粗放型屋顶绿化隔热效果分析

以自然通风层的屋顶绿化为研究对象,对有无绿化屋顶内表面温度进行比较,采用实测数据统计分析的方法,以全夏季为研究周期,按不同温度区间分析屋顶内表面温度的分布特性,比较2种状态下屋顶内表面温度的分布频率以及总温度,得到绿化屋顶内表面温度<34 ℃出现的频率占总周期的90％,是无绿化屋顶的1.6倍,大于36 ℃高温的频率为无绿化屋顶的4.6%,绿化屋顶内表面大于30 ℃的温度总量约为无绿化屋顶的1/3,且绿化屋顶的隔热性能与室外气温有较强的正向性,随着气温的升高,绿化屋顶的隔热性能体现得更加充分。     

屋顶绿化层对屋顶热环境影响测试研究

为研究屋顶绿化层对住宅楼屋顶热环境的影响效果,对某小区单元住宅楼有无绿化层屋顶进行连续测试。分析测试结果发现,在屋顶隔热板上设置绿化层后,白天,隔热板下表面平均温度、隔热层中空气平均温度、屋顶上表面平均温度分别降低7℃、3.6℃、2.8℃;隔热板下表面、隔热层空气、屋顶上表面最高温度也明显偏低,其中隔热板下表面最高温度昼间降低高达12.2℃,屋顶上表面最高温度昼间降低高达5.1℃。在屋顶设置绿化层能有效缓解阳光直射屋顶造成的屋顶过热现象,从而改善室内热环境,达到较好的建筑节能效果。     

屋顶绿化节能热工参数研究

夏季室内环境空调控制下的热工对比试验证明:屋顶绿化可使屋顶内表面平均温度降低3℃、内表面温度波幅降低80%以上、屋顶传入室内的热流量减少70%以上,绿化的附加当量热阻可达1.0 m2.K/W,有效地改善了室内热环境、减少了空调能耗。     

夏热冬冷湿润气候下绿化屋面对建筑环境影响的研究

绿化屋面是一种被动式建筑技术,通过提高建筑屋面对太阳辐射的反照率,以及附加的种植基质保温性能,实现减缓热岛效应、降低建筑能耗的作用。结合夏热冬冷湿润地区气候特点,使用温度实测、软件能耗模拟的方法,分析绿化屋面对建筑内部及外部环境的影响。通过对南京1个办公建筑屋面温度实测显示,夏季晴朗日间应用绿化的建筑屋面外表面比裸露屋面温度平均低约16℃。通过EnergyPlus模拟,有保温屋面增加绿化屋面后,其顶层全年能耗降低了2.6kWh/m2,无保温屋面增加绿化屋面后,其顶层全年能耗降低了14.1kWh/m2;通过Airpak对一个居住区的室外环境模拟,在应用屋顶绿化后,其室外环境温度可降低约0.2℃。     

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。     

藤架式屋顶绿化对建筑热环境影响研究

本文将位于夏热冬暖区的厦门市近郊藤架式屋顶绿化作为对象研究,实测屋顶绿化房间和紧邻无绿化措施房间的数据,采集两个房间室内和室外空气温度、楼板温度、PMV等多项影响人体热舒适的参数。通过实际测试与CFD模拟综合对比,分析夏季藤架式屋顶绿化对建筑顶层房间热环境的影响。数据显示,藤架式屋顶绿化使屋顶表面温度最大降低12.35℃,室内空气温度日均降低0.68℃,分析得出藤架式屋顶绿化在一定程度上改善了顶层建筑热环境,是一种有效改善居民生活热环境的途径。     

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。     

绿化屋顶与普通架空屋顶隔热特性对比分析

对福州某小区顶层两不同房间进行屋顶内表面温度、室内气温以及屋顶内表面热流的现场测试,结果表明,绿化屋顶能有效降低屋顶内表面最高温度、室内气温并可有效控制温度变化幅度,其内表面热流的变化幅度也大大小于普通架空屋顶的。绿化屋顶能降低屋顶热损失,改善室内热环境,节省制冷能耗。     

屋顶太阳能集热器对顶层房间冷热负荷的影响研究

屋顶太阳能集热器的存在改变了屋顶的太阳辐射得热,在一定程度上影响建筑的冷热负荷,特别是对于顶层房间,屋顶是受室外热作用影响最大的外围护结构。本文通过实验测量有太阳能集热器的屋顶和无太阳能集热器的屋顶的外表面温度,建立一维非稳态传热模型,对屋顶的内表面温度及传热量进行数值求解,获得屋顶的热流量数据并对实验结果进行分析。实验结果表明:太阳能集热器的存在会减少屋顶的辐射得热,降低建筑物的夏季冷负荷,增大建筑物的冬季热负荷。     

