Copenhagen’s Green Roofs Policy Will Boost the Transformation of the City to A Greener Living City
撰文 （丹麦）多拉茜 罗摩
Text by Dorthe RØMØ (Denmark)
翻译 蒋巧璐 邓巧
Translation by JIANG Qiao-lu and DENG Qiao
摘要：绿色屋顶项目通过释放屋顶空间的利用潜能，满足人们应对气候变化的挑战、在越加拥挤的城市中的公共场所进行休闲娱乐的需求，以及需要更加环保城市的同时，建造道路、停车场及其他类型建筑的需求。屋顶绿化是一种独特的解决途径，能够为人们带来众多益处，因此它也被认为是城市开发中最具有可持续发展、最能适应气候变化的手法之一。它是工业化城市向环保类型城市转变的关键。为推进这一进程，我们必须关注屋顶绿化的重要性，并将其纳入未来城市规划政策之中。
关键词：风景园林；屋顶绿化；评论
Abstract: Green roofs release the unused potential on roof tops to help people meet the challenge of climate changes and to meet the wishes for places to recreate in still more dense cities as well as for more roads, parking lots and buildings. Green roofs are a unique solution with many inherent benefits and can be regarded as one of the most sustainable and climate adapted solution for city development. Green roofs are going to be the key in the transformation of grey cities to green cities.To make this transformation happen we have to focus on the importance of making green roofs as a part of our policy for future city planning.
Key words: Landscape Architecture; Green Roof; Review
1 概述
本文简要介绍屋顶绿化对于减少热岛效应、收集雨水、支持生物多样性以及创建更加环保绿色城市的作用。哥本哈根屋顶绿化工程生动诠释了未来城市发展理念，利用植被对屋顶进行绿化，让更多的市民使用屋顶花园空间。文章最后还将讲述哥本哈根在未来规划设计中运用屋顶绿化的方式（图01）。
设想一下，如果建筑像雨后春笋般从土地上长出来，那么它们的屋顶就会变成被土壤和植被覆盖的绿色屋顶。
上述话语勾勒出了屋顶绿化创意的雏形：它将把自然重新带回城市，把灰色城市改造成绿色城市，让广大市民受益。通过不断反思我们发展城市的模式，我们相信能够实现屋顶绿化的美好愿景。但是为什么要这样做呢？难道是因为我们建设和开发城市的方式还不够高明吗？
在过去的几十年，很多城市都曾有这样的经历——一旦发生天气变化，比如突降暴雨，城市的排水系统就难以应对超负荷的雨水流量。这是由于我们在城市开发的过程中，为了修建更多的道路、停车场和建筑空间，原有的大量自然覆土场地被混凝土和沥青所覆盖，而雨水是很难渗透这些混凝土或沥青地面的。于是，当暴雨来袭时，雨水会以最快的速度从其表面流走，并在极短时间内溢出排水沟。
但是，如果在发展城市时，也进行屋顶绿化建设，那么结果将会大不相同。如果我们能够从宏观角度看待屋顶绿化，便不难发现，屋顶绿化具有同草地一样的功能——吸收、净化雨水，并使水流减速，甚至还能储藏一些雨水以备后用。这样就能减少排污系统的压力，即使遇上持久的雨天，或者遭遇暴雨，屋顶绿化便是雨水的减速装置①-②,[1]。这样，屋顶绿化能够有助于释放下水道容量，我们便可以减少修建应对暴风雨的排水基础设施，从而节约相关费用。因此，屋顶绿化现已成为波特兰暴风雨管理系统的一部分③，同时它正在全球范围逐渐兴起，让城市适应当今气候变化，减少气候变化所带来的负面影响。
当屋顶绿化吸收雨水时，我们可将雨水作为一种鲜活的资源进行使用。因此，我们不仅修建了屋顶绿化，也营造了一个支持生物多样性的生境，为长期定居或者迁徙路过的野生物提供栖息场所和食物。发展屋顶绿化以支持生物多样性，便会涉及到培养基和植物品种的选择[2]。
传统城市的地表大多以较强吸收、保存热量的灰暗表面为主，这些表面同时也带来了城市热岛效应②。而通过屋顶绿化，我们可以把自然再次带入城市，利用植被的蒸腾作用和树木的遮阴效果，有效减少热岛效应。一个有名的案例是芝加哥市政厅采用了屋顶绿化后，屋顶温度降低了约30℃④。另一项研究表明，如果像纽约这样的城市能将一半的平屋顶进行绿化，便能使整座城市的温度降低0.8℃⑤。瑞尔森大学的一个研究小组从2004年就开始研究多伦多屋顶绿化广泛实施所带来的潜在的环境效应，研究估算得出，如果多伦多在夏季将全市8%的屋顶进行绿化，那么整座城市的温度将会降低2℃②。
