I want more natural lighting with fewer electric lights, so I plan to install skylights in several rooms. What are the most efficient designs to save the most energy?—Jon B.
Most often, people install skylights for reasons such as making a room appear larger or providing a view of nighttime sky. Adding skylights to a room can reduce the need for lights if you’re at home a lot during the day.
But don’t install skylights to save money. A skylight will actually increase your electric bill.
A skylight essentially adds a window to your house, cutting a hole in what could otherwise be an insulated roof. Also, the additional heat through the skylight from the summer sun will significantly increase the money you spend on air conditioning. This added expense will far outweigh money saved on lighting. Electric co-ops do not recommend skylights for energy efficiency.
However, if you like the look of a skylight enough to pay higher utility bills, here are a few things to know:
In order to minimize the added cost of a skylight, nearly all the super-efficient true-glass glazing and frame options available in high-quality new windows are also available in skylights. The primary difference is that the top layer of multi-pane skylight glass is made from tempered glass for safety. Some of the hurricane-resistant skylights, which meet Florida’s strict safety codes, use laminated glass similar to a car’s windshield.
When selecting one, first decide whether you want a venting or a fixed type of skylight. Fixed ones are somewhat less expensive, but do not provide ventilation, which can reduce cooling costs and improve indoor air quality. The new weatherstripping seals make the venting ones virtually as energy efficient and leak-free as fixed ones.
If you ever use natural ventilation, even if for only a few weeks during spring and fall, selecting a venting model is your most energy-efficient choice. With the skylight located in the ceiling where the warm, less-dense air collects, opening it can create a natural breeze through your home. Most venting models are hinged on one end and the entire top of the skylight opens. For the most convenience, a remote-control electric operator can be installed. This uses a small amount of electricity and requires electrical wiring. Automatic rain sensors can be installed to close the skylight in case of a storm. Unless there is already an electric light in the ceiling, running new wiring may make the installation project too complex for the average do-it-yourselfer. For most installations, a removable long-hand crank is recommended.
The heart of a skylight is the glazing, which has the most impact on its energy efficiency. If you want efficiency with a good view of the sky, a multi-pane flat-glass skylight is best.
Since skylights tend to get dirty and covered with water spots, some manufacturers offer special glass. It is as energy efficient as other options, but has a super-smooth titanium dioxide coating on the exterior pane surface. When the sunlight shines on it, it dries with very few spots and less dirt.
If you just need additional natural lighting, a double- or triple-pane domed plastic skylight is adequate and less expensive than glass. Also, the domed top is somewhat self-cleaning when it rains. Some types of plastic naturally block most of the sun’s fading ultraviolet rays. In hot climates, consider a tinted skylight to block some of the summer heat and glare.
The following companies offer efficient skylights: Bristolite, (800) 854-8618, www.bristolite.com; Fox Lite, (800) 233-3699, www.foxlite.com; Royalite, (800) 875-9548, www.royalite-mfg.com; Velux, (800) 888-3589, www.veluxusa.com; and Wasco, (800) 388-0293, www.wascoskylights.com.