WINDOWS

Windows are some of most critical elements in green buildings. They not only provide daylighting and views of the exterior, but they can also provide passive heating, cooling, and ventilation. Windows are the least insulated part of any building, so product choices, size, and placement are essential to good green building design. Key factors to consider when choosing windows are frame material, glazing type, U-value, air leakage, solar heat gain coefficient, visual transmission, condensation resistance, and maintenance requirements. Window frame options include wood, composite wood, PVC, steel, and fiberglass. Each product varies in terms of cost, thermal performance, strength, durability, maintenance requirements, and installation requirements. Each side of a building experiences different environmental conditions and it is often appropriate to employ different glazing options on each side to respond to those conditions.

Also, consider repair and weatherization of existing wooden windows since it is easier and more practical than most people realize. Wooden windows, which are repaired and properly maintained, will have greatly extended service lives while contributing to the historic character of the building.

What Makes Windows Green?
Energy Efficiency
Framing Material
Window preservation and repair

5 Considerations for Consumers:

1. Look for low u-value ratings on windows since the lower the number, the more energy efficient the window
2. Insulate windows correctly to help eliminate air infiltration and water leaks
3. Understand prevailing winds of the building site and place windows accordingly to allow for natural ventilation
4. In existing windows, carefully remove trim pieces and fill any gaps with caulk or polyurethane foam
5. Consider insulated window coverings to reduce energy loss or to allow for solar heat gain