A cunning plan for insulating every solid wall home in the UK

Most people now realise that the challenge in terms of housing stock and carbon emissions is not new buildings but old ones. 80-90% of our homes will still be standing in 2050. We therefore have to retro-fit them with energy efficiency and energy generation measures if we're to have any chance of hitting the government's new national 80% emissions reduction target. I think local authorities have the ability to provide a solution so long as they concentrate not on eco bling like solar panels but on the "boring" stuff like insulation and double glazing.

Earlier this year the London Borough of Camden refurbished a four floor, five bedroom Victorian property to reduce carbon emissions by 80%. More than 1,800 people visited the Camden Eco House in the three months that it was open to the public on Sunday afternoons. It's proof that people want to see how a solid wall Victorian property in a conservation area can be refurbished to reduce carbon emissions and energy bills by 80% whilst protecting our heritage.

The key learning from the Camden Eco House was insulation, insulation, insulation - to paraphrase a former Prime Minister. Roof insulation, basement floor insulation and external or internal insulation on all the exposed walls. The reaction of most people to internal wall insulation - especially in London - is "oh that means I'll lose loads of floor space". Not true. Remember you only need to do exposed walls. In most homes that will mean one wall in each room.

Add in some decent double glazing (because the seals in 35% of double glazing - the cheap stuff - fails within the first three years) and hey presto you have an energy efficient cocoon that is better than new build and requires virtually no energy to keep it warm. A few years ago English Heritage would have baulked at replica Victorian double glazed sash windows. Now they accept them. They have had to. Bluntly - there is no point protecting heritage if there's no human society left to appreciate it!

Wind turbines, photovoltaic panels, grey water recycling, ground source heat pumps - none of these make much sense for individual urban households (although they might do in rural areas where there are few alternatives).

Wind is a complete no-no in cities because you need huge blades to make the turbines work cost-effectively and most urban areas a) aren't windy enough and b) when there is wind it blows in gusts and it never blows in exactly the same direction. That's not good for a traditional wind turbine although there are now double helix style turbines (www.quiet revolution.co.uk) that have been designed to cope with this. Unfortunately they're still extremely expensive and will never make sense for individual householders.

It would have cost about £10,000 to install a dual pipe system in the Camden Eco House to allow grey water recycling but this would never have paid itself back because water is underpriced. I think the Lib Dems need to think about whether there is a better way to price water. Let's have a free ration per person, as a human right, and then a progressive charging tariff to make those that use the most water pay more.

I have a lot of time for ground source heat pumps, which extract solar energy from the ground and which usually generate three times as much energy as you need to run the pumps, but the reality is that they have mechanised parts that will break and it's not clear a householder will recoup the £6,000-8,000 investment. Solar water - using the sun's rays to heat up water - will pay itself back within a few years. It's estimated that solar water panels will produce 40% of the annual hot water needs of the Camden Eco House. But this house had a south-facing roof. Most households in London do not even have a roof let alone a south-facing one.

There are photovoltaic (PV) cells on the Camden Eco House roof to generate electricity. They are expected to provide more than twice as much electricity as the house needs over the year. In other words the house will be a net exporter to the National Grid. Great news you might think, but you would be wrong! At the moment PV panels are still very expensive and are likely to break before they pay themselves back. However the Chinese and Germans are investing heavily in PV so the price should come down in time.

A national feed-in tariff, which the government has finally agreed to bring in after huge pressure from the Lib Dems, Tories and Labour backbenchers, should also help. It will mean that if you supply electricity to the Grid you will get paid more than it costs you to take electricity out of the Grid. Most European countries have feed-in tariffs, which is one of the main reasons why they obtain far more of their electricity from renewables than we do.

So on PV I would say watch this space. And in the mean time the lesson from the Camden Eco House is that we have to do the boring stuff not the eco bling!

Here is what will make sense for most homes in an urban area like Camden: 1) insulation; 2) double glazing; 3) solar water if you have a south-facing roof; and 4) localised heat exchangers (which are basically fans that expel stale air, bad smells and moisture but which use the waste heat to warm up incoming fresh air).

Now comes the real challenge. How do we do the rest of Camden? As of July Camden Council has agreed to put cavity wall insulation in all buildings - social and private - by 2013, but that's only a third of Camden's housing stock. And how do you persuade a private landlord to put in insulation when they don't pay the energy bills?

In short, how do we industrialise and incentivise the whole of Camden to put in insulation and double glazing? Well, here's my cunning plan.

Camden Council borrows the money long term at low interest rates, which should be easy even in the current credit crunch because we're about the only institutions out there that banks are prepared to lend to. We then "lend" the money for insulation and double glazing to householders and private landlords or their tenants. An extremely rough and ready calculation, based on the Camden Eco House, is that this would cost £10,000 for the average Camden property. You would have to sign up to get it done by a Camden-certified contractor when they are doing your area because we want to industrialise the rollout and because another key lesson from the Camden Eco House was that we had to train the builders really carefully. Putting in insulation that is going to be good enough to pass an air tightness test means it can't just be slapped on like plasterboard. This is going to be a huge challenge for the British building trade.

Your energy bill would go down after the work has been done. Camden could then recoup a proportion of the energy bill saving through the council tax. The key point, the thing which makes this so beautiful, is that the energy bill plus council tax will be LOWER after the refurbishment.

You could even get tough and raise the council tax for those that refuse to go through with the upgrade. I'm grateful to Prof Paul Ekins of Kings College London for this refinement although I fear it might adversely affect my re-election chances!!!

Landlords should be happy because they would get an upgraded property for free. Householders or private tenants should be happy because they would pay less overall in terms of council tax plus energy bills. If someone moves, then the loan would stay attached to a particular property because the incoming owners or tenants would still benefit from lower energy bills. Camden Council's Finance Director should be happy because he would get his money back in time plus interest. And environmentalists like me would be happy because Camden's carbon emissions would go down dramatically and the UK would have a model that could be rolled out nationally. We might even solve the banking crisis in the process because banks would end up with lots of safe long-term debt lodged with local authorities!

I raised this with the Chair of the Climate Change Committee Adair Turner before Xmas and he thought it sounded like a good idea. Actually he also said that his wife had been to see the Camden Eco House to get some ideas for their own house! I'm also waiting for an official response from Ed Miliband, the new Energy and Climate Change Secretary, to say that we can legally do it.

The only two flaws that anyone has yet found in the plan so far is 1) people might change their behaviour and consume more energy if the price goes down and 2) some homes may need significant amount of time and money to make them good after the internal wall insulation is installed because of fitted wardrobes or other internal design issues. On the first I think councils clearly have to combine such a scheme with an education programme - the only thing that will cost us. On the second I can see that it could be a problem but again I would stress that on average this is only one wall in each room and that most back and side walls can be done using external render.

That's the plan. I hope you like it. I hope we can persuade the Lib Dem leadership to support it and the government to allow it. Please email your comments to alexis@greenlibdems.org.uk

Cllr Alexis Rowell

Camden Eco Champion & Green Lib Dem Website Editor