Close Your Curtains at 19.45 to Reduce Heating Costs

Between afternoon spring sunshine and cooler evening hours, many homes face a costly gap: the property loses warmth faster than we would like, while energy prices remain high. A straightforward habit from around 19.45, recommended by energy experts in the UK, can also help households elsewhere cut heating costs - without buying any new technology, simply by drawing the curtains.

Why curtains should be closed from 19.45

Around the middle of March, daily routines start to change: daylight lasts noticeably longer and afternoon sun warms living rooms and bedrooms more effectively. This natural heat is worth retaining rather than allowing it to escape straight back through the windows.

“Closing your curtains consistently from around 19.45 keeps the heat stored during the day inside the home for longer, reducing the demand on your heating.”

The reason is straightforward. Even in modern properties, windows remain a weak point in the building envelope. Glass conducts heat more readily than an insulated wall, and panes become very cold overnight. Once the sun has set, the process reverses: the window transfers indoor heat to the cold air outside.

From mid-March, sunset in many areas falls at, or shortly before, 19.45. This makes it a useful rule of thumb: until then, sunlight can still make a modest contribution to warming the home; afterwards, heat loss through the glass becomes the dominant factor. Drawing the curtains at that point slows this loss.

The physics: curtains as a “second window pane”

A curtain is not a replacement for insulation, but it creates an additional thin layer between the room air and the window glass. This forms a pocket of air that slows down heat transfer.

“Dense fabric placed in front of a window reduces the flow of heat outdoors - a small change with a clearly noticeable effect on the indoor climate.”

The colder the night, the more apparent the difference becomes. Rooms where curtains are drawn early in the evening stay comfortable for longer, while uncovered windows can become “cold traps”. Anyone who then turns up the thermostat pays for that effect directly through their energy bill.

Which curtains actually make a difference

Not all fabrics perform equally well. Thin decorative net curtains are mainly intended for appearance. To achieve a noticeable result, more substantial material is needed.

What to look for when choosing curtains

• Fabric thickness: Heavy, tightly woven materials retain heat far more effectively than light, sheer fabrics.
• Thermal or blackout curtains: Multi-layered designs with specialist coatings or linings provide a significantly better insulating effect.
• Length: Curtains should cover the whole window area and reach close to the floor, without resting on a radiator.
• Width: Generous width ensures that the fabric closes properly at the sides, preventing cold areas around the edges.
• Colour and surface: Lighter fabrics with reflective inner surfaces can help distribute solar warmth around the room during the day, while serving as a barrier in the evening.

Many manufacturers sell so-called “thermal” curtains. Studies indicate that rooms fitted with these fabrics can maintain indoor temperatures from a few tenths of a degree up to several degrees higher than comparable rooms without curtains. That may not sound like much, but during the heating season it can often mean the difference between turning the heating back up and leaving the thermostat where it is.

How much can realistically be saved on heating costs?

Savings depend greatly on the type of home: an older property with large single-glazed windows or a modern home with double or triple glazing; a north- or south-facing aspect; a detached house or a flat within a larger building. The basic principle is simple: the poorer the window insulation, the greater the potential saving from curtains.

Energy experts report that some households have been able to keep their average room temperature stable by up to one degree without heating for longer, simply through consistent curtain management. Since each degree of reduced heating demand saves roughly five to six per cent of energy, this is not only about comfort but also about real money.

Mid-March routine: making the most of the evening sun

The key is to combine opening curtains during the day with reliably closing them in the evening. Anyone who spends the day at the office should not automatically shut everything in the morning simply because it is still cool outside.

A possible daily routine for your curtains

• Morning: Open curtains fully to let as much daylight and solar warmth as possible enter the home.
• Afternoon: In rooms receiving direct sunshine, make the most of the warmth and keep the window area uncovered.
• Around 19.45 (from mid-March): Close the curtains as soon as the sun has disappeared behind buildings or below the horizon.
• Later in the evening: Air rooms briefly and fully, then close the curtains again immediately afterwards.

People working from home can manage this even more precisely: shortly before dusk, walk around the property and close curtains wherever windows are large or where cold air can be felt radiating inwards.

When energy prices are high: small actions with a major effect

In many countries, including Germany, Austria and Switzerland, households have faced pressure from rising electricity and gas prices for years. Many people already lower their room temperature, take shorter showers or switch off standby appliances more rigorously. Drawing the curtains fits neatly into this list: there is no loss of comfort, it requires very little effort, and it has a genuine effect.

“Heating, airing rooms and managing curtains - those who keep all three in mind can often reduce their energy costs considerably without feeling cold.”

Online, users share experiences similar to those reported by the British portal: people who close their curtains diligently in the evening describe fewer draughts around the sofa, warmer bedrooms and radiators coming on less often. Tenants in poorly insulated older buildings in particular find this a noticeable relief.

What you should avoid

One common mistake is having curtains hang directly over a radiator, or even partly cover it. Warm air then builds up between the radiator and the fabric, with little of it circulating through the room.

• Fit curtains so that their lower edge does not touch the radiator.
• Use wider curtain poles so the fabric does not sit directly against the radiator.
• Where there are radiator recesses, make sure the curtain ends in front of the window reveal rather than in front of the radiator.

It is also worth keeping an eye on moisture. In rooms with high humidity, such as bedrooms or poorly ventilated older properties, condensation can collect on the glass behind permanently closed, dense curtains. Regular brief airing and a quick check behind the fabric help prevent mould growth.

Practical examples for different homes

In a typical city flat with two large living-room windows, a simple test can be worthwhile: on two cool March evenings, leave the heating at the same setting, but close the curtains from 19.45 on only one of those days. Many people notice while sitting on the sofa that the perceived temperature remains higher.

A similar experiment works in a detached house with large patio doors: place a thermometer in the living room, choose the same heating setting on two comparable evenings, and record how far the temperature drops overnight - once with curtains or vertical blinds closed, and once without them. Small measurements like these make the effect tangible and encourage the habit.

Other adjustments: combining curtains intelligently

Curtains can be paired with other simple measures. Many households achieve a kind of “cascade effect” when several small steps are combined:

• Fit draught-proofing strips to old window frames.
• Close roller blinds or Venetian blinds as well in the evening.
• Place rugs near cold external walls to reduce the feeling of draughts.
• Bleed radiators regularly so they operate efficiently.

Each measure has a moderate effect on its own. Together, however, they noticeably stabilise indoor temperatures - and curtains closed in the evening play a central role.

What terms such as “thermal curtains” really mean

The market for “thermal curtains” is expanding, often accompanied by ambitious promises. The term usually refers to multi-layered fabrics, often with an insulating lining or coated backing. The differences lie in their density, materials and construction.

Anyone looking to improve their home does not necessarily need to buy specialist products. Traditional heavy curtains made from tightly woven fabric can also work well. What matters is that they close properly, are not too short and are hung securely enough to be used every day - especially from mid-March, when there may still be daylight in the evening but no significant warmth entering through the window.