), a coiling coil on the supply air stream, and radiant ceiling panels. Control is carried out with a home automation system, with temperature and humidity sensors in each room. The solution offers both heating and cooling, working quietly and at low temperature, providing high thermal comfort and efficient performance when used with a heat pump. Reliable performance depends on correct system sizing, proper commissioning of the control system and of ventilation flow rates, and user maintenance and replacement of filters in the MVHR units. Systems such as this are not a good solution in homes where windows are open a lot on the summer and are better suited to warm and dry climates with lower levels of humidity. 

    The building is a multi-residential 6-storey building in the historic center of Girona, certified by Passivhaus EnerPHit – Demand method [Figure 1].  This private initiative – which was the first of its kind in Catalonia – put 4 new apartments of 129 m2 and a duplex of 162 m2 on the market.  

    Due to local heritage building regulations, insulation had to be installed inside, with some loss of thermal inertia. Active cooling using a cooling coil on the the ventilation supply air is a relatively simple concept which can be cost effective to install. However, thermal power can be limited when temperatures peak. The system presented here combines supply air cooling with radiant ceiling panels, to provide sufficient power to cover peak cooling loads.  

    Figure 1: completed building

    The project data and team are shown below: 

    • Certification class: Passivhaus-EnerPHit – Demand Method 
    • Useful / gross floor area: 678 m2 / 1.038 m2 
    • Developer: MBD Real Estate Group  
    • Builder: Busquets Sitja  
    • Architects: López-Pedrero-Roda Architects  
    • M & E Engineering: PGI Engineering 
    • Control/home automation: Progetic 
    • PHPP, Passivhaus design: Oliver Style, Bega Clavero 
    • Passivhaus Certification: Energiehaus Arquitectos  

    Description and operation of the system 

    Given space and floor-to-ceiling height limitations, 2 cooling systems were initially considered: 

    1. Ventilation supply air cooling only 
    1. Ventilation supply air cooling + radiant ceiling panels 

    The second option was chosen, given that operative temperatures in the summer could not be maintained at ≤ 25ºC using ventilation supply air cooling only. With 19 m2 of radiant ceiling panels (covering around 15% of the ceiling surface area), peak cooling loads could be met, calculated for an outdoor air temperature of 34.1 ºC, with an absolute humidity = 10,5 g/kg [1].  

    For each apartment, the system included the following equipment: 

    • Heat pump: Daikin EWYQ005ADVP air-water monobloc heat pump (5.20 kW cooling / 5.65 kW heating) [Figure 2] 
    • Heat & moisture recovery ventilation unit: Zehnder ComfoAir550 enthalpic [Figure 3] 
    • Cooling coil: Zehnder ComfoPost CW10 [Figure 4] 
    • Radiant ceiling panels: Zehnder NIC 150 & NIC 300 [Figure 5] 
    • Control system: 
    • 1 temperature & humidity sensor per room 
    • 1 Loxone mini server [Figure 7] 
    • Various elements providing on/off control of the heat pump, 3-stepped control of the ventilation flow rate, and on/off control of each radiant ceiling circuit and control of water supply temperature to the radiant ceiling panels with a 3-way valve
    Figure 2: Monobloc air-to-water heat pump
    Figure 3: Energy recovery unit
    Figure 4: Coiling coil, silencer, and supply air ducts (prior to insulation of ducts)
    Figure 5: Radiant ceiling panels, prior to fixing on non-radiant panels 
    Figure 6: Infrared image of radiant ceiling panels 
    Figure 7: Control system switchboard 

    In heating mode, the heat pump generates hot water, circulating it through the radiant ceiling panels at a supply/return temperature of 45 ºC / 40 ºC. At the same time, the coil on the ventilation supply air stream heats the air to around 40ºC. The fan speed is controlled to avoid excessively high flow rates, and which can lead to low relative humidity of indoor air. 

    In cooling mode, the heat pump generates cold water, circulating it through the radiant ceiling panels at a supply/return temperature of 7 ºC / 12 ºC. At the same time, the coil on the ventilation supply air stream cools air to around 15 ºC. The coil also provides some dehumidification of the supply air, lowering the ambient indoor air dew point temperature and preventing condensation on the ceiling panels. In cooling mode, controlling the temperature of rooms individually is not possible given that the cooling coil only works for the entire apartment. 

    The heat and moisture recovery ventilation unit also helps to increase the relative humidity of the indoor air in winter and decrease it in summer, improving thermal comfort and reducing the dehumidification load that the cooling coil needs to overcome. 

    With the ventilation flow rate of 0.4 ach (135 m3/h), radiant ceiling panels typically cover – for both heating and cooling – approximately 65% of thermal loads. The ventilation system with the heating/cooling coil covers the remaining 35%. 

    Radiant cooling systems must have a robust control system, to avoid problems of surface condensation. Temperature and humidity sensors were therefore installed in each of the 5 rooms where the radiant panels were located (dining room, kitchen and 3 bedrooms). The water temperature of the panels is adjusted with a 3-way mixing valve, based on the temperature and humidity data from the sensors in each room, ensuring the panel surface temperature remains above the dewpoint, avoiding condensation.  

    The control system also modulates the ventilation unit’s fan power, lowering or raising the flow rate depending on the temperature setpoint and dehumidification needs. A schedule prevents the fan from operating as full flow at night, to avoid noise problems. If maximum power is required at night this can be a problem. The control allows you to set different setpoint temperatures according to specific schedules or occupancy rates, for each day of the week. 

    In its default setting, the ventilation system works automatically with pre-established schedules (with the possibility of manual adjustment by occupants). Figure 8 summarizes its operation: 

    Figure 8: Ventilation speeds and schedules  

    Conclusions 

    Cooling with radiant ceilings can offer an efficient solution that adds power to ventilation supply air cooling systems in Passive Houses in the summer. As the system is predominantly radiant and running at low temperature, it provides good comfort and can be more efficient than convective systems. Ceiling panels can be sized to meet heating and cooling loads, which in residential buildings retrofitted to Passivhaus standard means a coverage of between 15% to 30% of the ceiling surface area. This replaces ducted fan-coil or split systems, which take up more space in suspended ceilings, often a limitation in retrofit.  

    The control system presented here offers a flexible solution at a reasonable cost, with a relatively user-friendly interface. The possibility of visualizing and monitoring data remotely and in real time, facilitates the optimization of the system and helps in terms of preventive maintenance. 

    Systems such as this are not a good solution in homes where windows are open a lot on the summer and are more suitable for use in hot dry areas, since, in areas of high humidity, the power of the system will be limited depending on the humidity level of the indoor air and the proximity to the dew point. Robust operation depends correct system sizing, proper commissioning of the control system and of ventilation flow rates, and user maintenance and replacement of filters in the MVHR units.