The facts are these, when it comes to New Zealand homes –

“Houses consume nearly 35% of the total electricity generated in New Zealand. Unfortunately the majority of New Zealand homes do not use energy efficiently.”
Energy Efficiency and Conservation Authority

“The average New Zealand home has an Air Change from inside to outside at a ratio of .85. This means that 85% of the volume of the air in your homes changes every hour. Your home does a great job of breathing, but this is highly undesirable for heating purposes.”
Bob Bennett of Gair Air

Much of this is due to loose construction and the use of minimum code insulation in homes. These problems are easily remedied at the initial construction, if a more intelligent approach is taken. This is the approach taken by Greentech Design, and advocated by the Energy Efficiency and Conservation Authority.