Sunshades Versus Light Shelves

Sunshades and light shelves often work together to mitigate glare and solar heat gain while increasing the amount of natural daylight in a space. But what exactly is the difference between these two products and how are they used?

The intended purpose of sunshades, which are always used on the exterior, is to provide shade. Light shelves are used only in  conjunction with sunshades. They are positioned on the interior of the building, level with the sunshade and 2-3 feet below the top of the window. They are used to reflect sunlight off of the ceiling into the building. This allows natural light to still flood a room, but without uncomfortable glare or heat gain.

Other benefits of this combination include decreased reliance on artificial lighting and air conditioning. Increased occupant well-being is another benefit as a result of having natural light without direct solar rays causing discomfort. Pat Boucher, regional sales manager at Oldcastle BuildingEnvelope® (OBE), says light shelves can reduce a building’s artificial lighting needs by 40-50%.

“The rule of thumb is that light shelves bounce light in about 2.5 times the distance of the light shelf’s width,” he says.

Nathan Seaman, national sales manager at Architectural Grilles & Sunshades of Frankfort, Ill., explains that since blinds don’t mitigate solar heat gain, sunshades and light shelves are a better alternative.

“In addition, buildings look better with sunshades—even if the project is a warehouse, if you add sunshades it really stands out. The product helps architects be more distinctive and put their signature on a building in a way that’s also functional,” he says.

Josh Wignall, director of marketing for EFCO Corp. of Monett, Mo., says sunshades have grown from a performance-based product to something seen as primarily aesthetically appealing.

“They create a cool flow on a building and give it more texture,” he says, adding that they’re also highly customizable.

Design Considerations

Boucher says it’s important for architects to consider sunshades early on to ensure the façade can handle the load. Wignall adds that heavy snowloads need to be considered when designing sunshades to ensure they have enough support and anchor points.

“They are exterior facing and can collect ice and snow. Architects have to plan for that if the building is in an area where that weather occurs,” he says.

Seaman says sunshades and light shelves work best in south-facing windows since that’s the façade receiving the most exposure to sunlight. However, the products also can work well on the east and west facades.

“On the west you’ll get sunlight in the morning and in the east you’ll get sunlight in the evening. These products can be used on those sides depending on a building’s purpose,” he says, explaining that, in an education project, they would work well if there are morning classes on the west side of the building and afternoon classes on the east side.

Direction also plays a part in determining whether to use horizontal versus vertical sunshades. Seaman explains that southern windows should have horizontal sunshades or a combination of both. If it only had vertical sunshades, there would be no protection at noon when the sun is highest. Vertical sunshades work well on the northern, eastern or western facades. He also says that vertical sunshades can restrict the view out of a window, whereas horizontal sunshades do not. Wignall points out that many designers will choose to use sunshades on the north façade to keep the aesthetics consistent throughout the building.

Logistics also should be considered. Bill Lang, director of product development services at OBE, says that cantilevered sunshades can be large and may require special equipment to be lifted into place.

Demand Changes

While these products are intended to be used together, sunshades increasingly are being specified on their own. Aesthetics is one major factor driving this demand. The ability to customize the shape and color of sunshades has driven architects to specify them as an eye-catching architectural feature, more so than a sunshading or energy-saving product in some cases, says Wignall. He adds that architects tend to use the glass itself to drive performance.

Boucher explains that OBE has developed a basic chassis as a starting point that can be used to customize sunshades with different materials. However, he’s noticed a rise in demand for single blade sunshades which aren’t as deep as traditional sunshades. Lang adds that single blade sunshades are often used on the east and west facades because they’re less expensive than cantilevered sunshades but provide the shading needed.

Looking ahead, sunshade manufacturers expect automated sun control to be an emerging trend. Seaman says motorized fins would allow for complete sun control throughout the day. While the technology exists, Wignall says budgets often aren’t there to support automatic sunshades.

Jordan Scott is an assistant editor for USGlass magazine. She can be reached at

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