Fenestration comes from the Latin word for windows, and refers to openings in a building or wall envelope. Fenestration products include not just windows, but other openings in a home’s exterior surfaces like doors, louvers, vents, wall panels and skylights.

The word fenestration isn’t used often outside the construction industry, as we refer to the individual products, i.e. windows. The window collage shared here (taken by Tina Gleisner in Massachusetts, New Hampshire, New Mexico, New York and Texas) was inspired by Andy Marshall’s 50 Historic Window Designs, with an incredible gallery of European windows. Andy believes that window’s are part of the architectural DNA of a building (house).

Fenestration is used within the construction industry and energy codes for a home’s envelope are part of the insulation and fenestration code.

• Insulation energy codes define minimum R-values for walls and ceilings surrounding a home’s conditioned (heated and/or cooled) living space, with the exception of openings like windows. Insulation’s R-value quantifies the ability of different products to resist heat flow in either direction. R-value depends on the type of insulation (material, thickness, and density) and with multiple layers, you add up the R-values of the individual layers.
• Fenestration energy codes define minimum U-factors for windows, skylights and doors. The U-Factor like R-values for insulation, quantifies energy efficiency based on the rate of heat transfer through these products. EnergyStar standards are set by the National Fenestration Rating Council (NFRC) and you should look for the NFRC energy performance labels when researching your new windows.