Sun Heat Through the Window: How to Lower Your Home's Temperature

If you live in Palm Beach, Broward, or Miami-Dade, you've probably noticed it: some rooms feel like a greenhouse by mid-afternoon, even when the air conditioning is running nonstop. Often the culprit isn't the AC, but the sun coming through the window.

In this article, we explain in plain terms how that heat gets in, which windows to address first, and which curtain fabric helps most for each room.

Glass lets sunlight through. When that light reaches the floor, furniture, and walls, it turns into heat inside the home. This is called solar heat gain, and it is a well-established concept: energy efficiency guides, such as those from the U.S. Department of Energy, identify it as one of the main ways windows increase cooling loads in warm climates.

Two general ideas that help explain it:

• Direct sun usually heats much more than indirect light.
• It's easier to stop heat before it builds up in the room than to remove it later with air conditioning.

A curtain doesn't change the glass, but it can reduce the amount of direct light that reaches the interior. That can help the room feel cooler and keep the air conditioning from working as hard. The effect depends on the window, its orientation, and the fabric, so we don't promise a specific number.

Not all windows in your home add the same heat. Start with the ones that get direct sun for the most hours:

• West-facing windows: these get the low, strong afternoon sun, just when the house has already been building up heat. They're often the hardest to manage.
• East-facing windows: these get strong morning sun. They're especially bothersome in bedrooms and kitchens.
• South-facing windows: these get high sun for much of the day. In summer the sun is quite overhead, so good light control helps.
• Sliding glass doors and large picture windows: more glass means more sun coming in, even if they don't face west.
• Daytime-use rooms: living rooms, home offices, and kitchens, where you spend the most hours.

A simple trick: walk through the house at different times of day and notice where the sun falls directly on the floor or furniture. Those are your priority windows. For more context on how the sun and heat behave in your area, see our climate and curtains page.

We offer one product line, custom Ripple Fold curtains, in three fabrics. Each handles heat differently.

This is the one that blocks light. If you have a west-facing window in a bedroom, a TV room, or any room where the sun hits hard, Blackout is the option that stops the most direct sun. It also helps you sleep or rest during the day. The room gets darker, and that's the tradeoff: it's not the best choice if you want to keep a lot of natural light.

It filters and softens light while maintaining privacy. It's a very good choice for the living room, dining room, or home office: you lower the intensity of the sun without leaving the room in darkness. For windows with strong sun where you still want to see daylight, it's usually the most comfortable middle ground.

It's nearly transparent and lets light through. It softens glare and gives a light, airy look, but it's the fabric that blocks direct sun the least. It works well in windows that don't get intense sun, or as a complement when you want a bright atmosphere rather than major heat reduction. If your main problem is heat from a west-facing window, Sheer alone probably won't be enough.

• Bedroom with afternoon sun: Blackout.
• Living room or dining room with a west- or south-facing picture window: Light Filtering, or Blackout if the sun is very intense.
• Home office with glare on the screen: Light Filtering.
• North-facing window or one with little direct sun: Sheer, if you want light and airiness.

You can see how all three look and feel in our fabric catalog, and order free fabric samples to try them in your home's natural light.

The curtain is part of the solution, not the whole thing. Some general measures that usually help:

• Close the curtains during the hours of most sun, especially on windows that get direct sun.
• Open the curtains at night or during cooler hours if you want to take advantage of natural light and ventilation.
• Keep your air conditioning well maintained.
• Avoid placing furniture or heat sources directly in front of sunny windows.

Keep in mind that curtains help with light, privacy, and comfort, but they do not protect against hurricanes or replace certified hurricane protection.

They can. By blocking direct sunlight from coming in, the room usually stays cooler. The results vary depending on the window's orientation, the type of glass, and the fabric you choose, which is why we don't provide savings figures.

Blackout blocks the most direct sunlight. If you'd prefer to keep some natural light, Light Filtering is a good middle ground. Sheer lets in a lot of light, so it isn't the best choice if your goal is to reduce heat.

Not necessarily. The most helpful approach is to close them during the hours when the sun shines directly on that window and open them once it no longer does. With Light Filtering, you can still enjoy good light even when the curtains are closed.

We have a step-by-step guide on how to measure. If you'd like support, you can request a free video call or a technical visit, and choose between professional installation or doing it yourself.