If two panes are better than one, then three might be even better. The EMAX3 triple-glazed skylight consists of an inner and outer pane of low-E glass with a pane of clear glass sandwiched between and argon gas insulating the two airspaces. The result is a skylight that provides up to 55 percent greater insulating value than double-paned skylights. Fixed and vented designs are available. Cost: $265 to $650. Wasco Skylights. 800-388-0293. www.wascoskylights.com.