Cool Roof Coatings Incorporating Glass Hollow Microspheres for Improved Solar Reflectance

EPA Grant Number: SU834300
Title: Cool Roof Coatings Incorporating Glass Hollow Microspheres for Improved Solar Reflectance
Investigators: Barsoum, Michel , Byrnes, Sarah , Eisele, Eric , Hagarman, James , Pugh, Daniel , Reid, Courtney
Institution: Drexel University
EPA Project Officer: Nolt-Helms, Cynthia
Phase: II
Project Period: August 15, 2009 through August 14, 2011
Project Amount: $61,829
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2009) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Awards , Sustainability


Elastomeric cool-roof coatings can be applied to buildings to decrease heat gain, yielding energy savings and mitigating the “urban heat island” effect. Most cool-roof formulations are based on titanium dioxide (TiO2). While TiO2 and several TiO2 replacements perform according to ASTM reflectance standards, the infrared (IR) absorption properties of these materials is rarely discussed. Carefully designed TiO2 replacements have the potential to effectively scatter visible and infrared wavelengths, increasing the overall reflectance of a coating beyond the upper limits defined by ASTM standards. This project has demonstrated that the introduction of voids, through the inclusion of glass hollow microspheres at high volume loadings can effectively scatter selected wavelengths.

The second phase of this project involves a further investigation into the efficacy of coatings formulated using glass hollow microspheres. This includes field testing, ASTM standard testing for reflectivity, tensile strength, weathering, and other properties, and additional formulation work. The research team also plans to implement the coating in various areas in the City of Philadelphia to study cool roof impacts on the urban heat island.


Test and implement an elastomeric cool roof coating developed for improved reflectance in the near infrared region. Increase community awareness on energy saving potential and environmental impacts of cool roof coatings. Further study how the infrared radiative properties of titanium dioxide replacements can increase the efficacy of roofing materials.


Elastomeric cool roof coating formulations will be tested in accordance with ASTM standards D2370, D4798, D471, D1653, C1549, C1471, G156, and other standards for tensile properties, accelerated weathering, permeance and swelling, emissivity, and reflectivity. Coating will undergo field testing in Philadelphia along with multiple controls, including other commercially available coatings. Thermal imaging will be employed as a non-contact technique to measure surface temperatures. Research team will coordinate with the Drexel Smart House student organization to demonstrate the impacts of cool roof coatings throughout the Philadelphia community.

Expected Results:

The team expects to adjust the formulation as a result of mechanical testing and accelerated weathering testing to yield a durable, economical formulation. The team will pursue licensing and commercialization of the formulation if appropriate. The team also expects to increase awareness regarding the infrared radiative properties of titanium dioxide and other coating materials within industry.

Supplemental Keywords:

building envelope, insulation, UHI,

Relevant Websites:

Phase 1 Abstract
Phase 1 Final Report

Progress and Final Reports:

  • 2010
  • Final

  • P3 Phase I:

    Cool Roof Coatings Incorporating Glass Hollow Microspheres  | Final Report