Why Many Houses Don’t Live Up To Their Star Ratings
Sustainable building consultancy Australian Living recently posed the question “What happens if my home doesn’t perform to the star ratings that I paid for?” to a number of building industry professionals. It garnered an interesting range of responses.
At the practical level, many replies focused on the behaviour of the occupants. It doesn’t matter how many stars the house has if windows are left open in the middle of winter, exterior shades aren’t used and if the home is fitted out with huge TV screens, halogen lights and other energy-gobbling appliances.
More concerning was the view that many builders just aren’t up to doing a proper job of installing insulation or sticking to the materials specified by the designers or architects.
Here are just a few of the comments:
“From a thermal perspective, it’s a huge problem, because even gaps as little as a millimetre, and small amounts of compression or dampness can significantly reduce the effectiveness of insulation.”
“Other problems can be caused by issues with build quality and installation details, for example leaving too many gaps in insulation, leading to a leaky building. Poor energy efficiency can also result from a lack of understanding of how to operate the home correctly, for example opening and closing windows at the wrong time.”
“The current state of the NatHERS software is such that a margin of error can be expected. It is common knowledge in the industry that, due in part to the inadequacies of the materials and fenestration libraries (which currently forcing the use of proxies) and the state of the core engine itself (both are years overdue for upgrades), and in part to the ability to ‘tweak’ results according to how the data is entered, it’s possible to vary results by up to half a star, perhaps more.”
“Did the certifier actually inspect all the relevant components and installations? In NSW, the Building Professionals Board publishes a long list of certifiers fined and/or disqualified for non-performance in such matters. Many certifiers recognise they do not know everything about everything …and call on others to certify what has been designed and installed.”
It seems that for home buyers who are truly interested in the energy performance of their new homes, trusting the star rating isn’t enough. The old rule of caveat emptor holds true.
Full responses are available here.