Energy use fails to measure up

Most New Zealand houses rate appallingly when it comes to using energy sustainably, according to a scheme developed by the Building Research Association (Branz).

The Green Home Scheme, released in 1997 and about to be updated, rates houses using four performance categories from fair to excellent.

Most houses being built, as well as existing houses, do not even reach the bottom of the scale.

Branz spokesman Chris Kane said the revamped Building Act required new houses to follow the principles of sustainable development, which the association welcomed.

The scheme advocates practices such as double-glazing, high levels of thermal insulation, heat storage materials, good ventilation in moist areas and solar power where possible.

Mr Kane said although sustainable energy standards were still fairly loosely applied to the new Building Act, they would become more precise.

People had historically tended to view their houses as fashion accessories, he said, and were reluctant to put a solar hot-water system on the roof, for example, but that was changing.

"It [sustainable energy] is starting to become top of mind for a lot of home-owners."

Branz research showed that a standard house compliant with the building code used an estimated 3000kW/hour a year in space heating and 2500kW/h a year in water heating.

A comparable house rated "very good" on the scheme could cut the figures to 1110kW/h in space heating and 1500kW/h in water heating.

An average home-owner could save $625 a year, which equated to a potential $18.8 million for the 30,000 new houses to be built this year.

Although energy-saving features added to the cost of homes, Mr Kane said those costs were a maximum of 5 per cent of total building budget, and often much less.

"But it starts becoming difficult to be counting solely the financial benefits because we have done research in the past which suggests that when you have a warmer, dryer house your family are a lot healthier."

A survey conducted in Dunedin a few years ago showed that in one house tested it was warmer in the fridge than the house itself, "which is just ridiculous".

Environmental savings of about 1.6 million tonnes of carbon dioxide a year could also be beneficial to New Zealand under the Kyoto Protocol, research suggested.

"It's not about tree-hugging - far from it," Mr Kane said. "It's about ensuring we extract maximum benefit from both our scarce and our widely available resources."

Improving resource use in the existing 1.2 million houses alone would save New Zealand householders about $410 million annually.

- NZPA