Experimental Study of Comfortable Outdoor Space Formation at High-temperature Season by Tree Planting with Spray System

摘要

The average temperature in Japan has become higher in recent years owing to global warming and the urban heat island. Many people suffer from heat strokes during summer. Therefore, measures must be taken to ease the summer heat. In this study, we tested a procedure during the summer of 2014 and 2015 aimed at ameliorating the adverse effects of the summer heat by planting trees in containers and installing mist sprays. We measured the air temperature, wet-bulb globe temperature (WBGT), solar radiation, and other such indicators of the atmospheric temperature in three areas: (1) townstreet, (2) tree planting, and (3) tree planting with water spray areas. The globe temperature could decrease by 3 °C in the tree planting area and 7 °C in the tree planting with water spray area. Further, based on the WBGT, which was used as a guideline for the prediction of the risk of heat stroke, the time ratio judged as “extremely hazardous” decreased from 42.9% to 20.7% of the total measurement time, thereby confirming that the trees and water spray greatly facilitate heat stroke prevention.