Mr. Pat Barry:

We need to take a more holistic approach. That is one of the reasons we developed the home performance index, which does not just look at embodied and operational carbon because we also need to look at land use, biodiversity and transport. That is why we need to get to the stage of rating every home according to its overall environmental impact, rather than on just one thing, such as energy efficiency or embodied carbon. Construction has many impacts and we need to start measuring all of them. It is a matter of weighting. Some homes are very low-carbon to run but will have a large volume of embodied carbon. They may also be using land inefficiently, which also has a carbon impact, or may be displacing biodiversity or having impacts on water. We have to measure all of these things.