What is Passive House Design?

By Shoko McKay
July 27, 2021

Australia is a land of extremes with temperature highs of +40°C regularly experienced in summer to below freezing in the higher and low-lying regions in winter.

In fact, our extremes have become so, well, extreme due to runaway climate change that the Bureau of Meteorology had to add two new colours to its heat maps in 2013.

Electric vehicles, wind and solar energy generation, and battery storage tend to get all the attention when we talk about tackling climate change. But it’s going to take a wide array of solutions to make a real dent.  One thing that doesn’t get talked about enough is how we can build our homes to make them as energy efficient as possible, particularly in light of the fact that households are directly responsible for about 20 per cent of Australia’s greenhouse gas emissions.

The passive house movement has been brewing for quite a few decades, and is now considered the most rigorous voluntary, energy- and health-based building standard in the design and construction industry. So, if you are motivated to improve the energy efficiency of your new build or soon-to-be-renovated home, and you’re keen to employ passive house design principles, here are a few points to get you started on your journey.

What is passive house design?

In simple terms, passive house design takes advantage of natural sources of heating and cooling, such as the sun and cooling breezes. Instead of bolting on expensive heating and cooling systems to poorly performing buildings, passive house design relies on building physics and carefully integrated, minimal building services and technology. This effectively ‘locks in’ thermal comfort, low heating and cooling bills, and reduced greenhouse gas emissions for the life of the building.

Here is a fantastic 90-second video that sums it up nicely. 
Source: Hans-Jorn Eich, a passive house consultant and founder of Pinwheel, Canada.

Does the concept work in Australia?

While it is a relatively new idea here, passive house design has been around in the USA and Europe for decades. There are approximately 60,000 certified Passive House buildings around the world, a few dozen of which have been completed in Australia and New Zealand.

It is true that passive house design originated in a cold climate, however the principles perform equally well in hot and temperate climates. In fact, certified Passive House designers model each home design using site-specific climate data, so the insulation requirements and other design features are adapted accordingly.

A word to the wise though – don’t go halfway. Increasing airtightness, while a good thing in principle, brings problems if insulation and moisture control are not done in the proper way, which is not the usual way.

Is it worth the cost?

The cost for a custom build is always dependent on factors such as complexity of design, level of finish, and size. Opinions vary among builders and on the internet as to the cost to build a passive house: some claim they’re not affordable, while others say they can be built for the same price as any custom build job.

While us mere mortals await the outcome of a serious analysis, it’s important to consider the long-term energy savings, reduced maintenance costs, the return on investment at the time of re-sale and, of course, reduced greenhouse gas emissions.

More info

Keen to learn more? Why not take a look at The Fern, Australia’s first Passive House apartment building, or this passive house in Tasmania, both of which have used Knauf Insulation products to meet and exceed thermal performance requirements.