They are the ground-breaking homes that have changed the way house builders in Europe in approach sustainability and heating.
And they could be the solution to an age-old problem in New Zealand.
According to Stats NZ, a third of New Zealand homes are too cold in winter, and more than a third are too warm in summer.
Wellbeing and housing statistics manager Dr Claire Bretherton says the biggest concern is that for around a third of homes the recorded temperature in winter is less than 18 degrees.
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Experts say home builders New Zealand should be embracing the Passive House – Passivhaus, as it is known where it originated in Germany
– trend, which they say will fix the issue and could reduce monthly power bills by 75 percent.
Passive Houses are, in effect, sealed through smart design and high tech insulation and ventilation to allow in and out just the correct amount of hot or cool air to maintain an even temperature in the house.
eHaus director Jon Iliffe says Auckland has one of the easiest climates in the world to build passive houses in, as it has less seasonal temperature fluctuations than in Europe or North America. However, the number of passive homes in New Zealand is in the hundreds rather than the thousands.
Iliffe’s family of five lives in a passive home and their electricity bill is around $100 a month. The house still requires heating but it’s 90 percent less than in a regular home, as the temperature inside, is constantly between 20C and 25C, winter and summer.
“It’s insanely different and the houses don’t fall apart, and you don’t spend so much on maintenance cost,” he says.
“You don’t need to repaint your bathroom and showers every six years and those things also save money, as well as the running costs.”
If the cost of running the passive house is so low, and we have the ideal climate, how come the trend is not booming?
The cost of constructing a passive house is on average 16 percent more than building a house to the standard New Zealand building code, estimated by the New Zealand Green Building Council to meet only 4 stars on their Homestar rating.
Iliffe says Kiwis' mentality is to build the quickest and the cheapest which is not the healthiest.
As the result of applying the minimum of building code and lacking heating, ventilation and insulation, New Zealand has major mouldy homes issue, Iliffe says.
“Kiwis have always been hard-working people who seem to put up with things thinking it’s the best that we can do. And as a building company, why would you build any better than a code if it’s going to cost more? In a competitive market, in order to sell houses, you have to have the best price and the cheapest material.”
In 10 years eHaus designed and built 62 residential projects with 72 now in progress from Invercargill up to Hihi Beach. Some are built up to International Passive House standards, which means energy use of only 15kWh per square meter a year, but others that use around using 50kWh of energy per square meter cost less to build and are specifically designed to our milder climate.
Building engineering company Oculus director James Powers says his company has projects under way for 800 passive units in Auckland, designed to meet changes under the Healthy Housing Act.
The new healthy homes standards states that by July 2021 they must also comply with the new healthy homes' standards within 90 days of any new tenancy starting. These require improvements in heating, ventilation and insulation, addressing leaky and mouldy rentals.
Units or apartments are the easiest residential buildings to transform into passive, Powers says.
As well as the 800 passive units in Auckland, the company has commercial projects under way too.
“For an apartment complex, where space is key, you have a lot of space taken up by a heat pump plus the expenses of running it. So, the passive house becomes more attractive as the costs are equivalent of complying with the healthy housing or going passive house,” Powers says.
People often focus on energy efficiency side of passive building but it’s mainly about comfort, he says.