1、Cool roofs: Many of the roofs across London are dark in colour and probably reach temperatures in excess of 50-60oC on hot sunny days. Consequently they will store and release a considerable amount of energy back into the atmosphere. High roof temperatures will accelerate the deterioration of roof m
2、aterials and in buildings with poor roof insulation contribute to increased demand for cooling energy and a decrease in indoor thermal comfort on upper floors. In contrast cool roofs built from materials with high solar reflectance or albedo and high thermal emittance may reach temperatures consider
3、ably lower than their low reflectance counterparts. This is because they absorb and store less solar energy during the day and thus are not major emitters of heat into the urban atmosphere at night. Apart from their reduced contribution to the development of the nocturnal heat island, cool roofs hav
4、e obvious benefits for the lifetime of roofs as excessive contraction and expansion is avoided through a damped daily temperature range and absorption of ultraviolet radiation is reduced. Also there will be gains in terms of indoor thermal comfort through the reduced transfer of heat through roofs t
5、o the upper floors of buildings and reduced demand for active cooling systems. To ensure the effectiveness of cool roofs as a climate management strategy their reflectivity must be maintained as this declines with roof age and roofs need to be kept clean, as dirt and pollution lower reflectivity.冷屋顶
6、：伦敦许多建筑的屋顶颜色很深，在温暖的天气里温度可能达到 50-60 摄氏度。因此这些屋顶会储存并释放相当大的能量到至大气中，并且较高的屋顶温度会加速屋顶材料的老化，建筑中老化的屋顶隔热材料会消耗更多的冷量并且降低楼上的室内热舒适性。相比之下，由较高太阳反射率或反照率和较高的热辐射材料建成的冷屋顶，可以达到一个相对于低反射率屋顶较低的温度。原因是它们在白天吸收并储存较少的太阳能，因此夜间不是大气的主要热辐射源。冷屋顶除了控制夜间的热岛效应外，它的寿命也更长，这是由于它对气温日较差的阻尼作用和对紫外线辐射吸收的减少，从而避免了过度的收缩和膨胀而造成的。同时冷屋顶减少了建筑物屋顶向上层房间传递的热
7、量和空调系统的运行，因而会增加室内热舒适感。为了保证冷屋顶作为建筑气候控制策略的有效性，随着屋顶寿命的减少需要维持其反射特性，并且保持屋顶清洁，因为灰尘和污染物的反射率低。Green Roofs: Like cool roofs, green roofs, which consist of a growing medium planted over a waterproof membrane, can have a marked impact on the climate of the upper floors of buildings and their immediate environs
8、. On hot sunny days rooftop temperatures may be up to 20-40oC cooler than a conventional flat dark coloured roof. As well as the gains achieved in terms of climate through their cooling effect as a result of evapotranspiration, green roofs reduce rainwater runoff by absorbing and slowly releasing la
9、rge amounts of water, act as insulators and reduce noise for upper floor occupants, increase urban biodiversity through providing habitat space for birds and small animals, increase urban aesthetics and contribute to quality of life. As the climate impacts of green roofs are likely to be greatest du
10、ring prolonged periods of hot dry weather their efficacy as a microclimate management strategy will depend very much on the maintenance of a regular programme of watering and vegetation care. Once water becomes limited and vegetation health deteriorates their climate behaviour will approach that of
11、a dry bare soil surface, which although not ideal will still maintain temperatures at a lower level than the more usual roofing mediums). 像冷屋顶一样，绿化屋顶由防水膜上培育的生长物质组成，可以影响上层房间及其周围气Comment a1: Page: 2The GLA does not believe in carbon sequestration through urban forestry候。在炎热的天气这种屋顶的气温可能比传统的平面深色屋顶低 20-4
12、0。借助蒸腾作用的冷却效果，从气候方面来讲绿化屋顶也非常有效：绿化屋顶通过对大量水的吸收和缓慢释放减少雨水的流失，作为隔音材料从而减少上层住户的噪音，为鸟类和小型动物提供栖息空间从而增加城市生态多样性, 促进城市美化并提升生活质量。在长期的干热天气中绿化屋顶对气候的作用效果可能是最好的，其微气候控制策略的效能主要依赖于定期的浇灌和植被维护工作。一旦缺水或植物健康恶化，其气候调节能力就与干燥裸露的泥土表面一致，这虽然不理想，但仍然可以使温度保持在较普通材料制作的屋面更低的水平。Planting Trees and Vegetation: Urban Greening can be a cost
