Installation Details · FAQ

How much energy do skylights actually cost in Illinois?

A modern Energy Star skylight loses roughly 2 to 3x the heat per square foot that a same-sized wall window does, because heat rises and concentrates at the ceiling plane. A 4×4 foot skylight in a Madison County home costs roughly $35 to $60 per year in extra heating, plus $15 to $25 in extra cooling — call it $50 to $85 per year per skylight.

That’s not enormous, but it adds up over a 20-year skylight life. Trill’s energy-conscious upgrades during a skylight replacement: triple-pane glazing (adds $200 to $350 per skylight, recovers about 30% of the heat loss) and a closed-cell foam gasket around the frame (a $40 detail that cuts air infiltration by 50 to 70%). The combination essentially halves the skylight’s energy cost. Worth it on south-facing skylights, less critical on north-facing.