风景园林专业英语翻译

A framework for using UGI to mitigate excess urban heat

We propose a hierarchical, five step framework to prioritise urban public open space for microclimate cooling (Steps 1–4) using the most appropriate ‘fit for place’ UGI (Step 5) (Fig. 1). The same principles will apply to privately-owned outdoor space, although this may be complicated by issues of multiple ownership (Pandit, Polyakov, Tapsuwan, & Moran, 2013). The framework operates firstly at the ‘neighbourhood’ scale, then the ‘street’ scale and finally the ‘microscale’ (Fig. 1). While the actual area would be defined by organisation implementing the framework, a neighbourhood would encompass hundreds of houses and urban features such as a shopping precinct, a school, a railway station, parks and playing fields. The street scale is a smaller unit within a neighbourhood, for example some houses and a strip of shops. The microscale is an area within a street canyon, equivalent to one or more property frontages perhaps. Integrating these three scales

is central to this framework, and is important to the strategic integration of UGI for microclimate cooling (Dütemeyer, Barlag, Kuttler, & Axt-Kittner, 2014). This framework is flexible and can be applied and adapted by green space mangers, planners and designers to meet their local circumstances. Local stakeholders can also be involved in the decision framework at any, or all, stages as determined by budget, time and engagement philosophy of the local government authority.

使用UGI缓解城市过热的框架

我们提出了一个层次,五步框架优先考虑城市公共开放空间的小气候冷却(步骤1 - 4)使用最合适的适合地方的UGI(步骤5)(图1)。同样的原则适用于私人户外空间,尽管这可能是复杂问题的多个所有权(Tapsuwan,潘迪特,Polyakov &莫兰,2013)。框架是首先在“邻居”,然后“街”的规模,最后的“微型”(图1),而实际的区域将被定义为组织实现框架,邻居会包含数以百计的房屋和城市功能如购物区、一所学校、一个火车站,公园和运动场。街道规模是一个较小的单位，在一个社区内，例如一些房子和一条商店。微尺度是街道峡谷内的一个区域，可能相当于一个或多个房地产前缘。整合这三个尺度是这个框架的核心，对于UGI微气候降温的战略整合也很重要(Dutemeyer, Barlag, Kuttler， & Axt-Kittner, 2014)。这个框架是灵活的，可以被绿地管理者、规划人员和设计师应用和调整，以满足他们当地的环境。地方利益相关者也可以在任何或所有由地方政府当局的预算、时间和参与理念决定的阶段参与决策框架。

Step 4—Develop a hierarchy of streets for new UGI integration

After selecting priority neighbourhoods for temperature mitigation, particular streets that are most vulnerable to high temperatures can be targeted. Urban streets can be viewed as canyons, with a floor (the road, walkway, verge and front yards) and two walls (the building frontages up to the top ofthe roof). Our fivestep hierarchy focuses on street canyons because: (1) they occupy a large proportion of the public domain in cities; (2) a lot of urban climate research is based around street canyons; (3) street features relevantto assessing the thermal environment are relatively easy to measure and often already available to local government agencies; (4) street geometry and orientation are important determinants of surface and air temperatures in urban areas (Bourbia & Awbi, 2004a, 2004b); and (5) the principles for cooling based on canyon geometry can be usefully applied to other urban open spaces, e.g. car parks (Onishi, Cao, Ito, Shi, & Imura, 2010) and intersections (Chudnovsky, Ben-Dor, & Saaroni, 2004; Saaroni et al., 2000). An important goal in using UGI to reduce surface temperature is to replace or shade impervious surfaces with vegetation (Oke, Crowther, McNaughton, Monteith, & Gardiner, 1989). Selection of UGI should therefore focus on the properties of the street canyon that determine level of solar exposure. These are building height (H), street width (W), height to width ratio (H:W), and orientation, but providing sufficient capacity for ventilation at night is also important. The street canyon H:W ratio determines the amount of shade cast by the buildings themselves across the canyon floor. Wide, open canyons (low H:W ratios) experience higher daytime temperatures due to high solar exposure, as compared to deep, narrow canyons (high H:W ratios) where buildings self-shade the canyon (Johansson, 2006). Canyon orientation influences the level of solar exposure, as east-west canyons receive more hours of direct solar radiation than north-south orientated canyons (Ali-Toudert & Mayer, 2006). If street H:W ratio is low (e.g. 0.5), an east-west oriented street will receive direct solar radiation while the sun is up, whereas north-south streets are solar exposed only in the middle hours of the day (Bourbia & Awbi, 2004a). The number of solar exposedhours is also related to a street canyon’s H:Wratio and solar zenith angle, which changes predictably through out the year. For Melbourne’s latitude (37.8? S), a street canyon

