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Green Basics


Skylights add natural light to building interiors

Skylights come in many forms, from inexpensive plastic domes to operable roof windows that double as rooftop emergency exits. Even the most basic skylight admits daylight into interior spaces that otherwise would have to be illuminated electrically. Skylights that open and close have the added advantage of venting stuffy air from upper story rooms. Depending on how they are placed, skylights also can provide great outdoor views.

Both plastic and various kinds of glass are used for skylight glazing. Plastic, usually acrylic or polycarbonate, costs less than glass, but it’s not as resistant to scratches and after long exposure to sunlight it may become brittle and discolored. Polycarbonate has higher impact resistance and is more expensive than acrylic. Plastic skylights are manufactured in a variety of shapes — domes, rectangles, circles, ovals, and triangles — that would be difficult to duplicate with glass. More expensive skylights are made with glass, and manufacturers now offer a tremendous variety of glazing options. That can be useful in choosing skylights for a particular roof location, or for a particular climate zone.

Skylights are manufactured by many companies, although there are only a few national players. The residential market for off-the-shelf skylights is dominated by Velux, a Danish company. Maine-based Wasco claims a distant second place.

Other manufacturers, such as Tam, Columbia,and Sun-Tek, are stronger regional forces. Fakro, is a major European manufacturer but it hasn’t made serious inroads in the U.S. to date. Three major window manufacturers ( Andersen, Marvin and Pella) have dropped out of the skylight business in recent years as the industry consolidated.

In addition to mass-marketed residential skylights, there’s also a booming trade in high-end custom skylights for residential as well as commercial buildings. Wasco considers itself the leader in that field.

Skylights can be mounted directly…

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One Comment

  1. Peter Konopka | | #1

    Solar tracking skylights
    We have been using several types of tracking skylights that can follow the sun's arch as it goes through it's daily cycle. The produce the maximum amount of light without the annoying shadow a normal skylight produces.

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Question & Answers


Is there an energy efficient skylight? I was thinking about a unidirectional skylight (e.g. lean-to, sawtooth) that only faces one direction for whichever use I want to use it for whether it be daylighting or passive solar. However, no one makes these that I can find in the U.S. The skylights would of course have glass only on one side or in one direction. Most companies that say they do custom are B.S. ers. Most of them can’t conceive of puttling glass on only one surface and blocking off the other. Anyway, I am no expert either so ………..???anyone? Thanks


  1. User avatar GBA Editor
    Martin Holladay | | #

    Most conventional skylights -- that is, skylights with flat (co-planar) glazing -- are what you call "unidirectional." The only type that aren't are cheap units with dome-shaped plastic glazing.

    If you install a skylight parallel to the plane of the roof slope, it will face the same direction as the roof slope in which it is installed. A skylight installed in a roof slope that faces north will also face north.

    If you install skylights in a flat or low-slope roof, you can build high curbs and then you can install the skylights to face any direction you want, at any angle you want.

  2. User avatar
    James Morgan | | #

    Lisa, you need to expect to explain your concept more clearly, perhaps with a sketch or a photograph of a similar installation. I suspect what you have in mind is more complex than what is usually called a skylight.

  3. User avatar
    Armando Cobo | | #

    Just in case you haven’t check these manufacturers:Renaissance Conservatories,, or Velux Residential or Commercial skylights, They build custom skylights.

  4. Rhena Edora | | #

    skylights are already energy efficient if your purpose is to lighten up dark spaces in your house without using artificial lighting. What type of roof do you have? If you we're looking for skylights, there are many types: roof windows, unit skylights, tubular daylighting devices (TDDs), sloped glazing

  5. User avatar
    Dana Dorsett | | #

    Aerogel-insulated skylights suitable for residential apps (with polycarbonate glazing) are now available that r about U0.22, eg:

    The aerogel itself acts as a diffuser, providing nearly shadow-free daylighting compared to clear-glazed skylights.

    There are commercial versions out there that run about U0.1 or even lower, but SFAIK they're all full-custom and quite expensive unless you're putting in a lot of square footage.

  6. Lisa Young | | #

    Here is the idea I am talking about. I need one curb-ready because has to retrofit onto one of those pre-fab aluminum/vinyl patio room kits with metal/foam roof. See attached photo for saw tooth skylight or some combination of sawtooth and monitor with south an/or north exposure. Hope this helps. I have contacted velux without luck. Other manufacturers are too far away (I am in California) thus shipping is high. Thanks for your help.

  7. User avatar GBA Editor
    Martin Holladay | | #

    The vertical glass units in your sketches are called windows, not skylights. Any window manufacturer should be able to help you.

    If you want to install glass in a sloped roof, you'll need a skylight. Again, any skylight manufacturer (including Velux) can help you.

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