Types of Windows and Glazing

Windows come in single and multiple glazings, double pane or triple pane. Each pane offers an extra, insulating air layer between you and the outdoors. For residential and commercial buildings, window styles include double- and single-hung, awning, casement, and sliders. Materials range from wood to vinyl, fiberglass, PVC, and aluminum. The best way to compare window efficiency is to look at the whole-unit U-value and Solar Heat Gain Coefficient (SHGC). The lower the U-value number, the more efficient the window. A higher SHGC indicates more solar heat gain.

  • Additional panes add extra air layers, more insulation
  • Low-E* window coatings help trap heat inside without impeding light
  • Exterior shutters, awnings, and interior blinds provide some insulation against summer heat gain

*Low-E means low emissivity, or low heat transfer through radiation. Low–E materials, such as windows, roofs, paint, blinds, and insulation, save money and energy by keeping heat in during winter and out during summer, reducing heating and cooling needs.

Types of Exterior Doors

Doors are available in many styles and materials—sliders, French doors, swing-in, swing-out, metal, fiberglass, and wood, among others. Some have windows, and older doors may contain non-tempered glass (which can be a safety issue). Improving doors is a good DIY project for your home or business, starting with simple measures like weather-stripping, door sweeps, storm doors, and striker plate adjustments to eliminate drafts.

Tips for Improving Window Efficiency

To make your windows and doors more efficient, start by fixing some common sources of air leaks: Replace cracked panes and glazing compound, improve weather-stripping, add caulking around window casings, and fill in unused pulley cavities. (Be careful not to caulk the window shut.) Also, check to make sure sash locks are present and well aligned. For older casement windows, replace stripped-out crank mechanisms. Last, consider adding Low-E storm windows.