绿色屋顶的节能效应及其景观价值

近年来,随着我国城市化进程的加快,环境问题日益显现,热岛效应、空气污染、污水溢流、噪音肆虐似乎成为了城市发展进程中的通病。绿色屋顶的出现,对于解决城市问题所起到的积极作用已逐步受到设计师、开发商和环境学专家的认可。为此,通过对绿色屋顶种类的划分,并对国外优秀案例的剖析,阐述了不同类型屋顶种植方式在城市中体现的节能效应及其景观价值。     

绿色屋顶的城市降温与建筑节能效果研究

目前,经济发展与环境保护的冲突日益明显,热岛效应、噪声污染、空气环境恶化等环境问题已经成为城市化进程中必须面对和解决的问题,绿色屋顶的出现使得城市环境问题得到了有效改善,符合当前我国节能减排的要求,对于城市降温以及建筑节能所产生的效果比较显著。因此,首先对绿色屋顶进行简要介绍,然后对其在城市降温以及建筑节能方面的效果进行探讨,从而为相关人员开展绿色屋顶施工提供技术指导。     

发展城市屋顶绿化的政策困境与出路

通过屋顶绿化扩大城市绿色空间和绿色面积,是改善城市生态环境的重要途径。大面积推广城市屋顶绿化,对缓解我国城市化进程中日趋突出的生态恶化、土地存量骤减、“热岛效应”等问题,无疑是一种现实而有效的应对之策,在当前建设资源节约型、环境友好型社会的新形势下加快发展屋顶绿化事业对缓解城市绿化用地紧张、改善城市空间环境等方面具有重要的意义。     

缓解城市热岛效应:基于美国“绿色屋顶”政策的域外借鉴与启示

“城市热岛效应”是世界各国城市发展过程中面临的最大气候问题之一。通过建立“绿色屋顶”可降低局部气温、节约能源成本和减少城市雨水径流量,对于缓解城市热岛效应有着诸多好处。笔者通过分析美国4个典型城市开展绿色屋顶项目所采取的激励或强制措施发现:一方面,各项措施对绿色屋顶项目的开展起到了强有力的推动作用;另一方面,在政策落实过程中也出现了对当地生态评估不足,以及片面强调“分配正义”却忽略“环境正义”等问题。希望这一研究结果能够对我国城市绿色建筑的发展提供积极的借鉴意义。     

屋顶绿化的效益

随着社会经济迅猛发展和城市化进程的加快,城市环境也随之恶化。屋顶绿化能有效地节能、减排、提供更多绿色空间、改善城市的生态环境。文中介绍了屋顶绿化的经济、环境、生态以及社会效益,说明了屋顶绿化的重要性。     

屋顶绿色空间的研究与设计方法探索——以游憩型商业建筑为例

屋顶绿色空间在城市化高速发展的背景下,已成为一种广泛应用的集约型城市公共空间。该文以城市核心区的游憩型商业建筑为例,剖析了屋顶绿色空间与建筑、城市公共空间的多维关系,探讨了在有限的城市空间里如何整合设计屋顶绿色空间,提出了游憩型商业建筑屋顶绿色空间设计应从城市规划设计角度出发,宏观把控与本体建筑、城市公共空间的整体关系,微观深入功能的复合化设计,消隐式细节处理的方法与策略。     

浅谈屋顶绿化与推广

随着我国城市化进程的加速,城市中绿地面积不足的现象日益凸显。作为城市重要环境财富的绿地空间越来越少,屋顶花园（绿化）．屋顶绿色问题正呈现在人们面前。     

高密度城市绿色屋顶社会功效分析及其设计策略研究——以上海市黄浦区为例

城市高密度发展,公共绿地空间逐渐趋向立体化,绿色屋顶成为重要的社会活动场所,具有调节生态、活动聚集、城市美化等社会功效,主要分为花园型、组合型、草坪型、餐饮型、室外活动型、自发活动型、美化型7种,并常设立于高密度城市主要的5类建筑（居住、商业、旅游、办公、科教文卫）中。然而,绿色屋顶的使用功能常与建筑类型不匹配,有些绿色屋顶与建筑之间无法顺畅地连接通达,还有部分绿色屋顶的使用率不高,导致其社会功效无法充分发挥。基于上海市黄浦区的286个已建成绿色屋顶的大数据分析,通过对绿色屋顶“功能耦合”“空间连接”与“使用活跃”的三大社会功效的探索,提出5类建筑可以更好地发挥高密度城市绿色屋顶社会功效,减少人居活动空间压力,促进城市结构立体化发展。     

大型屋顶绿色花园土方运输施工技术

大型屋顶绿色花园的建设已经逐步成为解决城市生态问题的关键,然而在建设城市大型屋顶绿色花园过程中,土方运输成为一个关键的问题。因此,大型屋顶绿色花园土方运输施工的相关技术,指出其中的关键环节和注意要点,以便提升我国城市大型屋顶花园土方运输效率。     

高密度城市屋顶绿化社会使用现状及发展策略

在城市与人口高密度发展的背景下,公共绿地空间逐渐趋向立体化发展,绿色屋顶成为重要的社会活动场所,除调节空气、改善环境等生态功能外,还具有活动聚集、餐饮娱乐、城市美化等社会功效.对高密度城市绿色屋顶进行社会功效评价,指导绿色屋顶的使用策略,进而充分发挥其社会使用功能.介绍高密度型国家和地区屋顶绿化社会使用促进策略,分析目...     