建筑玻璃屋面喷雾遮阳及降温效果

建立了雾粒遮阳及降温测试系统。对不同雾粒粒径、分布密度对太阳辐射的遮挡及对玻璃表面的降温效果进行了测试,结果表明,6种测试工况下的雾粒对太阳辐射的遮挡率为21.3%~38.5%,小粒径雾粒有更好的遮挡效果;在实验测试条件下,相同粒径雾粒分布密度每增加1倍,其遮挡率约增加8%;在太阳辐射照度为400~1 000W/m2范围内,随着太阳辐射照度的增加,雾粒对太阳辐射的遮挡量及遮挡率均呈上升趋势;运行喷雾系统后,玻璃盖板内表面平均温度下降了约16℃,内表面温度最高值由60℃降至43.9℃。     

Analysis of the green roof thermal properties and investigation of its energy performance

The advantages of the planned roofs are undoubtedly numerous from both the ecological and the social point of view. They act positively upon the climate of the city and its region, as well as upon the interior climate of the buildings beneath them. They give protection from the solar radiation, which is the main factor in passive cooling. By reducing thermal fluctuation on the outer surface of the roof and by increasing their thermal capacity, they contribute, to the cooling of the spaces below the roof during the summer and to the increase of their heat during the winter. Due to the decrease of the thermal losses, the green roofs save the energy consumption.This paper refers to the analysis of the thermal properties and energy performance study of the green roof. The investigation were implemented in two phases: during the first phase, extended surface and air temperature measurements were taken at the indoor and outdoor environment of the buildings where the green roof had installed and during the second phase of the study, the thermal properties of the green roof, as well as, the energy saving were examined, through a mathematical approach.     

Investigation of green roof thermal performance in temperate climate: A case study of an experimental building in Florianópolis city, Southern Brazil

Green roofs have been investigated as a bioclimatic strategy to improve the energy efficiency of buildings. Quantitative data on this subject are still needed for many specific climatic conditions. This paper deals with the investigation of the green roof thermal performance of an experimental single-family residence in Florianópolis (SC, Brazil), a southern city with a temperate climate. Field measurements during a warm period (01-March-2008-07-March-2008) and during a cold period (25-May-2008-31-May-2008) included internal air temperature of rooms, internal and external surface temperature of three types of roofs (green, ceramic and metallic), heat fluxes through these roofs, green roof's temperature profile, water volumetric content in substrate layer and meteorological data. During the warm period, the green roof reduced heat gain by 92-97% in comparison to ceramic and metallic roofs, respectively, and enhanced the heat loss to 49 and 20%. During the cold period, the green roof reduced heat gain by 70 and 84%, and reduced the heat loss by 44 and 52% in comparison to ceramic and metallic roofs, respectively. From the derived data it has been confirmed that green roof contributes to the thermal benefits and energy efficiency of the building in temperate climate conditions.     

复合防水蓄水屋面应用技术研究

屋面蓄水为夏热冬冷地区建筑顶层的隔热降温提供了条件。通过对苏州大学炳麟图书馆复合防水蓄水屋面隔热性能的测试分析,说明该类屋面能够改善建筑热工性能、降低室内空调能耗,是建筑节能的有效措施。     

Vertical greening systems and the effect on air flow and temperature on the building envelope

The use of horizontal and vertical greening has an important impact on the thermal performance of buildings and on the effect of the urban environment as well, both in summer and winter. Plants are functioning as a solar filter and prevent the adsorption of heat radiation of building materials extensively. Applying green façades is not a new concept; however it has not been approved as an energy saving method for the built environment. Vertical greening can provide a cooling potential on the building surface, which is very important during summer periods in warmer climates. In colder climates evergreen species create an external insulation layer and contribute to energy savings and loss of heat. In this study an analysis of the effect on air flow and (air and surface) temperature of vertical greening systems on the building level is presented. An experimental approach was set up to measure the temperature (air and surface) and the air flow near and on different types of green façades and a living wall system to evaluate the influence of wind velocity and its effect on the thermal resistance. A comparison between measurements on a bare façade and a plant covered façade has taken, in the beginning of autumn, to understand the contribution of vegetation to the thermal behaviour of the building envelope.     

