Like Haya said, most houses are not insulated especially the older ones. The newer 'insulated' ones aren't much better - just some insulation around the outer walls (fat lot of good that does considering the number of windows they have) and roof. Most windows aren't double-glazed as well so lots of heat escapes that way.
How much would it cost to insulate? A LOT, cos it entails ripping out walls and roofs. This is in a country where even changing a tap is expensive.
Btw, central heating is very uncommon in NZ. They're pretty backward in the heating and stay-warm department. Lots of people from colder climates in Europe/North America have complained that they've never felt so cold indoors in their lives.
Another thing to watch out for is damp. Very common and troublesome in winter, especially in the older houses. A dehumidifier generally takes care of that problem. Or you could always get a heat-pump (expensive) which effectively heats up the place and keeps it dry.
QUOTE(haya)
There are also different types of insulation, such as heat insulation, sound insulation (coz their houses are made out of cardboard) etc.
There's Pink Batts which does both the heat and sound insulation job. Their tagline is "warm, dry, quiet".
Duh! Seems like NZ taxes. houses and insulation cost are crazy inbalance....
Even earn 6000 per month... 1500 go to income tax.... 10% housing loan... 300k - 400k per house.....living expenses.... that explain why not much ppl has $$$ to insulate the house lol May be it is time to learn some housework how to insulate heat b4 going there.