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Gov't free house plans defy physics and disregard Australian climatic conditions
The Australian federal government, through the Department of Industry and Science’s YourHome.gov.au website, has released free architect‐designed plans and base specifications for homes to achieve a minimum 7 Star NatHERS rating in a range of climate zones.
A review of the plans and base specification, then the Star Ratings, however, leads to equal parts confusion and concern. A recommended choice for a major component of the building envelope “to create a comfortable home with low impact on the environment – economical to run, healthier to live in and adaptable to your changing needs” is, in all but one climate zone: single glazed, non‐thermally improved aluminium framed windows. The lone exception was for Darwin, where aluminium frames with low solar gain low e glazing is given.
This base specification recommended by YourHome.gov.au appears not only to defy physics, but also to disregard the wide variety of climactic conditions present in Australia. It also appears to dismiss data from both the Window Energy Rating Scheme (WERS) of the Australian Window Association (AWA) and the National Fenestration Rating Council (NFRC) - a non‐profit US organization that was formed in response to the energy crises of the 1970s - by specifically allowing what is arguably the worst performing window configuration from an energy conservation standpoint.
The mere suggestion that using single glazed, basic aluminium framed windows will automatically achieve compliance to 7 stars is dubious at best and flies in the face of Australia’s push towards energy efficient products.
Building elements to achieve 7-stars
Whatever climate you live in, controlling energy transfer, and thereby energy costs are of critical importance. This leaves architects, builders and consumers with two choices: reduce the amount of glazing area in their homes or invest in energy efficient windows.
When you consider all the accumulated knowledge with regard to framing conductivity, glazing conductivity, conductive heat transfer, radiated heat transfer, and spacer configurations, it is dismaying that the Department of Industry and Science’s YourHome.gov.au would allow the poorest performing option as the base specification when trying to encourage more energy efficient housing. Why haven’t they specified, for example, a maximum U-value for the windows?
Although the base plans may have been optimised on all other building elements to achieve 7 stars, it is hugely disappointing that they have overlooked the opportunities for higher performing windows to achieve the rating.
Excerpt taken from original article by Vinyl Council of Australian Chief Executive Sophi MacMillan published on Sourceable. Read full article here.
Image courtesy of http://www.yourhome.gov.au/house-designs/design-options