LowEmissionAsphalt-136pg-WhitePaper-May2023

P a g e | 89 For UHI, one not need speculate. Future paving-related bid lettings are going to include UHI mitigation. Agency consortias such as the Global Cool Cities Alliance (GCCA) 188 have grown rapidly and focus on promoting heat-reducing infrastructure strategies. Cities like Los Angeles 189 and Phoenix 190 are already leading the way with actve “cool pavement” paving programs. The use of “cool pavement” products is expanding rapidly and the Infrastructure Investment and Jobs Act of 2021 (IIJA) includes billions of dollars in cool pavement focused appropriations. Historically, “high albedo” pavements, which are lighter colored roads, sidewalks and parking lots have been implemented to improve reflectance. But such products are visible light (VL) centric and unable to reflect ultraviolet light (UV). They hence are poor at mitigating pavement emissivity critical to UHI management. These “white asphalts” also tend to be aestethically challenging with poor durability, require signifiant new pavement rebuilding costs, and tend to reduce human comfort levels. Porous pavements can reduce stormwater runoff by allowing rain to pass through the surface, recharging groundwater while reducing flood risk, but do not effectively redirect solar energy and are insuitable for vehicular traffic loads. An emerging technique is to deploy photocatalyst materials such as titanium dioxide (TiO 2 ) into roads and roadway materials as the added catalyst is very effective at reflecting UV and reducing pavement emissivity. New testing standards for pavement related UHI mitigation developed by the EPA require low emissivity. Not just improved albedo. 188 www.globalcoolcities.org . 189 Cool Streets LA: www.streetsla.lacity.org . 190 Phoenix Cool Pavement Program: www.phoenix.gov/streets/coolpavement .