Building Envelope

Your building's envelope consists of exterior walls, the roof, windows, doors, exposed floor and other openings. Infiltration/exfiltration can lead to significant energy losses. In infiltration, outside air leaks into the building. Exfiltration occurs when indoor air leaks out of the building. Both exfiltration and infiltration burden your building's heating and cooling system. Infiltration and exfiltration occur through cracks and other openings around windows, doors, dampers, skylights, and other breaks in a wall, and whenever a door or window is opened. Infiltration can be tied to a building's characteristics.

Tips for reducing energy use include the following.

1. Reduce temperature in stairwells. If necessary, protect piping from freezing.

2. Seal elevator shafts at the top and bottom. Be sure that a penthouse machine room door is weather-stripped and kept closed.

3. Seal vertical service shafts at the top and bottom and, in tall buildings, at every sixth floor.

4. Weather-strip doors and keep them closed.

5. Comply with building code-venting requirements. Check the fire resistance ratings of materials used. Skylights or smoke relief vents may be required.

Reducing Infiltration/Exfiltration

Regardless of the type of building, the following tips can help you reduce infiltration.

For windows and skylights:

1. Replace broken or cracked window panes.

2. Weather-strip operable sash if crack is evident.

3. Caulk around window frames (exterior and interior) if cracks are evident.

4. Rehang misaligned windows.

5. Be certain that all operable windows have sealing gaskets and cam latches that are in proper working order.

For doors:

1. Replace any worn or broken weatherstripping.

2. Install weatherstripping where one has been installed previously.

3. Rehang misaligned doors.

4. Caulk around door frames.

5. Inspect all automatic door closers to ensure they are functioning properly. Consider adjustment to enable faster closing.

6. Inspect gasketing on garage and other overhead doors. Repair, replace or install as necessary.

For exterior surfaces:

1. Caulk, gasket or otherwise weatherstrip all exterior joints, such as those between well and foundation or wall and roof, and between wall panels.

2. Caulk, gasket or otherwise weatherstrip all openings, such as those provided for entrance of electrical conduits, piping, through-the-wall cooling and other units, outside air louvers, etc. Where practical, cover all window and through-the-wall cooling units when not in use. Specially designed covers can be obtained at relatively low cost.