Q3 2022: The power of turning down the thermostat

Download PDF

Dr Iain Staffell, Professor Richard Green, Professor Tim Green and Dr Malte Jansen – Imperial College London

Britain’s homes, shops and offices are currently consuming as much energy as ever.  But they could be a potent force in reducing the country’s reliance on imported gas and exposure to volatile fuel prices.  Homes consume about three-fifths of the country’s gas, with commercial buildings and industry consuming about one fifth each.  By far the largest use is heating, as around five in six British homes are kept warm by a gas boiler.  So how much can we realistically cut gas demand in the short term?

Improving insulation and other home retrofits must be the starting point in any conversation.  Uptake of insulation measures plummeted a decade ago after government slashed support for green measures.  The installer industry then scaled back, and is now stretched to the limit with households wanting to improve their insulation before winter.  While insulating our homes will undoubtedly help in future years, it is not going to make a large dent on consumption in the coming three months.

There are several ‘quick fixes’ that people can try to reduce their gas consumption.  Martin Lewis and others have become household names for spreading the word about low-cost measures to reduce energy bills.  Draught excluders and temporary second glazing can quickly cut the amount of heat lost through gaps and single-glazed windows.  One change that costs nothing and can be made immediately is to turn down the flow temperature on gas boilers, lowering the temperature of the water entering your radiators.  Often this is set high by the installer and never touched again, but it doesn’t allow modern boilers to make the most of their energy-saving features.  Getting flow temperatures below 50°C allows them to operate in ‘condensing mode’ and achieve their full efficiency when burning gas.  This will cut gas consumption by 8–10% with no change in comfort, and now that most boilers in the UK are condensing models, this could have a major impact at the national scale.  If your radiators are more than pleasantly warm to touch, it’s worth looking into.

A third option is to look at how warm we keep our homes.  This is naturally a sensitive topic, as nobody wants to endure lower living standards, and many simply cannot as they are already unable to afford enough warmth.  Already one third of households are suffering fuel poverty, with many families only heating a single room to save money, or avoiding using their heating altogether.  At the other end of the spectrum, many homes are kept at summer temperatures throughout the depths of winter.  The average UK house is kept at over 20°C, living up to the stereotype of people walking around in a t-shirt through winter. 

Lowering room temperatures by just 1 degree (e.g. from 20 to 19°C) will reduce a typical household’s gas consumption by 8–11%, saving in the region of £150–200 per year on gas bills (depending on the size of house).  This puts in sharp contrast the value of some energy-saving tips: turning the TV off standby mode or unplugging mobile phone chargers has next to no impact on bills.  With everyone looking to cut back on energy costs this winter, it is worth noting that running the Christmas tree lights will cost around ½ to 1p per hour.  In contrast, turning the heating down by 1°C will save an average home around £1 per day through winter.

If everyone in Britain lowered their household temperature by 1°C, the country would save 50 TWh of natural gas over the winter months, comparable to the savings seen in Germany.  This would be good news for the environment, saving around 10 million tonnes of CO2 per year, or 3% of Britain’s total emissions.  It would also be good news for the economy.  Households would save around £5 billion collectively, and the government would save an extra £3 billion on funding the Energy Price Guarantee in the new year, which would lessen the need for tax rises and spending cuts.

The modelled saving in gas consumption from lowering room temperatures by 1°C, measured across a population of 2,000 British households.

Live Grid Data