Pavement watering as an urban heat mitigation technique

Climate change, rapid urbanisation, and ageing populations are reinforcing the need for urban heat mitigation techniques. Pavement watering is one such technique, where evaporative cooling is induced through wetting urban surfaces. The aim of this research is to assess the potential cooling benefits of pavement watering. To do this, a 10 × 10 m section of a car park was watered, and experiments were conducted at midday, the afternoon, and the evening across three days. Pavement watering was found to induce a mean cooling of up to 0.6 °C in air temperature and 2 °C in UTCI at 1.5 m. Benefits were related to prevailing conditions, with lower wind speeds associated with greater cooling. Surface temperature was also found to decrease by up to 9.0 °C, and the surface energy balance of the watered carpark was characteristic of a highly evaporative surface. However, there were limitations of the experiments; notably, the assumptions made to correct observations increased uncertainty, and the small scale of the experiment likely limited the observed cooling benefits. Despite this, pavement watering was shown to reduce air temperature and surface temperature, as well as improve thermal comfort, and thus may potentially be used in emergencies to provide cooling in urban areas.