如果我们将屋顶绿化作为城市基础设施的一部分，它们将会是实现可持续发展和调节气候的有效宏观手段，能够降低城市温度，减少暴雨来临时排水系统的压力。同时，由于屋顶绿化使用了密集城市中尚未开发的空间——屋顶，并将其改造成愉悦的绿色空间，因而增加了城市的价值。
2 绿色城市
通过屋顶绿化，我们可以营造更加环保的城市，以应对气候变化的挑战，满足公众对休闲娱乐公共空间的需求，同时还能将大自然的美景带回城市。屋顶绿化也为城市创造了更多的价值。哥本哈根市的一个建成项目便是未来城市发展模式的典型范例（图02）。
在哥本哈根市中心，“绿色植物屋顶”由3组相连的屋顶组成，并与市中心的公共开放空间相连。从街道上可以看到其中的一个绿色屋顶，它的设计灵感来源于斯堪的纳维亚的森林。这一层位于银行两栋高楼之间的停车场的上方，包含一个雕塑台阶，上面覆盖着树木（图03）⑥。从这里可以进入下一个绿化屋顶——丹麦国家档案馆的屋顶平台。档案馆平台面积约220m×30m，由两部分组成——一侧位于记录办公室的仓库上方，另一侧正对着丹麦国家铁道部一座旧办公大楼的外立面。丹麦国家档案馆的屋顶平台是该项目最先完成的一部分，至少还有4个项目将会修建，最终形成一个有规划的、逐步上升的通道。丹麦国家档案馆屋顶绿化项目于2009年9月7日落成。
该项目的初衷是为公众提供一个行人通道，同时在哥本哈根市中心修建一个毗邻哥本哈根港口、安静舒适的绿色花园。
项目的主要设计元素受到了丹麦国家档案馆墙面上的浮雕的启发。这些元素展示了国家档案馆的功能，并以符文进行书写。屋顶花园也采用了同样的地形划分，以此来区分不同的活动区和植被区。设计师们在花园中设计了一条主道作为贯穿整个花园的主轴。在主道的两侧，空间划分为许多不同的花坛和树墙， 为公众提供一个可进行午餐和阅读的休闲场所。花坛与长椅互相融合，随着时间的推移，它们将会被藤蔓和开花植物覆盖，从而形成一处界限清晰的小空间。屋顶花园的植被设计理念是通过在与主干道互相垂直的区域以及拐角处播种、栽种植被，以创建两个主要的植被混合区和草坪区。所选用的植物都有很强的抗旱能力。栽种区域则会根据屋顶花园各区域的微型气候来筛选植被。微型气候的影响因素包括阳光、阴影、风、介质深度以及周围建筑结构（图04）⑦。穿过这里，将会来到第3个屋顶花园——蒂沃利会议中心的绿色屋顶（图05）⑧。
3 政策与规划
怎样才能将我们所居住的城市改造成一个绿色环保的城市呢？首先，我们需要关注数百年以来那些最具有可持续性和最能适应气候变化的城市发展方案。通过参观世界其他国家和地区的一些成功案例，我认识到根据不同的使用目的，屋顶绿化可以有不同的类型。
在哥本哈根，我们花了3年来筹划和推广屋顶绿化项目。该项目以2008年废水计划项目的启动作为开始。废水计划方案是我们第一个专注于不同雨水处理方法的项目。从那以后，我们举办了一些专题研讨会和议会，以提高人们对屋顶绿化的认识。同时，我们也为某幼儿园修建了一个绿化屋顶，作为示范案例。该屋顶的修建与所在大楼的全面整修工作紧密相连。屋顶将包括感官体验、乔木、灌木、苔藓、肉质植物、草本植物和草，致力于向人们展示屋顶绿化的概念和潜质。
但是为了让屋顶绿化紧随城市发展，我们需要让绿化屋顶成为一项强制性的措施，将其作为未来城市发展规划的一部分。在哥本哈根，屋顶绿化已成为2009年气候计划项目的一部分⑨-⑩，这是未来城市规划的一个里程碑。在这项计划中，我们将屋顶绿化作为城市未来发展的一项目标——这也是2012年市政规划的一项要求。至今为止，已有两个城市规划将屋顶绿化作为一项强制性的规划方案，其中一个是在北欧最大的城市开发区“北港”，在这里我们为可持续发展和气候适应创建了新的标准。作为项目进程的一部分，屋顶绿化也已经成为环保和生物多样性策略导则的一部分。屋顶绿化相关标准要求的制定，将有助于推动创造性的宏观城市发展方案，激发我们重新审视城市建设和发展的模式，同时提高人们对屋顶绿化的关注。这一项目的推进，还受益于科研院校、私人企业和政府部门的通力合作。科研院校带来了新知识和相关文献，私人企业则以设计方案的建筑师、风景园林师和未来将不断发展的屋顶绿化市场为代表，而政府部门则提供卓有远见的城市规划。这样的合作模式像是螺旋结构，两两相交（图06）。潜力是支持或组织个人行为一项的多种因素结合体，包括知识、价值、态度、自然和社会条件等。
4 结论
综上所述，我们有很多有利的理由来开展屋顶绿化项目，它让那些被人类带走的自然美景重新回归城市；通过营造绿色屋顶空间，可为建筑和城市增值。这种绿色发展还将降低市区温度，减少下水道系统的压力，为生物多样性提供栖息地。为增强此项目的发展，我们需要一个专门的政策或是规划项目来推动屋顶绿化的发展。第一步就是要提高人们对这一技术的认识；第二步则是要将屋顶绿化作为规划设计方案的一部分，并与相关的利益方进行螺旋式合作。
注释:
①参见波特兰市环保局于2008年出版的《暴雨水管理设备监督报告之摘要篇》；
②参见2005年10月31日瑞尔森大学发布的《多伦多市屋顶绿化技术的环保益处和成本报告》；
③参见http://www.portlandonline.com/bes/index.cfm?c=31892；
④参见http://www.cityofchicago.org/city/en/depts/doe/supp_info/monitoring_the_cityhallrooftopgardensbenefit.html；
