What is a Passive House?
A Passive House (PassivHaus) is a home built specifically to provide clean, fresh air and maintain a consistent temperature (between 20° – 25°) all year round, requiring minimal heating or cooling systems.
There are five key principles in building a Passive House: Insulation; High Performance Windows; No Thermal Bridges; Heat Ventilation Recovery and Air-Tightness.
Passive House explained in one minute
Watch the following 1 minute video for a quick summary of the benefits and principles of a Passive House.
Benefits of building a Passive House
Low Energy Bills
Passive homes allow for energy savings of up to 90% compared with typical existing buildings. Even if energy costs increase, Passive House occupants don’t have to worry. The building is practically independent of imported energy sources, and can even be supplied with renewable energy.
Adds Value
Building or retrofitting your home for the future helps give value to your property. The materials used are sustainble and designed to last for 60 years, being the life of your home.
Health Benefits
Improved air quality, clean, fresh, warm, filtered air, condensation control, and no dust mites. This mean no mildewed walls, no cold draughts, and no cold feet inside a Passive House.
Reduced CO2 Emissions
Achieved through minimal heating and cooling. For example, the house only requires 3 kilograms of wood per square metre to maintian the temperature of 20-25° throughout the seasons.
Unmatched Comfort
Passive Houses use energy sources inside the building such as the body heat from the residents or solar heat entering the building. They are often praised for their high level of comfort at any time of the year.
Affordability
The premium upfront costs average about 10-15% more than a custom home build. When factoring in the operating costs, Passive House emerges as the most affordable way to construct any building for guaranteed annual ongoing energy savings.
Passive House Principles
Complete Insulation
Passive homes required a continuous layer of super-insulation throughout the building envelope (all the walls, floor, and ceiling). This provides unmatched comfort in your home – even in extreme weather conditions. Good thermal protection can be achieved for all construction methods.
Heat Ventilation Recovery
Heat Recovery Ventilation (HRV) is required in a Passive Home (given the building is airtight). A HRV system delivers continuous clean fresh air to the home. The incoming (fresh) air is either heated or cooled (depending on the season) by the outgoing (stale) air to maintain a stable indoor temperature. Most HRV systems have a 90-95% efficiency rate which means if the outdoor temperature is 0 degrees and inside is 25 degrees the incoming air will be heated to 23 degrees just by going through the HRV system.
High Performance Windows
Passive homes require High Performing Windows which seal extremely well. Double glazing is a minimum, however triple glazing is often preferable. By positioning the windows strategically (larger windows facing North), the house will be passively heated by the sun during the colder months.
Air Tightness
Passive homes are built airtight using high performance building wraps known as membranes. Air-tightness is vital in controlling the indoor environment, unwanted air is prevented from entering the home. Air-tightness is measured using a blower door test. The measurement is what's known as Air-changes per hour. An air-change is the total volume of air in the building leaving per hour. The average Australian home has an air-change rate of 15 ACH, to achieve Passive House, this needs to be a maximum of 0.6 ACH
No Thermal Bridges
Thermal bridges are carefully managed in a Passive Home. A thermal bridge is the ability for energy (heat or cold) to be transferred into the building via a material component. Thermal bridges are minimised and eliminated where possible to prevent cold/hot spots, on the inside of the home, as well as condensation.
“I would highly recommend Stuart and his team. Stuart really cares about a high quality outcome for his clients - especially when it comes to high-performing and low-energy homes that are healthy, comfortable and durable.”
— Talina Edwards Architecture