Green roofs provide which benefits?

• A. Improved insulation, biodiversity support, and rainwater management.
• B. They replace the need for any insulation.
• C. They dramatically increase roof heat absorption.
• D. They eliminate the need for drainage systems.

Answer: (A)

Green roofs work by adding a shallow soil layer and vegetation on top of a roof, creating multiple benefits for building performance and the surrounding environment. The extra layer acts as insulation, helping to keep heat out in hot weather and retain warmth in colder weather, which can lower energy use for cooling and heating. It also provides habitat for plants, insects, and birds, supporting urban biodiversity and offering ecological value in built areas. Additionally, the vegetation and growing medium absorb rainfall and slow its drainage, reducing the peak and volume of stormwater runoff and helping lessen the strain on drainage systems.

This setup doesn’t replace traditional insulation, and it doesn’t cause a dramatic increase in heat absorption—green roofs typically moderate temperatures and can lower cooling loads rather than boost heat gain. Drainage systems are still needed to remove any excess water, though the green layer helps manage and delay runoff.