Clawson Windows | Energy Values

The energy values listed for our windows are derived by using the Montana Energy Default Table, or in the case of our most popular windows, through professional testing representing NFRC certified values.

What does that mean? Well, to begin with, NFRC is an acronym of the National Fenestration Rating Council. The Council is a conglomerate of utilities, manufacturers, builders, and code agencies of the government. It was formed in June 1989 to develop a uniform thermal rating system for windows and doors that all building code jurisdictions throughout the country would adopt. This would allow consumers to fairly and accurately make energy comparisons among a variety of manufacturers.

Contrary to popular opinion, the NFRC does not establish energy standards nor do they govern or legislate any energy requirements for building codes. Those standards are determined by federal, state and local officials.

NFRC certification does not mean a window automatically meets any energy standard, rather that the window has been tested by an NFRC certified laboratory using the guidelines established by the Council.

All Clawson NFRC certified windows bear an NFRC label with the energy data listed clearly on the front. We want you to be informed about our windows.

	U-Values

VINYL
Vinyl Casement	NFRC Certified
Clear glass	0.42
Low E 272	0.32
Low E 366	0.31
Low E 272 w/ argon fill	0.29
Low E 366 w/ argon fill	0.28
Vinyl Slider	NFRC Certified
Clear glass	0.46
Low E 272	0.33
Low E 366	0.32
Low E 272 w/ argon fill	0.29
Low E 366 w/ argon fill	0.28
Vinyl Single Hung	NFRC Certified
Clear glass	0.46
Low E 272	0.32
Low E 366	0.32
Low E 272 w/ argon fill	0.29
Low E 366 w/ argon fill	0.28
Vinyl Picture	NFRC Certified
Clear glass	0.46
Low E 272	0.32
Low E 366	0.32
Low E 272 w/ argon fill	0.29
Low E 366 w/ argon fill	0.28
Vinyl Patio Door	NFRC Certified
Clear glass	0.48
Low E 272	0.33
Low E 366	0.32
Low E 272 w/ argon fill	0.29
Low E 366 w/ argon fill	0.28


WOOD AND CLAD
Clad Casement	NFRC Certified
Clear glass	0.49
Low E 272	0.37
Low E 366	0.36
Low E 272 w/ argon fill	0.34
Low E 366 w/ argon fill	0.33
Clad Direct Set	NFRC Certified
Clear glass	0.47
Low E 272	0.32
Low E 366	0.31
Low E 272 w/ argon fill	0.28
Low E 366 w/ argon fill	0.27
Wood Casement
Clear glass	0.48
Low E 272	0.37
Low E 272 w/ argon fill	0.34
Clad Double Hung & Slider
Clear glass	0.57
Low E 272	0.48
Low E 272 w/ argon fill	0.42
Wood Double Hung & Slider
Clear glass	0.54
Low E 272	0.44
Low E 272 w/ argon fill	0.39
Clad Sliding & Swinging Patio Door
Clear glass	0.47
Low E 272	0.37
Low E 272 w/ argon fill	0.33
Wood Sliding & Swinging Patio Door
Clear glass	0.46
Low E 272	0.35
Low E 272 w/ argon fill	0.31

Energy values for the wood casement, direct set, wood and clad slider, double hung, wood and clad sliding and swinging patio door are currently calculated using the Montana Energy Default Table.