Thermal imagery showing how energy-efficient Christchurch houses are should be used by anyone considering renting or buying a property in the city, an energy analyst says.
The imagery is available free of charge through the Christchurch City Council's website and allows people to zoom in on any property in Christchurch and gauge whether it is adequately insulated.
Council energy analyst Yvonne Gilmore said that even though the thermography predated the earthquakes, it was still a useful tool for house hunters.
Canny buyers or renters could use the information to lower their heating costs by getting any unexpected gaps addressed.
"It gives people power," Gilmore said.
"It doesn't give them all the answers, but hopefully it will prompt them to ask the right questions. It's a way to heighten awareness of the value of insulation in homes."
If the footprint of the house was covered predominantly in yellow and orange it indicated a relatively high roof temperature, which suggested either the house was overheated or there was insufficient roof insulation, or both.
If the house was mainly coloured blue or green it indicated the roof was cold, and that either the house had well-performing thermal insulation or was underheated.
It is estimated that nearly 60 per cent of New Zealand's homes have inadequate ceiling and floor insulation.
Many built before insulation became mandatory in 1978 have no insulation and others may have old insulation well below today's standards.
Improving a home's ability to keep in the heat wouldcut heating costs and improve people's health, Gilmore said.
❏ To find out how energy-efficient your house is, log on to http://thermals.ccc.govt.nz/framesetup.asp.
Thermal imagery is a tool to show the external surface temperature – and therefore the efficiency of thermal insulation – of buildings and homes.
It helps you check how much heat is escaping from your home, particularly through the roof. In winter 2009, a plane equipped with an infra-red camera flew over Christchurch and, over several days, took thermal photographs of the city.
The council then combined that imagery with satellite photography to create an interactive map that shows the relative roof temperature of buildings in the city.
Different colours show different roof temperatures.
If you have insulation, less warmth will be lost through the roof and it will show as a lighter green-blue colour on the thermal image.
If you have poor insulation, then you will lose more heat through your roof and this will show as orange-red.
- The Press