Energy Efficiency and the Blower Door Test

A 2013 CSIRO report on Melbourne homes found that the average Australian home had an ACH of over 19.5!
What type of Energy Efficient Home are you after? That’s a very serious question given the cost of homes today.

So many now are claiming to build Energy Efficient Homes. Some win awards for their EEH. They claim up to 10 stars for this! Why bother with a ‘High Performance Build’ (HPB also known as Low Energy) and all this testing? The answer is somewhat simple and most of the developed world has recognised this by including it in their building codes. WHY?

It’s simple really. Leaky homes are hard to heat and hard to cool. If you live or have lived in such a home, you will understand what we mean. The only way to know whether your home is leaky or ‘tight’ is to measure its air leakage rate with a Blower Door & Thermography test. (Yes it is expensive, but it’s included in your Pure build). Air leakage is the uncontrolled movement of air into and out of your home. A passive solar design build relies on the passage of air through the home, hot or cold. A ‘High Performance Build’ home by contrast must be as airtight as possible. So immediately we see a conflict.

There are two primary types of Energy Efficient Home. A Passive Solar Design Home (the vast majority on offer in Victoria) which supposedly relies on Mother Nature and her infamous unreliability … particularly in Melbourne. Building orientation is all important to capture solar gain and prevailing breezes to cool. Fling open your doors and windows…no energy bills! Do this in summer- in 30+ degree days or nights? Do this in winter- in 5 degree nights or days? For some this is bearable. Not so for most humans. They want heating and cooling…but if the home is leaky, which by it’s nature it will surely be, you’re back to square one.

The High Performance Building champions air tightness measured in ACH at a level of 50pascals. It is a markedly different build. You control the passage of air through your tight home, not Mother Nature. Your heat/cool dollars spent to keep you comfortable inside have an excellent chance of doing just that; not heating or cooling Mother Nature outside. Building orientation and solar gain are still sought after but it’s not a necessity. Just as well, because most owners are not lucky enough to have the perfect block orientation.

Blower Door combined with Themography Testing cannot be cheated. It is the only way to accurately measure the air tightness of your build and the effectiveness of your EEH. Every hole in the fabric of the building that lets in air under pressure is detected and seen. There is nowhere to hide for the complacent builder’s work. Further, unless supreme attention is paid in sealing the external fabric of the building from day 1 in the construction process, it may be too late to rectify some of the holes facilitating air movement in and out of the structure prior to handover.

Every trade involved in the build needs to be aware that every hole made in the fabric needs to be airtight patched. Miss it and there’s a problem in the making that may not be detected until too late. If a builder can manage to achieve this attention to detail, he can become a HP builder.

The ‘Real Living’ star rating is the ONLY Star Rating that really counts because it reflects real living, not a computer-generated theoretical rating. Logically, how can a theoretical rating ever truly work in practice? How many home owners even bother to consider this?

So there you have it… High Performance Build (HPB) or Passive Solar Design (PSD) Home. Energy Efficiency at different ends of the spectrum.

The COPENHAGEN 55 HPB at Croydon Hills was awarded 1.36ACH and 9.7 stars ‘Real Living’ rating. Coburg Passive House Build awarded 0.56ACH. Blackburn Low Energy awarded 0.84ACH. The STERLING 24 HPB was awarded 1.62ACH and 9.4 stars in ‘Real Living’ rating. The Langwarrin Custom Eco Mansion 33 HBP level1 was awarded 3.3ACH and 8.8 stars in ‘Real Living’ rating. These are outstanding world class results for Melbourne builds.

The HPB PassivHaus Gold Standard is 0.6ACH; except to build it costs almost double and then some more than a PURE home!