Glossary of Terms

Window Styles

  • Double-hung - Both sashes slide up and down
  • Single-hung - Only the bottom sash slides upward
  • Sliding window - Both sashes slide from left to right
  • Casement window - Hinged at the sides and open to the outside.
  • Awning window - Hinged at the top and open to the outside

Window Frames

  • Aluminum
    • Pro: Used often for customized window design.
    • Con: May cause conductive heat loss and condensation
  • Vinyl
    • Pro: Saves energy, low-maintenance.
    • Con: Lesser-quality vinyls may have problems with resistance or brittleness, color consistency, and contraction and expansion.
  • Wood
    • Pro: Unaffected by temperature extremes (produce higher R-values).
    • Con: Require more maintenance.
  • Clad Wood
    • Wood frames covered on the exterior with a layer of aluminum or vinyl.
    • Pro: Easier to maintain.
    • Con: Cost more than solid wood.
  • Fiberglass
    • Pro: Highest R-values.
    • Con: More expensive

Types of Glass

  • Dual-Pane (Standard insulating) - Two layers of clear glass. A layer of inert gas — typically argon or krypton — is sealed between inner and outer panes. Reduces heat loss.
  • Triple-Pane – Three layers of clear glass that s eal two layers of gas within the frame – used in extreme northern climates
  • Low-E (Low Emissivity) Coating - Protective coating that keeps the heat from transferring back through the window. Protects furniture and carpet from sun damage.
  • Argon-filled Low-E Insulating - – 35% more energy efficient than ordinary dual-pane glass in winter and 41% more efficient in the summer. Argon gas is heavier than air so is less prone to convection or thermal movement.
  • Obscure insulating – Increases privacy
  • Tempered glass – Adds safety; won’t shard on impact

Window Parts

  • Head – Forms the top of a window frame – it’s the main horizontal member on the top
  • Jamb – Forms the sides of a window frame – it’s the main vertical member
  • Sill – Forms the bottom of a window frame – it’s the main horizontal member on the bottom
  • Frame – The enclosure in which window sash are mounted
  • Glazing – Window glass
  • Pane – A framed sheet of glass within a window
  • Sash - the framework of a window in which panes of glass are set.
  • Muntin Bar (grilles) - a strip separating panes of glass in a sash
  • Glazing Bead – A removable trim that holds the glass in place. Helps the window shed water and keeps it weather tight

Energy Terms

  • Energy Star – U.S. Govt. program designed to reduce the consumption of fossil fuels through the education of consumers. In order for windows to be considered Energy Star-qualified, they must be tested by the National Fenestration Rating Council (NFRC), a program that helps consumers compare window products and options. They must meet specific, predetermined U-value ratings.
  • U-Factor – Measures the window’s ability to conduct heat
  • SHGC - The Solar Heat Gain Coefficient (SHGC) measures how well a window blocks heat from sunlight. Look on the NRFC label for the rating.
  • R-Value - Resistance to Heat Flow a higher value indicates a better heat insulating property. 0.9 is the R-value of an ordinary single-pane sash with a 15 mph wind on one side.
  • Warm Edge Spacers – Material in between the panes of glass. Reduces condensation around the perimeter of the window. These spacers keep the edges of the window glass warmer.