Have we succeeded in reducing our household energy use?

In campaigning on environmental issues, I want to make sure that I’m not demanding changes from people that I’m not prepared to make myself. I want to be able to try things out and share what I’m learning. With these things in mind, I set myself a target a few years ago: get our house to an A rating for efficiency by 2020, and zero carbon by 2025.

I’ve tracked our progress along the way with some of the important steps: adding solar panels and battery storage, underfloor insulation and solid wall insulation.

As we’ve been making these changes, I’ve been tracking our bills and energy use so that we can see if it’s making a difference. I’ve now got five complete years worth of data, and so we can do some comparisons.

First of all, our gas use. This is our main use of fossil fuels and the biggest source of household emissions now that we have an electric car. It will be eliminated eventually when we electrify our heating, but for now we have been focusing on insulation and reducing our gas use. Here’s how that’s gone over the last five years:

Our gas use in 2018 was 8,012 Kwh – that was after double-insulating the loft, fitting double glazing throughout the house and draught-proofing. After the latest round of work, by 2022 we had got that down to 4,530 Kwh. (If I had more sophisticated analytical skills I would include degree-day data and make sure it wasn’t simply warmer winters, but I tried and failed at this.)

According to OFGEM, the average gas use for a three bedroom house is 12,000 Kwh a year. We have a headstart by being mid-terrace and we get to use our neighbours as insulation, but our house is not far off a third of the average use.

What about electricity? We get half our electricity from the solar and half from the grid, and we’re on a 100% renewable energy tariff from Ecotricity. Our electricity isn’t a source of carbon emissions and hasn’t been a priority over the last few years. As we’ve been using more electricity for heating and to charge the car, our use has risen. We still end up below the average though.

Average electricity use for a three bedroom house is 2,900 Kwh. We’re just below that at 2,830 Kwh, and that includes an electric car that is mainly charged at home.

My main priority has been to reduce emissions, but what does this reduced energy use do for our bills? British Gas reports that three-bedroom homes typically had an energy bill of £2,499 in 2022. Ours was much lower. Once you add the money that we made by selling our surplus solar power, the net cost to us as a household was £849.

That’s a price difference of £1,650 between our home and the average. Energy prices have been very high recently, so we don’t normally make that big a saving. But it doesn’t take very many years of those sorts of savings to pay back the investments we’ve made in insulation, solar and batteries.

What about our carbon emissions? Here’s a comparison using Climate Change Committee figures for a household average, and my calculation of our home’s energy footprint:

We’re not done yet. We will electrify our heating and hot water at some point, and wrestle that last tonne of CO2 to zero. Writer salaries being what they are, I’ve had quote for a heat pump and have filed it in the ‘not yet’ box. They’re getting cheaper all the time, with British Gas and Octopus both announcing prices that are more within our range, so I’m confident we can still get something done by my 2025 target.

I’m pleased with what we’ve done so far, and that’s it’s working. It gives me confidence that we can decarbonise housing and heating across Luton and the UK, because I’ve seen it can be done at home. It isn’t easy, but it is entirely possible.