¾«¶«´«Ã½

Heating our homes can be expensive and draughty old housing stock leaches carbon dioxide. But making homes more energy efficient can be a costly upheaval and is therefore often done piecemeal.

Tom Heap meets the team from who are proposing a new model - retrofitting modern technology like insulating 'wraps' around the house, replacing roof tiles with solar panels and fitting ground source heat pumps into old housing stock. It's done on scale and on a whole-house basis to keep costs down with the aim of creating net zero energy homes but also to create 'kerb appeal' so that neighbours will want to 'keep up with the Joneses'.

Tom is joined by climate scientist Tamsin Edwards to discuss whether tackling inefficient, poorly insulated housing head-on can provide great gains for people and planet.

What our experts say

We asked Society Fellows from the Open University and, writer on environment, sustainable building and energy to offer some observations on the potential of retrofitting existing buildings to a net zero standard in reducing carbon emissions. Their points take some of the themes of the programme a step further.

What are the limiting factors?

Kate de Selincourt

• Energy (especially gas) is too cheap in this country to make it realistic to pay for individual retrofits - of the depth and quality needed - through bill savings alone. However, if any retrofit is carried out to a low level of improvement, it makes it harder and less commercially attractive to then re-retrofit to the levels needed. Thus, we need to do retrofits that are as thorough - or 'deep' - as Energiesprong, but we will need to look more widely for options to fund them.

• Mass retrofit can easily be afforded when the full value of the ‘co-benefits’ is taken into account, but this needs an intelligent and joined-up approach to investment in the building stock. Public investment is needed alongside private investment. But it is an investment that pays back, because there are public, as well as private, benefits.

• Individual design by someone who understands buildings is almost always needed in deep retrofit. This has now, finally, been recognised by the government. While this adds to the upfront cost, it vastly saves in the long run, both in terms of achieving the needed savings, and in protecting the property from damage. Do it once, do it right!