H:Wratio of between 0.5 and 1.0 would provide some self-shading during the day, but be able to dissipate heat at night (Bourbia & Awbi, 2004b; Mills, 1997; Oke, 1988). Implementing UGI is one of the easiest ways to modify street canyon microclimates, other than fac? ade awnings and overhangs to shade footpaths (Ali-Toudert

& Mayer, 2007). Ranking canyon geometry and orientation can help prioritise streets for tree planting or other UGI interventions. Using the RayMan model (Matzarakis, Rutz, & Mayer, 2010), we hierarchically prioritised streets of different geometry, based on self-shading by buildings at the summer solstice (Fig. 3). For east-west oriented canyons the proportion of the street canyon floor exposed to the sun is calculated at solar noon (Fig. 3a), and for north-south oriented canyons the proportion of the day that the canyon floor is shaded is calculated (Fig. 3b). The amount of shading was then equally divided into four priority classes (Fig. 3a and b). It should be noted that these priorities are specific to Melbourne and will vary with geographic location. This hierarchical approach demonstrates that wide/very wide, east-west orientated streets should be

prioritised for street trees because of high solar exposure (Fig. 3c). Street trees would provide less benefit in narrow street canyons with a high degree of self-shading. In an analysis of daytime thermal imagery, Coutts and Harris (2013) found that street trees in Melbourne were particularly effective at reducing surface temperatures in canyons with a H:W< 0.8, whilst above this H:W the effects of trees on surface temperature were reduced, which is consistent with our findings. In narrow canyons, where there is adequate light, green walls and fac? ades as well as ground level vegetation should be prioritised over trees due to reduced space, and because they allow better ventilation and long wave cooling at night. Appropriate plant selection is very important in these situations. As H:W increases, light levels drop and wind turbulence may increase, and few plant species are likely to tolerate these conditions. There is a paucity of empirical data on the performance of plants suitable for green walls and facades in deep, narrow urban canyons (Hunter et al., 2014; Rayner, Raynor, & Williams, 2010).

步骤4:为新的UGI集成开发街道层次结构

在选择了降温的优先社区后，可以针对最易受高温影响的特定街道。城市街道可以被视为峡谷，有一层(道路、人行道、边缘和前院)和两堵墙(建筑正面一直延伸到屋顶)。我们的五步结构主要关注街道峡谷，因为:(1)它们占据了城市公共领域的很大一部分;(2)很多城市气候研究都是基于街巷峡谷;(3)与热环境评估相关的街道特征相对容易测量，而且当地政府机构通常已经可以获得;(4)街道几何形状和朝向是城市地区地表和空气温度的重要决定因素(Bourbia & Awbi, 2004a, 2004b);(5)基于峡谷几何形状的冷却原理可以有效地应用于其他城市开放空间，例如停车场(Onishi, Cao, Ito, Shi， & Imura, 2010)和十字路

口(Chudnovsky, Ben-Dor， & Saaroni, 2004);Saaroni等，2000)。使用UGI降低地表温度的一个重要目标是用植被代替或遮蔽不透水的表面(Oke, Crowther, McNaughton, Monteith， & Gardiner, 1989)。因此，UGI的选择应该侧重于街道峡谷的性质，这决定了太阳照射的水平。这些包括建筑高度(H)、街道宽度(W)、高宽比(H:W)和朝向，但在夜间提供足够的通风能力也很重要。街道峡谷H:W比例决定了建筑本身在峡谷底部投下的阴影量。宽而开阔的峡谷(低H:W比值)由于高的太阳照射，白天的温度会更高，而深而窄的峡谷(高H:W比值)则是建筑物自遮阳的峡谷(Johansson, 2006)。峡谷方向影响太阳照射的水平，因为东西方向的峡谷比南北方向的峡谷接受更多小时的直接太阳辐射(Ali-Toudert & Mayer, 2006)。如果街道H:W比值较低(例如0.5)，当太阳升起时，东西向的街道将直接受到太阳辐射，而南北向的街道仅在一天的中午时分受到太阳辐射(Bourbia & Awbi, 2004a)。太阳照射时间的多少也与街道峡谷的H:Wratio和太阳天顶角有关，天顶角在一年中会发生可预测的变化。对于墨尔本的纬度(37.8?S)，一个街道峡谷H:Wratio在0.5和1.0之间，将提供一些自遮阳白天，但能够在晚上散热(Bourbia & Awbi, 2004年b;米尔斯,1997;好的,1988)。实施UGI是改变街道峡谷微气候最简单的方法之一，除了fac、遮阳棚和悬挑来遮挡人行道(Ali-Toudert & Mayer, 2007)。对峡谷的几何形状和方向进行排序可以帮助优先选择街道进行植树或其他UGI干预。使用雷曼模型(Matzarakis、Rutz &梅耶,2010),我们分层次优先的街道不同的几何形状,根据建筑的曲棍球在夏至(图3)。为东西向的峡谷街道峡谷地板的比例计算暴露于太阳中午太阳(图3),以及南北面向峡谷峡谷的天地板的比例是阴影计算(图3 b)。然后将阴影的数量平均分为四个优先级(图3a和图b)。需要注意的是，这些优先级是墨尔本特有的，并且会随着地理位置的不同而变化。这种分层的方法表明，宽/非常宽，东西向的街道应该优先考虑街道树木，因为高太阳照射(图