⑤参见美国哥伦比亚大学环境环球研究院发布的《纽约都市区屋顶绿化研究报告》 ；
⑥参见http://www.sla.dk/byrum/sebgb.htm；
⑦参见http://www.schonherr.dk/da/rigsarkivet/；
⑧参见http://www.sla.dk/byrum/sebgb.htm；
⑨参见http://www.kk.dk/sitecore/content/Subsites/Klima/SubsiteFrontpage/~/media/491B1EC4F6B14FC9A31F9373AA54F02D.ashx；
⑩参见http://www.kk.dk/sitecore/content/Subsites/CityOfCopenhagen/SubsiteFrontpage/LivingInCopenhagen/ClimateAndEnvironment/GreenRoofs.aspx；
,参见http://livingroofs.org/；
-图01由哥本哈根市政府提供；图02由L&T事务所提供；图03由米谢拉 布鲁爱尔提供；图04由斯诺好事务所提供；
图05由P 马尔莫斯事务所提供。
参考文献：
[1]伦敦设计.活着的屋顶和墙体技术报告:支持伦敦规划政策[M].伦敦:大伦敦政府,2008.
[2]史蒂芬 布赫内森.城市野生物空间:瑞士屋顶绿化作为生境的设计案例[J].城市生境,2006,4.
作者简介：
多拉茜 罗摩/生物学家/专注于研究环境的水问题（如湖泊和溪流）/丹麦哥本哈根淡水系统的维护的发起人/哥本哈根废水处理规划的项目经理
译者简介：
蒋巧璐/四川大学景观建筑设计本科生/风景园林新青年志愿者
邓巧/新西兰林肯大学风景园林本科生/风景园林新青年志愿者
1 Introduction
This article will shortly describe the potential of green roofs with focus on reduction of UHIE, rainwater retention, supporting biodiversity and creating greener cities. As an illustration of the idea of future city development, a green roof project from Copenhagen composing of tree connecting green roofs which are accessible for the public will be described. The way Copenhagen has chosen to bring green roofs in future planning will be covered in the last part(Fig.01).
Imagine: “If buildings sprang up suddenly out of the ground like mushrooms, their rooftops would be covered with a layer of soil and plants” (Verlyn Klinkenborg 2009).
I think that’s framing the idea about green roofs and that we and the society would benefit from a transformation of the grey cities to green cities by bringing nature back to town. And I believe we can do that by rethinking the way we develop our cities.
But why should we, isn’t the way we have built and developed our cities smart enough?
Many cities have experienced in the last decades and city storm drains can’t handle more intense rain that we get as part of climate change. This is because when we have developed our cities, the natural land cover has been replaced by concrete and asphalt. Roads, parking lots and buildings are built with impervious surfaces that can not store rainwater and just let it flow as quickly as possible into the storm drains. Therefore, the capacity of drains are used up.
