Skylights can make a major contribution to energy efficiency and comfort in new and retrofit low-rise buildings. Daylight is an excellent source of ‘cool light’ and the ‘right size’ of skylight can admit just enough light. The many available kinds of skylights can use the same energy efficient technologies used in other window designs.

Skylights can be installed in existing and new homes. Daylight provides ‘cool light’, meaning that a given amount of light is accompanied by less heat gain than most types of artificial light. Skylights provide some of the best ways to admit daylight and distribute it evenly, saving energy and improving visual comfort levels.

Skylights increase the amenity of internal spaces that might otherwise have no windows and allow additional flexibility in architectural design. They particularly suit one- and two story construction. A skylight can admit over three times as much light as a vertical window of the same size.

A variety of skylight shapes exist for sloping or flat roofs. Some skylight shafts exert nearly as much influence over the energy properties as the actual skylight itself. Sky lighting may take the form of general glazed areas such as atriums, attached conservatories or sun rooms. In this form roof lights are less likely to be factory manufactured items and more likely to be constructed onsite. Excellent day lighting is provided by skylights which have the potential to displace much artificial lighting, improving light quality, reducing heat generation and saving on energy costs.

Under an unobstructed, overcast sky the amount of light, or luminance, from directly above (the zenith) is about three times as much as from the horizon. A skylight can admit over three times as much light as a vertical window of the same size. While this performance differential may be reduced in reality (e.g. by a long shaft), in most situations a skylight has the potential to be a very effective day lighting device. Even under overcast conditions use of skylights can result in spaces that can be predominantly daylight with little supplementary artificial lighting required.