Ensuring energy efficient homes

Let’s move next to the buildings themselves and how this impacts home energy usage. Cambridge University’s Tim Forman  - who has recently moved house - is an expert on retrofitting buildings to make them more energy efficient, and he spoke with Chris Smith. So first up, how does the new place compare with the old in terms of energy efficiency?

Tim - I'm now in a flat - well-insulated, airtight, draft free. The neighbourhood's nice, but to me, energy efficiency is most important. So the move has gone well, thanks.

Chris - Have you got neighbours above and below and to either side, because of course that's the best way to be energy efficient. I know some students that used to purposely choose flats in that sort of position in houses or in streets so that they couldn't have the heating on all the time. They just relied on their neighbours to do it instead.

Tim - That is absolutely a key benefit to a flat! Far more efficient having fewer external walls. And of course also shared facilities and a reasonable amount of space rather than a far too large an amount of space.

Chris - We're on the subject of housing. And this week, the UK government announced a legally binding target to reduce the CO2 emissions of the UK by an ambitious 78% compared with the levels as they were in 1990. And to do all of that by as soon as 2035. Now that is one of the world's most ambitious global targets for this. But the lion's share of our current household carbon budget is actually eaten up by what we've just been talking about and that's heating. And that potentially means a mass retrofit for the buildings we all live in, which are currently far from efficient, in many cases. And this is something the government are very acutely aware of and they have a plan in place for, they tell us. And that's what business secretary Kwasi Kwarteng told BBC Radio 4's Today programme this week. Let's listen to what he said.

Kwasi Kwarteng - Heat and buildings is a big challenge. I mean decarbonising heat sources, and also, improving energy efficiency of homes is a big challenge. We've got a heat and building strategy, which will be very clear, will be very full of policies, will be very full of directions and that's going to be coming out only in the next couple of months.

Chris - So Tim Forman, how big is the problem facing the UK government? What have they got to drag up hill in terms of what sort of boulder have they got to get to the top of Everest to solve this problem? How bad are our homes?

Tim - I think Everest is a fair metaphor Chris. Frankly it's difficult to overstate. It's a huge challenge. We've got in the UK perhaps Europe's least energy efficient housing. The complexity of the challenge - it's probably not an overstatement to say it's roughly equivalent to the space race in terms of the level of innovation and mobilising across society that's required.

Chris - Indeed there's a report in one of the newspapers this weekend saying that some of the technologies that are going to be needed to solve this problem don't even exist yet. When we say retrofitting though, Tim, what is going to happen to the average home in order to get it up to the standards that we're going to need everyone's home to be at, to meet this very ambitious goal?

Tim - We can think about it if we consider the energy that goes in and the energy that goes out, if you will. So by the energy that goes in, I mean the energy supply, and we're all probably but now familiar with things like solar panels, which are de-carbonising our energy supply. The other side of the issue, and perhaps the more important side of the issue, is the actual energy efficiency. So if we think of the home as a sort of an equation, we have a certain amount of energy that needs to go in to keep it at a comfortable temperature. And a certain amount of that energy is going to be leaking out as waste. What we really need to do is address the waste first, so that we're not attempting to use greener supplies of electricity for buildings which are inherently very inefficient.

Chris - We think that about 80 to 90% of homes are currently plumbed into our UK gas distribution network. The building regulations say that close to 2030, we won't be allowing any new houses to be connected to that network. We'll have to have other sources of heat and energy provision going into those homes. So what does that mean in practice then? What will be heating our homes and heating our water in the future?

Tim - There's a lot of excitement at the moment around hydrogen, as a direct replacement for natural gas heating. I think that certainly has a great deal of potential. Fundamentally, the most important thing is that the energy that is being supplied to a home needs to be green. And we need to dramatically reduce the amount of that energy that's required to keep a home comfortable. So we know we can do that. We just don't know exactly how we can mobilise the financing and the innovation, the technology, and the labour supply and the skilled workforce to do that. Those are the real challenges.

Chris - Do we know how big the price tag is Tim and who's going to pay for it?

Tim - Frankly I don't think we do. We can make lots of estimates. And I think we can make very educated estimates. Until I think we are some way into this, I'm not sure that we can say with real confidence what this will cost. Safe to say that it's a national scale investment. The other side of that though, is that it's a once in a generation opportunity. There's a huge opportunity to make gains through efficiency. So in many ways, this is a very smart investment to make.

Chris - But will it be something we're comfortable living with? As one person pointed out in a letter to the Daily Telegraph this week, they live in a house with a balcony and there's an air source heat pump under that balcony. And when it's running, you can't go on the balcony, you'd be deaf! And if a whole street ran heat pumps like that, then everyone would be deaf. And the neighbourhood would be one noisy neighbourhood. So what sort of looks nice from far is sometimes far from nice.

Tim - I think that's a fair statement. I would say though that an energy efficient home is typically a more comfortable home, certainly. And it's typically a more healthy home. Perhaps the noisy heat condensers aside, I think generally speaking, energy efficiency improvements are all around improvement in homes.

Chris - Do you think we're going to make it, Tim? Do you think that the government is going to be so wide of this target that they're going to make us a laughing stock? Or do you think we're honestly going to get there?

Tim - You've really put me on the spot with that question. I'm an optimist by nature. I have to believe that we can do this. I think we have the technology, roughly speaking, that we need for the moment. I think it's primarily a social problem, a human problem. We've seen, you know, maybe if you'd asked me a year ago, my answer would have been different, but in the last 12 months, we've seen incredible amounts of mobilising across the scientific community, across society. And that's exactly what we need in housing. And perhaps if we've learned one thing in the last year, we know that real radical change is possible and that's what we need.