Amazing indoor air quality

Reason #1 to choose a certified Passive House home

By Amanda Bielski, Ethos Homes |  01 September 2021

Spring is officially here and it’s wonderful … unless you suffer from seasonal allergies, as increasing numbers of people seem to. 

The clean, filtered, fresh air you get in a Passive House is one reason why I’m really looking forward to my family moving to Bushland Park. My husband Pete and his team have between them built eight certified Passive Houses in Christchurch. Soon it will be our own family’s turn to enjoy the benefits of Passive House living.

When people first hear about ‘airtight envelopes’, some worry about it being stuffy in a Passive House. Nothing is further from the truth! Pete will explain why airtightness is so important in another post, but short version: it plays a very important role in creating such an energy-efficient, comfortable building. 

The indoor air quality in a Passive House is amazing. You can’t see it, it really is something you need to experience for yourself. It’s all thanks to a mechanical ventilation system that delivers fresh air (filtered of dust, pollen and other pollutants) and extracts stale, moist air from bathrooms and kitchens. 

There’s a small unit, about the size of a clothes drier, that is often tucked in a cupboard in the laundry. Then the ducting is concealed in the ceiling with discreet vents in each room. The whole system uses very little energy—less than a 50w halogen light bulb—and it’s extremely quiet.

You can see the ventilation ducting snaking through the ceiling service cavity in this pic from the Martin Certified Passive House. There are four ducts visible that will supply fresh, filtered air; they won’t be obvious at all once the ceiling lining is fitted. Photo: Ethos Homes

In the homes being built at Bushland Park, the mechanical ventilation also has a clever heat-exchange system that recovers up to 95% of the energy in the stale air being expelled. This is used to warm the incoming air if it’s cold outside (and cool the air when it’s hot). It means the incoming fresh air is already about the same temperature as inside the house. So no draughts and an even, comfortable temperature right throughout the house: upstairs, downstairs, the south-east corner, the toilet at the end of the hallway. Everywhere!

We’re so lucky to live in New Zealand, for many reasons. While Christchurch does have problems with the inversion layer creating smog in winter, we don’t experience pollution like so many millions of people do in other parts of the world. (Can you imagine growing up, never having seen stars? Or where the sky is grey, never blue?) However, if someone in your family does suffer from hayfever, allergies or asthma, the filters in the MVHR system can be further upgraded.