But if we choose to develop our cities with a green roof infrastructure,and look at it on a macro scale, it can reduce the pressure on our sewer system because green roofs act the way as meadow does, absorbing water, filtering it, slowing it down, even storing some of it for later use and if it rains for long time or we have more intense rains, green roofs provide an important delay mechanism on our systems①-③. This effect of green roofs can release some capacity in the sewer and by that we can save infrastructure cost which can be needed for building bigger stormwater systems. Therefore, green roofs have become a part of Portland stormwater management④ as well as they are part of a worldwide growing effort to adapt our cities to climate change and mitigate the negative impact of climate change.
When green roofs absorb rainwater, we use rainwater as the living resource because when we create green roofs we are at the same time creating a living system that provides habitats to support wildlife. Habitats provide food and places for wildlife to live in or migrate though. Developing green roofs with a main purpose to support biodiversity is a matter of choices in the design concept of green roofs. This is about choosing the right substrate, thickness of the substrate and plants⑤.
A conventional city is composed of many dark surfaces which absorb and trap the heat to creat urban heat island effect. But green roofs plants bring nature back to town and can reduce the UHIE②due to the evapotranspiration and shade effect. One very famous case study is the one on Chicago City hall where it was documented that the green roof reduced the temperature on the roof with about 30 celcius⑥. Other studies documented that if cities like New York had half of their flat roofs covered with green roofs the temperature in the city would be reduced with 0.8 degrees Celsius⑦. A team from Ryerson University in 2004 prepared a study on the potential environmental benefits of widespread implementation of green roofs to the City of Toronto. The study calculated an estimated city-wide temperature reduction of 2 degrees Celsius in summer months if only 8% of Toronto’s city roofs are greened ②.
If we take green roofs into consideration as part of the city infrastructure, they will be a sustainable and climate adapted solution on a macro scale by reducing the temperature in cities and release the pressure on the stormwater systems. Green roofs will add value to the public and cities by creating green attractive spaces and using an unexploited potential in a dense city, the roof tops.
2 Greener cities
We can meet the challenge of the climate change and the need of the public for places to recreate and bring the beautiful view of nature back to cities by creating greener cities with green roofs. And by doing this we add value into our cities. A project realised in Copenhagen shows the idea of future city development(Fig.02):
The Green Botanical corridor is composed of three linking roofs accessible for the public that connects areas in the centre of Copenhagen.
From the street you walk up at the first of the three roofs. This one is composed of a sculptural staircase cover with trees which was inspired by the Scandinavian landscape. It’s a roof on a parking lot between two tower buildings of a bank(Fig.03)⑩. From this green roof, you can walk on to the next one, the roof terrace of the Danish State Archives. The roof terrace has an area of approximately 220m by 30m, defined by two large Record Office storage buildings on one side , and the facade of an older building, housing offices for Danish National Railway, one the other side. The roof terrace of The Danish State Archives was the first part of the project to be realised, and at least four other projects created the planned, elevated passage. The roof terrace of The Danish State Archives was inaugurated on September 7, 2009.
The primary purpose of the roof garden is to provide a pedestrian passage for the public, and to create a silent garden in the centre of Copenhagen, which lies close to the port of Copenhagen.
The project’s major design element is inspired by the reliefs on the brick facades of the defining walls of The Danish Archives. These indicate the function of the building and are written in runic letters. The same typology is used in the surfaces of the roof garden, defining the different spaces for activities and the different types of vegetation. The garden is planned with a primary path creating an axis running across the total length of the project. Along the axis, several spaces are defined as elevated beds and espaliers, which have been created for the public to sit and enjoy lunch, reading or relaxing.The beds have integrated benches and the espaliers will,be overgrown with intertwining flowering plants to create well-defined spaces. The vegetation concept in the roof garden is to create two major mixtures of plants and cut lawns, planted and sown in perpendicular sections and by the turns of the major axis. All species used in the project can tolerate dry spells. The combinations consist of several different species which will establish according to the different microclimates in the roof garden. These are related to sun, shade, wind, the depth of the growth media, and will vary in relation to building construction, and so on (Fig.04)⑨, .Finally you move from this roof to the third one, Tivoli Congress Center (Fig.05) ⑩.
