I. Energy Efficiency
http://www.energystar.gov/index.cfm?c=windows_doors.pr_windows
http://www.energystar.gov/index.cfm?c=windows_doors.pr_taxcredits
http://www.efficientwindows.org/
II. Product Integrity and Installation
http://www.installationmastersusa.com/
http://www.vinyl-replacement-windows.com/
III. Industry Information
http://www.reedconstructiondata.com/