Keeping Your Home Cool in Summer: Do Blackout Curtains Block Heat?

When summer temperatures rise, many homeowners ask:

Do blackout curtains block heat?

The answer is yes, blackout curtains can help reduce the amount of heat entering a room by blocking sunlight and reducing solar heat gain. However, the effectiveness of blackout curtains depends not only on the curtain fabric itself, but also on the colour of the lining, how the curtains are fitted and the type of curtain track or pole used. Read on to find out more.

 

Do Blackout Curtains Keep Heat Out?

Blackout curtains can help keep rooms cooler by reducing the amount of direct sunlight entering through windows.

Sunlight passing through glass creates what is known as solar heat gain. This is one of the main causes of overheating in UK homes during summer.

According to guidance from the British Blind and Shutter Association (BBSA), shading windows during the day is an effective way to reduce overheating and improve comfort in homes during hot weather. The BBSA recommends keeping blinds or curtains closed during the hottest parts of the day and opening them at night to allow buildings to cool naturally.

Does the Colour of the Curtain Lining Matter?

Yes – very much so.

Many people assume that a dark curtain will block heat better, but when it comes to reducing solar heat gain, the colour of the lining or blind backing is extremely important.

To reflect heat effectively, the window-facing side of the curtain or blind should ideally be:

• White.

• Off-white.

• Very pale in colour.

• Reflective or solar-coated.

Light-coloured backings reflect a greater proportion of solar energy back towards the window, whereas darker colours tend to absorb heat. This means that a dark-coloured lining facing the glass may actually absorb solar energy and transfer more heat into the room. Reflective white or pale backings are generally considered more effective for reducing summer overheating.

Many blackout blinds and thermal linings therefore incorporate a white or light-coloured backing specifically to improve solar reflection.

Are Blackout Curtains Better Than Regular Curtains?

In most cases, yes.

Blackout curtains are designed using densely woven fabrics or specialist blackout linings that significantly reduce light transmission. Because they block more sunlight than standard curtains, they can also reduce heat build-up in sunny rooms.

Benefits include:

• Reduced glare.

• Improved privacy.

• Better sleep during lighter summer mornings.

• Lower solar heat gain.

• Protection against UV fading of furnishings.

Do Thermal Curtains and Blackout Curtains Do the Same Job?

Not necessarily. Although many curtains combine both properties, they serve slightly different purposes.

Blackout curtains:

• Primarily block light.

• Help reduce solar heat gain.

• Improve room darkening.

Thermal curtains:

• Provide insulation.

• Help reduce heat loss during winter.

• Can also improve comfort during summer.

Many homeowners choose curtains that provide both thermal insulation and blackout performance for year-round comfort.

Can Curtain Poles and Tracks Improve Blackout Performance?

Absolutely. Even the best blackout curtains can allow both light and heat into a room if there are gaps around the edges.

Fit Curtains Higher Above the Window

One of the simplest ways to improve room darkening is to install the curtain pole or track higher than a standard fitting position.

Mounting curtains closer to the ceiling:

• Reduces the amount of light entering above the curtain.

• Creates a larger barrier against solar heat gain.

• Makes windows appear taller and more impressive.

For the very best blackout performance, many homeowners choose to fit curtain tracks directly to the ceiling.

Extend Curtains Beyond the Window Width

Good curtain coverage at each side of the window is equally important. Curtains that extend well beyond the window recess help:

• Reduce light leakage at the sides.

• Prevent sunlight bypassing the curtains.

• Improve thermal performance.

• Create a fuller, more luxurious appearance.

As a general guide, extending the pole or track beyond each side of the window can significantly improve blackout performance.

French Curtain Poles

Traditional curtain poles often leave a gap between the curtain and the wall, allowing unwanted light to spill into the room.

French curtain poles, sometimes called wrap-around curtain poles, return back towards the wall at each end. This allows the curtain to wrap around the window opening, helping to minimise side light gaps.

When combined with:

• blackout-lined curtains

• a high fitting position

• generous overlap beyond the window width

French curtain poles can dramatically improve room darkening.

At LINEAR, our French Curtain Poles are specifically designed to help reduce light gaps at the sides of curtains and are particularly popular for bedrooms and media rooms.

Ceiling Fixed Curtain Tracks

Curtains fitted directly beneath the ceiling often perform better than those mounted lower down because there is less space for light and heat to escape above the curtain.

Ceiling-fixed curtain tracks are particularly suitable for:

• Bedrooms.

