Which term describes any opening, usually glazed, in a building envelope, such as windows, skylights, glass doors, or glass block walls?

• A. Fenestration
• B. Infiltration
• C. Latent heat
• D. IEQ

Answer: (A)

Fenestration refers to openings in the building envelope that are typically glazed, such as windows, skylights, glass doors, or glass block walls. These elements are central to daylighting and outside views while also influencing thermal performance because glazing controls heat transfer and solar gains. In commissioning and energy analyses, understanding fenestration helps explain how much heat enters or leaves the building through the envelope, how daylight reduces artificial lighting needs, and how properly sealed openings affect air movement. The other terms don’t describe the openings themselves: infiltration is about unintended air leakage through cracks and gaps, latent heat relates to energy changes during moisture phase changes, and IEQ (indoor environmental quality) covers the overall indoor environment rather than the architectural openings specifically.