Select Your Quote Type Below to Begin! 
Replacement Windows
Window Diagram | Common Types of Windows | Types of Materials Used in Replacement Windows
Request a Replacement Windows Quote
Rating Systems
There are several rating systems available that indicate the properties each window may have. Many manufacturers represent the energy efficiency of windows in 2 categories.
- U-Values (conductance of heat)
- R-Values(resistance to heat flow)
If a window's R-value is high, it will lose less heat than one with a lower R-value. Conversely, if a window's U-value is low, it will lose less heat than one with a higher U-value. In other words, U-values are the reciprocals of R-values (U-values = 1/R-value). NOTE: Most window manufacturers use R-values in rating their windows.
Usually, window R-values range from 0.9 to 3.0 (U-values range from 1.1 to 0.3), but some highly energy-efficient exceptions also exist.
When comparing different windows, you should ensure that all U- or R-values listed by manufacturers:
- Are based on current standards set by the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE)
- Are calculated for the entire window, including the frame, and not just for the center of the glass
- Represent the same size and style of window.
5 factors affecting the R-value of windows
- The type of glazing material (e.g., glass, plastic, treated glass)
- The number of layers of glass
- The size of the air space between the layers of glass
- The thermal resistance of conductance of the frame and spacer materials
- The "tightness" of the installation (i.e., air leaks-- see previous discussion).