From Greenhouse to Green House

The threats of climate change
CO2 emissions and savings


Approximately 28% of UK emissions of CO2 are from space heating, water heating and cooking in places people live (see Twenty-five million whole-house makeovers will match the Government’s global warming goals). One of the quickest and cheapest ways to cut UK emissions of CO2 is to cut emissions from these sources. The greening of electricity supplies is also important but is probably best treated as a separate issue.

It has been suggested that much of the UK housing stock is beyond redemption and that it should be demolished and replaced (see Call to demolish polluting homes). We believe that the main alternative policy, 'eco-renovation', has not been properly explored and that wholesale demolition and rebuilding has several disadvantages:

  • The practical difficulties of replacing enough of the UK's housing stock quickly enough to make a significant impact on CO2 emissions.
  • High costs.
  • Loss of the 'embodied energy' of existing buildings.
  • Social disruption: demolition of houses may also demolish the social structures that have grown up around them.
  • Loss of heritage.

Given the use of high levels of insulation, ventilation via heat exchangers, and some other techniques, it is feasible to create housing with zero net emissions of CO2 (see Passive House Institute and PassivHausUK). Clearly, this is easier to do with a newly-built house but we believe it is possible to go a long way down this road by upgrading existing buildings (see, for example, A passivhaus renovation: heritage meets energy efficiency, A passivhouse (passive house) renovation?). Germany has already introduced a large-scale programme of eco-renovation to bring existing buildings up to the passivhaus standard.

Some attempts have been made or are being made to go in that direction:

but we believe much more needs to be done to explore what is feasible to do, to develop new techniques, to see what snags there may be and to assess the costs of different options. We need to be much more ambitious than simply providing cavity-wall insulation and loft insulation.


In particular, we see the need for several 'demonstrators'. Each of these would be an 'ordinary' home of a particular kind (Victorian terrace house, '60s bungalow, flat in a tower block, etc) and each one would be upgraded as far as possible towards the goal of achieving zero net emissions of CO2. There might still be a need for a small amount of heating but, if this was provided from some 'green' source (such as bio-fuels or ground-source heat pump run on green electricity) then it should be possible to achieve zero net emissions of CO2.

Since there is clear commercial potential in the zero-carbon eco-renovation of the UK's stock of buildings, it is possible that companies like B & Q may be willing to promote and pay for the demonstrator projects mentioned above.


Upgrading the UK's stock of buildings will cost money and we must be prepared to spend it. We should remember that, amongst other things, the Stern Report concluded that the economic benefits of strong, early action to combat climate change considerably outweigh the costs.

A generous framework of incentives will be needed to encourage householders and others to do what is required.

A competition

One way to raise awareness of these issues and drive things forward would be to organise a competition, open to anyone with an 'ordinary' house or flat:

  • This would be relatively easy and cheap to organise and could generate a lot of publicity.
  • The challenge would be to reduce CO2 emissions to as near zero as possible. For any particular category of home (Victorian terrace house, '60s bungalow etc) the winner would be the home that comes nearest to achieving zero CO2 emissions. If there was more than one that achieved zero net emissions, then the winner would be whoever had done the job at lowest cost.
  • Prizes as small as £1000 could be enough to motivate people. The main motive would be meeting the challenge and the kudos of winning.
  • It would be best if the competition were run by some such organisation as Friends of the Earth since the media are likely to pay attention to what they do.
  • The competition would be very useful publicity for the organisation itself and could bring in many new members.
  • The competition would help to highlight what the Government needs to do to encourage zero-carbon eco-renovation of UK homes on a large-scale.
  • The competition could be the subject of a TV programme or series of programmes along similar lines to our proposal for a TV series about zero-carbon eco-renovation.
  • As mentioned in connection with demonstrators, companies with a commercial interest in zero-carbon eco-renovation may be willing to provide sponsorship.