Launch Slideshow

Let There Be Light

Let There Be Light

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    3form. Translucent panels from the Varia Ecoresin line allow for a range of daylighting uses in walls, partitions, and doors, or at the ceiling to soften rays from a skylight. Made with Ecoresin, a material with 40 percent post-industrial recycled content, the panels come in a variety of gauges, textures, and colors, and with varying levels of light diffusion. 801-649-2500. www.3-form.com.
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    Duo-Gard. Translucent illumaWALL is made of polycarbonate or resin art panels that transmit diffused natural light. At night, integral LEDs can be programmed to change colors. Pictured is a meditation room designed by the Virginia Tech School of Architecture for ABC's Extreme Makeover: Home Edition. The double-glazed walls filled with Nanogel Aerogel (optional) achieve R-10 with high light transmission. 800-872-4404. www.duo-gard.com.
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    NanaWall Systems. The Segmented Curves vanishing glass wall system on this California home has nine angle changes, bringing in more daylight than a flat wall while redefining the boundaries between indoors and out. The Energy Star-rated glass, which balances solar gain and U-value, is held in an SL70 thermally broken aluminum-frame folding system. 800-873-5673. www.nanawall.com.
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    Pella. Designer Series windows are available with triple-pane glass, which the company says can cut a home's heating and cooling bills by nearly a third. Between-the-glass blinds and shades let homeowners adjust light levels and are protected from dirt and dust. Cellular shades come in 15 colors and offer top-down or bottom-up light control. 800-374-4758. www.pella.com.
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    Solatube. Daylighting goes multifunctional with the ventilation add-on kit, for use in moist areas like baths and laundry rooms. The fan, which turns on with a switch, attaches seamlessly to the 160 Daylighting System, which illuminates up to 200 square feet, or the 290 DS, which lights 300 square feet. 888-765-2882. www.solatube.com.
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    Technical Glass Products. Pilkington Profilit channel glass can be formed into straight or curved walls for interior or exterior applications. The self-supporting glass is available in a variety of textures and colors with varying translucency, allowing light through while maintaining privacy. Nanogel Aerogel insulation can be added for a soft, even dispersion of light and enhanced energy efficiency. 800-426-0279. www.tgpamerica.com.
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    Velux. The electrochromic SageGlass skylight can be tinted with the touch of a button, reducing solar heat gain by 75 percent while maintaining the sky view. An automatic timer lets users program the glass to darken during specified times of the day. The glass has a double low-E coating that's balanced to let in natural light while limiting solar gain. 800-888-3589. www.veluxusa.com.

Skylighting is twice as efficient at letting in light as side lighting, Brown says, but the light is harder to control. Daylighting consultant Matthew Tanterri, president of Tanterri & Associates in New York, agrees. "One of the biggest mistakes I see in residential buildings is the gratuitous use of skylights without understanding the solar heat gain implications."

As a rule of thumb, skylight size should never be more than 5 percent of the floor area in rooms with many windows, and no more than 15 percent of the room's floor area in spaces with few windows, according to the Department of Energy Office of Energy Efficiency and Renewable Energy.

Maximize Efficiency

As important as calculating daylighting efficiency is ensuring that all that extra glass isn't sending energy use through the roof.

In recent years, window and skylight manufacturers have addressed thermal conductivity issues by offering a range of shading options and high-performance technologies such as low-E coatings; dual, triple, and laminated glass; and thermally broken frames.

Energy ratings take some of the guesswork out of specing climate-appropriate glazing. ASHRAE Standard 90.2 establishes minimum residential requirements for U-value and solar heat gain coefficient (SHGC) by climate zone. And the National Fenestration Rating Council labels manufacturers' products for U-value, SHGC, and visible transmittance (VT), or the amount of visible light transmitted through a window assembly. Most values fall between 0.3 and 0.8; the higher the VT, the more light is transmitted. Manufacturers of translucent solutions such as polycarbonate also typically list VT levels for their products in varying thicknesses and tints.

San Francisco builder David Warner, owner of Redhorse Constructors, takes performance measures a step further. He often sends a physical house model to Pacific Gas & Energy, the local utility, to evaluate daylighting effects. "They will model your project with light all day and give you back a film showing how light penetrates your structure," he says.

Brown predicts the next decade will deliver more daylighting products with advanced coatings and smart glass that responds to the light level. "These technologies exist now; it's just a cost question," he says.