One in three New Zealanders can't afford to heat their homes properly in winter, an especially acute issue for younger people, a survey shows.
A University of Otago public health professor said the findings were concerning because living in a cold house can have serious heath implications.
A nationwide Canstar Blue survey of 2060 people found 74 per cent have changed their behaviour to limit their electricity usage.
Professor Philippa Howden-Chapman said the results were in line with the university's research.
"While everyone agrees that energy efficiency is a good idea and we don't want to waste energy, energy for keeping ourselves warm is really important. It's a very good use of energy and when people can't afford to do that, you're looking at costs that flow to the country as a whole, through the workplace and the hospital system."
The survey found 41 per cent of the female respondents found home heating a challenge, compared to 29 per cent of the males. Forty-five per cent of younger people (aged 18 to 29) faced a chilly winter.
Professor Howden-Chapman said those in that age group tended to be flatting rather than owning their own home, so were at the mercy of their landlords.
"Should we have standards for renting homes? I think we should. Why are so many people living in so many homes that are cold and damp?"
However, it was positive that 74 per cent had changed their behaviour to save electricity because this meant people were thinking about how much they were using power, Professor Howden-Chapman said.
Electricity Authority chief executive Carl Hansen said people should shop around for the cheapest deal before committing to a provider.
Mr Hansen said this would enhance retail competition, creating better deals for consumers.
The authority's figures show that switching power companies can generate average annual household savings of $175. Of the respondents to the Canstar Blue survey, more than half (56 per cent) had used an online tool to compare plans and providers but just 17 per cent had switched electricity companies.
Canstar general manager Derek Bonnar said this showed there was an active interest in managing costs even if it didn't lead immediately to switching providers. "With the concerns people are expressing about their power bills and home heating, plus the wider impacts poorly heated homes have on health, there is obviously still a need for more promotion and education on the ability to switch electricity providers, and how to economically heat the home," he said.
Kiwis and electricity
36 per cent can't afford to heat home adequately in the winter
74 per cent have changed behaviour to limit electricity use
23 per cent have taken a fixed-term contract electricity retailer
17 per cent have switched providers in the past 12 months.