If you are interested in sustainable building, it is highly likely you have heard of Passivhaus or Passive House.
Passive House (also known as Passivhaus where it originated in Germany) is an international method or technical standard of designing and constructing a building to achieve a very high level of energy-efficiency (with little or no heating or cooling required). Passivhaus buildings are the most comfortable, healthy, durable and efficient buildings in the world!
It is not to be confused with Solar Passive Design Principles (which includes orientation/natural ventilation/insulation/shading/thermal mass etc.) although most of these principles can still play a part in the overall design.
It is not an architectural style, but more concerned with the building science of how the building is put together and how it performs - and has a rigourous and robust thermal-modelling to ensure quality-assurance of the result. This means you are not really restricted by how you want your home to look and feel.
A home is one of the largest investments we will make, and we're finding more and more people want to ensure they are getting what they are paying for! The passivhaus thermal modelling has been proven to be very accurate in terms of understanding heating and cooling requirements, in addition to ensuring high quality indoor environment (healthy air quality with low C02 levels, ideal temperature and humidity levels, and no condensation/mould-growth) - all with minimal heating/cooling requirements and savings.
Unfortunately, the same cannot be said for relying solely on the NatHERS 7-star-rating system... it's all educated guesswork if the home performs as predicted. Do you want to leave it up to chance?
Here's a super simple 90 second explanation for you:
THE BASIC ELEMENTS OF A PASSIVHAUS:
- Highly insulated building envelope This is to walls, roof and floor - so the building is like a thermally-insulated esky where the inside temperature is independent from the outside temperature.
- Great windows In our climate, high-quality and well sealed double-glazed windows should suffice, sometimes triple-glazing is preferable. Windows are the weakest point in the thermal envelope of your building - we don't want to compromise on these.
- Airtight envelope If you have gaps in your building, it is like trying to have a warm bath without the plug in - you have to constantly keep filling it up with more hot water! We want to avoid this. This is one of the biggest leaps in the way we currently build in Australia - until recently air-tightness and its benefits/implications simply wasn't considered.
- Solar orientation Passive Solar Design Principles that are fundamental to all our projects – allow for northern solar gain in winter, and shade windows to prevent hot summer sun from entering house
- Controlled Ventilation An air-tight building still needs fresh air - but it must be controlled - no leaky drafts and air gaps all over the place. You can still open in windows in a Passive House, but also a low-energy and highly-efficient mechanical ventilation system is required to ensure fresh air circulates throughout the building.
- Elimination of Thermal Bridges This is one of the most ignored issues with current buildings - especially with steel/aluminium framing that conducts heat/cold through the building fabric - particularly aluminium-framed windows! Construction details are important here.
- Form Factor Consideration of size and shape of the building. Less surface areas of walls
Passivhaus aims for a comfortable indoor air temperature between 20-25 degrees celsius all year round, and uses 60% to 90% less energy for heating/cooling than a 6 star house. It is a life-cycle costing approach - so although it will cost a bit more up front in construction costs (while passivhaus is still new in Australia), it will have reductions in the cost of heating/cooling building for over 60 years (not to mention the amount of carbon emissions saved). It is worthwhile to note that energy to heat and cool is still the MOST energy consumed over a building's lifetime - much more so than the embodied energy of the construction materials.
What's the real reason people love living in Passivhaus homes?
They are so comfortable and healthy! They stay a passively comfortable temperature all year round, with no cold drafts and no cold surfaces (even in the middle of winter) - this seems almost unimaginable when around 90% of our housing stock are essentially "wooden tents"! There is also a very real and frightening issue with the indoor air quality of many of our current buildings - which includes the high levels of pollutants, dustmites, chemicals, and mould...that many occupants breathe in everyday (this is causing a lot of ill-health effects). A passivhaus provides a constant supply of fresh filtered air, and is calculated with building physics to ensure a healthy indoor environment that is much better for our well-being.
Interested in chatting with us about Passivhaus?
We understand the practical applications of high-performance buildings - whilst looking holistically at each project (building science + architecture that enriches your soul). We have hands-on experience with the design and construction of passivhaus homes with our Award-winning Certified #OwlWoodsPassiveHouse. We have a bunch more currently under Construction that are also aiming to be Certified Passivhaus, or Certified Low-Energy projects (including a straw-bale Passivhaus, a Passivhaus with a butterfly-roof and greenhouse-conservatory, and more. We have many more on the drawing-board, including Enerphit projects too... so watch this space as we share news of their progress on social media!
We are also members of the Australian Passive House Association as this is a wonderfully supportive community. Talina and Mia were part of the small working group who produced the 'Passivhaus in Australia' book, and Talina is currently a Board Director at APHA.
We are very passionate about sustainable buildings and look forward to sharing more about passivhaus with you - you'll find the enthusiasm of those of us involved is quite contagious!