New ratings system makes energy efficiency visible in homes

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The Home Energy Ratings now available to New Zealand home owners will, for the first time, make the energy efficiency of a home easily visible and measurable, Energy Efficiency and Conservation Authority chief executive Mike Underhill says.

A home energy rating is an independent assessment of the energy performance of a home, expressed as a star rating. The assessment also includes recommendations about the most cost-effective ways to improve the home’s energy efficiency and reduce energy costs.

Mr Underhill gave two examples of assessments — a renovated 1930s house rated three and a half stars, and a new home rated five stars.
“These show how the home energy ratings will give home owners, and home buyers, an easy-to-understand measure of energy efficiency.”

The older house is a 1930s stucco brick bungalow in Point Chevalier, Auckland, with a recent extension. The home’s extension has many good features that bring the home’s rating above average compared to houses of a similar era.

The assessment process identified some areas for further improvement, particularly in the older part of the house where insulation levels could be improved.
The assessment report gives a list of recommendations that would increase the star rating, with the potential to reach six and a half stars with full insulation and double glazing on all windows.

Home owners Matt and Megan say the assessment has been useful. “It’s been good to sit down with someone who knows what they’re talking about and can tell you which things make the best sense cost-wise and are actually going to make a real difference to your power bills.”

A sample assessment of a new home rated a timber-framed, two-storey show home, with wood and plaster cladding, at five stars.
“The five star rating is good. To get an extra star, the house would have to be better oriented on the section to maximise passive heating from the sun,” Mr Underhill says. “To get to seven stars, the house would need double glazing and fewer and smaller windows on the east and west.

“This highlights the value of getting an assessment at the design stage, while it’s still possible to adapt the plans,” he says.
RMBF chief executive Pieter Burghout says the Federation supports this programme because it will help builders validate to their clients that they build quality homes that meet consumer demand.

“New Zealanders need to know how their homes stack up energy wise — and once they know, they will also need to know how to redesign their proposed new home or fix their existing home, should they want to do so.”