Also, be aware when you burn soft woods like pine and douglas fir they usually result in more creosote buildup in your chimney. This can result in chimney fires if you are not careful and clean your chimney regularly. This especially true if you burn your wood slowly to maximize burn time.
When we lived in Alaska, we heated with wood and burned a LOT. We would burn 10 cords or 36 cubic meters ever winter to heat our small 55 square meter cabin. The only type of wood available was spruce, which is very similar to pine and fir. We had to clean our chimney about ever 3 weeks or risk a chimney fire.
I have not heard about this being a problem in NZ, but in Alaska there were many houses burned to the ground after a chimney fire each winter.