• South-facing rooms.

• Media rooms.

• Large glazed areas.

• Homes requiring improved blackout.

Our ceiling-fixed decorative curtain tracks and bendable ceiling tracks allow curtains to be positioned as close to the ceiling as possible, helping to minimise light gaps and improve blackout performance.

What Is the Best Way to Keep a House Cool During Summer?

The BBSA advises that shading windows during daylight hours and ventilating buildings during cooler periods can significantly improve comfort during hot weather.

1. Keep Curtains and Blinds Closed During the Day

Close curtains before direct sunlight reaches the window. Preventing heat entering the room is generally more effective than trying to cool the room later.

2. Open Windows at Night

Open windows during cooler evening and overnight periods to encourage natural ventilation. The BBSA recommends using cooler night-time temperatures to help buildings release stored heat.

3. Combine Blinds and Curtains

No single furnishing solution can create total blackout or maximum thermal performance on its own. Combining a blackout blind with blackout curtains often provides the best results for:

• reducing summer heat gain

• blocking early morning light

• improving sleep quality

The BBSA notes that different shading products perform different functions, and in many situations more than one shading solution may be beneficial.

4. Choose Reflective, Light-Coloured Backings

Where heat reduction is a priority, choose blinds or curtain linings with white, pale or reflective backings facing the window. These surfaces reflect more solar energy and are generally more effective at limiting overheating.

5. Reduce Gaps Around Curtains

Using:

• French curtain poles.

• Ceiling-fixed curtain tracks.

• Floor-to-ceiling curtains.

• Wide curtain returns beyond the window opening.

can all improve both light control and thermal performance.

Will Blackout Curtains Make a Room Completely Dark?

Not usually. Light often enters around the top and sides of curtains.

For the best possible blackout, consider:

• Blackout-lined curtains with a pale or reflective backing.

• A blackout blind behind the curtains.

• A French curtain pole.

• A ceiling-fixed curtain track.

• Floor-to-ceiling curtains.

• Installing the pole or track higher than usual.

• Extending curtains beyond the window opening.

At LINEAR, we often recommend combining more than one furnishing solution because no single product alone will usually achieve total blackout. Our room darkening solutions combine carefully chosen curtain poles and tracks designed to minimise light gaps around the window.

Why Are Overlap Arms Important for Blackout Curtains?

Many curtain tracks allow the curtains to meet in the middle, but they can still leave a small gap where light enters. For rooms where improved blackout is required, overlap arms can make a significant difference.

Overlap arms allow one curtain to overlap the other at the centre of the window, helping to:

• Reduce light leakage through the centre of the curtains.

• Improve room darkening.

• Create a neater finished appearance when closed.

• Reduce heat entering through the centre gap.

When combined with blackout-lined curtains, overlap arms can help create a much darker room, particularly in bedrooms and media rooms.

At LINEAR, many of our decorative curtain tracks can be supplied with curtain overlap arms to improve blackout performance. When used alongside a ceiling-fixed installation, generous side returns and well-fitted blackout curtains, overlap arms can form part of a highly effective room darkening solution.

For the best possible blackout, we recommend considering:

• Ceiling-fixed curtain rails.

• Overlap arms.

• French curtain poles
  
  

• Curtains extending well beyond the window opening.

• Blackout linings with pale or reflective backings.

• Combining blinds and curtains where appropriate.

Frequently Asked Questions

Do blackout curtains block heat?

Yes. Blackout curtains help reduce solar heat gain by limiting the amount of sunlight entering a room.

What colour curtains are best for keeping heat out?

The room-facing colour is largely a design choice, but the window-facing lining or blind backing should ideally be white or very pale to reflect solar heat effectively.

Should curtain linings be white?

For reducing summer overheating, white or pale linings are generally considered the most effective because they reflect more solar energy.

How high should curtain poles be fitted for blackout curtains?

For improved room darkening, curtain poles or tracks are often fitted higher than standard positions, ideally as close to the ceiling as practical.

Is wider curtain coverage important?

Yes. Extending curtains beyond both sides of the window reduces light leakage and improves blackout performance.

What is the best curtain pole for blackout curtains?

French curtain poles are often considered one of the best options because they reduce light gaps at the sides of the curtains. Ceiling-fixed curtain tracks can also improve blackout performance.

What is the best way to achieve maximum blackout?

For maximum darkness, combine a blackout blind with blackout curtains fitted on either a French curtain pole or a ceiling-fixed curtain track.