Energy efficiency in homes is low hanging fruit
Government targets to ensure all newly built homes are zero carbon by 2016 are admirable, but this is a drop in the ocean compared to the savings that could be made by more aggressively tackling the emissions from the existing housing stock.
While it is a message most with an interest in green buildings may already be familiar with, it was Mr Dunn's figures and his analysis of the introduction of Energy Performance Certificates (EPCs).
"There are millions of properties out there where these savings can be made tomorrow," he said.
"I'm not saying that new build doesn't have a place but the big saving which can be achieved quickly and most cost effectively is in our homes."
He pointed out that only around 1% of the housing stock is replaced each year and a crude extrapolation of that would suggest it would be a century before the UK's homes were truly zero carbon.
Improving energy efficiency is a win/win situation, he said, with financial and environmental benefits - but the challenge is getting the upgrades realised.
He also warned that weak enforcement on new build presented a risk that targets would not be met.
"There's an emerging gap between what people are designing and what's being built," he said.
"There's a real concern that only if we increase the number of site inspections can we address that."
Mr Dunn's presentation can be seen in full in the footage below.