Do I need an energy assessment for this?
By Alex Wood
By Danielle Warfe
24 November 2021
When we receive plans for building work on dwellings, we’re often asked if an energy assessment is needed for the work. And like so much in building surveying, the answer is “possibly, send through what you’ve got and let’s have a look”.
What is energy efficiency?
The National Construction Code (NCC) sets the minimum standards of safety, health, amenity and sustainability for building work in Australia. Here, sustainability refers to a building being constructed in a way that will promote the efficient use of energy and contribute to reductions in the country’s greenhouse gas emissions.
In Tasmania, this means the energy used to heat a dwelling needs to be used efficiently, and this will depend on the location of the building, its orientation and configuration, as well as the materials used in its construction.
When is it required?
Energy efficiency needs to be addressed for all new buildings and all new building work, which includes extensions and additions to your home. So even if your home extension is a small one, if it’s adding to your indoor space and will be kept warm in winter (i.e. if it’s “conditioned” space), then energy used for heating can’t be more than what is currently used.
Where the new building work is a separate space (like a sunroom), or only involves upgrading the windows and doesn’t add any more floor space, then you probably won’t need to demonstrate energy efficiency. But check this with your building surveyor to be sure.
How can you demonstrate it?
Energy efficiency can be addressed in a number of ways. You can go the recipe route, a deemed-to-satisfy solution set out in the NCC. One such solution (the “elemental” method) is to specify energy efficiency measures for individual elements of the building, such as the walls, roof and glazing, so that prescribed levels of energy use and insulation are met.
Another is to engage an energy assessor to model the proposed design using National House Energy Rating Scheme (NatHERS) software to get the required number of stars – where more stars indicate a more efficient use of energy. The benefit of this approach is that your energy assessor can offset different building elements against each other (e.g. the south-facing view window vs. more insulation in the roof).
Or you can go the bespoke route and tailor a solution specific to your dwelling (i.e. a performance solution). This will often require the input of an energy specialist and involve comparing your proposed design against a reference design to demonstrate that energy usage will not increase. We’ve seen a number of tools used for this comparison, including the NatHERS software and the glazing calculator.
So when we’re asked “do I need an energy assessment for this?”, we say not necessarily: energy efficiency must be addressed, but which method you use is up to you. And seeing as this is all a bit technical, we’ve got the same information but with pictures here.