Tools & Tips: Curbing Skylight Heat Loss

From on May 06, 2008 in Window Replacement

Rendered SkylightSkylights have long been a popular window choice for new and remodeled homes. They are an excellent way to let in natural light and provide comfortable views of the night sky. Skylights have an uncanny knack for making a huge difference in the brightness and warmth of a home. But amongst these positive aspects is one glaring drawback, heat loss.

Unfortunately, skylights can be a major proponent of heat loss in your home due to the simple fact that heat rises. Being that skylights are simply windows in the roof, they provide warm air its most direct path as it reaches skyward to meet cooler air. A skylight in the roof will lose, on average, 35-45% more heat during cold months than a similar window on the side of the house. Fortunately, there are ways to benefit from skylights without suffering too much from heat loss.

The most common way to curb heat loss in a skylight is through glazing. Glazing consists of multiple layers of glass with inert gases, such as argon or krypton, between each layer. These gases help to prevent heat loss through radiation at night and in winter. Skylights, just like other energy efficient windows, may also have a low-emissivity (low-E) film covering one side of the window.

Low-E coatings help block solar heat gain and heat loss. Low-emissivity windows have a high energy efficiency rating. If it is heat loss you are trying to prevent then the film should be placed on the inside pane of the window. This will, however, minimize heat gain, which you may find beneficial in the winter also. Thankfully, a solution has been set forth to solve this problem and allow skylight owners to have the best of both worlds: solar windows.

Solar windows are actually a simple design. They are really just a new take on low-E windows, which puts the glazing on a pivot that allows you to rotate the glass. This basic innovation allows you to reflect heat out in the summer and inward during winter. Solar window design works for all windows, including skylights, although practicality may be an issue for hard-to-reach skylights. Distribution of solar windows, invented in Germany, still seems to be in its infancy in the US. But with such a simple but highly advantageous design, there is little doubt that they will catch on.