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Your Utility Bills: Tubular skylight works well

Dear Jim: I want more natural light indoors to reduce electricity usage for lighting. Also, I see better in natural light. I thought a tubular skylight would be the easiest to install myself. Does this make sense? – Jen H.

Dear Jen: Even though a tubular skylight does penetrate the attic insulation envelope, installing one or two can cut your electric bills overall. As you mentioned, many people, especially as they age, can see better under natural light and it creates a nice ambiance indoors.

Of the two basic skylight options, standard rectangular or tubular, a tubular one is more energy-efficient.

Since it creates a smaller hole in the insulated ceiling, less heat is lost during winter or gained during summer. Weatherstripping on the top and bottom eliminate air leakage.

The amount of light that comes in from a small tubular skylight is quite amazing. In my garage, I installed one 10 inches in diameter. I can easily work on my car in there without any additional electric lights on. At night, if there’s a full moon, enough light comes through so I can walk safely in there.

To get a rough idea of how much light there is from a tubular skylight, figure on the equivalent brightness of three 100-watt incandescent light bulbs from tube that’s 10 inches in diameter. One that’s 14 inches in diameter provides about twice as much light.

A tubular skylight is pretty much like it sounds. It’s a sheet metal tube that extends from a hole in the room ceiling up through the roof. The top is covered with a clear plastic dome, and the bottom is covered by a clear light diffuser. It looks similar to a sealed recess light from indoors.

The inside surface of the tube is highly reflective. The sunlight that enters the top dome reflects back and forth in the tube until it comes out the bottom diffuser. Since it is so highly reflective, very little brightness is lost. This allows it to catch light even when the sun is not directly overhead, but it is still wise to locate it in the sunniest spot.

To catch even more of the indirect light from the sun during morning and evening, select a tubular skylight with a prismatic top dome.

This dome bends the indirect light rays so they come more directly down the tube into the house. All of the clear acrylic domes filter out the ultraviolet fading rays.

The light from the tubular skylight can become very bright, especially around noon. Optional internal remote-controlled dampers are available to reduce the light intensity. Also, a optional small light fixture can be mounted in the tube to provide light, similar to a recessed one, at night. For a bathroom application, a vent fan option is also available.

The following companies offer tubular skylight kits:

ODL, 866-635-4968,; Solatube, 888-765-2882,; Sun-Dome, 800-596-8414,; Tru-Lite, 520-622-5152,; and Velux, 800-888-3589,


Dear Jim: I am building a superefficient smart house. I plan to install a direct-vent gas fireplace with an unusually tall design. Would it be difficult to build one myself? – Seth W.

Dear Seth: A direct-vent fireplace is most efficient because the firebox is sealed from the room air. The proper amount of combustion air is needed for various fire levels, so it may be difficult to set up the controls for a do-it-yourself one.

A vent-free gas fireplace is also very efficient and simple to build because it is open. Since the fumes are not vented outdoors, its operating time is limited each day depending on the size of the room.