Biophysical properties and thermal performance of an intensive green roof

Green roofs have been increasingly enlisted to alleviate urban environmental problems associated with urban heat island effect and stormwater quantity and quality. Most studies focus on extensive green roofs, with inadequate assessment of the complex intensive type, subtropical region, and thermal insulation effect. This study examines the physical properties, biological processes, and thermal insulation performance of an intensive green roof through four seasons. An experimental woodland installed on a Hong Kong building rooftop was equipped with environmental sensors to monitor microclimatic and soil parameters. The excellent thermal performance of the intensive green roof is verified. Even though our site has a 100 cm thick soil to support tree growth, we found that a thin soil layer of 10 cm is sufficient to reduce heat penetration into building. Seasonal weather variations notably control transpiration and associated cooling effect. The tree canopy reduces solar radiation reaching the soil surface, but the trapped air increases air temperature near the soil surface. The substrate operates an effective heat sink to dampen temperature fluctuations. In winter, the subtropical green roof triggers notable heat loss from the substrate into the ambient air, and draws heat upwards from warmer indoor air to increase energy consumption to warm indoor air. This finding deviates from temperate latitude studies. The results offer hints to optimize the design and thermal performance of intensive green roofs.     

Modeling the reduction of urban excess heat by green roofs with respect to different irrigation scenarios

Urban heat reduction by evaporative cooling from extensive green roofs is explored by applying irrigation scenarios to green roofs located in different climate zones using a coupled atmosphere-vegetation-substrate green roof model. The model,which is integrated in the building energy simulation software Energy Plus,is validated with eddy covariance surface energy fluxes from a green roof in Berlin,Germany. The original model wasmodified to include interception and an improved runoff calculation. Three irrigation scenarios were defined( no irrigation,sustainable irrigation by harvested runoff water,unrestricted irrigation) to study the heat reduction potential in terms of surface energy partitioning and sensible heat fluxes( QH). The irrigation scenarios are compared to two white roofs( albedo equal to 0. 35 and 0. 65) and a black roof.High correlation of sensible and latent heat( QE) fluxes between measured and modelled data for the original and the modified version of the green roof model were observed( for the original model,R~2= 0. 91 and 0. 81 for QH and QE,respectively,while for the modified version R~2= 0. 91 and 0. 80,respectively). The modified version was applied to study irrigation,due to lower systematic errors for QH,QEand better performance for the substrate moisture content. In comparison to a black roof the green roof reduces urban excess heat by 15%-51%with sustainable irrigation,by 48%-75%with unrestricted irrigation,but drops to 3% for unirrigated roofs in the different cities. Sustainable irrigation can be effective in climates with high annual( or summerly) precipitation.     

绿色屋顶的生态系统服务评估模型构建

城市高密度发展与绿色空间需求的矛盾促使城市公共空间向立体化方向延展,为绿色屋顶的发展带来了机遇,绿色屋顶的生态系统服务功能可为人们提供生态、经济和社会效益。参考生态系统服务的通用国际分类（CICES）体系和深圳生态系统生产总值（GEP）评估指标体系,通过文献研究选取评估指标和决策方案,使用层次分析法（AHP）和专家评估法,首次构建了绿色屋顶的生态系统服务评估模型,并通过案例研究与模型结果进行对比分析,结果表明：1）在生态系统服务中,调节和维持服务在准则层中最为重要,气候调节在指标层中最为重要;2）在5种绿色屋顶类型中,生物多样性屋顶最为重要;3）专家对绿色屋顶生态系统服务的重要性评估在一定程度上可反映实际项目中决策者对绿色屋顶的主导生态系统服务功能的定位。该评估模型具有一定的应用价值,对辅助城市绿色屋顶规划布局的选址和选型具有重要意义。     

国内外屋顶的绿化设计

屋顶绿化是建筑节能的一种有效措施,具有显著的生态效益和景观价值,已越来越多地引起了建筑领域及相关人员的广泛关注。通过系统分析屋顶绿化在促进建筑节能、改善环境和蓄积雨水等方面的作用和效果,研究总结了国内外屋顶绿化设计的方法及其主要影响因素,包括配置模式、植被材料和栽培基质等方面的研究成果,对国内外屋顶绿化政策和实践的发展进行了回顾和比较。     

Comparative environmental life cycle assessment of green roofs

This paper describes the life cycle environmental cost characteristics of intensive and extensive green roofs versus conventional roofs. A life cycle inventory and environmental impact assessment is used to document and analyze the similarities and differences in the environmental impacts of the fabrication, transportation, installation, operation, maintenance, and disposal of all three roof systems. This is important because there are additional resources committed to green roofs from which environmentally relevant benefits, such as reduced electrical energy use for building cooling, are derived. The extensive green roof design for the case study presented here is from an actual 1115 m² (12,000 ft²) green roof project on a retail store in Pittsburgh, PA, USA. The case study includes a conventional ballasted roof, an extensive, or shallow growing medium green roof, and an intensive, or deep growing medium green roof. For the life cycle inventory and the material use, both the types of material used and the transportation distances to the site are with respect to this project.     

