Investigation of cooling effect of urban green area on air temperature and relative humidity

Abstract

      In this study, the cooling effect of urban green areas on air temperature and relative humidity is investigated. In order to compare the maximum and minimum values from green areas of different sizes, two parks were selected: a small one, Wongweinpahon 24 Park covering the area 1.2 rai (1,920 m²) and a large one, Prachanivech Park covering the area 10 rai (16,000 m²). The study period covered summer and winter seasons. The following factors were considered: solar intensity, surface temperature, air temperature and relative humidity. The  analysis results between solar intensity and all temperature values show positive correlation. That was solar intensity varied directly to surface and air temperature. The average values from the two parks show that Prachanivech Park had lower air temperature and higher on relative humidity than Wongweinpahon 24 Park. The high temperature values were often found in the surrounding of the parks, either in open field or grassland areas where have lower shade from trees. Conversely, the lower temperature values were often found inside the park areas where have more shade from trees. With a large green area, Prachanivech Park has higher cooling effect than Wongweinpahon 24 Park, where has a smaller green area. Thus, as a result of their cooling effects, green areas were therefore found to have the capability to decrease the surrounding air temperature.