Heat pumps don't pump up power bills - study

The dramatic rise in the number of household heat pumps in Christchurch has had no effect on power use, a study has found.

A study by electricity companies Orion and Meridian Energy and Environment Canterbury (ECan) has allayed fears that power consumption would rocket with conversions from open fires or solid burners to electrical heat pumps.

Installing a heat pump typically increased a household's power consumption by 2 per cent, but that was balanced by reduced electricity use in homes that had converted to more efficient burners, pellet fires or gas, it said.

In homes where heat pumps have replaced open fires there has been a 2 per cent drop in power use.

Orion chief executive Roger Sutton said that showed how inefficient open fires were, with householders forced to also run heaters to stay warm.

People who changed from a built-in woodburner to a heat pump had a 4 per cent increase in power consumption, and those changing from a freestanding woodburner to a heat pump had an 8 per cent increase.

About 15,500 householders have taken part in the Clean Heat project since it began in 2003. The study was of more than 3400 participants whose conversions were completed before July 2007.

Sutton said the result was "fantastic", given the explosion in heat-pump use in recent years.

"The results confirm the Clean Heat project has had very limited impact on electricity use overall, despite 9300 homes in total shifting from a wood or coal-based form of heating to heat pumps," he said.

ECan director of operations Ken Lawn said the results bucked expectations.

"Anecdotally, we would have expected electricity use would have gone up a bit. We'd always said we're insulating the homes so we're not making a significant difference [to power demand], and it turns out we're not making any at all," he said.

"In a sense it's a triple whammy – improving air quality in Christchurch, producing warmer homes, and at no extra use of electricity. When you look at all that, it's pretty damn good."

The Clean Heat project allows low-income earners who qualify for rates rebates to get fully paid conversions. Those with a community services card have to pay only $500 towards new heating and up to $500 towards the cost of insulation.

ECan air-quality committee chairman Sir Kerry Burke said there had been concern 10 years ago that Christchurch supply lines might not be able to deliver the electricity on a scale that enabled conversions.

"But this shows that has not been the case," he said.

- © Fairfax NZ News