People automatically assume that a straw bale house is an energy efficient house- but is it enough to pass Australia’s 6 Star Energy Rating requirement?
There are good reasons why we don’t build houses like we used to.
It is common in Australia, when meeting people for the first time, to ask people what they do. Or, as is the case for me nowadays, asking if I’m retired. The sad part is that people have been asking me that for five years so I can only assume that I look old, or at least worn out.
When I tell them I am a straw bale building consultant the conversation can last some time. If Jan (my wife) is with me, she will quickly move on as she has heard it all before. One of the most frequent comments from people, when they know that I am in the building industry, is the statement – “They don’t build houses like they used to, do they?” To which I must reply “No and thank goodness”. This obviously raises another line of building dialogue.
It is a good thing that we no longer build like we used to. We now have strong guidelines that, in most instances, result in a much more energy efficient house than the houses we built back in the 1970s. It wasn’t until about 1980 that we had access to the timber framing code, and we certainly didn’t generally give much, if any, consideration to energy efficiency.
We now have to prove that any proposed domestic building work will comply with a 6-star energy efficiency rating. At design stage, an assessor will evaluate the building and establish the energy rating. This evaluation takes many things into consideration. However, in this article we will only look at the impact of double glazing and house orientation.
One of the misconceptions of straw bale construction is that the straw bales provide so much insulation that they are a solution in themselves. However the straw bale walls, while being classified as a super insulator, represent only part of the equation. In TOB 193 February/March 2016, I explained that we are about to build a very small straw bale house in Inglewood, Victoria. It is this home that I am using to demonstrate the impact of orientation and double glazing. Andrew Mason of Smart Construct provided the assessment, so you can be sure that this is an accurate assessment.
Inglewood is in central Victoria. This area is classified as a heating zone, as there is more energy used in heating the home than cooling it. The plot is a standard old fashioned ¼ acre (1000m2), and in most instances people would build the house parallel to the boundary. The energy assessment for the home with this ‘standard’ orientation and single glazed timber windows was 5.7 stars. Andrew checked out the impact of a range of orientations, with the worst possible being 5.4 stars. The best orientation varies from one property to the next. I highly recommend that you have an energy assessor advise you on the best orientation for your property. By twisting the building on the Inglewood property, to the orientation Andrew recommended, we achieved 6.3 stars. Still with single glazed timber windows.
There is considerable cost involved in upgrading from single glazed to double glazed windows, so I was eager to know the true impact of this upgrade on this small house. The addition of double glazing, with best possible orientation, saw an increase from 6.3 stars to 7.4 stars. This is a significant increase in efficiency, particularly considering that the proposed home is only 6 metres wide facing north. It may be that the impact of double glazing on a full house, with the longest face toward north-south, could be significantly greater.
As mentioned, the Inglewood property is in a heating environment. We pay little attention to controlling overheating in summer. It is important that you design your home to also perform well in summer. Make sure that you have appropriate eaves to protect your north facing windows from summer sun. Try to keep your western walls free of significant windows, thereby avoiding the heat generated by hot afternoon sun.
Energy efficiency is an important aspect of all new Australian homes. Not just to comply with building codes, but so that we all have comfortable and sustainable living environments. If you would like to know more about how we can teach you to build your own straw bale, energy efficient house, head to our online workshop page. We offer a 30 day money-back guarantee.
Also feel free to ask us questions below! Both Micah and Gabbi worked as Thermal Performance Assessors and are well equipped to answer your energy-efficiency-related queries!