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< /p>

UGI(

步骤

5)(

图

1)

。同样的原则适用于私人户外空间

< br>,

尽管这可能是复杂问题的多个所有权

(Tapsuwa n,

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

< br>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: