As the clocks prepare to go back and heating schedules are reset, households with garden offices, studios and summer houses face a familiar question: what does it cost to keep an outbuilding usable through the colder months?
This year the answer is shaped by the regulator. Ofgem has raised the energy price cap by 4% for 1 October to 31 December 2026, taking a typical household paying by direct debit for gas and electricity from £1,663 to £1,723 a year. The regulator linked the rise to higher wholesale gas prices.
There is a partial offset for anyone heating with electricity. The government has removed VAT from domestic electricity bills between 1 October 2026 and 31 March 2027, while gas still carries 5% VAT. That matters for garden buildings, many of which rely on standalone electric heaters rather than a connection to the home’s central heating. The relief may be short-lived, however: some energy market analysts expect the cap to rise by a further 12% to 14% in January 2027.
Fabric before fuel
Energy specialists generally agree that the heater is only part of the picture. A building loses warmth through its floor, walls, roof, glazing and the gaps around doors, so a thin-walled summer house designed for occasional summer use will behave very differently from a lined and insulated structure.
For owners assessing an existing building, the practical questions are straightforward. Is there insulation in the walls, floor and roof? Is the glazing single or double? Does the door seal properly when closed? Is the floor raised off the ground, or sitting directly on a cold base? Each of these affects how quickly a room warms up and how long it holds that warmth once the heater is switched off.
Condensation is the other winter concern. A building that is heated during the day and left to cool overnight can collect moisture on cold surfaces, which may damage stored items, electronics and the timber itself over time. Guidance on garden building in winter typically recommends balancing modest background heat with adequate ventilation rather than sealing a space completely.
Heating only what you use
For people who work from home, the economics are not straightforward. Some weigh up whether heating one well-insulated room in the garden is preferable to heating the whole house during working hours. The answer depends on the size of each space, how well each is insulated, the tariff in use and how long the room is occupied, so there is no single rule that applies to every household.
What is clear is that control helps. Thermostats and timers allow a room to be brought up to temperature shortly before use rather than heated all day, and the higher unit costs this winter make that kind of discipline more valuable.
Specifying for the colder months
Those planning a new building have the advantage of designing for winter from the outset. Insulated walls, floors and roofs, better glazing and a well-prepared base are options offered by many manufacturers, including providers of bespoke garden building services in Essex and elsewhere in the country. Discussing intended use at an early stage, whether occasional storage or a daily workplace, gives buyers a clearer sense of which specification suits their needs.
With prices moving again in the new year, the way a garden building is built may prove as important to its running costs as the tariff its owner chooses.