Friday, August 23, 2013

In this post, I continue to look at the great end-of-summer home improvement project -- installing a skylight.

The U.S. Dept of Energy says when homeowners consider adding a skylight they need to determine what type of design will work best, and where to place it to optimize its contribution to their home’s energy efficiency, daylighting, and ventilation.

So the DOE experts suggest selecting your skylight based on the local climate and your home's design. For labeling energy-efficient skylights, Energy Star has established minimum energy performance rating criteria by climate.

As a rule of thumb, a skylight size should never be more than 5 percent of the floor area in rooms with many windows and no more than 15 percent of the room's total floor area for spaces with few windows.

You should also consider a skylight's position if you want to maximize daylighting and/or passive solar heating potential. Those on east-facing roofs provide maximum light and solar heat gain in the morning, while west-facing skylights provide afternoon sunlight and heat gain, the agency says.

South-facing skylights provide the greatest potential for desirable winter passive solar heat gain than any other location, but often allow unwanted heat gain in the summer. But you can prevent unwanted solar heat gain by installing the skylight in the shade of leaf-shedding trees or adding a movable window covering on the inside or outside.

Without this seasonal natural cover, skylights can result in unwanted seasonal heat gain or loss. So manufacturers offer heat-absorbing tints, insulated glazing, and low-emissivity (low-e) coatings, or install a translucent insulation material between several glazing layers to create a more thermally efficient assembly.

In our final report, we'll take a look at other important considerations if you're planning to tackle a skylight installation.

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