A hot apartment with no AC usually loses the fight at the window, where afternoon sun pours straight through the glass and bakes everything inside. The best curtains to keep heat out do it without drilling, without making the place dark, and without wrecking your deposit.

This guide is for renters and small space dwellers who want to block heat without permanent installs. If your room mainly overheats late in the day from a west window, start with our west facing room cooling guide, then come back here for the window treatment details. And if you have ever wondered why your apartment feels hotter than it is outside, the window is usually the answer.

What actually blocks heat: the fabric, the color, or the fit?

The biggest factor is not the curtain label, it is what faces the glass and how tightly the panel seals the window. A light panel with a white or reflective backing bounces sunlight back out before the room absorbs it, and the U.S. Department of Energy estimates that well managed window coverings cut heat gain by up to 77 percent. Cellular, or honeycomb, shades add trapped air pockets that slow heat further, blocking as much as 60 to 80 percent of summer heat gain at the window.

Dark, thin, or loosely hung curtains do very little, no matter how heavy the fabric feels. For a rented apartment, the winning formula is simple: choose a light or reflective face, mount the panel close to the glass with small side gaps, and keep it closed through the hottest hours of the afternoon.

Here is how the main options compare at a glance:

Window treatment	Heat it blocks	Renter friendly	Rough cost
Cellular (honeycomb) shade	Up to 60% alone	Yes, tension fit	Mid
Reflective window film	Up to about 78% at the glass	Yes, static cling	$10 to $30 a roll
Light thermal blackout curtain	Several degrees cooler	Yes, tension rod	Low to mid
Solar shade	Cuts radiant heat, keeps the view	Yes, tension fit	Mid
Reflective roller shade	Bounces sun at the glass	Yes, no drill options	Low to mid
Light linen or cotton curtain	Modest, best for looks	Yes	Low to mid
Layered stack (shade plus drape)	The most, up to 77%	Yes	Higher

The 7 best heat blocking window treatments for a no-AC apartment

1. Cellular (honeycomb) shades

These are the most effective interior option, and they are the one I recommend first. The honeycomb pockets trap a layer of air that slows heat moving through the glass, cutting summer heat gain by up to 60 percent on their own. Double or triple cell versions block the most. No drill tension fit versions install inside the window frame with no screws, so they come off clean at move out.

2. Light thermal blackout curtains

Blackout fabric with a thermal lining is the classic heat blocker, and a good panel can make a real temperature difference in a sunny room. The catch is color and fit. Choose a light or white face, or hang a light thermal liner behind a darker decorative curtain so the room still looks warm without absorbing heat.

3. Solar shades

Solar shades use a tight weave that cuts glare and radiant heat while keeping your view. They are ideal for a window you do not want to fully cover, like a living room with a nice outlook. Pick a lower openness percentage for hotter, sunnier windows.

4. Reflective roller shades

A roller shade with a reflective or white backing bounces sunlight straight back outside before the room heats up. They sit slim against the glass, come in no drill versions, and pair well with a soft drape on top so the hard reflective layer stays hidden.

5. Light linen or cotton curtains

If you care most about how the room looks, breathable natural fabric in a pale shade is the move. Linen and cotton let air pass, wick moisture, and reflect more sun than synthetic sateen. They block less heat than a cellular shade alone, so treat them as the pretty top layer, not the whole defense.

6. The layered stack

The strongest setup is two layers: a cellular or solar shade close to the glass, plus a light lined drape over it. The shade does the heat work and seals the sides, the drape trims light leaks and makes the window look finished. This is how you get real cooling and a room that still photographs well.

7. No drill mounts and removable film

The mechanics matter as much as the fabric. Tension rods, adhesive brackets, and magnetic clips let you hang heavy panels without a single hole. Add a removable static cling window film, usually 10 to 30 dollars a roll, to reject part of the heat at the pane before your curtains even work.

What color curtains keep a room coolest?

Light colors keep a room coolest, full stop. Pale shades reflect sunlight back out, while dark fabric absorbs it and then radiates that stored warmth into the room after the sun moves on. White, oat, sand, pale sage, and soft clay all work well on a sunny window.

There is a nice overlap with current style here. The all gray, cool toned window look is fading, and 2026 is leaning into warmer, softer tones like terracotta, olive, and muted ochre. You can stay on trend and stay cool at the same time, as long as the panel that faces the glass is light or reflective. If you love a deep, moody color, keep it as the front decorative layer and put a light thermal liner behind it.

Do blackout curtains actually keep heat out?

Yes, but only when they fit tightly and face the right way. Blackout fabric blocks light extremely well, and paired with a thermal lining it can drop a sunny room by several degrees. The failure point is almost always the gaps. Sun leaking around the sides and top of a loose panel undoes most of the benefit.

To make blackout curtains earn their keep, mount the rod wider and higher than the window so the panels overlap the frame, let the fabric fall close to the wall, and overlap two panels in the middle. A tightly sealed light blackout curtain beats a heavy dark one that floats an inch off the glass every time.

How do renters hang heat blocking curtains without drilling?

You have more no drill options than most people realize. Tension rods sit inside the window frame with no hardware. Adhesive or magnetic curtain brackets hold a wider rod above the frame and peel off at move out. For blinds and shades, look specifically for tension fit or spring loaded versions that press into the recess.

Removable window film is the other renter friendly layer. Static cling reflective film needs no adhesive, cuts a large share of solar heat at the glass, and comes off with a corner pull when you leave. Apply it in the morning while the glass is cool, and photograph the window before you start so you have a clean record for your deposit. For a whole apartment plan, pair these with the zoning ideas in our south facing room cooling guide.

A quick summer setup order

1. Seal the hottest window first. Add a cellular or reflective shade close to the glass on whichever window gets the harshest sun.
2. Layer a light drape on top. Choose a pale linen or thermal panel and mount the rod wider than the frame.
3. Close the gaps. Overlap the panels, let them fall to the wall, and clip the outside edges if your lease allows.
4. Add film if needed. Use static cling reflective film on the sunniest pane for extra rejection at the glass.
5. Run it on a schedule. Keep everything closed from late morning through the hottest part of the afternoon, then open up once the outside air cools.

Final thought

Blocking heat at the window is the highest impact thing a renter can do without AC, and it does not have to mean living in a dark cave or wrecking your deposit. Start with a light, reflective layer close to the glass, seal the side gaps, and add a soft drape on top for the look. Do that on your worst window and the whole apartment feels different by dinner.

Written by Jihyun Lee, who has cooled more than one top floor rental through a single window blasted by afternoon sun, no AC and no drilling allowed.