Should we be reducing building insulation to improve energy efficiency?

By Ken Collins 22/04/2010

energy efficiencyI recently read an article on the cost of reducing our carbon footprint to pre-1990 levels. It suggested that the actual cost to consumers would be minimal, adding only a few percent to daily consumables. That is except for air travel, which would jump 150%. In effect they tried to debunk the myth that taxing the use of carbon and reducing the amount of carbon used is highly costly.

Reading towards the end, their assumptions were based on two significant developments. First that all vehicles would be electric powered. And second that almost all power worldwide is generated by renewable or nuclear sources. i.e. no gas or coal fire stations.

This got me thinking about assumptions we all make when it comes other things, like the energy use in buildings.

Conventional wisdom suggests that we put stacks of insulation into buildings so they cost less to heat. However, on a recent office building project the services engineer identified that the greatest energy use, and therefore cost, was not in heating the office, but in cooling it!

With large areas of glass, and a lot of electrical equipment, the heat load the building was absorbing meant that it needs a lot of cooling to keep it comfortable.

Their recommendation was to actually reduce the amount of insulation to let heat escape!

It came down to a smarter approach where the correct glass was needed to limit the heating value of the sun, and putting the insulation in the right places, with the right amount, so as not to loose too much heat, but not retain too much either.

This was contrary to the standard models used to determine insulation in NZ buildings, which takes a simplistic blanket approach.

The only thing now is for the cost of the technical calculations to come down to be within reach of the average budget. Thermal modelling of individual buildings from services engineers is still an expensive business, where the cost often outweighs the benefits, even if this more intelligent and detailed approach can save on both building cost and operating cost.