Course: GFM 103 Exterior Environmental Management

Reading and Audio-Visual Assignments

(2/2)
Cool Roofs Now Cool Pavements

Conventional paving materials can reach peak summertime temperatures of 120–150°F (48–67°C), transferring excess heat to the air above them and heating stormwater as it runs off the pavement into local waterways. Due to the large area covered by pavements in urban areas (nearly 30–45% of land cover based on an analysis of four geographically diverse cities^1), they are an important element to consider in heat island mitigation.

Cool pavements include a range of established and emerging technologies that communities are exploring as part of their heat island reduction efforts. The term currently refers to paving materials that reflect more solar energy, enhance water evaporation, or have been otherwise modified to remain cooler than conventional pavements.

In addition to reducing heat islands, the benefits of cool pavements include:

- Reduced stormwater runoff and improved water quality: Permeable pavements can allow stormwater to soak into the pavement and soil, reducing runoff and filtering pollutants. Both permeable and non-permeable cool pavements can also help lower the temperature of runoff, resulting in less thermal shock to aquatic life in the waterways into which stormwater drains.
- Lower tire noise: The open pores of permeable pavements can reduce tire noise by two to eight decibels and keep noise levels below 75 decibels, although noise reduction may decline over time.^2
- Enhanced safety: Permeable roadway pavements can improve safety by reducing water spray from moving vehicles and increasing traction through better water drainage.
- Better nighttime visibility: Reflective pavements can enhance visibility at night, potentially reducing lighting requirements and saving both money and energy.
- Improved local comfort: Cool pavements in parking lots or other areas where people congregate or children play can provide a more comfortable environment.

Comparing the costs of cool pavements with those of conventional paving materials is difficult. The cost of any pavement application varies by region, the contractor, the time of year, materials chosen, accessibility of the site, local availability of materials, underlying soils, size of the project, expected traffic, and the desired life of the pavement.