佛甲草辐射特性的研究

在对植被屋顶进行热工性能研究时,绿化植物的发射率、长波辐射吸收率和太阳辐射吸收率是3个基本参数,对分析和计算植被屋顶的能量平衡有着重要意义。然而,目前学术界缺少常用绿化植物辐射特性的基本数据。本文研究了国内最常见的绿化物种——佛甲草的辐射特性,测得佛甲草叶片对太阳辐射的吸收率为0.67～0.69,发射率为0.81～0.84;同时利用太阳辐射传感器现场测得单位土地面积上密植的佛甲草草坪对太阳辐射的吸收率为0.83,估算得到其长波辐射吸收率约为1,在无进一步实验结果之前,可暂时认为单位土地面积上密植的佛甲草草坪发射率等同于叶片的发射率(0.83)。     

无土植被屋顶的设计及施工

隔热目的是控制外围护结构的内表面温度及其波动幅度,并使内表面最高温度与室外最高综合温度之间有一定的延迟时间。在外围护结构中,隔热要求最高的是屋顶。植被屋顶,有铺上种植和无土种植两种,指的是在屋顶上种草或其它植物,利用植物叶面的蒸腾和光合作用吸收太阳辐射,具有很好的隔热能力。无上植被屋顶是用某种介质代替土壤铺在屋顶上,由营养液供给植物营养。可以代替土壤的种植介质,有蛙石、木屑、砾石、粗砂、钢渣和岩棉等。植被屋顶的隔热性能与植被覆盖密度。介质层厚度和基层的构造等因素有关。无土植被这种屋面形式,由于选…     

屋顶绿化对空气中二氧化碳含量的影响

以国内最常见的佛甲草植被屋顶为例,研究了屋顶绿化对二氧化碳的吸收和减排效果。分析发现,考虑单个植物体的整个生命周期,屋顶绿化对空气中的二氧化碳含量几乎没有影响。若保持植被屋顶较高的生物量,则可以通过植物本身固定碳元素;植被屋顶还能通过降低建筑的能耗来间接减少二氧化碳的排放。后两种途径均能达到一定的效果,但与城市的二氧化碳排放量相比则微不足道。     

屋顶绿化夏季对室内的降温效果试验对比研究

随着城市化进程的不断加快,城市绿色植被面积不断减少,造成城市空气质量恶化,热岛效应逐渐加重,而屋顶绿化则是解决上述问题的方法之一。本文利用三个木屋模型建筑,分析埘比了两种不同植物的屋顶绿化在夏季对室内的降温效果。研究表面,两种绿化对降低屋顶内表面温度和室内温度效果明显,不同的绿化方式其降温效果也有一定差异,对屋面植物定期浇水维护可以使降温效果进一步加强。     

屋顶绿化对建筑围护结构节能的模拟研究

采用模拟方法对绿化屋顶的能耗性能进行模拟,选取济南、上海、广州作为3个气候区代表城市,采用EnergyPlus对绿化屋顶和裸屋顶进行模拟对比。模拟屋顶绿化情况下不同叶面积指数、植物高度、土层厚度对建筑能耗的影响,得到在不同气候区下,不同参数的变化对能耗的影响不尽相同。并得到绿化屋面的最优参数配置:土壤厚度z=0. 2 m,植被高度H=0. 1 m,LAI=5,济南、上海、广州全年能耗最大节能率分别为5%、6. 6%、9. 3%。研究并得出建筑层数及面积与绿化屋顶能源性能的关系,发现其他条件一定,层数越高,绿化屋顶对降低能耗作用越小;建筑面积越大,绿化屋顶降低能耗性能越显著。     

某绿化屋顶夏季热工性能模拟研究及验证

本文以上海市共青森林公园某改造的佛甲草绿化屋顶建筑为例,利用Fluent软件建立与实测数据相吻合的稳态和瞬态屋顶绿化传热模型,并以2个模型为基础,分别探讨不同布置形式对绿化屋顶热工性能的影响以及绿化屋顶在动态情况下的传热特点,以此探讨屋顶绿化节能性。模拟结果表明,屋顶绿化的存在使屋顶外表面温度分布差异显著,可带来12.2℃的表面温差;不同布置形式对绿化屋顶热工性能影响巨大,且植被宽度越宽、间距越小对裸屋顶表面温度的影响越明显;在全天24 h的完整周期内,绿化屋顶表面各测点温度存在一定的时间延迟与温度衰减,并且距离植被越近表现越明显;与裸屋顶相比,该绿化屋顶模型植被覆盖率仅为38.9%,却减少了24.73%的传热量。     

浅析玉米高产栽培技术

<正>玉米,亦称玉蜀黍、包谷、苞米、棒子。是一年生禾本科草本植物,是重要的粮食作物和重要的饲料来源,也是全世界总产量最高的粮食作物。玉米是C-4植物,因其光合效率高,净光合作用值较C3植物如小麦、水稻等高出三倍;同时证明玉米是非光呼吸作物,它虽也进行光呼吸,但其强度很低,养分消耗少,积累多。这是玉米高产的生理基础。目前,玉米对光能利用率是很低的,一般只有1-3%,低的还不到1%,可见玉米的增     

