BRD Studio has been using Passive House design principles in our homes since we begun so it is only logical that we would become Certified Passive House Designers to begin delivery an even higher quality of home and performance. As such we recently completed the Passive House Designer course and have been accredited by Passive House Institute.
This makes BRD Studio one of the only places in the country where you can engage an architect, passive house designer and builder all under one roof.
The Passive House concept was developed back in Germany in 1991 by a professor Dr Wolfgang Fiest. Born out of a need to build homes that were not only sustainable, but were ultra-low energy, comfortable, affordable and have excellent indoor air quality. The name comes from the German “PassivHaus”, the literal translation is passive building. Passive House is passive only in the sense that the building envelope does most of the work to maintain the comfortable temperature inside the building (without the active input from the occupants).
According to the Australian Passive House Association, a Passive House is designed and built in accordance with five simple building-science principles:
Mechanical ventilation heat recovery
High performance windows
Thermal bridge free construction
For Passive House accreditation, the building envelope must achieve an extremely low air leakage performance (less than 0.6 air changes per hour at 50 pascal).
Airtightness is the first line of strategy in achieving energy efficiency, comfort and affordability. It involves the construction of highly insulated exterior walls, roof, windows and floor slab.
Airtightness is often seen as a challenge in the Australian climate with our tendency to fling open doors and windows to let the breeze in, but Passive House design does not mean that you need to live in an airtight box. The difference is that when you close the doors and windows, there are no gaps for warm or cold air to escape, maintaining a comfortable indoor environment.
Australian building codes do not currently require mandatory air leakage testing, but such testing (e.g. a blower door test) is required at various stages of construction for full Passive House accreditation.
2. Thermal insulation
Thick and continuous insulation provides proper thermal separation between the heated or cooled inside environment and the outdoors. This improves thermal comfort and reduces the risk of condensation.
3. Mechanical ventilation heat recovery
Mechanical Ventilation with Heat Recovery (MVHR) is the process of improving the indoor air quality without opening windows or doors. It does not mean that windows and doors cannot be opened, only that they don’t need to be opened to achieve fresh air quality.
MVHR is for indoor air quality control and not for heating or cooling buildings, but MVHR systems do recover warm and cool air that would otherwise have gone to waste. They also clean the air from pollution and help to regulate humidity.
4. High performance windows
Windows play an important role in Passive House design to allow solar radiation to warm up the interior in winter, but minimise radiation in the warmer months. Windows are typically designed to be airtight and double or triple glazed.
5. Thermal bridge free construction
Good insulation will not be of any value if it is not continuous. This means keeping penetrations through the insulation to a minimum, and where it can’t be avoided, using low or non-conducting materials. The aim is to avoid thermal bridges along which heat can escape. Thermal bridges can also increase the condensation risk.