Best Heat-Blocking Curtains to Keep Your House Cool This Summer

Quick answer: The best heat-blocking curtains have three things — a reflective, light-colored backing, a dense multi-layer weave, and enough size to cover the whole window tightly. Together they stop and reflect the sunlight that becomes indoor heat. Thermal-plus-blackout panels in a lighter color are the strongest performers; hung high and wide and closed before the sun hits, they keep a room noticeably cooler and take load off your AC.

Wondering whether they actually work before you shop? We covered the evidence in do thermal & blackout curtains keep heat out in summer. This guide is about which to choose.

What makes a curtain “heat-blocking”

• Reflective / light backing. A white or light-colored backing bounces sunlight back out through the glass before it turns into heat. A dark fabric facing the window absorbs sun and re-radiates warmth inward.
• Density and weave. A tightly woven, multi-layer or coated panel blocks more radiant heat than a thin single layer. This is what separates a true thermal curtain from a decorative one.
• Color (outside-facing). Lighter shades on the window side reflect more heat; you can still have a darker look indoors by choosing panels with a light backing.
• Coverage. The best fabric fails if heat leaks around it. Full, tight coverage over the whole window is half the performance.

We put real thermal fabric to the test here: Seriously, do thermal curtains really work?

Best heat-blocking curtains by room

• Bedroom: thermal blackout in a lighter color — blocks heat and light for cooler, darker summer sleep. See blackout curtains.
• Living room (big sunny windows): light-colored thermal curtains, or layer with a roller blind for two barriers.
• West- and east-facing rooms: these take the most direct sun — prioritize your heaviest, most reflective panels here.
• Kitchen / home office: a light-filtering thermal panel cuts glare and heat while keeping the room usable.

How to get the most cooling from them

• Close them before peak heat — in the morning on sun-facing windows, before the room warms up.
• Hang high and wide and let panels reach the floor so heat can't leak at the sides and top — our light-gap guide shows how.
• Prioritize the sunniest windows first — you'll feel the difference fastest there.
• Add a second layer — a roller blind close to the glass plus curtains in front traps insulating air and blocks even more heat.

Blackout vs thermal — which blocks more heat?

Most quality blackout panels block a lot of solar heat as a side effect of blocking light. Thermal panels add an insulating layer built specifically to slow heat transfer. For summer, the best of both worlds is a thermal + blackout panel in a lighter color — strong reflection, real insulation, and darkness for sleep.

Pair with a blind for even more

Two layers beat one. A motorized roller blind scheduled to close against the afternoon sun, with thermal curtains in front, is the most effective no-AC-upgrade setup for a hot, sunny room.

The Deconovo difference

Deconovo thermal and blackout curtains are OEKO-TEX® Standard 100 certified and trusted in 21,000,000+ homes worldwide — designer-quality, sustainably crafted comfort that keeps summer rooms cooler and winter rooms warmer.

Frequently asked questions

What curtains are best for blocking heat?
Dense, thermal or thermal-blackout panels with a light or reflective backing, sized to cover the whole window tightly. Lighter outside-facing colors reflect the most heat.

Do heat-blocking curtains really keep a room cooler?
Yes. By reflecting and blocking sunlight at the glass they cut solar heat gain — the U.S. Department of Energy estimates closed draperies can reduce heat gain by up to about a third.

What color curtains block heat best?
Light or white on the window-facing side reflects sunlight best. Choose a light backing if you want a darker look from inside.

Are blackout or thermal curtains better for summer heat?
A thermal-plus-blackout panel in a lighter color usually performs best, combining reflection, insulation, and darkness.

When should I close them to keep cool?
In the morning before direct sun hits, especially on east- and west-facing windows, and keep them drawn through the hottest part of the day.