Energy efficiency ratings don't measure air tightness, experts have said new measures may be needed

A new regulatory approach to how houses are measured may be needed, experts have said, as current rating systems do not measure air tightness.

Energy efficient ratings measure the thermal comfort of a home, or how well a structure responds to external temperatures.

The rating takes into consideration the layout, orientation, construction materials and methods, the shading of the sun and how well your home takes advantage of local breezes. But air tightness does not form part of the rating.

Light House Architecture and Science director Jenny Edwards said the energy efficiency modelling done at the design stage of building approvals made an assumption the building was air tight but there was no requirement to test houses on this.

"There is no real relationship between energy efficiency and air tightness and that's the first real issue," she said.

"I've tested houses that have good energy efficiency ratings that are still quite leaky and I've tested old houses with low energy efficiency ratings that are actually nice and airtight."

Ms Edwards said the events of recent weeks could cause a shift in the industry as previously builders and architects had not had to think about the impact of outdoor air quality in Australia.

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Michael Ambrose, a research team leader at CSIRO said Australia produced some of the most leaky houses in the world.

He said the next step could be to introduce measures that rate air tightness.

"There is quite a bit of a push to have better air tightness and potentially the next move in the regulatory world is to actually mandate an air tightness level," he said.

"At the moment there is none and the regulations simply say it must be well sealed but that's wonderfully vague, there is no actual measure of what they do mean by well sealed."

Mr Ambrose said while it was hard to measure air tightness newer, more energy efficient homes generally performed better.

"By default we tend to find newer homes do perform better than older homes mainly because they are still required to put weather sealing on doors and windows and that does help," he said.

"Everything else in the house is new, the tiles are new, they have insulation in the ceiling so that helps.

"But we still don't actually have any requirement that you home must have an air tightness level of XYZ."

Jonathan Milford is all too familiar with the impact of smoke haze in leaky houses, as he has been forced to stay elsewhere during the heights of the smoke haze.

He estimated that his Dickson home was built in the 1970s.

He said it was very leaky with windows that don't shut properly.

"It's a little bit less smoky inside than out but it's not too much less smoky," Mr Milford said.

"We haven't had a chance to get an air purifier because by the time I realised it would be a good idea they were all out of stock."