cool loungeroom in straw bale house

There are good reasons why we don’t build houses like we used to.

It is not uncommon in Australia, when we meet people for the first time, to start up a conversation by asking people what they do, or as is often the case for me nowadays, asking if I’m retired. The sad part is that people have been asking me that for about 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, and 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,’ which obviously raises another line of building dialogue.

We should all be pleased that we no longer build like we used to, as we now have strong guidelines that, in most instances, result in a stronger house that is much more energy efficient 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.

 

New standards

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. The assessment has been provided by Andrew Mason of Smart Construct so you can be sure that this is an accurate assessment.

 straw bale house frame in construction

Orientation

Inglewood is in central Victoria, which 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 building on this property 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 will vary from one property to the next, and I would 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 recommended by Andrew we achieved 6.3 stars, still with single glazed timber windows.

 

Double glazing

windows in a straw bale houseThere 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. In this instance the addition of double glazing rather than single glazing along, with the 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, so 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 so little attention is given to controlling overheating in summer. For this reason, it is important that when designing your home, you do not forget that you also need your home to perform well in summer. Make sure that you have appropriate eaves to protect your north facing windows from summer sun and try to keep your western walls free of significant windows, thereby avoiding the heat generated by hot afternoon sun.