Strategies for Success: Doors/Windows
Jul 1, 2005 12:00 PM, by Mike Kennedy
Doors and windows are a ubiquitous component of education facilities. Beyond their obvious functions — providing a path in and out of a building and letting sunlight into interior spaces — doors and windows are a critical part of the building envelope.
But unlike exterior walls or roofs, which are supposed to keep outside elements from entering a building at all times, doors and windows have contradictory duties — they are designed to keep elements out and at the same time let them in.
When doors and windows start letting the wrong things in or out, that's a good indication they may need to be repaired or replaced.
As these critical parts of the building envelope age and deteriorate, they may no longer be able to keep moisture and other unwanted outside elements from penetrating the facility. Door and window frames whose seals are inadequate can let air leak in and undermine the building's energy efficiency. Water leaks can be even more serious and lead to dangerous mold growth or structural damage.
“New windows provide better weatherization and energy savings for the school,” says The Collaborative for High Performance Schools Best Practices Manual.
The manual offers many suggestions for monitoring the condition of doors and windows, and repairing or replacing them when necessary:
Weatherstripping around doors should be inspected routinely and typically is replaced every five to 10 years.
Caulking around exposed surfaces may need to be refinished or replaced when the building exterior is repainted.
Check windows for airtightness. Condensation on the window interior may be a sign of an inadequate seal.
Window glass should be tempered or laminated to resist breakage.
Replacement door and window frames should have thermal breaks to reduce heat transmission. The guide also recommends aluminum frames, which are more resistant to moisture and weather deterioration.
Avoid painted wood or steel sash windows because they have high maintenance costs.
Exterior doors should be metal-clad for durability and fire resistance, and should be recessed or shaded to prevent door surfaces from getting too hot.
In high-risk areas, security screens on windows can prevent breakage and intrusion.
Replacement windows should have double panes and low-e coatings to reduce heating and cooling costs.
Some older window units may contain lead paint, which can contaminate surrounding soils, and should be replaced.
NOTABLE
U-FACTOR
Measures how well a product prevents heat from escaping a building. Ratings generally fall between 0.20 and 1.20; lower numbers provide better heat prevention.
SOLAR HEAT GAIN COEFFICIENT
Measures how well a product blocks heat from the sun. It ranges from 0 to 1; lower numbers block heat better.
VISIBLE TRANSMITTANCE
Measures how much light comes in through a product. It ranges from 0 to 1; higher numbers offer better potential for daylighting.
AIR LEAKAGE
Measures how much outside air comes into a building through a product. Rates typically range from 0.1 to 0.3; lower numbers keep air out more effectively.
CONDENSATION RESISTANCE
Measures how well a product resists the formation of condensation. It ranges from 1 to 100; higher numbers provide better resistance.
Source: National Fenestration Rating Council
