Airtightness is another important principle of Passive House design in New Zealand. “Having an airtight building envelope means there is no way that any draughts can pass through any area of the building. Any draughts increase energy use and mean that warm air can pass from the house out through any gap in the building envelope. As it does this, warm air meets cold outside surfaces and condensation can form, which is a risk for mould spores and moisture; two elements that are particularly hazardous for human health. Moisture damage is also detrimental to the long-term durability of the building structure.”
During the construction process, two tests are undertaken to ensure a Passive House meets the required standard. Once the house is fully closed in, a blower door test is done, which involves first pressurising the house, and then de-pressuring the house, to see how much air leaks through the building envelope. The blower door test allows the leaks to be identified and sealed up.
Once the house is completed and all trades have finished, a second test is undertaken to ensure there are no gaps anywhere in the building envelope that degrade the airtight performance of the building envelope.
Ventilation is the third key principle of Passive House design that Elrond says is particularly important in New Zealand. “You need to have a ventilation system that is a whole house balanced system. Our indoor air quality is really poor because we don’t ventilate well. In Passive House design, that is not the case. Passive House dramatically improves indoor air quality by ensuring there is consistently filtered, fresh, clean air inside the home.”
There are currently about 12 certified Passive Houses in New Zealand, with scores more under construction. “People are starting to become more interested in Passive House design and what it can offer; it’s definitely growing in popularity in New Zealand and I believe it needs to.“
Get in touch with VIA Architecture on ArchiPro here to find out more about what Passive House design can achieve.
Photos in the article are of a certified Passive House apartment complex where Elrond Burrell was the Project Architect.