Heat Mirror film is a coated film suspended between panes that blocks which parts of the spectrum?

• A. Visible light
• B. Infrared only
• C. Radio waves
• D. Infrared and Ultraviolet

Answer: (D)

This item tests how glazing can selectively block parts of the spectrum to reduce heat transfer while still letting daylight through. Heat Mirror is a coated film placed between panes of glass that reflects infrared radiation, which carries most of the heat from sun exposure, and also filters ultraviolet radiation that can fade furnishings. At the same time, visible light passes through, so interiors stay bright. This combination—blocking infrared and ultraviolet while transmitting visible light—explains why infrared and ultraviolet are the correct parts of the spectrum to block. Blocking only visible light would darken the space, blocking infrared alone wouldn’t address UV protection, and blocking radio waves isn’t related to how windows manage solar heat.