4. Home energy use

Given various technological and environmental limitations on the speed and scale of reducing the carbon footprint of energy supply, a large decrease in average home energy demand is also necessary – at least within the next decade or so. Currently, the leading option available to UK householders for obtaining home energy completely from very low carbon energy sources seems to be to convert your heat supply to a heat pump (most commonly ‘air source’), together with signing up for a 100% renewable electricity tariff – but the situation is complicated. These supply options are discussed further in the section below (target 5), but are the reference point for the discussion here.

Current average home energy consumption in the UK (for heating, hot water and electricity) is estimated to be about 7,000 kWh per capita per year (HoCI, 2021: 154; see also UK Power, 2021). Data from the Climate Change Committee (2020: 134) and Centre for Alternative Technology (2019: xiii) indicate that total future UK household energy consumption (mostly or completely as electricity) will eventually need to be about 200 TWh/y to meet net zero targets (including a virtual phase-out of the domestic use of gas and other fossil fuels). With a UK population of about 67 million, this translates to about 3,000 kWh per capita per year. Since such a transition is envisioned to take more than a decade to complete (and so stretch beyond our 2030 timescale), we make our target less stringent at 3,500 kWh/cap/y.    

On average, consuming 1 kWh of UK electricity emitted 254 gCO₂e in 2021. This is 212 gCO₂e from power station operation (BEIS, 2021) plus an extra 20% (42 gCO2e) for lifecycle effects (Berners-Lee, 2020: 51–52). So consumption of 3,500 kWh emitted just under 0.9 tCO2e in that year. As the UK government has set a target to “fully decarbonise our power system by 2035” (HM Government, 2021: 19), this level is likely to fall annually depending on how successful the implementation programme is in practice, with revised unit emissions figures published annually by BEIS (although we note the particular controversies surrounding the use of biomass and nuclear technologies, some of which are discussed under ‘target 5’). We consider how consumers signing up for a 100% renewable energy tariff and other supply-side actions can reduce the figure of 0.9 tCO2e in the next section.

To reduce consumption to below 3,500 kWh/cap/y, a variety of measures are viable depending on personal circumstances. Living in a house with a higher than average number of occupants is a potential option - average UK occupancy is 2.4 people per household (Office for National Statistics, 2021). There are also a range of energy efficiency measures from low-cost options like draft-proofing doors and windows to mid-cost options such as loft and cavity wall insulation to higher cost options like double/ triple glazing and solid wall insulation. (NB It is worth getting bespoke professional advice especially on the higher cost options.) Other energy-saving measures range from low-tech options such as setting the thermostat lower, wearing warmer clothes and using hot water bottles to high-tech options such as programmable thermostats for each room. In general, following the adage of ‘heat the person, not the space’ is useful guidance in deciding which options to prioritise. For more discussion see, e.g., Berners-Lee (2020: 204–206).