The microclimate, surface energy flux and human skin burn risks of artificial turf as compared to natural turf

• Artificial turf had significantly greater air temperatures than natural turf at 1.5m. • Artificial turf did not decrease human thermal stress (UTCI). • The maximum hourly mean surface temperature of artificial turf was 71.6 °C. • Artificial turf posed a risk of skin burn for almost four hours of the day. • Artificial turf had high surface temperatures due to low albedo and low evaporation. There are increasing concerns over the human heat stress and burn risks of using artificial turf in private outdoor spaces such as backyards. This study aimed to compare the microclimate, human heat stress, surface energy fluxes, and human skin burn risk of artificial turf as compared to natural turf in a backyard environment in summer in Melbourne, Australia. The outdoor experiment consisted of nine identical plots (6 × 6 m) with three treatments (each treatment had three replicates): artificial turf, unirrigated natural turf, and irrigated natural turf (4 mm d –1 ). These three treatments were measured continuously for 51 days during summer. The artificial turf had significantly greater daytime (10:00–16:59 local time) mean air temperature (28.8 °C) than the unirrigated (28.2 °C) and irrigated (28.0 °C) natural turf. The differences in daytime mean radiant temperature among the treatments were too small to make a noticeable difference in human heat stress, measured in universal thermal climate index and wet-bulb globe temperature. The artificial turf had significantly greater daytime mean turf surface temperature (49.9 °C) than the unirrigated (31.7 °C) and irrigated (29.9 °C) natural turf. The turf surface temperature of the artificial turf exceeded the 48 °C skin burn threshold for almost four hours of the day when averaged over the 51 days of measurement. The lower albedo of artificial turf (0.09) increased the absorption of incoming shortwave radiation, compared to natural turf (0.19). The lower specific heat capacity of artificial turf also led to its greater surface temperature.