Daytime irrigation leads to significantly cooler private backyards in summer

Backyards play important roles for individual households because they provide a private and safe green space for social and environmental interactions, relaxation, gardening and children's activities. The use of backyards is highly dependent on their thermal conditions. Turf is a common surface type in backyards but unirrigated turf can be as warm as pavement, bringing thermal discomfort and discouraging people from using them. Under certain conditions, turf irrigation provides an opportunity to reduce thermal stress by increasing evapotranspiration. This study aims to measure the impacts of turf irrigation on microclimate in a backyard environment in the warm season in Melbourne, Australia. The experiment consisted of four 6 m × 6 m turf-covered plots. Daily irrigation was applied at four amounts: 0, 2, 4 and 7 mm for six weeks. In Week 6, the 4-mm irrigation reduced daytime soil temperature, turf surface temperature, air temperature and universal thermal climate index by 1.7, 2.3, 0.6 and 0.4 °C, respectively. All daytime impacts were significant (p < 0.05, t-test). Irrigation has the potential to significantly improve the thermal conditions of backyards in combination with the use of tree shade. Copyright © 2022 Elsevier B.V. All rights reserved.