Hideki Takebayashi

The authors, in collaboration with Kobe City, have been continuously conducting feasibility studies on the introduction of heat countermeasure technologies such as water sprinkling, misting, sunshades, and water tables in areas such as station plazas, bus stops, and urban streets. This presentation reviews the history of these efforts and discusses how to identify areas where heat mitigation measures should be prioritized, how to predict the effectiveness of such measures, and how to verify the implementation results. As a specific example, Kobe City renewed two parks in the downtown area with consideration for heat countermeasures. Sunshades, water basins, misting, cool benches, grass, trees, gardens, etc. were installed. We conducted measurements to evaluate the thermal environment improvement by each technology and also captured infrared images of the entire park by using a drone. We are also discussing with Kobe city officials how to disclose the results of the effectiveness verification to the public. We also verified the effectiveness of the misting system in the plaza in front of the station, bus stops, parks, etc. Unfortunately, the system was not effective when the wind was strong. Therefore, we have developed a system to evaluate the feasibility of mist installation based on the reproduction of wind environment by CFD.

In this study, we analyzed the spatiotemporal characteristics of pedestrian behavior in street spaces using pedestrian count data—specifically, the number of pedestrians passing in front of infrared sensors installed throughout the downtown area. The analysis focused on three main questions: (1) whether the thermal environment affects pedestrian behavior, (2) how to characterize the spatiotemporal patterns of pedestrian activity, and (3) how to effectively present the results to urban planners and designers. A temporal and spatial analysis method was examined using hourly pedestrian count data over one year at more than 100 locations in the street canyon. The temporal characteristics of the pedestrian count data were classified into weekday and weekend clusters according to the peak hours within a day. The spatial characteristics of the pedestrian count data were clearly defined by distance from the station, office district, and commercial district, according to peak commuting, shopping, etc. Results from principal component analysis and cluster analysis did not reveal a significant influence of the thermal environment on the temporal variation in pedestrian counts. Instead, the data suggested that weekday versus weekend distinctions were the primary determinants of daily and annual patterns, while seasonal and weather-related factors had relatively minor effects. The analytical approach developed in this study represents a valuable and practical contribution that may be applicable to other urban contexts as well.

Adaptation measures to urban heat islands are classified into the following three categories: measures to reduce solar radiation incident on the human body, measures to control and cool ground and wall surface temperature, and measures to control and cool the air and human body temperature. Case studies are conducted to evaluate the effects of the implementation of a cool water circulation sunshade and to examine the adverse effects of cool pavements on the human thermal environment, in addition to the effects of mist sprays on the human body. The effect of the sunshade, watering road, and mist spray, which are typical adaptation measures to urban heat islands, on the human thermal environment was estimated using Wet Bulb Globe Temperature (WBGT) as an indicator for heat stroke prevention and Standard New Effective Temperature (SET*) as an indicator for thermal comfort assessment. The effect of solar radiation shielding on improving the human thermal environment was the most significant, with a large decrease in the amount of solar radiation absorbed by the human body, resulting in a large decrease in SET* and WBGT of 2.7 °C and 1.0 °C, respectively, on fine summer days.

For the Osaka-Kansai Expo, to be held from April to October 2025, it is necessary to manage the exhibition site with consideration for countermeasures against heat in order to make safe and active use of the outdoor space. In this study, we compared meteorological data observed at Expo site on the sea coast, and at the Osaka Meteorological Observatory in the city center to analyze the quantitative relationship between meteorological elements at both locations, calculated thermal environment indices using these meteorological data, and considered the effects of implementing adaptation measures against the heat. The effect of solar radiation shading is predominant in lowering SET* and WBGT. During the medium temperature period, before mid-June and after mid-September, solar radiation shading avoids uncomfortable conditions, and during the high temperature period, from late June to mid-July and mid-August to early September, solar radiation shading, surface cover improvement, and mist spraying reduce the risk of heat stroke. However, during the extremely hot period, from late July to early August, the risk of heat stroke cannot be avoided by any of the adaptation measures to heat.

In recent years, in order to serve as effective solutions to outdoor human thermal environments under the influence of urban heat islands, adaptation measures such as awnings, louvers, directional reflective materials, mist sprays, and evaporative materials have been developed. In this study, a simplified evaluation framework for adaptation measures to urban heat islands is examined. Adaptation measures to urban heat islands are classified into the following three categories; measures to reduce solar radiation incident on the human body, measures to control and cool ground and wall surface temperature, and measures to control and cool air temperature and human body. Case studies are conducted to evaluate the effects of the implementation of cool water circulation sunshade and to examine the adverse effects of cool pavements on the human thermal environment, in addition to the effects of mist sprays on the human body. The effect of the sunshade, watering road, and mist spray, which are typical adaptation measures to urban heat islands, on the human thermal environment was estimated using Wet Bulb Globe Temperature (WBGT) as an indicator for heat stroke prevention and Standard New Effective Temperature (SET*) as an indicator for thermal comfort assessment.

Continuous measurement of road surface temperature using an infrared camera throughout the summer season was conducted to clarify the duration of surface temperature decrease due to roadway watering according to weather conditions and watering time. Watering during sunny daytime conditions resulted in a maximum reduction in surface temperature of about 10 °C and an average reduction of about 6 °C. The duration of the surface temperature decrease was short (less than 30 min) for sunny days and long (more than 30 min) for cloudy days. On sunny days, if the evaporation rate was faster and the surface temperature decrease was larger, then the duration of the evaporation was shorter. Effective roadway watering plans were investigated according to the street configurations by simulating the thermal environment considering the solar radiation shielding condition of pedestrians on sidewalks. Simulation results in the downtown area of Kobe city indicated that watering the nearby roadways resulted in only 20% and 39% comfort for the northern sidewalks on the east–west road at 10:00 and 16:00, but about 70% comfort for the southern sidewalks and 60–90% comfort for the eastern and western sidewalks. Guiding pedestrians to a shaded sidewalk and then watering the nearby roadway to lower the surface temperature in the sun improves the thermal environment for pedestrians.

This study analyzed the relationship between the urban environment, as represented by the urban heat island phenomenon, and the number of crimes. Although very interesting, I judged that this manuscript should not be published as an academic paper be...