Both interior solar shades and exterior solar screens block heat, glare, and UV. The amount they block differs significantly, and the gap is bigger than most people expect. Exterior solar screens stop solar radiation before it touches the window. Interior solar shades catch what is already inside, after the glass has heated up.
The U.S. Department of Energy is direct on this. Exterior shading is the most effective window treatment for reducing solar heat gain. Interior solar shades still help, but they work in a fundamentally different way, and the gap matters in hot climates. Below is the quick verdict, the physics behind it, and how to pick the right solar treatment for your windows.
Which blocks more heat: interior or exterior?
Exterior solar screens block more heat than interior solar shades. According to the U.S. Department of Energy, exterior shutters and shades are most effective at reducing solar heat gain because they intercept sunlight before it reaches the glass.
Interior solar shades reduce heat by absorbing or reflecting sunlight after it passes through the window. The shade traps some of that heat and re-radiates it back into the room. Helpful, but not as efficient as stopping the light outside in the first place.
Note on terms: Solar shades and solar screens refer to the same fabric category. We use “interior solar shades” for indoor versions and “exterior solar screens” for outdoor versions to match how the products ship.
Why exterior solar screens block more heat
Exterior solar screens work because of where they sit relative to the glass. The fabric mesh blocks shortwave solar radiation outside the building envelope. The window glass never heats up, and the conduction and convection that would push warm air into the room never start.
Interior shades, by contrast, do their work after the heat has already entered. Once shortwave UV passes through the window, it converts to longwave radiation when it hits the shade fabric or any surface inside the room. Longwave radiation cannot pass back through the glass as easily, so the heat stays trapped indoors.
The performance gap shows up most in hot, sunny climates. West-facing rooms, sunrooms with large glass walls, and patio enclosures benefit most from exterior placement.
What interior solar shades still do well
Interior solar shades are not a consolation prize. Indoor placement has its own advantages that exterior screens cannot match.
Interior shades give you full design control. Fabric, color, and texture become part of the room. Exterior screens are functional first and live outside the architecture. Interior shades also handle screen and TV glare better because they sit closer to the eye line.
Interior shades cost less to order, less to install, and require less weather-resistant hardware. Maintenance is easier too, with no wind, rain, or UV exposure to the mounting system.
Use interior solar shades when the room gets indirect or moderate sun, when style is the priority, when the window is on an upper floor without easy exterior access, or when the budget points toward a single layer of treatment.
Interior vs exterior at a glance
Both options share the same fabric science, but the placement changes the performance.
| Feature | Interior solar shades | Exterior solar screens |
| Heat blocking | Good | Most effective per the DOE |
| Glare reduction | Strong | Strong |
| UV protection | Good | Strongest, blocks UV before glass |
| View preservation | Yes, with the right openness | Yes, with the right openness |
| Weather exposure | None | Full sun, wind, rain |
| Style integration | Wide design range | Functional, exterior-first |
| Maintenance | Easy, indoor cleaning | Requires occasional outdoor cleaning |
| Best for | Most rooms, glare, style | Hot climates, large or sun-facing glass |
How to choose between interior and exterior
The right answer depends on three things: your climate, the window’s exposure, and how you use the room.
- Climate. Hot, sunny regions benefit most from exterior solar screens. Mixed and cooler climates often do fine with interior solar shades alone.
- Window direction. West- and south-facing windows with hard afternoon sun get the biggest gain from exterior placement. North- and east-facing windows usually do not need it.
- Room use. Sunrooms, screened porches, and patio enclosures are exterior-first. Living rooms, bedrooms, and home offices are usually interior-first.
- Access and budget. Ground-floor windows are easy to mount exterior screens on. Upper-floor windows often require motorized exterior screens, which add cost. Interior shades are the lower-cost entry point overall.
For homes that need maximum control, layering works. Use exterior screens during the day to block heat and run interior solar shades in the evening for privacy and glare.
Solar shades and screens to consider
Each option below is custom-made to your exact window or opening and available with a cordless or motorized lift.
Blindsgalore Envision Solar Shades
The Blindsgalore Envision Solar Shades are our most popular interior solar shade. Multiple openness factors, a wide neutral color range, and the option to upgrade to a motorized lift make this the default starting point for living rooms, kitchens, and home offices.
Blindsgalore Harmony Solar Shades
The Blindsgalore Harmony Solar Shades round out the interior lineup with a refined fabric finish. Best for rooms where the shade itself reads as part of the design.
Blindsgalore Classic Outdoor Solar Screens
The Blindsgalore Classic Outdoor Solar Screens are the budget-friendly exterior pick. Built with weather-resistant fabric and hardware, these are well-suited to patios, porches, and ground-floor exterior window mounts.
Blindsgalore Signature Motorized Outdoor Solar Shades
The Blindsgalore Signature Motorized Outdoor Solar Shades are the upgraded exterior pick. Motorized lift with remote and smart-home control through Alexa and Google Home makes this the right choice for upper-story windows, three-season rooms, and large patio openings.
Cool the room before it gets too hot
Exterior screens stop the heat at the source. Interior shades catch what is left and add style and glare control. The smartest setups use both. Order up to 10 free swatches so you can compare interior and exterior fabrics side by side. For a second opinion, our in-house experts answer at (877) 702-5463.
Love your view, even on the hottest afternoon.
Frequently asked questions
Exterior solar screens block more heat than interior solar shades because they stop sunlight before it touches the window glass. Interior shades reduce heat after light passes through and are still effective, but less so. The DOE confirms exterior shading is the most effective option for reducing solar heat gain.
Exterior solar screens can technically be used indoors, but they are built with heavier, weather-resistant fabric, not designed for indoor aesthetic integration. For indoor use, interior solar shades give a better fabric range and finish at a lower price.
Interior solar shades lower solar heat gain through the windows, which reduces the cooling load on the air conditioner. The savings are smaller than what exterior screens deliver, but still meaningful, especially with a low openness factor and a lighter fabric color.
Exterior solar screens require occasional cleaning and weather inspection. Wipe down the fabric with a soft brush or low-pressure rinse a few times a year. Retract the screen during heavy storms or high winds to extend its lifespan.
Yes. Motorized exterior solar screens are the practical choice for upper-floor windows because manual operation requires outdoor access. A motorized lift with remote or smart-home control lets you operate the screen from inside.
Blindsgalore brand solar shades carry a 3-year limited warranty with a free upgrade to a 5-year warranty. Coverage applies to defects in materials and workmanship when the product is properly installed and operated. Fading is not covered.