Windows

• Spend as much as you can
• Get triple-pane windows and fiberglass frames
• Look for Energy Star certification
• Add a metallic film that is applied as a coating to the window. North, south, east/west walls will each have different requirements for the coating
• Northern facing windows will always be a net loss, high quality southern facing windows can be a net gain

Doors

• Get a door with a foam core and a foam or neoprene seal
• Look for Energy Star certification

Cost: $20,000 - $30,000

References:

• Ecohome windows and doors
• Ecohome window shopping