What is the minimum SRI requirement for a high reflectance roof to contribute towards heat island reduction?

The correct answer, which states that the minimum Solar Reflectance Index (SRI) requirement for a high reflectance roof to contribute towards heat island reduction is 90, is based on the criteria set forth in the LEED rating system. The SRI is a measure of the solar reflectance and thermal emittance of a surface; higher SRI values indicate greater ability to reflect solar radiation and emit heat, thus reducing heat buildup in the urban environment.

A roof with an SRI of 90 or higher is considered very effective in minimizing the heat absorbed, which can help mitigate the heat island effect commonly found in urban settings. LEED aims to promote environmentally responsible building practices, and incorporating high reflectance materials assists in reducing energy consumption associated with cooling and enhances outdoor thermal comfort.

The minimum requirement of 90 serves as a benchmark to ensure that roofs contribute meaningfully to heat island reduction strategies and ultimately support the sustainability goals of LEED certifications. As such, achieving this level of reflectance is critical for buildings aiming for LEED accreditation under the Operations and Maintenance criteria.