Applying expanded metal mesh for outdoor shades in outdoor thermal environments.

This study investigated the applicability of expanded metal meshes (EMMs) in horizontal shading devices. We performed simulations and experiments with EMMs with different opening ratios and directions. We established various experimental and control groups to measure air temperature, surface temperature, and black globe temperature. After the comparison of simulation and experimental data, we used Grasshopper to simulate long-term climate situations. The research results can serve as reference for users in Tainan and provide customized suggestions. The findings can serve as a paradigm for parametric design to analyze EMMs. In design projects involving outdoor horizontal shading devices, these results can be used in the design phase for evaluation. Full-day measurements revealed that EMMs with small openings exhibited favorable shading effects. In the Tainan area, we suggest using north-facing EMMs; in our simulations result, 70% of sunshine did not pass through the mesh in a day. For shading equipment in the morning, west-facing EMMs should be used because they blocked 50-90% of sunshine. For recreational areas in the afternoon and evening, east-facing EMMs can block 50-90% of sunshine after noon. In Taiwan, south-facing EMMs are not advised because their shading performance is suboptimal in the morning and afternoon.

Thermal comfort along the marathon course of the 2020 Tokyo Olympics.

The Olympic Games will be held in Tokyo in 2020 and the period will be the hottest period of the year in Japan. Marathon is a sport with a large heat load, and it is said that the risk of heat stroke rises more than other sports activities. The thermal environment of the 2020 Tokyo Olympic marathon course is analyzed by using wet-bulb globe temperature (WBGT) and Universal Thermal Climate Index (UTCI) map of the center area of Tokyo. The change due to the place, the effect of the shadow of the building, and the position on the course was analyzed from the distribution of WBGT and UTCI in the short-term analysis of sunny day from August 2 to August 6, 2014. To make the distribution map, we calculated distributions of sky view factor and mean radiant temperature of the 10 km × 7.5 km analyzed area in the center of Tokyo. Distributions of air temperature and humidity are calculated from Metropolitan Environmental Temperature and Rainfall Observation System data, which is a high-resolution measurement network. It was possible to incorporate the local variation of temperature and humidity of the analyzed area. In the result, the WBGT is about 1 °C lower and the UTCI is about 4-8 °C lower in the shadow of buildings from 9:00 to 10:00 than in the sunny side. As a cooling method, making a shadow is a relatively effective method. The variation along the course considering the distribution of meteorological data within the area is about 0.5 °C WBGT and 1 °C UTCI range. If we allow the error of this range, one-point meteorological data can be applied for the estimation along the course. Passing the right side (left side in the case of return) of the course could keep the accumulated value slightly lower along the course in the morning because the marathon course roughly runs from west to east and buildings' shadow is on the relatively right side (south side). But practically, the effect of changing the position on the course was small. The long-term analysis on the degree of risk for each hour was also carried out by using one-point data of the first 10 days of August from 2007 to 2016. The risk increased rapidly after 8:00. It will be safer if the marathon race is finished before 9:00 or if the race is held after 19:00.

The application of a high-density street-level air temperature observation network (HiSAN): The relationship between air temperature, urban development, and geographic features.

The urban heat island effect in cities has become an important problem in relation to not only urban climate but also public health and urban planning. Tainan, which located in Southern Taiwan, is a compact city with intense development. Therefore, this study investigated the urban thermal condition by employing a high-density street-level air temperature observation network (HiSAN). A total of 100 measurement points were set in various urban development areas. The geographic factors in Tainan can be used for indicating the relationship between thermal conditions and urban built environments to comprehensively compare the approaches, such as conducting traverse measurement and utilizing only a single datum or a small amount of weather station data. Buffer zone analysis was used in this study for zones of different sizes, and it was determined that a 300-m scale is optimal to illustrate the effects of land features on microclimate. The results revealed that the thermal condition in Tainan is influenced by urban development factors, such as the floor area and land cover area, and by geographic factors, such as the distance to the sea. A better cooling effect can be obtained from a vegetation area during the night time and from a water body during the daytime. Moreover, different cooling effects are observed based on the distance to the sea. Through these results, a model for predicting the thermal condition for different periods can be established using a multiple regression model. Urban planners and architects can proffer design and planning suggestions for different areas based on the findings of this study to reduce thermal stress in urban areas.

The application of a high-density street-level air temperature observation network (HiSAN): Dynamic variation characteristics of urban heat island in Tainan, Taiwan.

The effects of urban heat island (UHI) have recently become a crucial issue. This study utilized a high-density street-level air temperature observation network (HiSAN) to understand the UHI characteristics in Tainan City. A total of 100 measurement points were established throughout the city. The average distance between two neighboring measuring points was 1.9 km in rural areas and 0.8 km in metropolitan areas. The UHI caused a temperature differences of at least 3 °C in each month over the study period, and the UHI's centric point moved from west to east during the day and from east to west at night, mainly because of the physical effects of the different urban environment including location and the impermeable surface area (ISA), total floor area, and sky view factor in urban areas. The results also indicated that factors such as ISA and distance to the coast had the strongest influence on thermal conditions at various times, especially in the areas far from the coast during the hot season. This was mainly because of differences in how heat was retained over the study area. The HiSAN method can be used by urban planners, architects, and policymakers to mitigate the thermal stresses caused by complex urban environments.

Patterns of shoot mortality in Betula platyphylla in northern Japan.

To understand the development of crown structure in Betula platyphylla Sukatch., mortality patterns of long shoots were analyzed quantitatively. We selected 25 saplings growing under various light conditions and measured the relative photosynthetically active radiation (rPAR) at, and the three-dimensional position of, first-order branches. A long shoot was assigned "no buds" (NB) status if it lacked buds at the end of the growing season, including at the tips of short shoots. A long shoot was classified as dead if it was NB and all the offspring long shoots issuing from it were NB. The probability that a leafy long shoot (a current-year long shoot with leaves or an older long shoot with short shoots with leaves) would become NB by the end of the season was positively dependent on shoot age and branch age, and negatively dependent on shoot length, centripetal shoot order, branch height and rPAR at the branch. Randomization tests revealed that shoots became NB and dead in clusters of connected shoots. In particular, shoot clusters originating from 3-year-old shoots were more likely to die than expected if each shoot was assumed to become NB regardless of the connection. Stepwise logistic regression revealed that the maximum rPAR within the crown of an individual tree had a significant effect on the mortality rate of 3-year-old shoot clusters, together with the rPAR at the level of the branch and other structural entities. Correlative inhibition is an important mechanism for determining shoot mortality patterns.