Advantages of natural light.
Q. I like natural light and thought I could save some electricity on lighting by installing a skylight or tubular skylight. Which type is better?
A. 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 replacing all your light bulbs with LEDs is the least expensive option. Although not as natural as true sunlight, the higher temperature ones, 4,000 degrees Kelvin rating, produce a more natural light. Also, ones with a high CRI (color rendition index) make colors look more realistic.
A tubular skylight is generally a more efficient and less expensive 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.
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 at night, 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. As a reference, 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 are still using incandescent bulbs, the annual electricity savings from installing a large tubular skylight is about $90. If you typically use compact fluorescent bulbs, or preferably LEDs, the annual savings is about $20. This might not sound like a lot per year, but the tubular skylight should last for many years.
A tubular skylight requires no maintenance other than wiping off the clear or globe in the ceiling. The dome on the roof should stay clean from just the rain. It is not difficult to install one yourself, especially if you have an asphalt shingle roof.
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 very 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 that also works as an exhaust fan.
The following companies offer tubular skylight kits: ODL, (866) 635-4968, www.odl.com; Solatube, (888) 765-2882, www.solatube.com; Sun-Dome, (800) 596-8414, www.sun-dome.com; Tru-Lite, (520) 622-2152, www.tru-liteskylights.com; and Velux, (800) 888-3589, www.veluxusa.com.
* Write to James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit dulley.com.