Minimum Requirements for Roofing Material

This document sets out the minimum requirements for roofing material used as part of the Million Cool Roof Challenge. If you have any questions regarding the minimum requirements please contact team@coolroofschallenge.org.


Minimum Requirements of the Product

Any roofing material is eligible as long as it meets the following requirements.

  • Product shall to be tested by a nationally recognized laboratory or equivalent*. Authentic testing report or label clearly stating the procedure used for testing shall be documented. KCEP may collect random sample of the product for testing to check performance.

  • Products lacking a recognized laboratory tested report must go through the alternate testing method described in Alternative Cool Roof Product Measurement Tutorial.

  • Minimum Product Performance (Values for Reflectivity and Emissivity)

    • Solar reflectance (SR) equal to or greater than 0.70

    • Thermal emittance (TE) equal to or greater than 0.75

* Examples of such processes exist within the Cool Roof Rating Council (U.S.), South African Bureau of Standards (RSA), ASTM (U.S.), JSTM (Japan), European Cool Roofs Council (EU), MOHURD (China) Recommended testing standards to be certified by the laboratory testing:

  1. ASTM C1549: Standard Test Method for determination of Solar Reflectance near ambient temperature using a portable solar reflectometer

  2. ASTM C1371: Standard Test Method for determination of Emittance of Materials near Room Temperature using portable emissometer

Alternative Cool Roof Product Measurement

This Alternate approach shall be used in the case where an applicant wishes to use a product that has not already had its solar reflectance and thermal emittance tested by a recognized laboratory.  Applicants have two testing alternatives to the procedure described above:

  1. Applicants may refer to the testing procedures in Alternative Cool Roof Product Measurement Tutorial and perform the test procedures themselves.  The applicant will submit test reports, equipment used, methods and procedures used, and results to the Challenge for review. Applicants will follow procedures as described in ASTM C1549 (Standard Test Method for determination of Solar Reflectance near ambient temperature using a portable solar reflectometer) and ASTM C1371 (Standard Test Method for determination of Emittance of Materials near Room Temperature using portable emissometer).

    The Challenge reserves the right to request a sample of the product for independent testing and verification.  The applicant will be responsible for the cost of the testing ($1000/sample). Materials being tested under this alternative may not be used until a final approval has been transmitted by the Challenge team to the applicant.

  2. Applicants may submit a small sample of proposed product for testing by Challenge technical experts.  Applicants will prepare a 4 square inch (10.2 square centimeters) flat metal coupon coated with the proposed product at the thickness specified by the manufacturer (or a identically sized specimen of the proposed material if it is not a coating product). The coupon or specimen should be sealed in an envelope and sent to the Global Cool Cities Alliance’s Washington office (1500 Decatur St NW Washington DC 20011).  Applicant name, contact information, and a description of the product should be included. The cost to perform the test is $1000/sample and will be paid by the applicant. Materials being tested under this alternative may not be used until a final approval has been transmitted by the Challenge team to the applicant.

Applicants that are unable to test their proposed products according to one of these three approaches may submit a request to have their products considered for approval on a case-by-case basis to the Global Cool Cities Alliance (kurt@globalcoolcities).  Applicants must demonstrate why testing is not feasible for the proposed product.