The seat beside a window can be the chilliest place in the room in January and uncomfortably hot on a sunny July afternoon. Window coverings help tackle both problems, but their job changes with the season: slowing heat loss in winter and limiting incoming sunshine in summer. The material and fit matter, along with when you open or close them.
Construction and fit make the difference
Heat passing through glazing and air leaking around a frame need different responses. A covering adds resistance to heat transfer; a failed window seal needs attention to the window itself. If you feel air entering around a closed window, investigate the frame and seals before relying on thicker fabric.
Insulating linings can help slow heat transfer, while cellular designs enclose pockets of relatively still air. Cornell’s guidance on energy-saving window treatments explains why installation matters too: room air circulating freely behind a covering can undermine its insulating effect.
When discussing options with a window-covering specialist such as The Blind Company, ask how the covering will fit at the sides, top and bottom, as well as what insulation its construction provides. Fabric samples tell only part of the story.
Cold glass can also make someone sitting nearby feel cooler, even without a draught. A covering may improve comfort in that spot, while any effect on heating bills depends on the existing glazing, the rest of the building and how the home is heated.
Use winter sunshine, then close at dusk
On bright winter days, open coverings where direct sunshine can enter and warm the room. Keeping them closed all day blocks that useful solar warmth along with the light. At a window shaded by a neighbouring building, opening the covering mainly provides daylight rather than direct solar heating.
Close coverings at dusk, not just at bedtime. With the sunshine gone, their role shifts to providing an additional insulating layer between the heated room and colder glazing. Closing them earlier extends that benefit through the evening.
Check that each covering is fully closed. A partly raised blind or curtains that fail to meet leave areas of glass exposed. Make this a dusk habit, adjusting the timing as daylight hours change. A reminder can be useful on busy evenings.
Get ahead of summer sunshine
During hot weather, reverse the approach at windows receiving strong sun. Lower blinds or close curtains before sunlight has spent hours warming floors, furniture and other internal surfaces. Once the room feels hot, that heat has already built up and needs to escape.
Each window has its own timetable. An east-facing bedroom may need shading early in the morning, while a west-facing sitting room receives strong afternoon sunshine. Trees, nearby buildings and the depth of the window recess alter exposure, so follow the actual pattern of light rather than compass direction alone.
Spend a sunny day noticing when direct light reaches each window. Closing coverings on the sunlit side while leaving them open in shaded rooms can help limit solar gain while preserving daylight elsewhere.
External shading, such as an awning, intercepts sunshine before it reaches the glass; internal coverings act inside the window. Their usefulness depends on the window and shading design. Both manage incoming solar heat rather than actively cooling a room as an air-conditioning system does, so pair shading with opportunities to release accumulated warmth.
Let cooler air in and keep moisture in check
When outdoor air is cooler than indoor air, opening windows can help release heat, provided it is safe to do so. Check the conditions first: opening a window to hotter outdoor air brings that warmth indoors.
Keep intentional ventilation openings usable throughout the year. The Energy Saving Trust’s advice on windows and doors addresses ventilation alongside energy efficiency and condensation. Draught-proofing unwanted gaps and preserving purposeful ventilation are separate jobs.
In winter, check behind closed coverings for persistent moisture on the glass or frame. Condensation calls for attention to moisture levels and ventilation, not simply more insulation. Open coverings to inspect the window, wipe away surface moisture and investigate recurring damp.