[2] Researchers at the Lawrence Berkeley National Laboratory predict that increasing solar reflectance of pavements to 35% from the standard 10% could lead to a 1 °F reduction in ambient temperature.
[9] Research into cool pavement technologies is still in its early stages, with current work focusing on maintenance, effectiveness quantification, and cost-efficient large-scale implementation.
[1] These pavements require moisture from rain or irrigation systems to function effectively and are engineered with permeable, water-absorbing materials such as soil additives and porous asphalt.
[1][11] However, evaporative pavements come with limitations including needing significant amounts of water which may be scarce in arid regions, and being generally less durable than traditional asphalt.
[4] In contrast, PCM-incorporated pavements utilize materials that absorb, store, and release heat as they transition from solid to liquid states.
[4] This increase is also achieved by mixing in aggregates covered with cement paste and asphalt binder before pavement is laid, which creates connected pores that hold water.
[4] So far, energy-harvesting cool pavements have not been proven successful at handling heavy traffic, as the energy harvesting elements are prone to damage or decrease in efficiency after being subjected to road maintenance.
[11][5] Reflective cool pavements can also increase visibility at night, reducing the need for streetlights which makes streets safer and also limits energy consumption.
[6] However, the enhanced albedo of the road can also reflect more light into drivers' eyes, creating a high glare that can impact visibility.
[16] Cool pavements can combat this as increased albedo and reduced temperatures prevent nitrous oxides and volatile organic hydrocarbon gases from reacting and creating ozone.
For instance, increasing pavement reflectivity (albedo) in Los Angeles has been estimated to save over $90 million annually in energy costs.
[5] Lower energy use translates to reduced greenhouse emissions and air pollution, depending on the fuel sources powering local grids.
In 2007, researchers estimated that if global pavement albedo increased by 35 to 39 percent, it could lead to carbon dioxide reductions valued at approximately $400 billion.
[20] In 2022, a project installed over 700,000 square feet of reflective pavement in Pacoima, California, a city in Los Angeles County known for its high summer temperatures.