生态工程绿色屋顶和绿色垂直墙面

绿色屋顶和绿色墙面可以增强保温效果即夏季保持凉爽和冬季保温,增强视觉美感,改善室内外微气候环境,吸附氧化氮和悬浮粒子以及为鸟类和昆虫创造栖息地来增强生态价值;文章在生态工程的背景下展示绿色屋顶和绿色室外墙面的影响力,并质疑对采用绿色墙面作为建筑外层迟疑不决的做法;特别提到悬浮微粒、浮尘沉积与植被的关系。概括并比较了住宅建筑及工业和其他商业建筑墙面绿化的不同种类,并通过具体例子来展示多功能的可能性;还展示了如何组织大型绿色建筑的实施,使绿色墙体作为综合设计的一部分,确保其从设计概念到建成后日常维护期的可行性。     

垂直绿化改善建筑室内、外热环境效果分析

垂直绿化已成为一种节省空间的节能措施。为研究夏热冬暖地区垂直绿化改善室内热环境和周围热环境的效果,对用爬山虎绿化的建筑的内外壁温及建筑周围室外温度进行实测分析;并用CFD模拟了有、无绿化房间的辐射温度,室内空气温度,PMV、PPD热舒适性指标进行对比分析。测试结果表明,垂直绿化建筑周围热岛效应仅为0.9℃;不同朝向的有绿化墙壁比没绿化的壁面温度有不同程度的降低。效果最好的外壁温平均降低了6.8℃,内壁温平均降低了1.72℃。CFD模拟结果显示,绿化后房间空气温度和辐射温度的平均值分别降低了0.4℃和1℃;PMV-PPD也有改善,而且舒适指标的最大值也减小了。分析可得垂直绿化是一种绿色有效、主动的隔热节能方式。     

Assessment of green roof thermal behavior: A coupled heat and mass transfer model

Green roofs have a positive effect on the energy performance of buildings, providing a cooling effect in summer, along with a more efficient harnessing of the solar radiation due to the reflective properties found inside the foliage. For assessing these effects, the thermodynamic model was developed as well as the thermo-physical properties of the green roof components were characterized. Its typologies and vegetation styles should also be studied. The proposed model is based on energy balance equations expressed for foliage and soil media. In this study, the influence of the mass transfer in the thermal properties and evapotranspiration were taken into account. We then added the water balance equation into our model and performed a numerical simulation. By assuming the outdoor conditions, the roof support temperature and the drainage water as inputs, the model evaluates the temperatures evolution at foliage and soil ground levels. A parametric study was performed using the proposed model to classify green roofs depending on the considered climate condition. Comparisons were undertaken with a roof slab concrete model; a significant difference (of up to 30 °C) in temperature between the outer surfaces of the two roofs was noticed in summer. The model was experimentally validated according to green roof platform, which was elaborated. The mass transfer effect in the subtract was very effective in reducing the model errors. Simulation results show that the use of vegetation in the roof building improves not only thermal comfort conditions, but the energy performance of a building.     

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.     

Passive cooling in hot,arid regions in developing countries by employing domed roofs and reducing the temperature of internal surfaces

Natural ventilation due to wind effects through buildings employing domed roofs was estimated by a flow network analysis. The dome was assumed to have an opening at its crown. When compared with flat roofs, the domed roofs always increase the air flow rate through the building. The increase in natural ventilation becomes significant in buildings with doors and windows all in one wall, or whenever the wind effects on the building envelope do not produce large pressure differences at the openings.The large air flow rate in the buildings with domed roofs may be utilized to store night air coolness in the structure more effectively and keep the mean radiant temperature of the interior surfaces low for thermal comfort in summer. The lowest internal surface temperatures can be obtained when the surfaces are kept moist and evaporatively cooled.Through a one-dimensional energy analysis the inside surface temperature of a horizontal slab was estimated for various slab materials and thicknesses and external and internal conditions. The inside surface temperature was compared with the case of employing a roof pond. It was found that lower temperatures can be obtained by evaporatively-cooled moist internal surfaces than that which can be obtained by unshaded roof ponds: For a building whose internal surfaces (walls and ceiling) are kept moist a large ventilation rate is needed to prevent water vapor build-up in the space. A domed roof with a hole in its crown can produce the necessary ventilation for such a building.     

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.