There are several techniques that can be used when designing a home to ensure it is naturally cooler in summer and warmer in winter. Clare Parry clarifies the confusion surrounding passive house design and explains how builders can become experts in this area.
The Roebuck student residences at Dublin University in Ireland are an example of a successful Passivhaus installation overseas.
Mention the term ‘Passivhaus’ to any building professional and you may get an array of responses or a barrage of questions: an unnecessarily strict demand that takes efficiency too far; an unnecessary remedy for a problem we don’t have; or perhaps the panacea for all our building woes.
So what is it all about, really – is it something new, something different, or both?
The Passivhaus (or Passive House) design standard is effectively a guarantee of build quality. Being an ‘as-built’ standard it has marked benefits over the often applied design-only standards prevalent among our many building codes and guidelines. The English translation of Passive House can cause some confusion, with the literal translation to ‘house’ not picking up the implied
meaning of ‘building’, and the common misconception that it is the same as Passive Solar design. Due to this, even English literature often uses the German version of the name.
The Passivhaus standard came of age fairly recently in Europe, with the first official Passivhaus opened in Germany in 1992. This row of four terrace houses is still operating, achieving excellent internal comfort without the use of any major heating and/or cooling equipment. In southern Germany’s often freezing climate (which can reach temperatures of -25˚C), this is no mean feat.
The Passivhaus design principles have since been widely adopted, developed and even enshrined in the local building regulations in some regions. Based around the principles of the international thermal comfort standard ISO 7730, Passivhaus is essentially an ultra-low energy standard. Compared to typical buildings, a Passivhaus building is predicted to consume up to 75-90% less energy in operation. The core concept of Passivhaus is providing a truly energy effi cient and comfortable building while maintaining a focus on affordability.
Passive House in Australia
Design teams have adapted their techniques to different building types and climate zones, across the globe, drawing on Passivhaus principles. What is it that makes this standard so successful and what can be learned from an Australian perspective?
In Australia, sadly, we are falling behind in our application of lowenergy standards. And while we have a multitude of tools available, accounts for most of the discomfort due to draughts or excessive heat gains. A typical Australian home built before 2000 would likely achieve an airtightness test result in the realm
of 10 air changes per hour (ACH), measured in a pressurised building (to 50Pa), and in many homes this can be up to 25 ACH. Achieving this may require careful use of appropriate layers, tapes and/or vapour membranes to form a continuous airtight barrier.