Jun-ichiro Tsutsumi

Field surveys on cooling effects of vegetation in an urban area

Abstract 1. 1. Three kinds of field survey on different scales were carried out in Fukuoka City in summer to examine the relationship between the quantity of vegetation and air temperature. 2. 2. The field of the largerst scale measurement is across the city. 3. 3. Several parks and shrines of various sizes in the city were selected as other measurement areas. 4. 4. The most detailed measurements are carried out in a park with an area of 1.25 ha located in a down town area of the city. 5. 5. Though the amount of vegetation is expressed in a unique way in each survey, it is clearly found that the greener it is, the lower is the air temperature.

Numerical simulation of air flow in an urban area with regularly aligned blocks

Numerical simulation of air flow distribution in a built-up area is an effective way to analyze and predict the urban thermal environment. A cyclic boundary conditions method for the numerical simulation of air flow around a block is used to model the unlimited spread of a built-up area. An equation for the calculation of the pressure difference between the windward and the leeward boundaries is proposed. Another simulation model which has 10 blocks aligned with the wind direction is used for comparison. The inflow boundary conditions are given by a wind tunnel test. The cyclic boundary conditions produced stable calculation results. The simulation results of the cyclic boundary conditions model are similar to those of the 10-block model in the cavity space. There is, however, a little difference between the results of these two models, and between them and the wind tunnel test in the higher area above the cavity and at the crossing point of the streets.

Investigation and numerical simulation of the wind effects on thermal comfort in a house

Abstract Full-scale measurement of indoor thermal factors and numerical simulation of indoor air flow are presented in this paper. The measurement was carried out in summer in two dwelling units of an apartment building; one was ventilated naturally through opening windows and the other was unventilated. Indoor thermal conditions of these two houses were estimated by the predicted mean vote and compared to find that the thermal conditions in the ventilated house ranged in the comfort zone while it was in the hot zone in the unventilated house, which depended upon the indoor air flow speed. Numerical simulation of indoor and outdoor air flow of a single unit house was carried out to predict the air flow speed by natural ventilation through opening windows. Multi-mesh system and k-a 2-equation model were applied for the indoor and the outdoor turbulent air flow for which the scales were greatly different.

Effects of Green Curtains to Improve the Living Environment

A green curtain means vertical planting of vines over a building surface. It is expected to improve indoor thermal environment of the building in summer, because it has a number of leaves shading a wall surface and windows of the building. However, it is also supposed to be obstacles to natural ventilation. Some experiments were done to confirm these environmental performances of green curtains. Model green curtains for the experiments were made of bitter gourd vines. A questionnaire survey for green curtain users was also carried out in Hamamatsu, Japan, to collect data about the amount of energy saved by green curtains and about the effect of green curtains on natural ventilation in residential houses. Results of the experiments and the survey indicate obvious effects of green curtains on indoor thermal environment.

Thermal comfort sensations of tourists in a subtropical region

The purpose of this study was to examine the relationship between changes in thermal environment and thermal comfort sensations in tourists who came to subtropical Okinawa from the mainland of Japan. A series of surveys of the thermal comfort sensations of tourists were carried out four times in 1 year in the Okinawa airport and the answers were analyzed in comparison with meteorological data that were observed at the Okinawa meteorological observatory. Thermal, comfort and humidity sensations in Okinawa and at tourists home were the main questions in the interview. The relationship between these three sensations was not clear in the female subjects, while some relationships were found in the male subjects. One significant conclusion that can be drawn from this study is that when the thermal sensation in Okinawa is higher by two levels than the subjects home thermal sensation then the comfort sensation of all the subjects is highest.