13、effective way of ameliorating harsh urban climates at the individual building to neighbourhood scale. Trees and vegetation are good modifiers of climate, as they not only provide shade (surface peak temperature reductions of 5-20oC may be possible) but are natural cooling systems as they consume lar
14、ge amounts of available energy in the atmosphere through the process of evapotranspiration; the energy is used to convert water contained in the vegetation into water vapour which is transpired through leaves to the atmosphere. For some locations elsewhere it has been estimated that evapotranspirati
15、on can result in the reduction of peak summer temperatures by 1 5oC. If tree and vegetation planting is integrated with a well designed programme of roof greening the potential gains for human thermal comfort at the neighbourhood scale could be significant. In the case of London the cooling effect o
16、f expansive vegetated surfaces such as Richmond, Hyde and Regents Parks are clear. As with green roofs, additional benefits arising from urban trees are that they act as carbon stores, can reduce urban flooding through intercepting heavy rainfall, filter pollutants from the air and contribute to qua
17、lity of life. In choosing the type of tree for urban greening care should be taken not to select trees that are major sources of volatile organic compounds (VOCs) as during warm weather these will enhance the formation of ozone.种植树木和植被：从单体建筑到街区尺度， “城市绿化”是一种经济性的改善恶劣城市气候的方式。树木和植被是良好的气候调节者，它们不仅提供树荫（其地表
18、温度可降低 5-20 oC） ，而且是天然的空调系数，因为其蒸腾作用会消耗大气中大量的能量，用于使植物中的水分转化成水蒸气通过叶子蒸发到大气中。在某些地方已经证明蒸腾作用可以使夏季最高气温降低 1-5oC，如果树木和植被种植能与设计良好屋顶绿化工程相结合，那么在街区尺度的人体热舒适潜在收益将是巨大的。在伦敦广阔的植被表面的冷却效果的案例中，如里士满市、海德、摄政公园，都是很成功的。树木是碳的仓库这使的城市树木有了更多好处，同时绿化屋顶通过蓄存大量的降雨可以降低城市发生洪水的几率，它们还过滤空气中的污染物，并提高生活的质量。选择城市绿化树种时要注意不能选择释放挥发性有机物的树种，在温暖的天气里，
19、这些树种会增强臭氧的形成。Cool Pavements: Like many of Londons roofs, the streets and to a lesser extent, the pavements of London are typified by dark surfaces. The installation of cool pavements comprised of material with high solar reflectivity and good water permeability is potentially a very effective way of
20、 mitigating high urban temperatures through decreasing absorption of solar energy and encouraging water storage in the urban surface and thus evaporative cooling. High albedo roads and pavements may also have benefits for nighttine street lighting. As yet little is known about the climate impacts of
21、 cool pavements at the street canyon to neighbourhood scale as research on pavement climate properties is still very much in its infancy. However demonstration projects in cities such as Phoenix Arizona have clearly shown the climate benefits of cool parking lots for example. For London, discernible
22、 climate impacts of cool pavements could be achieved for large parking areas, terminal facilities, airports, and urban roadways with large expanses of paved surfaces when re-surfacing or new surfacing is planned. 冷铺路面：像伦敦许多的屋顶一样，街道和小尺度的路面铺装使用典型的暗色冷铺装，它们由较高太阳反射率的材料组成，并且具有良好的透水性，所以它们对于减轻城市高温是非常有效的办法，它
23、降低对太阳能的吸收和促进城市地表水的贮存因而易于蒸发冷却。高反照率的路面和铺装也会对夜晚城市的灯光有益处。至今没有人知道，作为路面气候特性研究，邻里尺度的街道胡同冷铺路面的气候影响研究还处于初期。无论如何，亚利桑那州凤凰城的示范工程已经清晰的显示了冷色地面停车位的气候益处。对于伦敦来说，在重建或新建大型铺装路面时，冷铺路面的气候影响可以应用于大型停车场、终端设备、机场和城市道路的建设中。Sky view factor: In addition to the above local-to-neighbourhood scale interventions, which can be applie
24、d to existing or new urban development, are those concerned with urban morphology, or the arrangement of buildings and transport routes. An important determinant of the rate of release of heat from the urban environment at night and thus the rate of urban cooling is sky view. This describes the rela
25、tive openness between buildings. A restricted sky view, as found for narrow streets and tall buildings, will prevent the free escape of heat emitted from street and building surfaces. This will contribute to the accumulation of heat within street canyons and thus the elevation of air temperatures. I
