Smart living: What is a 9-star house made of?

By Sophie Vorrath on 8 March 2012

When construction company Mirvac unveiled its 9.2-star rated Harmony 9 display home in Melbourne in March 2011 – to show what could “one day” be achieved by incorporating smart features that generated energy on site, reduced cooling and heating requirements, saved water and minimised the embodied CO2 in construction materials – design director John Eckert likened it to a concept car in the auto industry. “Not everything we have learnt is suitable for implementation straight away,” he said, “but our knowledge paves the way forward for the entire development industry.”

But in that very same month, a 9-star energy rated home (well, 9.1 stars, to be precise) had become a living, breathing reality for one Melbourne family. Known as Penola House, it was built in suburban Preston by a small construction and design firm called Positive Footprints, under close instruction from the home’s ambitious and eco-conscious owners, Elizabeth Wheeler and Rodney Vlais – who are now living in it, in high thermal comfort, with their young son.

What is a 9-star energy rated house? According to the NatHERS scale – the federal government-administrated Nationwide House Energy Rating Scheme that was introduced to assess the potential thermal comfort of Australian homes on a scale of zero to 10 stars – occupants of houses rated at or around the 10-star mark are unlikely to need much, if any artificial cooling or heating. At the other end of the scale, a zero-rated house means the building shell does practically nothing to reduce the discomfort of hot or cold weather.

As the NatHERS website points out, houses built in 1990 averaged about 1 star on the scale. And before the introduction of national energy efficiency regulations for houses in 2003, less than 1 per cent of Australian houses achieved 5 stars. These days, however, the average “well-designed home” is now being built at around 6 stars.