In terms of energy-efficiency, new roof installations must be:

In terms of energy-efficiency, new roof installations must be:

• A. Non-reflective with high emittance
• B. Reflective with high thermal emittance
• C. High insulation value only
• D. Ventilation only

Answer: (B)

To achieve energy efficiency, a roof should minimize heat gain from the sun and shed heat quickly once it’s absorbed. A reflective surface reduces the amount of solar energy the roof absorbs (high solar reflectance), while high thermal emittance ensures the roof can radiate the absorbed heat away efficiently. Together, these properties keep the roof cooler and reduce the building’s cooling load. High insulation value helps slow heat transfer through the roof, but it doesn’t prevent solar heat from being absorbed at the surface. Ventilation can move air, but it doesn’t address radiant heat gain as effectively as a cool, reflective roof with good emissivity. So the best match for energy efficiency is a roof that is reflective and has high thermal emittance.

To achieve energy efficiency, a roof should minimize heat gain from the sun and shed heat quickly once it’s absorbed. A reflective surface reduces the amount of solar energy the roof absorbs (high solar reflectance), while high thermal emittance ensures the roof can radiate the absorbed heat away efficiently. Together, these properties keep the roof cooler and reduce the building’s cooling load.

High insulation value helps slow heat transfer through the roof, but it doesn’t prevent solar heat from being absorbed at the surface. Ventilation can move air, but it doesn’t address radiant heat gain as effectively as a cool, reflective roof with good emissivity.

So the best match for energy efficiency is a roof that is reflective and has high thermal emittance.