The Domestic Energy Users Network says heat pumps are a major reason why many New Zealanders are paying higher prices for power.
Molly Melhuish, a spokesperson for the advocacy group, says many consumers have received winter power bills almost twice as high as they were last year.
She says people have put in heat pumps believing they are efficient and will therefore save them money. The pumps are inefficient on colder days, she says, putting up power bills.
Ms Melhuish says the largest power bills are experienced by households in the coldest parts of the country.
Transpower has confirmed energy consumption in 2009 increased slightly on last year but usage is still significantly down on 2007.
Ms Melhuish says power prices in New Zealand are too high as consumers are covering the cost of building unnecessary new power stations.