26、n addition, if streets are oriented at an angle that is perpendicular to the prevailing wind, during intense urban heat island events this will reduce the chances of ventilation of the street canyon and removal of heat and pollutants that accumulate between buildings. For this reason new development
27、s should optimise sky view and consider street orientation.视角（天空可视）系数：除了上述邻里尺度的相互作用，可体现在现存和新兴城市发展影响中的，还有包括城市形态，以及建筑群和交通道路的布局。夜间城市环境放热速率即城市冷却速率的决定性因素是视角。它反映了建筑物之间的开阔性。有限的狭窄街道和高楼间的视角，会抑制街道和建筑表面放热向外的自由扩散。这就导致了“街道峡谷”中热量的堆积并因此造成空气温度升高。此外，如果街道朝向与风向垂直，在较强的城市热岛效应时，会减少该街道峡谷的通风，同时减少了堆积在建筑物间热量和污染物的排放。基于以上原因，城市
28、新的发展应该优化视角并考虑街道的走向。Heat wave detection and preparedness: In parallel with the application of engineering options for managing the urban heat island are plans to reduce the health risks of hot weather by setting out the practical actions that the public, health and social care professionals should ta
29、ke in the event of a heatwave. The national Heat Wave Plan published by the Department of Health has been implemented locally and was triggered for the first time in July 2006. An evaluation of the effectiveness of the Heat Wave Plan is currently underway, and the initial feedback indicates that it
30、had a positive impact. The Philadelphia Heatwave Preparedness Plan (Box 1) is a good example of an integrated heat wave plan.热浪监测与防备：在应对城市热岛效应时，在工程设备应用的同时应设法降低高温造成的健康危害，可以通过向公众展示其实际的影响，使健康专家和社会关怀者也参与到热浪事件中来。由卫生部发布的国家热浪规划已在国内生效，并在 2006 年七月首次执行。热浪规划的作用评估现在还在进行中，从最初的反馈看来其影响是正面的。费城的热浪防备规划（第一版）就是一个不错的整体热
31、浪规划范例。Natural greenery has the effect of providing shade and reducing heat absorption on an otherwise exposed concrete surface. Maximising landscaping in the estates will also help to mitigate urban heat island effect and create an environment conducive for the residents to rest and relax. In additi
32、on, the soft organic surface provided by the green helps to absorb environmental noise, as opposed to bare concrete surfaces which tend to reflect noise, thereby creating a cool and quiet environment within the precinct. The benefits of greenery have resulted in the generation of many ideas that enh
33、ance green at every space within a precinct, and cool the living environment naturally. Some of the initiatives introduced in the HDB estates include converting surface car parks to multi-storey car parks to free up more space for landscaping, and introducing high-rise greening through green roofs a
34、nd green balconies. Provision of green roofs not only reduces the overall ambient temperature of the estates but also enhances the thermal comfort of the residents living in the units at the top-most storey. The HDB has introduced the Pre-fabricated Extensive Green (PEG) roof tray system, its own pa
35、tented green roof system in which the system is modular, portable, lightweight and easy to install. The PEG roof tray system ensures no heavy construction work and easy installation at existing estates. The system not only performs well in Singapores tropical climate but it is also costeffective and
36、 requires very little maintenance. Rooftop greening for 10 existing multi-storey car parks through the use of PEG trays, with an estimated total area of 30,000 m2, has recently been carried out.自然绿化覆盖于混凝土表面，以提供遮荫和减少热量吸收的效果。最大程度的景观美化将有助于控制城市热岛效应，并创造一个有利于居民休息和放松的环境。此外，不同于反射噪音的混凝土表面，绿色的柔软的有机表面有助于吸收环境噪音
37、，从而营造一个凉爽、安静的区域。屋顶绿化所带来的益处衍生出很多的思考：应该在每一个空间区域内增强绿化、自然冷却居住环境。在城市建设区将地面停车场转化成多层停车场、高层屋顶绿化、绿色阳台绿化等举措的实施释放出更多的美化空间。屋顶绿化不仅降低了房屋的整体环境温度，也增强了顶层住宅居民的热舒适感受。建设局推出 PEG 屋顶系统，这种系统获得自己的专利，它具有模块化、便携、重量轻、易于安装的优点。PEG 屋顶托盘系统安装简易，并适宜在现有屋顶安装。该系统不仅在新加坡这样的热带气候作用良好，而且成本效益低，不需要过多维护。PEG 的托盘使用以来，现已有近 30000 平方米、10 多层停车场的屋顶绿化投入使用。
