14th January, 2016 | Jessica Hogg
As a Certified Passivhaus Designer, I’ve had some interesting discussions with both friends and colleagues about their perceptions of what they think a Passivhaus building actually means.
It’s time to shed some light on a few of the myths and misconceptions surrounding the Passivhaus concept.
Passivhaus is just for houses
In this case, the clue is certainly not in the name. Originating from Germany, the term ‘haus’ does not simply translate as ‘house’ but is actually equivalent to the word ‘building.’ There is absolutely nothing that requires the development to be a dwelling in order for certification to be achieved. Residential, non-residential, new-build and refurbishments can all be certified; in actual fact, the cost benefits are generally increased with commercial developments.
You can’t open windows in a Passivhaus building
This is another false statement; building occupants can open windows whenever they wish. Thermal comfort and occupant well-being is part of the ethos behind the standard, and providing a connection with outside is essential. The misconception comes from the fact that Passivhaus buildings do have mechanical ventilation, maintaining that the indoor environment quality doesn’t rely on users opening windows.
Triple glazing is a requirement
The Passivhaus standard is a whole-building assessment, with compliance determined in part by the predicted energy demands of the development. This allows the designer a certain amount of flexibility in choosing how to meet this energy target. In temperate climates in Australia, triple glazing may not be necessary to achieve these performance standards.
They all have the same ‘look’
The only thing limiting the aesthetic impact of a Passivhaus is your imagination. There are particular architectural features that are certainly beneficial to achieving the standard, such as increased glazing on the north orientation for example, but there are plenty of interesting and intriguing designs in all sorts of procurable building products to create whatever you desire.
The air quality is very poor
In actual fact, the opposite is true. One of the requirements for Passivhaus certification is that the building meets a very low level of air permeability, which means that it has very few leaks in it. This ensures that the indoor environment can be closely controlled, with no unnecessary losses from conditioned air escaping through gaps in the building fabric. The mechanical ventilation system provides fresh air, which has been filtered and passed through a high efficiency heat recovery unit. This maintains a very high level of air quality, greatly minimising any risk of condensation or mould growth in the building, and maximising the health and well-being of the building users.
Passivhauses are very expensive
The investment in higher quality building components will be mitigated to a degree by a reduction in the size of heating and cooling plant required. However, a Passivhaus is very likely to cost more upfront than their borderline NCC compliant counterpart, particularly in a developing market such as Australia.
But when the long-term projections are accounted for, a Passivhaus building will save you money, and as energy prices continue to rise, these savings will be further realised. But something to bear in mind are the non-economic benefits that are associated with Passivhaus – more comfortable, healthier buildings.
It’s encouraging to see that the uptake of Passivhaus design is on the rise in Australia, and for the first time, the South Pacific Passivhaus conference will take place in Australia early next year. At a time when NCC compliance certainly isn’t pushing the forefront of energy efficiency, unfortunately we must rely on the grassroots push from below.
Even if a certified Passivhaus isn’t sought for a project, it can function as an excellent design guide to ensure our buildings are designed for the climate they’re in, maximising energy efficiency whilst ensuring thermal comfort and occupant well-being are at the forefront of the design.
I mean, we are building buildings for people, aren’t we?