climate change energy

The importance of renewable heat

When we’re talking about renewable energy, we’re usually talking about renewable forms of electricity generation – solar, wind, and so on. That’s the general impression in the media, and they are certainly the connotations that come to my own mind.

In fact, a renewable electricity supply is only one half of the energy transformation, and it may be the easier half. The other side of the problem is renewable heat. It’s less discussed, but in many ways the bigger challenge.

Here is where UK households use energy around the house, broken down by CO2 emissions:

domestic energy use by_co2

As you can see, the biggest slice of our energy use is heating, by some distance. These results are from the 2013/2014 National Energy Survey, and the share of heating can vary across years, depending on how cold the winter is. It’s usually over half and sometimes around 60%.

For 83% of households, heat and hot water are provided by gas central heating. It’s low maintenance and cost effective, and there are good reasons why most of us switched to gas heating over the last few decades, especially since it could be extracted from the North Sea. But it is a fossil fuel, and we know that if we are going to cut emissions, we need to cut our gas use.

As our own gas production has peaked and gone into decline, we’re also importing more of our gas. With demand increasing in other parts of the world, it’s also getting more expensive. So we have three reasons to reduce our dependence on gas – lower emissions, energy security, and more predictable prices.

Heat from electricity is wasteful and expensive, so using renewable energy to run electric heaters isn’t a solution. We need to dramatically reduce our heating needs through better design and insulation, and we need to move towards renewable heat.

I will look at some of the different sources of renewable heat next time.


  1. In our book as you may remember we saw this as the biggest problem with renewables. I have heard mixed reports about heat pumps but the main problem is that firstly all the technologies are low temperature systems and require very well insulated buildings. The second problem is they are very disruptive to retrofit. This explains DECC’s relative lack of activity in this area.

    1. Yes, some useful material in your book on this, and it’s not surprising that initiatives like the renewable heat incentive have lagged behind. A tough one to crack, if you can’t rebuild our leaky housing stock from scratch.

  2. Here in the US, natural gas is abundant and cheap. About $2.50. And of course everyone thinks the supply will never end.
    It may take a while as there is a lot of the US to frack.
    I think we should take this time of abundance and use it to create solar panels and wind turbines. Hopefully Elon Musk will come up w/ some great battery technology so I can store my extra solar electricity and get 100% off of the grid.
    We drove through Boston Saturday night and we observed how many office towers had all of their lights on. On a Saturday night. You would think the stock holders would complain about the waste and hope to get higher dividends.

    1. What you are talking about here is not heat but electricity. This is much easier than heat which is why there has been so little action on it.

  3. I don’t really understand this. Yes, there is a lot of work to be done improving existing housing stock, but it is not hard to heat water using evacuated tubes. This can also by used to heat a house via hydronics. One can go even simpler, and construct solar space heating, trombe walls, etc. But yes, perhaps the days of wearing shorts/t-shirt inside in the middle of winter are numbered.

    Fascinating that cooking uses so little on average — I am guessing that is because of the pervasive use of preprocessed ingredients (eg. bottled pasta sauce) that is so often called “cooking”. That 2% would be much higher if people cooked from scratch and didn’t heat their houses so much. That is the difficulty, as far as I’m concerned — though I think it could be achieved with smarter cooking.

    1. We’ve had decades of cheap heat and have developed bad habits, is probably part of the answer. We have some of the cheapest gas in Europe, though you wouldn’t know it from the complaining. Because it’s cheap, we don’t prioritise efficiency and waste £1 in every £3 we spend on gas.

      Yes, there are lots of good solar heating techniques. Unfortunately the best ones (passive solar) have to be installed when houses are built or are to do with the orientation of the house. Great for new build, but we can’t afford to rebuild everything. There are still limited applications for retrofitting, but not a solution in itself. I should write a post on solar heating though – some interesting techniques.

      We should of course be building much better houses. Since we know how to build houses with no heating requirements, there’s no excuse for not building them. That’s why it’s so disappointing that the government bottled it on zero carbon houses.

    1. Thanks for this Michael. I’ve just had a very quick scan and there are only hints of the problems I outlined above and heavy emphasis on heat pumps. In our book we case studied a church that had fitted a heat pump. They built a new building after an arsonist burnt the old one down. The problem was even in a new very well insulated building they were cold in the very cold winters we had. I did however meet someone in Fintry who installed one and used his existing cast irion radiators. His borehole struck an artesian well and flooded the high St but was very effective. Biogas is on the face of it a great option but relies on us being wasteful with food. District heating using a variety of technologies is in my view the way fwd, but in many ways is a very difficult option. One reason the tram system cost so much in Edinburgh was that they kept coming up against pipes they did know existed.

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