屋顶绿化对室外微气候的降温增湿效果

在高密度城市中,建筑屋顶具有巨大的开发利用潜力,通过结合绿化打造屋顶休闲空间,不仅可以改善屋顶上部微气候,还能有效提高城市绿量。以重庆典型气候条件下绿化屋顶常用的3种屋顶绿化植物为研究对象,采用实测与理论分析相结合的方法,探究不同屋顶绿化植物对周围环境的降温增湿效果。实验结果表明,屋顶绿化的降温增湿作用从正午高温之后持续至次日日出,增湿作用夜间效果更为突出,植物的降温效果在其表面最显著;植物叶面积指数与其反射辐射量呈反向相关。3种植物中,小叶景天综合效果最好,在其表面日间最大降温11.7℃,在300、700mm处夜间分别降温4.64、3.97℃,其最大增湿效果出现在19:00,增湿33.1%。     

立体绿化植物选择

根据生态景观要求和土壤基质厚度的差异,从植物应用的角度出发,可将屋顶绿化分为草地式和群落式两类。草地式屋顶绿化以栽植低矮的草本植物为主,形成近屋顶表面植被层的屋顶绿化形式;而群落式屋顶绿化以应用乔木、灌木、藤本、草本等两种以上的植物类型．形成种类多样、层次丰富的屋顶绿化类型。因此,在绿化植物选择上,应针对不同的屋顶绿化类型,选择适宜的绿化植物。     

屋顶绿化植物的选择与配置

本文在分析了屋顶绿化的植物选择原则的基础上,对屋顶绿化的植物选择与配置作了简要的归纳介绍.同时,针对不同类型屋顶绿化总结了其植物造景的常用设计方法,并粗略介绍了屋顶绿化的养护与管理.     

Theoretical and experimental analysis of the energy balance of extensive green roofs

This paper analyzed the energy balance of extensive green roofs and presented a simple but practical energy balance model. Field experiment justified the validation and accuracy of this model. Experimental results demonstrated that within 24 h of a typical summer day, when soil was rich in water content, solar radiation accounted for 99.1% of the total heat gain of a Sedum lineare green roof while convection made up 0.9%. Of all dissipated heat 58.4% was by the evapotranspiration of the plants-soil system, 30.9% by the net long-wave radiative exchange between the canopy and the atmosphere, and 9.5% by the net photosynthesis of plants. Only 1.2% was stored by plants and soil, or transferred into the room beneath.     

Experimental measurements and numerical modelling of a green roof

Green roof utilisation has been known since ancient times both in hot and cold climates. Nowadays, it has been reconsidered at issue of energy saving and pollution reduction. In this paper, some measurement sessions on a green roof installed by the Vicenza Hospital are described. A data logging system with temperature, humidity, rainfall, radiation, etc. sensors surveyed both the parameters related to the green roof and to the rooms underneath. The aim is to evaluate the passive cooling, stressing the evapotranspiration role in summer time. Furthermore, the enhanced insulating properties have been tested during winter time. A predictive numerical model has been developed in a building simulation software (TRNSYS) to calculate thermal and energy performances of a building with a green roof, varying the meteorological dataset for a specific geographic zone.     

关于屋顶绿化节能技术化问题

建筑节能提倡采用生态节能技术，尤其是建筑绿化节能技术。围绕屋顶绿化的节能技术化问题进行讨论，分析了屋顶绿化节能效果影响因素，提出了屋顶绿化节能性能参数的确定方法。     

Ecological energetics of tropical intensive green roof

Few green roof studies cover intensive and tropical types and specific canopy microclimate. We examined the ecological energetics of a sky woodland in humid-tropical Hong Kong. Environmental sensors monitored the microclimatic and soil parameters for 14 months. Key biophysical variables of transpiration, wind, light, and through-canopy energy flux are modeled to investigate seasonal and weather effects. The woodland forms a cloistered subcanopy environment with rather stable microclimate. Transpiration and latent heat loss are enhanced by solar radiation and low relative humidity, but less by wind. On sunny days, about 20% of incident solar radiation can reach the soil surface. The canopy reflected more near-infrared radiation (NIR) than photosynthetically active radiation (PAR), highlighting a hitherto neglected passive-cooling mechanism. The highest transpiration rate occurs in autumn rather than summer due to dry-mild weather. The woodland canopy could reduce 300 W m⁻² energy flux into the substrate. The canopy warmed by solar energy transmits heat to subcanopy air. Latent and sensible heat loss in the subcanopy domain is suppressed, thus dampening the passive-cooling effect. The capability of the tropical intensive green roof to reduce temperature is relatively inefficient comparing with temperate region counterparts. The findings could inform design and choice of green roofs.     

从建筑节能的角度谈屋顶花园的营造设想

阐述了屋顶花园的定义,分析了屋顶花园在建筑节能方面的优势,提出了对屋顶花园有现实意义的设想,指出高密度的屋顶绿化可以净化空气,增添城市绿量,增加城市魅力,值得大力推广。     

Development Trend of Vertical Greening in China and Countermeasures

Current situation of urban green spaces was analyzed, vertical greening, elevated floor and roof garden were effi cient ways of expanding urban green coverage area. The signifi cance of expanding green areas, improving soil, renovating and maintaining green plants was discussed.     

温度监测系统的设计及在屋顶绿化节能效果检测中的应用

为了监测屋顶绿化的节能效果,设计并实现了屋顶绿化温度监测系统。该系统可以实现现场数据的实时采集,并且采用无线数据传输模块,可以对屋顶绿化的热工性能远程监测,通过该系统可以得到种植不同植物屋顶的热工参数。采用多项式最小二乘法对温度传感器的模拟量信号与温度值间的关系进行拟合,提高了系统的采样精度。     

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.