Investigation on the cooling potential of urban greenery spaces in summer

Basically, urban greenery spaces have a lot of roles such as recreational function, evacuation space, environmental conservation, and the landscape planning. Recently, in addition to these things, most scientists insist that urban greenery spaces have a wide variety of potential, which are relevant to biodiversity conservation, maintenance of ecological networks, absorption of greenhouse gas emissions, and the cooling of surrounding areas. In these roles, especially, we considered that the cooling potential by greenery spaces are very important because the urban heat island phenomenon has become a serious topic of public concern during summer. This is the reason why we are addressing this issue. Based on these ideas, this paper aims to quantify the cooling potential of urban greenery spaces in summer. Initially, we have observed that greenery space and anthropogenic heat emissions have a great effect on the temperature in downtown areas from the various data collected from 27 observation points in Minato-Ku, Tokyo. Secondly, we have clarified the cooling potential of greenery spaces. Judging from the regression analysis, it can be said that the cooling influence by greenery spaces of 22,500 square meters is equivalent to the heating influence by the anthropogenic heat released from seventy office buildings of the average size in Minato-Ku, this having a total floor area of about 211,726 square meters. Furthermore, the cooling potential of a greenery space of 22,500 square meters from July to September can be expected to reduce about 236 times as much quantity of carbon dioxide as the same greenery space absorbed for one year. Our calculations take into consideration the fact that the reduction of temperature caused by greenery spaces makes air-conditioner usage will be reduced, therefore less fossil fuel will be consumed in electricity. In conclusion, greenery spaces in urban downtown areas have the function of air-conditioning given by nature.