Papers by Keyword: Heat Island

Abstract: We investigated to add some high functionality to the brick by controlling the porous structure of the brick. It was succeeded in this study that a great many minute continuous pores which lead to capillary action were introduced inside of bricks in order to bring about “UCHIMIZU effect” for suppressing urban heat island phenomenon. But, as for the high water retainable pavement material like that brick, it is broken by water freezing in winter, and from this reason any pavement material with “UCHIMIZU effect” are not readily spread in through the all over Japan. Then, preparation of the brick which had both water retainability and frost resistance was tried by introducing much space into the brick inside to be able to permit the solidification expansion of water, and examined influence on properties of the brick by the quantity of porosity. From results, it was suggested that water retainability and frost resistance were able to be given to the brick at the same time by using the cavity formation materials.

Abstract: The recent abnormal climate and extreme weather events have frequently given unexpected casualties and damages. In particular, in cases accompanying with heavy rainfall or extremely hot weather in a short period of time, there increases possibility leading financial damage by flooding, heat island phenomenon etc.. One of the main factors that are caused these problems is impermeable area including asphalt and concrete pavement which is increased by urbanization. So, it is interested in porous pavement to solve the environmental problems in Korea. In this study, a block pavement system for sidewalk to control surface temperature of pavement and rainwater runoff was developed. The block pavement system is composed of permeable or water-retentive block and rainwater storage which can harvest and supply rainwater. Surface temperature of permeable block pavement is reduced about 10°C compare with it of impermeable block pavement. Also, rainwater runoff was not happened during the period of rainfall.

Abstract: A large amount of research has been published in Taiwan on the reduction of the urban temperature for different strategies. The most important strategy for reducing ambient temperature is increasing green space in city. For analyzing the effect of the vegetation on the thermal environment, this paper collects temperature data from one green roof and one normal roof which are belong to a same office building to analyze the thermal influence of vegetation. The result of this research shows that in summer the maximum cool effect of green roof was -1.60 oC and -0.26 oC in average. Therefore, it can also provide useful data to governments for calculating the environmental benefit if they carry out a green roof policy in mitigating heat island effect in the future.

Abstract: Recently, increasing of impervious surface as concrete or asphalt pavement with urban development brought increasing of air temperature in city. So many researchers have explored ways to reduce the urban heat island effect and water-retentive or water absorbing pavements have been found to be very effective. In this study, to evaluate the reduction effects of urban heat reduction of water-retentive pavement, surface temperature of pavement, air temperature, wind speed and albedo were measured for 3 years (2008~2010, summer period). And the intensity of sensible heat flux was calculated to estimate a influence on air temperature. Experimental results indicated that water-retentive was effective to reduction of air temperature by decreasing of surface temperature of pavement compare to other pavements. This is showed that water-retentive pavement can be contributed to mitigation of urban heat island.

Abstract: A large amount of research has been published in Taiwan on the reduction of the urban temperature for different strategies. The most important strategy for reducing ambient temperature is increasing green roofs or green spaces in city. For analyzing the effect of the vegetation on the thermal environment, this paper collects temperature and humidity data from two building roofs, one park and two streets which are located within same area and tries to analyze the thermal influence of vegetation in study area. The result of this research shows that the maximum cool effect of green roof was -1.60 °C and the maximum temperature difference between park and street was -2.00 °C. Therefore, it can also provide useful data to governments for calculating the environmental benefit if they carry out a green space and green roof policy.

Abstract: In this paper, a building canopy model is coupled with CFD for the analysis of microclimates within urban blocks under different urban and architectural planning. This model considers radiant heat exchange in the building canopy, water evaporation of vegetations and heat released from the air conditioning systems. Using this model, thermal environment of a real urban block is analyzed. The simulation results show that heat released from the air conditioning systems is one of the most important factors affecting outdoor thermal environment. Temperature of vegetation is significantly lower than that of road surfaces. However, air temperature difference is not great between zones with vegetation and other zones at 1.5m height.

Abstract: Vegetation evaporation is believed to be an important control measure in heat-island mitigation. The impact of vegetation on mitigating heat island intensity in four major cities in China is investigated using a numerical method. The simulation results show that increasing vegetation cover can significantly reduce outdoor air temperature in summer in the four cities investigated. However, the evaporation rates of plant and magnitude of temperature decreases are different in the four cities because different climate characters.

Abstract: Anthropogenic heat released from air conditioning systems is one of the most important factors contributing to the heat island in summer. A model to predicted heat island intensity is built. Using this model, a typical office building cluster is simulated, and the effect of heat released by air condition on outdoor thermal environment and heat island intensity is discussed. Furthermore, the reaction of heat island intensity rising on the performance of air conditioning systems is also investigated.

Abstract: Urbanization together with increased population and industrialization has increased impermeable areas including asphalt and concrete pavement, leading to potential dangers of environmental disasters in urban area. While environmental pavements have been investigated to mitigate these problems in some countries such as Germany and Japan, little work has been done in Korea. Furthermore, most studies on environmental pavements have focused on permeable asphalt pavements. This study was intended to develop new materials for water-absorbing pavement blocks to control pavement temperature and storm water runoff. Bottom ash, which is a coal combustion by-products, was used as a composing material for these blocks. A polymer with water absorption ratio of 76% was used as a water-retention material for the pavement blocks. The effect of block compositions on mechanical characteristics, compressive strength and porosity were examined as well as thermal characteristics. This water-absorbing polymer is likely to be suitable to be used with the bottom ash blocks. The time required to fill the pores of the blocks with the polymer ranged from 9 to 14 sec, indication that the polymer can be readily applied to the blocks. The final products with optimum compositions satisfied the Korean Standard for blocks and possessed an excellent water-retentive ability. Experiments are ongoing to measure the properties of the blocks for further application as a new construction material.

Abstract: Urban area may be warmer than surrounding regions due to asphalt and concrete for roads, buildings, and other artificial structures. Especially, pavements have become an important contributor to this effect by altering land-cover over significant portions of an urban area. Therefore, researchers have studied ways to reduce the heat island effect such as cooling pavement, porous pavements such as water-retentive or water absorbing pavements. Accordingly, this study aims at the development of water-retention asphalt pavement for urban areas in order to solve problems related to the distortion of water cycle and the heat island phenomena. Experimental results indicated that asphalt pavement using developed water retaining material was effective to decrease its surface temperature compare to other pavements. A correlation between air temperature and surface temperature of the pavement was obtained to estimate the efficiency of the developed pavement materials.