Penn State Center for Sports Surface Research: Synthetic Turf Heat Evaluation – Progress Report January 2012

Executive Summary
Laboratory and outdoor tests were conducted to compare surface temperatures of infilled synthetic turfs composed of various fiber and infill colors/materials. In the laboratory study, the following surface temperature tests were performed: 1) synthetic turf system (infill installed into fibers), 2) fiber, and 3) infill. Surface temperature was evaluated by placing each sample under a 250 W infrared heat lamp. A total of 11 fiber/infill combinations were tested in the synthetic turf system trial. While temperature differences of up to 20 degrees were found among synthetic turf components (fibers and infills) when tested independently, when combined into synthetic turf systems, differences were 12 degrees or less. With temperatures of all tested treatments exceeding 150° F when evaluated as synthetic turf systems, no product in this study produced a substantial reduction in surface temperature compared to a standard green fiber/black rubber system. Outdoor testing was also conducted in the summer of 2011. The surface temperatures of many of the same treatments included in the laboratory test were also evaluated outdoors during warm, clear conditions. Outdoor testing only included synthetic turf systems and did not include individual component tests. Results from the outdoor testing were similar to the laboratory tests.

The issue of high surface temperature on infilled synthetic turf continues to be a significant concern. Because surface temperatures can reach up to 200° F (Williams and Pulley, 2002), usage of synthetic turf fields may be limited during the peak heating hours of the day in the interest of athlete safety. Numerous methods have been attempted to mitigate high surface temperature (Serensits, et al., 2011). For example, the use of irrigation water has been shown to rapidly drop surface temperatures immediately after watering; however, temperatures quickly rebound to near pre-irrigation levels (McNitt et al., 2008). Other research has examined the effect of painting black crumb rubber infill white in an attempt to lower surface temperature (Devitt et al., 2007). Once installed in the carpet fibers, the white infill reduced surface temperature by only a few degrees.

Because some have questioned the safety of crumb rubber infill, alternatives to standard infill have become increasingly available to consumers. Many of these products claim advantages over traditional crumb rubber infill including reduced surface temperature. While marketing materials may claim lower surface temperatures, no scientific reports exist that substantiate such claims. The influence of fibers on surface temperature has also been recognized. One manufacturer claims to produce a fiber that significantly reduces surface temperature; however, again, there is no publicly available scientific evidence to support the claim.