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:
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.