Friday, November 05, 2010

Skylight Design and Position Considerations

By Mark J. Donovan

Skylights can provide natural lighting to a room. They can also provide some level of warmth if chosen and positioned carefully. By carefully considering skylight design and construction, and the placement of the skylight(s) within your home or room, you can maximize these two major benefits.

When selecting a skylight make sure to fully understand the energy performance rating assigned to the skylight relative to your climate, as well as its position within the home.

The National Fenestration Rating Council (NFRC) tests, certifies, and labels skylights, as well as doors and windows, for their energy performance. There are a number of factors they evaluate in the energy performance of skylights including, (1) heat gain/loss via U-factor (the rate at which a skylight conducts non-solar heat flow), solar heat gain coefficient, and air leakage, and (2) sunlight transmittance. Skylight design features that influence the energy performance include glazing, general construction and materials, and operation.

In regards to positioning a skylight in a home or room, a skylight facing a southerly direction will provide the most warmth, however the warmth could be excessive during the summer months. When positioning a skylight in a southerly direction consider including skylight shades or shade trees to help combat the solar heat during the summer months. A skylight west-faced positioned will provide afternoon natural light and warmth. A skylight east-faced positioned will provide morning natural light and maximum heat gain. A skylight faced in a northerly direction will provide relatively constant lighting but minimal heat gain throughout the day.

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