泵送轻质屋顶绿化基材技术

屋顶绿化是改善城市环境的关键举措,本文分析了屋顶绿化的常见形式,介绍了简单屋顶绿化形式各层的材料特点、现有的简单屋顶绿化技术方案及存在的问题。在此基础上,论文介绍了一种新发明技术-泵送轻质屋顶绿化基材技术的材料组成和施工。     

Modeling the heat diffusion process in the abiotic layers of green roofs

Green roofs have been increasingly installed to alleviate some common environmental problems. The thermal benefit of living vegetation on rooftop has been extensively studied. The individual and joint contribution of the non-living green roof layers, namely soil, rockwool (water storage) and plastic drainage layers, to thermal performance of green roof has seldom been assessed. This study evaluates the insulating and cooling effects of these abiotic materials. A one-dimensional theoretical model was developed to assess the heat diffusion process in the layers. The model was validated with empirical results from three experimental plots. A calibration procedure was successfully applied to determine key model parameters. The model can capture the most critical features of temperature variations and thermal performance of common abiotic green roof materials. The appreciable water-retention capacity of rockwool plays the dual role of supplying water to the soil to enhance evaporative cooling, and increasing the specific heat capacity of the green roof. The plastic drainage sheet with ample air spaces serves as an excellent thermal insulator. The model remains robust despite seasonal and weather variabilities. Our research findings contradict with some researches in the temperate region that the thermal dissipation in green roofs with dense vegetation is lower than thermally insulated bare roofs. The theoretical model could be used to simulate the micro-environmental conditions and predict the thermal performance of different materials to improve green roof design.     

A combined experimental and simulation method for appraising the energy performance of green roofs in Ningbo’s Chinese climate

A passive means of lowering the energy demand of buildings is the application of green roofs. The complexity between heat and moisture exchanges in green roof layers and the large variations of green roof types make the need for experimental or simulation assessments necessary for quantifying the energy benefits from green roofs. The current treatment of green roofs in simulation programs is either over-simplistic, for example by ignoring heat and moisture exchanges such as evapotranspiration, or the more advanced models have limitations and require inputs that are rarely available in practice. In this paper a combination of experimental and modelling techniques are used to assess the potential heating and cooling load reductions from the application of green roofs in the subtropical climate of Ningbo in China. The method provides a generalised energy performance assessment of green roofs in Ningbo by overcoming the limitations of existing green roof simulation models.     

Seasonal heat flux properties of an extensive green roof in a Midwestern U.S. climate

Green roofs, or vegetated roofs, can reduce heat flux magnitude through a building envelope as a result of insulation provided by the growing medium, shading from the plant canopy, and transpirational cooling provided by the plants. This study quantifies the thermal properties of an inverted 325 m² retro-fitted extensive green roof versus a traditional gravel ballasted inverted roof in a Midwestern U.S. climate characterized by hot, humid summers and cold, snowy winters. In autumn, green roof temperatures were consistently 5 °C lower than corresponding gravel roof temperatures. Even during chilly and moist conditions, the heat flux leaving the building was lower for the green roof than the gravel roof. Temperatures at the top of the insulation layer were more variable for both green roof and gravel roof on winter days with no snow cover than on days with snow cover. Variation in temperatures between roof types in spring was similar to those in autumn. Peak temperature differences between gravel and green roof were larger in summer than other seasons (sometimes by as much as 20 °C). Over the course of a year (September 2005-August 2006), maximum and minimum average monthly temperatures and heat fluxes were consistently more extreme for the gravel roof than the green roof.     

Green roof energy and water related performance in the Mediterranean climate

Performance of vegetated roofs are investigated in terms of their expected benefits for the building and the urban environment, due to their recognised energy and water management potential scores. A review of related worldwide experiences is reported for comparison purposes. The investigation is here performed within the specific climatic context of the Mediterranean region. Full-scale experimental results are provided from two case studies, located in north-west and central Italy, consisting in two fully monitored green roofs on top of public buildings. The attenuation of solar radiation through the vegetation layer is evaluated as well as the thermal insulation performance of the green roof structure. The daily heat flow through the roof surface is quantified showing that the green roof outperforms the reference roof, therefore reducing the daily energy demand. As for water management, it is confirmed that green roofs significantly mitigate storm water runoff generation – even in a Mediterranean climate – in terms of runoff volume reduction, peak attenuation and increase of concentration time, although reduced performance could be observed during high precipitation periods.