> There are plenty of factors. Most of the country has reasonably temperate weather all year round, especially on the more populous north island.

I've been cold more in NZ than anywhere else, and I don't get cold all that easily. Only lived in South Island though, where the average is colder than Western Europe (but the housing much worse). North Island is indeed warmer.

Maybe (part of) the problem is just that "one size fits all" set of laws doesn't really suffice if there are fairly significant differences in e.g. climate within a country.