5 Myths About Passive Houses That Will Make You Change Your Mind
Developed in Germany in 1990, Passivhaus, or Passive House, is a rigorous standard for achieving energy efficiency in buildings - including your home.
Its focus is to minimise energy consumption by optimising insulation, airtightness and ventilation, which can all in turn, radically reduce your carbon emissions.
But there are some strong myths surrounding the Passive House that might be stopping you from considering it as an option for your own home build.
In this article, I take a look at the top five myths surrounding Passive Houses and share what the reality really is, so you can think about whether you’d like to build your own Passive House.
Passive House Myth #1 - You can’t open the windows
Some people believe that living in a Passive House means you’ll be contained within an hermetically sealed home and cut off from the environment around you and that you won’t be able to open the windows.
While the Passivhaus standard does involve creating a building envelope with the aim of being able to control the comfort level inside your home, you can absolutely open your house up to the great outdoors.
It’s only when the environment outside becomes uncomfortable - either too hot or too cold or too smoky - that you may wish to close up your house and with conditioned, filtered fresh air cycling throughout. This will make your home comfortable indoors and you can be confident that your building envelope won’t be leaky and losing all that air through gaps in the doors, walls and windows.
The underlying standard of Passivhaus is to create building envelopes that are airtight and well insulated, giving good thermal and acoustic protection. It has a focus on thermal bridge-free construction, where heat transfer through building elements is minimised, improving indoor air quality through Energy Recovery Ventilation (ERV) and using an appropriately sized HVAC (heating, ventilation and air conditioning) system.
The on-going cost saving to your energy bills and in turn to the environment means that you are not losing conditioned air and money through gaps and uninsulated elements of your home.
And to enable certification, the quality control of the Passivhaus standards can be tested and reported on, which recognises that the standards of construction need to be reliable, so that we can reach much better comfort levels within our homes.
Passive House Myth #2 - Passive House Design & Construction is Extremely Expensive
Passivhaus design and construction and certification is still relatively new in Australia with around 65 passive homes built and certified in Australia since 2015.
While specialty materials and construction methods are required, with good quality, custom design, it’s actually possible to build a Passive House for the same total cost as a custom designed non-Passivhaus.
There’s also the long-term cost-savings to consider, as the day-to-day running of a Passivehaus is much less than a conventional house, in addition to being being healthier and much more comfortable.
There are three standards of Passivhaus which range from Passivhaus Classic which has a renewable primary energy demand equal to or less than 60 kWh/m2/year, up to Passivhaus Premium which goes down to 30kWh/m2/year. This means that Passive Houses use 80 to 90% less energy than ‘normal’ residences and 60% - 70% less than 5-star GreenStar rated homes.
Passive House Myth #3 - You can’t turn an existing home into a Passivehaus
You can definitely turn your existing home into a Passive House.
The Passivhaus Institute has developed a standard for renovations called EnerPHit. This standard aims to transform existing dwellings and reduce their heating demand by up to 90% using passive methods and components.
This means you could save up to 90% on your ongoing energy bills, by converting your home into a Passivhaus.
Passive House Myth #4 - A lot of mechanical air conditioning equipment is required.
Passivhaus HVAC is specifically sized and designed to provide very efficient heating and cooling which runs continuously. For a single family Passive House, the HVAC typically is the size of a clothes dryer and uses less energy than a 50w halogen light globe.
Thanks to the high performance building fabric required meet Passivhaus standards which involves quality controlled joins between walls and windows and junctions, the conditioned fresh air provides very good indoor air quality.
Passive House Myth #5 - Passivhaus interiors are susceptible to mould
Passive Houses are exceptionally healthy because, even though you can open the doors and windows when outdoor conditions are comfortable, there is a constant mechanical ventilation system, with heat recovery, which airs your home with fresh, filtered air.
This means that Passive Homes are not just kept at a constant temperature, but at a comfortable level of relative humidity as well. So Passive Houses are not at all susceptible to mould, and provide the benefit of being able to provide a quiet indoor environment and keep air pollution and pollen outdoors if required.
As a result, Passivhaus means that buildings are more comfortable, with controllable temperature, good acoustic insulation, clean fresh air, no mould, low to no ongoing energy costs and simpler, smaller services.
Passive Houses are the way of the future.
Advanced economies all around the world such as Scotland, Vancouver, New York and China, have adopted Passivhaus standards with over 100,000 buildings already built to these standards.
These standards are yet to become the norm in Australia but as they do, we have the potential to go even further.
With predictions of the hottest summer on record in Australia, wouldn’t it be good to be confident you will be comfortable in your home and not have soaring energy bills?
Imagine living in homes and buildings that potentially produce more energy than they consume? Not just net zero, but net positive in terms of carbon emissions, while also ensuring your family’s healthy home environment and comfort.
Passive Homes are definitely the future of building.