Energy Saving Potentials and Air Quality Benefits of Urban Heat IslandMitigation
Energy Saving Potentials and Air Quality Benefits of Urban Heat IslandMitigation
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2005-08
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H. Akbari
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作者：
H. Akbari
节能潜力和城市热岛缓解的空气质量效益1 Hashem Akbari Heat Island Group劳伦斯伯克利国家实验室H_Akbari@lbl.gov http://HeatIsland.LBL.gov/摘要城市地区的气温往往高于农村地区，这是由于逐渐的地表改造，包括用建筑物和道路取代自然植被。“城市热岛”一词描述了这种现象。建筑物和人行道的表面吸收太阳辐射，变得非常热，这反过来又使周围的空气变暖。被“铺过”的城市没有得到植被自然冷却效果的好处。随着空气温度的上升，对空调（A/C）的需求也随之增加。这导致发电厂的排放量增加，以及气温升高导致烟雾形成增加。在美国，我们已经发现，空气温度的这种增加是城市空调使用峰值电力需求的5- 10%，以及城市地区人口加权烟雾浓度的20%。为城市降温的简单方法是使用反射表面（屋顶和人行道）和种植城市植被。在大范围内，植被的蒸散和反射表面对入射太阳辐射的反射增加，将在夏季使社区冷却几度。例如，对加利福尼亚州洛杉矶的计算机模拟显示，用反射表面重铺约三分之二的人行道和屋顶，并在每间房屋种植三棵树，可以使洛杉矶平均降温2- 3 K。这种降低空气温度将减少城市烟雾暴露在洛杉矶盆地大致相同的数额，消除盆地整个道路上的车辆废气。缓解热岛效应是一种有效的空气污染控制策略，不仅可以节省冷却能源成本。我们估计，在美国，当完全实施时，从凉爽的表面和遮荫树中节省的冷却能源约为每年50亿美元（每个空调房屋约100美元）。1.在世界各地，城市气温上升速度快于农村地区。例如，从1930年到1990年，洛杉矶市中心记录了增长。这篇论文是早期发表在《太阳能》上的一篇论文的删节和更新版本（Akbari et al 2001）。
Energy Saving Potentials and Air Quality Benefits of Urban Heat Island Mitigation 1 Hashem Akbari Heat Island Group Lawrence Berkeley National Laboratory H_Akbari@lbl.gov http://HeatIsland.LBL.gov/ ABSTRACT Urban areas tend to have higher air temperatures than their rural surroundings as a result of gradual surface modifications that include replacing the natural vegetation with buildings and roads. The term “Urban Heat Island” describes this phenomenon. The surfaces of buildings and pavements absorb solar radiation and become extremely hot, which in turn warm the surrounding air. Cities that have been “paved over” do not receive the benefit of the natural cooling effect of vegetation. As the air temperature rises, so does the demand for air-conditioning (a/c). This leads to higher emissions from power plants, as well as increased smog formation as a result of warmer temperatures. In the United States, we have found that this increase in air temperature is responsible for 5– 10% of urban peak electric demand for a/c use, and as much as 20% of population- weighted smog concentrations in urban areas. Simple ways to cool the cities are the use of reflective surfaces (rooftops and pavements) and planting of urban vegetation. On a large scale, the evapotranspiration from vegetation and increased reflection of incoming solar radiation by reflective surfaces will cool a community a few degrees in the summer. As an example, computer simulations for Los Angeles, CA show that resurfacing about two-third of the pavements and rooftops with reflective surfaces and planting three trees per house can cool down LA by an average of 2–3K. This reduction in air temperature will reduce urban smog exposure in the LA basin by roughly the same amount as removing the basin entire on- road vehicle exhaust. Heat island mitigation is an effective air pollution control strategy, more than paying for itself in cooling energy cost savings. We estimate that the cooling energy savings in U.S. from cool surfaces and shade trees, when fully implemented, is about $5 billion per year (about $100 per air-conditioned house). 1. Introduction Across the world, urban temperatures have increased faster than temperatures in rural areas. For example, from 1930 to 1990, downtown Los Angeles recorded a growth This paper is an abridged and updated version of an earlier paper published in Solar Energy (Akbari et al 2001).