3c)。在高度自遮阳的狭窄街道峡谷中，街道树木提供的效益较小。Coutts和Harris(2013)在对白天热图像的分析中发现，墨尔本的街道树木在H:W< 0.8时对峡谷地表温度的降低效果尤为显著，而H:W以上树木对地表温度的影响降低，这与我们的研究结果一致。在狭窄的峡谷中，有充足的光、绿墙和fac运动场，由于空间减少，地面植被应该优先于树木，因为它们允许更好的通风和夜间的长波冷却。在这种情况下，适当的植物选择是非常重要的。随着H:W的增加，光的水平下降，风的湍流可能会增加，几乎没有植物能够忍受这些条件。在城市深谷和狭窄峡谷中，适合绿色墙体和立面的植物性能经验数据较少(Hunter et al.， 2014;Rayner, Raynor， & Williams, 2010)。

Step 5—Select new UGI based on site characteristics and cooling potential The final step selects and implements new UGI that is ‘fit-forplace’. The order of UGI elements presented in this section reflects

their priority given the goal of surface temperature reduction. The primary goal for new UGI implementation should be to maximise ‘overhead’ vegetation canopy cover,to reduce canyon surface temperatures as well as provide shading of pedestrian space and transpirative cooling. The secondary goal should be to implement

either ground or wall ‘surface’ vegetation cover, also to reduce surface temperatures and provide transpirative cooling, but no (or little) shading. Surface vegetation cover includes vertical greening systems, greenroofs andgrassedgroundsurfaces. Table2presents a simple guide to how different UGI elements provide surface cooling benefits.

2.8.1. Trees In most cases, tree canopies are the optimal solution for shading both canyon surfaces and the pedestrian space, and they also provide evapotranspirative cooling (Rosenzweig et al., 2006; Spronken-Smith & Oke, 1999) (Table 2). The amount of shade trees provide depends on their architectural form and canopy density (Pataki, Carreiro, et al., 2011; Shashua-Bar, Potchter, Bitan, Boltansky, & Yaakov, 2010). Thick or dense canopy trees provide particularly good shade, meaning that broadleaf trees are generally more effective than needle-leaf trees (Leuzinger et al., 2010; Lin & Lin, 2010). However, trees that provide the greatest shade during hot summer days can also trap heat under their canopy at night (Spronken-Smith & Oke, 1999). To minimise heat trapping, street trees should notform a continuous canopy,thereby allowing ventilation and long-wave radiation to escape (Dimoudi & Nikolopoulou, 2003; Spronken-Smith & Oke, 1999). A mix of tree species, with different canopy architectures, could be considered for the same reason (Pauleit, 2003).

根据现场特点和冷却潜力选择新的UGI，最后一步选择并实现新的UGI，这是“适合的地方”。本节中给出的UGI元素的顺序反映了其优先考虑的表面温度降低的目标。新的UGI实施的主要目标应该是最大限度地增加“架空”植被冠层覆盖，降低峡谷表面的温度，同时提供行人空间的遮阳和循环冷却。第二个目标应该是实现地面或墙壁“表面”植被覆盖，同时降低表面温度，提供循环冷却，但没有(或很少)遮阳。地表植被覆盖包括垂直绿化系统、屋顶绿化和地面绿化。表2给出了一个简单的指南，介绍了不同的UGI元素如何提供表面冷却的好处。

2.8.1发布。在大多数情况下，树冠是遮蔽峡谷表面和行人空间的最佳解决方案，它们还提供蒸发蒸发冷却(Rosenzweig et al.， 2006;Spronken-Smith & Oke, 1999)(表2).遮荫树的数量取决于其建筑形式和树冠密度(Pataki, careiro, et al.，2011;Shashua-Bar, Potchter, Bitan, Boltansky， & Yaakov, 2010)。浓密的冠层树提供了特别好的树荫，这意味着阔叶树通常比针叶树更有效(Leuzinger et al.， 2010;Lin & Lin, 2010)。然而，在炎热的夏天提供最大阴凉的树木也可以在晚上将热量困在树冠下(Spronken-Smith & Oke, 1999)。为了尽量减少热量的聚集，街道树木不应该形成连续的树冠，从而允许通风和长波辐射逃逸(Dimoudi & Nikolopoulou, 2003;施普林肯-史密斯和奥克，1999)。出于同样的原因，可以考虑不同树冠结构的混合树种(Pauleit, 2003)。