The Eco Engineer is currently working with Zero Energy Retrofit
If we are to reduce the energy consumption and CO2 emissions of residential housing, not only must new houses be designed to meet these aims but existing housing stock must be retrofitted for energy efficiency. Whilst we could wait for the existing housing stock to be replaced by new build, this would certainly not address the problem quickly enough, given that the typical life expectancy of a New Zealand House is 100 years. And it is not only 'old' houses that will need to be retrofitted, since the vast majority of houses built today in New Zealand fall well short of the thermal performance required to achieve zero energy operation.
All existing houses have already had a lot of energy invested in them in terms of materials, construction, maintenance, landscaping and infrastructure. The majority of existing housing is well placed for work, schools, shops and other ammenities. For these reasons the most sustainable option is often to retrofit a house to make it more energy efficient, healthy and appropriate to your current needs.