I want more natural light to lower my use of electric lights. I am not a big do-it-yourselfer, so a skylight with a lightwell is not an option. Will a tubular skylight help?—Chris D.
Using electric lights in a home is a major energy consumer. Using compact fluorescent bulbs can reduce this elec-tricity use by 75 percent, but the total is still significant. Also, during summer, all the heat that light bulbs (any type) create must be removed by your air conditioner, so it is a double cost.
But a tubular skylight will be less energy efficient than a roof with no hole for a skylight. Be sure to consider all the energy tradeoffs.
Installing a tubular skylight, however, is a good alternative to a standard skylight and is less expensive.
Most tubular skylight kits are designed similarly. A small tube, usually in the 9- to 21-inch-diameter range, runs from a hole in the roof to a hole in the ceiling below. The interior surface of the tube is highly reflective.
The roof end is covered by a clear bubble dome to catch more light. Some tubular skylights use a prismatic dome designed to capture more of the sun’s lower rays during morning and evening. The lower end of the tube, which is flush with the room ceiling, is covered with a frosted diffuser cover so it looks similar to a recessed light.
A tubular skylight will not produce as much light as a large skylight and it provides no view of the sky. But installing a regular skylight in a room with an attic above requires the construction of a lightwell. This often requires a professional installer.
Another advantage of a tubular skylight over a large standard skylight is energy efficiency. Even the best skylights, with efficient glass or triple-pane plastic, have a much lower insulation R-value than the roof. A tubular skylight requires only a small hole from the ceiling to the roof, and the interior of the reflective tube is relatively airtight. It will lose much less energy at night than a skylight and gain less heat during the summer.
You have several options when selecting a tubular skylight. First, check the roof area for shady spots you should avoid. Also, go up into the attic and look for a clear path for the tube from a sunny roof location to the room you want to brighten. The straightest and shortest path is best. More length and bends reduce the brightness at the ceiling diffuser.
Most tubular skylight kits include a commonly used length of straight reflective tubing. If you need elbows or additional tube length to fit around trusses or other obstructions in the attic, they are available from the manufacturers.
If you can’t find a straight and direct path from the roof to the room ceiling, another option is to install a flexible tubular skylight. These are made of a reflective accordion-like tube, which can be flexed around attic obstructions. This makes installation easier, but some brightness is sacrificed due to the twists and turns in the tube wall.
Another option would be several skylights in one room or one in several rooms, as a grouped design. The reflective tubes run from each of the diffusers in the room(s) to a single opening, similar to a small rectangular skylight in the roof.
The following companies offer tubular skylight kits: Solatube, (800) 966-7652, www.solatube.com; Sun-Dome, (800) 596- 8414, www.sun-dome.com; Sun Pipe, (800) 844-4786, www.sunpipe.com; Sun-Tek, (800) 334-5854, www.sun-tek.com; Tru-Lite, (800) 873-3309, www.tru-lite.com; and Velux, (800) 888-3589, www.veluxusa.com.
Mail requests and questions to James Dulley, Kentucky Living, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com