Which statement best describes the effect of window-to-wall ratio on a building's mechanical system?

• A. WWR has no impact on heat transfer.
• B. WWR can regulate heat gain and loss, affecting mechanical design.
• C. WWR only affects daylighting, not mechanical.
• D. WWR determines glazing color.

Answer: (B)

Window-to-wall ratio controls how much of the facade is glazing, so it directly affects heat transfer and solar gains. More glazing means more heat entering or leaving the interior, which changes cooling and heating loads that the mechanical system must handle. Therefore, a higher WWR can drive larger equipment, different HVAC strategies, and control approaches to meet indoor conditions. The other statements ignore or downplay the impact on heat transfer, or suggest WWR affects daylighting or color only, which doesn’t address mechanical design.