Amount of exhaust heat from room air conditioners have increased in urban areas because of increasing in number of sultry nights. In this report, influences of high outdoor temperatures at night and operating mode of room air conditioners at bedtime on COP and exhaust heat were examined. Based both on the steady and the unsteady simulation results, COP is impacted by outdoor temperature and operating mode of room air conditioners, and exhaust heat is impacted by outdoor temperature. Next, space-time characteristics of exhaust heat in Osaka city were examined. Based both on the actual performance prediction of the room air conditioner and space-time analysis results, in two or three hours after sleeping, the generation of exhaust heat per unit area in a residential area (Hannan-cho, Abeno-ku) is at least 16W/m2.

A field experiment is performed in Tsukuba City, Ibaraki Prefecture, on the early morning 17 Feb 2008. As a result, we found the actual condition of the city-scale urban heat island phenomenon under the clear weak wind weather condition. The shape of the heat island is rectangular with northwest-southeast direction, and its center is found in the Takezono area including commercial areas. The heat island intensity at 0600 Japan Standard Time (JST) is 5℃. Observed vertical profile of the temperature reveals that the atmospheric stability is almost neutral over the central park near the station although it is strong stable over the open space in the University of Tsukuba. Additionally, the temperature difference between the two sites is confirmed from surface to 30 m above the ground, and the difference in the surface air temperature between the two sites is 4℃.

In order to develop measures that effectively mitigate urban heat island phenomenon, a simulation model capable of predicting urban thermal climate precisely must be developed. This paper analyzes sensitivity of estimated air temperature in a meso-scale climate model to how anthropogenic heat is released. The result showed that the total amount of heat release from the residential, transportation and industrial sectors, the pattern of heat release from the residential and industrial sectors, the height of the industrial sector have a significant influence on air temperature during night and early morning while atmosphere is stable.

The on-site estimation method for the evaporative flux from the green roof using the TDR water content sensor of the soil is examined in comparison with the method of the weight change observation of grass and soil. Evaporative flux estimated by the method of the weight change observation is a little large, because of the insufficient shield around the test weight and the wind velocity variation of the test weight surface. The evaporative efficiency calculated by the estimation method using the TDR sensor is around 0.2 - 0.3, which is almost agree with the values in the conventional study. Two methods using the TDR water content sensor are compared. In the one method a TDR sensor is set vertically in the soil, and in the other method several TDR sensors are set horizontally in the soil. In the method setting a TDR sensor vertically, the observation result is influenced by the cavity nearby surface. And in the method setting several TDR sensors horizontally, the observation result cannot follow the water content ratio change of the surface neighborhood. If the installation of the TDR sensor is carried out more carefully in consideration for the cavities of the surface neighborhood etc., the on-site estimation of the evaporative flux from the green roof is possible.