Dear Jim: I want to reduce my electric bills with the upcoming summers air-conditioning costs. I thought about installing a skylight or tubular skylight so I need fewer lights. Which would be best? – George M.
Dear George: If this mild winter was any predictor of the upcoming summer temperatures, we are in for some high electric bills for air-conditioning. With the low cost of natural gas and more electric utility companies switching to natural gas, hopefully electric rates will stay reasonable.
Although the amount of electricity used for lighting in the typical house is only a fraction of that for heat, cooling and water heating, it still constitutes a significant annual cost. Using more natural lighting instead of light bulbs is not difficult to accomplish. Also, at the same brightness, most people can see much better under natural light than under artificial light.
If saving electricity is your primary concern, then a tubular skylight is often a better choice than a traditional rectangular skylight for natural lighting. A traditional skylight provides more lighting and a view of the sky. Its drawback is it creates a large hole in the insulation envelope of your roof and loses energy. It also costs much more than a tubular one.
I installed a tubular skylight in my garage and it provides adequate light for most activities out there during the daytime. When there is a full moon, it actually produces enough light for me to walk to my car in the garage.
Tubular skylights are available in several diameters depending upon how much light you need and the space available. According to ODL, a small 10-inch-diameter model produces as much light as three 100-watt incandescent light bulbs. A larger 14-inch model is equivalent to using five 100-watt bulbs.
If you use incandescent bulbs, the annual electricity savings from installing a large tubular skylight is about $90. If you typically use compact fluorescent bulbs, the annual savings is about $25. This might not sound like a lot per year, but the tubular skylight should last for many, many years. It requires no maintenance and should easily pay back its initial cost.
Tubular skylights use a sheet metal tube that extends from above the roof to the ceiling below. The interior of the sheet metal has an extremely reflective coating so little brightness is lost as the sunlight bounces back and forth on its way down. A clear dome seals the top of the tube above the roof and a flat diffuser snaps over the bottom in the ceiling.
In order to control the brightness, optional dimmer flappers are available to reduce light intensity. These can be operated by an electric motor (requires wiring) or a solar panel with a remote control. Another nice feature for bathrooms is a model which also works as an exhaust fan.
The following companies offer tubular skylight kits: ODL www.odl.com; Solatube, www.solatube.com; Sun-Dome, www.sun-dome.com; Sun Pipe, www.sunpipe.com; Tru-Lite, www.tru-lite.com; and Velux, www.veluxusa.com.