3 Policy and Planning
How do we transform our cities to green cities? First of all we need attention and awareness to the most sustainable and climate adapted solution concerning city development in these centuries. By visiting some of the successful solutions around the world, I realise that green roofs offer many options depending on the purpose of the roof. We can share these knowledge and we will be able to move the transformation of grey cities to green cities. In Copenhagen we have been promoting a green roof program for nearly three years which began with our wastewater plan in 2008. This was the first plan document where we began focusing on alternative ways to handle rainwater. Since then we have held a couple of workshops and congresses to give attention and awareness to green roofs. In addition , we also have created a demonstration roof on a kindergarten. It is a roof which is laid in connection with the total restoration of the building. The roof includes senses, trees, bushes and mosses, succulents, herbs and grasses. The intention with the roof is to show and tell the idea and potential of green roofs.
But to boost the city development with green roofs needs to make green roofs mandatory and to think the green roofs as part of the plan for future city development. In Copenhagen green roofs became a part of our climate plan 2009,- which was a milestone for further planning process. In this plan we sat a goal that green roofs should be a part of future city development as a requirement in the next Municipal plan 2012. But already today green roofs are mandatory in two local plans for city development.One of them is in the first developing area in the biggest city development area in North Europe called North Harbour for which we have a vision of setting new standards for sustainable and climate adapted solutions. As part of the planning process, green roofs have become a part of different guidelines for environment in building and development and in our strategy for biodiversity. Setting up requirements for green roofs can help boosting the creative and spectacular solutions and push the need of rethinking the way we build and develop our cities and most of all give attention and awareness to this solution. The process has been benefited from cooperation between the institutions of science, the private sector and the public authorities. Universities bring new knowledge and documentation and the private sectors are represented by architects and landscape architects with design solutions and a growing green roofs market. The public authorities offer ambitious and visionary city planning. This cooperation works like a triple helix constellation.
Action potential is a function of knowledge, values and attitudes, physical and social action conditions that support or discourage personal action intentions.
4 Conclusion
There are many good reasons for green roofs. One is to give back what would have been taken away to bring the beauty of nature back to cities. The green roofs add up the value of the building and the city by creating green spaces on roofs. These green development will reduce the temperature in cities, reduce the pressure on the sewer system and create habitat to support biodiversity. To boost this development, a green roof policy or a green roof plan program is needed. The first step in this process is to create awareness and common knowledge of this technology. Second step is to ensure that green roofs are a part of the plan documents and start up triple helix cooperation projects together with shareholders.
Photo Credit:
Fig.01 City of Copenhagen; Fig.02 Lundgaard & Tranberg; Fig.03 Michaela Brüel; Fig.04 Schørnherr K/S; Fig.05 P. Malmos A/S
Notes:
①http://www.portlandonline.com/bes/index.cfm?a=232643 &c=36055
②Report on the Environmental Benefits and Cost of Green Roof Technology for the City of Toronto, Ryerson University, October 31, 2005
③ Living Roofs and Walls, Technical Report: Supporting London Plan Policy, 2008
④ http://www.portlandonline.com/bes/index.cfm?c=31892
⑤Space for Urban Wildlife: Designing Green Roofs as habitats in Switzerland by Stephan Brenneisen, Urban Habitats, Vol. 4 no. 1
⑥http://www.cityofchicago.org/city/en/depts/doe/supp_info/monitoring_the_cityhallrooftopgardensbenefit.html
⑦ Green Roofs in the New York Metropolitan Region, Research Report. Columbia University Center for Climate Systems Research and NASA Goddard Institute for Space Studies. New York.
⑧http://www.sla.dk/byrum/sebgb.htm
⑨ http://www.schonherr.dk/da/rigsarkivet/
⑩http://www.sla.dk/byrum/sebgb.htm
,http://www.kk.dk/sitecore/content/Subsites/Klima/SubsiteFrontpage/~/media/491B1EC4F6B14FC9A31F9373AA54F02D.ashx
-http://www.kk.dk/sitecore/content/Subsites/CityOfCopenhagen/SubsiteFrontpage/LivingInCopenhagen/ClimateAndEnvironment/GreenRoofs.aspx
Biography:
Dorthe RØMØ has a background as biologist who has been working on environmental issues with water, particularly in lakes and streams, for many years. She has the responsibility as entrepreneur on the maintenance and operation of the freshwater system in Copenhagen, Denmark. Dorthe has been working with planning and as Project Manager on the city’s Wastewater Plan.
About the Translators:
JIANG Qiao-lu is studying her Bachelor Program at the School of Landscape and Architecture of Sichuan University. She is also a volunteer of YouthLA.
DENG Qiao is studing her LA Bachelor Program at the Lincoln University of Christchurch, New Zealand. She is also a volunteer of YouthLA.
《风景园林》2012第1期导读
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