University of Otago physicist and Sustainable Energy Programme director Associate Professor Michael Jack said it was because the cities had low use of LPG/natural gas to heat homes and water.
He said the research showed how much energy was used in each New Zealand region to heat its homes and hot water, and the carbon emissions associated with that.
By contrast, Taranaki and the upper West Coast both used a lot of fossil fuels for space and water heating, meaning they had the most potential to reduce carbon emissions, by switching to cleaner forms of energy.
He said heating water and spaces in residential and commercial buildings was the third-largest contributor to global energy-related carbon emissions, which was a known factor in climate change and global warming.
When it came to reducing these emissions in New Zealand, he said there had been a major focus on decarbonising industrial heat — like shifting away from gas and coal — but much less focus had been placed on decarbonising residential heat.
“In fact, we only have estimates for the total national demand for residential heat in New Zealand.”
Researchers mapped the geographical distribution of residential space heating, domestic hot water and associated greenhouse gas emissions using climate, housing and census data.
“This breakdown is important for targeted regional initiatives to identify focus areas and develop detailed plans for low-carbon energy distribution networks, such as electricity distribution networks and district heating schemes.”
The breakdown revealed some surprising findings, he said.
“The regions that had a higher proportion for carbon emissions are not necessarily the coldest parts of New Zealand — they are more related to the proportion of carbon-intensive fuels used in that area.”
Assoc Prof Jack hoped the research results would be used to develop detailed, regionally-specific decarbonisation strategies that could also reduce reliance on limited gas resources.
There were potential savings for homes and businesses if gas and inefficient electric heaters were replaced with heat pumps.
“This will reduce the demand for and protect, the country’s natural gas resources,” he said.
New Zealand Green Building Council chief executive Andrew Eagles said the research showed there was a “huge opportunity” to ease the pressure on the heating systems in homes and buildings and the regions that should be prioritised.
“Gas supplies are depleting and industrial users, who are often major breadwinners in these regions, are struggling.
“It’s low-hanging fruit that will support Kiwi families to keep bills down while freeing up supply,” he said.
