We are often asked about the difference between glass and plastic skylights. When I started this business in 1988, we were installing 95% plastic domed skylights and 5% glass, now it’s completely the other way around.
In the 70’s and 80’s, domed skylights were the norm and what most people expected a skylight should look like. Today, energy efficiency improvements with glass have made them far superior to domes. The Low-E coatings and argon gas (between the 2 panes of glass), have made sealed glass units so much more effective at cutting out heat gain in summer and heat loss in winter. They also cut down harmful UV rays that come into your home and are much quieter in the rain.
The most recent improvements to glass from Velux skylights, have made them even more effective at cutting out any heat gain and with a new “clean” coating on the exterior pane water dispurses evenly removing dirt and reducing water spots.
Dome skylights have their virtues as well. Because of the curvature of the acrylic, domes tend to bend in a little bit more light than glass skylights. The curvature also allows rain and snow to drain off more easily from the skylight. Snow also melts off easily due to domes losing heat; that’s the only time that poor energy efficiency is a virtue.
Our experience in skylight replacements has shown us that our clients much prefer the comfort of an energy efficient skylight. We often hear people tell us of the excessive heat build up from their old builder grade dome skylights and the change to their new glass skylight has made the upstairs so much cooler. In fact, we’ve often been told “now the A/C works upstairs”.