Passivhaus (which translates to Passive House) is a design standard for energy-efficient buildings that aims to minimise the need for mechanical heating and cooling. As we will see, this has multiple benefits that doesn’t only include reduced energy cost but also enhanced indoor comfort, longevity and aesthetic appeal. Incorporating bise soleil, shutters and sun screens at the design stage of new builds contribute to Passivhaus standards due to the shading capabilities and reduction in solar heat gain they provide. Passivehaus buildings allow for space heating and cooling related energy savings of up to 90% compared with typical building stock and over 75% compared to average new builds. Passive House buildings use less than 1.5 l of oil or 1.5 m3 of gas to heat one square meter of living space for a year – substantially less than common “low-energy” buildings. Vast energy savings have been demonstrated in warm climates where typical buildings also require active cooling.
There are 5 Passivhaus Principles that include:
1) Thermal insulation –
All opaque building components of the exterior envelope of the house must be very well-insulated.
2) Passive House windows –
The window frames must be well insulated and fitted with low-E glass filled with argon or krypton to prevent heat transfer.
3) Ventilation heat recovery –
Efficient heat recovery ventilation is key, allowing for a good indoor air quality and saving energy.
4) Airtightness of the building –
Uncontrolled leakage through gaps must be smaller than 0.6 of the total house volume per hour during a pressure test at 50 Pascal (both
pressurised and depressurised).
5) Absence of thermal bridges –
All edges, corners, connections and penetrations must be planned and executed with great care, so that thermal bridges can be avoided.
Thermal bridges which cannot be avoided must be minimised as far as possible.
Why live in a Passivhaus?
Considering that heating and energy consumption for buildings is 40% of the UK’s total energy usage and a significant contributor to carbon emissions, the Passivhaus principles and standards represent a new type of home that can help combat these emissions.
In response to the pressing issue of climate change, the government introduced a target of net zero emissions by 2050. In 2021, the British Government announced that compliance with the Future Homes Standard (FHS) would become mandatory.
Passivhaus is a choice to not only comply with FHS and to reduce your own carbon footprint, but also the choice for an improved quality of life:
• Energy Efficiency: consuming around 75% – 95% less energy than standard UK buildings, making them a sustainable and environmentally
friendly option.
• Low energy bills: Passivhaus buildings have significantly reduced heating and cooling costs compared to traditional buildings.
• Quieter Living: A Passivhaus can be quieter than a standard new-build home, creating a more peaceful living environment.
• Better air quality: Efficient ventilation systems integrated into the building allow pollutants to be removed and maintain a good quality
of air throughout.
• Improved health: The continuous supply of fresh air and efficient heat recovery systems contribute to improved health conditions,
reducing the risk of respiratory issues and allergies.
• Warmer in Winter: Designed for a median internal temperature and for every internal surface to stay above 17ºc all year round.
• Cooler in Summer: Consideration for window positioning, deeper window reveals, ventilation and shading all avoid excessive solar gain
in Summer months.
• Eco-friendly: By reducing energy consumption, Passivhaus buildings contribute to lower carbon emissions, mitigating climate change and
reducing the environmental impact of construction.
• Higher Property Value: The energy efficiency, comfort, and quality assurance associated with Passivhaus buildings can lead to higher
property values, making them an attractive investment for homeowners.
These benefits are all achieved as part of the fabric-first approach of a Passivhaus.
What are the drawbacks of Passivhaus?
While building a Passive House affords plenty of positive features and benefits, there are a few downsides to consider:
• Higher Initial Costs: Building or retrofitting to Passivhaus can be more expensive than constructing a standard building due to the need
for high-quality materials and specialised design and construction techniques. The Passivhaus Trust conducted an in-depth report into the
additional building costs and found Passivhaus’ best practice costs were around 8% higher than comparable projects.
• Strict Design and Construction Requirements: The Passivhaus standard requires strict adherence to design and construction principles,
which can be challenging to achieve and may require specialised expertise.
• Maintenance Requirements: Passivhaus buildings require regular maintenance to ensure that they continue to perform at their optimal
level. This includes monitoring and maintaining the ventilation system, changing filters, and ensuring that the building envelope remains
airtight.
• Limited adaptability: It can be hard to adapt a Passivhaus. Even small changes to the structure, especially anything that might need
to run through a wall like fibre-optic cable, can impact the integrity.
• Potential for Overheating: In some cases, Passivhaus buildings may be prone to overheating, particularly in warmer climates or during
heatwaves. This can be mitigated through careful design and the use of shading devices.
Shading Considerations: Proper shading helps minimise solar heat gain, optimise thermal comfort, and reduce energy consumption in Passivhaus buildings. By strategically placing shading elements, such as shutters, brise soleil and sun screens, designers can control solar exposure and prevent overheating. This is especially important for south-facing facades, where solar gains are most significant.
Case Studies and Applications
Numerous buildings worldwide exemplify the successful integration of Passivhaus and solar shading systems such as brise soleil. For instance, the Bullitt Center in Seattle, designed to be the greenest commercial building in the world, employs both principles. It uses high-performance insulation and windows while incorporating sun-shading devices that adapt to seasonal changes.
Another example is the Druk White Lotus School in Ladakh, India, which uses a combination of thick insulation, airtight construction, and strategically placed brise soleil to create a comfortable learning environment in a harsh climate.
Conclusion
Passivhaus and brise soleil represent the forefront of sustainable building design. Their integration showcases how energy efficiency and architectural beauty can coexist, providing solutions that are not only environmentally responsible but also enriching to human experience. As the demand for sustainable architecture grows, the harmonious use of these principles will undoubtedly play a crucial role in shaping the buildings of the future. Architects, designers, local authorities and companies such as Contrasol play a vital role in achieving Passivhaus standards while ensuring optimal solar performance. 🌞🏡
