Martin Lewis' Money Saving Expert (MSE) has weighed in on the perennial debate over whether it is better to leave heating on all day or switch it off when not needed. The conclusion, according to MSE, is that "leaving the heating on all day leads to greater heat loss and means higher cost".
The guidance comes as energy bills have increased by £60 a year from October, after Ofgem raised the energy price cap by 4%. That amounts to an additional £5 per month for the typical household. The price cap is rising to £1,723 annually for typical households not on a fixed tariff who pay by Direct Debit in England, Scotland and Wales, up from the current £1,663 cap.
The case for low and slow
The "low and slow" method suggests that maintaining radiators at a steady low temperature throughout the day delivers better energy efficiency. However, not everyone is persuaded, and MSE has intervened to resolve the debate definitively.
Drawing on expertise from the Energy Saving Trust, British Gas, an independent plumber and MoneySavers social media, this represents the most comprehensively researched answer obtainable. There are valid points on both sides, and the correct answer may depend on individual circumstances.
What experts say
The Energy Saving Trust insists that leaving heating on throughout the day is the less efficient choice. It advocates warming your home only when necessary, ensuring you pay only for what you genuinely need. Installing a programmable thermostat is regarded as the most effective means of maintaining your desired temperature at times that work best for you.
However, if you possess a contemporary boiler or heat pump, work from home, or spend most evenings and weekends at home, Heat Geek contends that the low and slow approach proves superior. Heat pumps are a low-carbon type of electric heating that draw warmth from outdoor air. A modern condensing boiler, fitted after 2005, reclaims some waste heat before it dissipates.
When low and slow may not suit
Under these conditions, sustaining a consistent indoor temperature of 18 or 19°C may prove more economical. Maintaining lower temperatures with gentle heating responsiveness - resisting turning up the thermostat when feeling chilly - enables the boiler to reclaim more waste heat.
That said, this method might not be suitable if you're regularly out of the house or have plasterboard walls, which typically heat up more rapidly. Nevertheless, if your home has cavity wall and loft insulation or underfloor heating, low and slow is the advised strategy. Others also argue that low and slow prevents moisture accumulating within the walls each time the system is switched off, which can draw warmth out of your home while also promoting damp and mould growth.
Trial and error approach
As there is no clear-cut answer, MSE recommends a trial and error approach - monitoring energy usage with each method. Take meter readings at the start and end of each trial period and compare the outcomes, making sure you match the temperatures of the weeks being tested as closely as you can.
