Do Curtains Keep the Heat In

Curtains are often seen as a finishing touch to a room, chosen mainly for their colour, pattern, or ability to block out light. Yet, many homeowners also wonder whether curtains have a more practical role in keeping homes warm, particularly during colder months. With rising energy costs, it is a fair question to ask whether drawing your curtains in the evening can make a measurable difference to indoor comfort and heating bills. The answer is yes, curtains can help to keep heat in, but their effectiveness depends on the type of curtain, how they are used, and the overall insulation of the property.

How heat is lost through windows

To understand how curtains can help, it is worth looking at how heat escapes from a home. Even with modern double or triple glazing, windows are one of the weakest points in terms of insulation. Glass has a much lower thermal resistance than a wall, meaning it allows heat to pass through more easily. On cold days and nights, warm air inside naturally moves towards the cooler surface of the glass. This process, known as thermal transfer, results in noticeable heat loss. Without any barrier, homes lose a significant amount of warmth through their windows, which means the heating system has to work harder to maintain comfortable temperatures.

The insulating effect of curtains

Curtains provide an additional layer of protection between the room and the window. By creating a pocket of still air between the fabric and the glass, they slow down the rate at which heat escapes. This barrier is particularly effective when curtains are made from thick, heavy fabrics such as velvet, lined cotton, or specialist thermal materials. Well-fitted curtains that extend below the window sill and are drawn fully closed can significantly reduce heat loss, especially when combined with other energy saving measures. In this sense, curtains act in a similar way to insulation by trapping air and reducing thermal transfer.

Thermal and blackout curtains

Standard decorative curtains can provide some level of heat retention, but modern thermal and blackout curtains are designed with energy efficiency in mind. Thermal curtains often have additional linings or layers that increase their insulating properties. Blackout curtains, while primarily used to block light, are usually made from dense materials that also help to reduce heat loss. For homeowners looking to improve warmth without replacing windows, investing in thermal curtains is a cost effective option that provides both practical and comfort benefits.

Curtain length, fit, and positioning

The effectiveness of curtains in keeping heat in is also influenced by their size and placement. Curtains that only just cover the window or that leave gaps at the sides or top will allow warm air to escape. Full length curtains that extend below the sill and fit closely against the wall are much better at retaining heat. Similarly, curtains that hang directly in front of radiators can reduce their efficiency by blocking heat from circulating into the room. In these cases, it is better to tuck the curtain behind the radiator or choose shorter designs that avoid covering the heating source.

Day and night use

Curtains are most beneficial when drawn at night, as this is when the temperature difference between inside and outside is greatest. During the day, it is often better to keep them open, especially on south facing windows, to let in natural sunlight which can provide free warmth. In winter, this combination of letting in solar heat during the day and closing curtains at night can help maintain a stable and comfortable indoor environment without over-relying on central heating.

Comparing curtains with other solutions

Curtains are not a substitute for good quality glazing, insulation, and draught proofing, but they can make a noticeable difference as part of a wider energy efficiency strategy. For example, homeowners with older single glazed windows may experience significant improvements in comfort by installing thick curtains, even if they cannot afford to replace the glazing immediately. On the other hand, in well-insulated modern homes, the benefit may be smaller but still worthwhile, particularly in very cold weather.

Energy savings and household bills

Although curtains alone will not cut energy bills dramatically, they contribute to reducing overall heat loss, which means your heating system does not need to run as frequently. Research has shown that properly lined curtains can reduce heat loss through windows by up to 15 to 20 percent. Over the course of a winter, this can add up to noticeable savings, especially for households that heat large living rooms or bedrooms for long periods. Combined with habits such as closing doors, blocking draughts, and insulating lofts and walls, curtains play a valuable supporting role in keeping homes efficient.

Additional comfort benefits

Beyond energy savings, curtains also contribute to the feeling of comfort in a home. Rooms with uncovered windows often feel colder due to draughts and cold spots, even if the thermostat reads the same temperature. By providing an insulating barrier, curtains reduce these uncomfortable effects, creating a cosier atmosphere in the evenings. For many households, this sense of comfort is as valuable as the reduction in heating costs.

Practical examples in the UK

In older properties with large single glazed sash windows, thick curtains with thermal lining are often the most effective short term way to reduce heat loss. In newer homes with patio doors or floor-to-ceiling glazing, specialist thermal drapes or layered curtains can make living spaces more pleasant in winter. Even in rental properties, where tenants may not be able to change the glazing, fitting suitable curtains is a simple and affordable step to improve warmth without breaching tenancy agreements.

Conclusion

Curtains do help keep heat in, particularly when they are thick, well-fitted, and properly lined. While they cannot replace modern insulation and glazing, they act as a valuable extra layer that slows heat loss through windows and contributes to household energy savings. For UK households facing rising heating costs, using curtains effectively is a straightforward and low-cost way to improve comfort and efficiency. Closing curtains at night, choosing thermal fabrics, and ensuring a good fit can all make a meaningful difference to how warm and welcoming your home feels.