The Canterbury Earthquake Recovery Authority is advising residents to prepare for the onset of winter.
Interim chief executive John Ombler spoke at a Civil Defence briefing on Friday and warned that some houses may not provide the warmth they once did.
A cold-snap is forecast for Christchurch at the weekend.
Mr Ombler says winter will be tougher than most, given the damage to some homes following the 22 February quake.
About about 400,000 residential heating units have been ordered, installed or repaired to date.
Mr Ombler says residents who have no heating or whose home is not weather-tight should phone 0800 326 243 sooner rather than later.
He also advises that the elderly, young children and those suffering asthma get a flu vaccination.
