Numerical Study of the Thermal Performance of Three Roof Models in Hot and Dry Climates

The thermal performance of three roofing models: tile, corrugated and earth terrace is numerically analyzed. The mathematical equations which govern the three roofing models are established by the electrical method of analogies. These equations are discretized by an implicit finite difference method and solved by the Gauss-Seidel algorithm. We analyze the influences of geometric parameters (Xlo, Xlarg, α and Ep) on the evolution of the temperatures of the different environments of our three roof models. In particular, we have shown that the effectiveness of a roof in reducing the temperature inside a room is linked to its physical properties. The results obtained that for the same geometric parameters, the earth roof terrace and the earth tile roof compared to the corrugated metal roof improve thermal comfort by lowering the interior temperature of 5ºC and 4.6ºC.

Analysis on thermal measuring of green roof

Comparison of thermal performance between a green roof room and a bare roof room was presented during the cooling period in Shanghai. The results show that the electricity can be saved about 0.08 kW·h/(d·m2),and the heat flux can be reduced by about 70%; the inner surface temperature variation is about 1.0 ℃ comparing with the indoor temperature when using the green roof,and the extra equivalent heat resistance is 1.0 m2·K/W.

Eliminating Fastener Thermal Bridging in Low Slope Roofs: Energy Efficiency Savings versus Installation Costs

Low-slope roofing assemblies include a wide range of insulation and single ply membrane attachment methods. Previous studies have shown that mechanical attachment using metal fasteners leads to significant thermal bridging and consequent loss of insulation value and reduction of long term thermal efficiency. This study calculates the costs associated with mechanical attachment in terms of lost insulation value, increased long-term energy costs, and the material and labor costs associated with installation of these common systems. Energy efficiency reductions using metal fasteners were modeled for eight US cities in a range of climate zones. From the data, it was possible to calculate target costs (labor plus materials) that would make adhered systems cost effective. There are many options available to adhere single ply roof system components, such as solvent-based adhesives and low-rise urethane foams, together with different application approaches such as broom, spray, and ribbon methods. The cost targets derived in this study can help optimize the use of such materials and application methods such that the thermal bridging due to fasteners could be substantially reduced or eliminated.

Experimental Study of the Thermal Behavior of a Bioclimatic Building Prototype in a Sahelian Zone

Buildings constructed with modern materials (cement blocks, sheet metal, reinforced concrete, etc.) in the Sahelian zone often generate excessive electricity consumption and consequently very high electricity bills. This study is a contribution to the development of new building types based on the principle of bioclimatic construction. The aim is to find materials suited to the Sahelian climate and improve thermal comfort. To this end, an experimental study of the hygrothermal behavior of a bioclimatic building prototype with a domed roof is being carried out. Site meteorological data, air temperature and relative humidity of the building’s internal environment were measured for three climatic seasons in Burkina Faso. The data acquisition system consists of thermocouples, solarimeters and humidity meters, and the data are processed using Excel and Origin Pro software. The results show that, despite the high temperature values (between 36˚C and 39˚C) of the internal environment measured in the hot season, good thermal performance is achieved, in particular an average phase shift of 7.17 h and an average damping of 10.81˚C. The dome-roofed building could therefore contribute to limiting heat transmission to the building interior, improving thermal comfort all year round. Analysis of humidity profiles shows that indoor humidity varies between 66% and 80% for the September period, and between 44% and 69% for the January period. The high values of internal ambient humidity could be reduced by very good ventilation of the building. This study shows that the proposed bioclimatic building prototype with domed roof could be integrated into the Sahelian habitat.

Optimum Distribution of Two Different Phase Change Materials between Various Components of Roof Air-Conditioned Room, Suitable to Reduce Annual Energy Consumption

Obviously, the outside annual climate change caused either by a major solar input during the hottest period or by a temperature drop during the coldest period leads to discomfort in inside buildings. This effect can be reduced by storing heat transmitted in phase change materials (PCM) as latent heat, in order to ensure a good situation of thermal comfort during all months of the year. In this work, thermal behavior of two roofing systems is studied. One roof is constituted only by usual materials in building. In the other, two phase change materials (PCM) are introduced according to three configurations. Study is interested to assess incorporation effect of two PCMs within the roof and to evaluate the optimum locations to reduce the energy consumption of air-conditioned room. Mono-dimensional numerical model validated analytically and experimentally, is used to carry out a parametric analyzes to determine characteristics of the layers in which the roofs are formed regardless of external climate effect. Numerical calculations are performed for three configurations of roof. Results show that insertion of phase change materials in roof provides best energy consumption saving regardless annual climate change. Generally, the three configurations lead to different results, depending on the combination of PCMs. This difference becomes less important when selection of PCMs take account the thermal comfort level and temperatures of hottest and coldest periods.

Performance Evaluation of Hybrid Green Roof System in a Subtropical Climate Using Fluent

Energy disaster is one of the major obstacles in the progress of human society. There are some on-going researches to overcome this for a sustainable environment. Green roof system is one of them which assist to reduce energy consumption of the buildings. The green roof system for a building involves a green roof that is partially or completely covered with vegetation and plant over a waterproofing membrane. Green roofs provide shade and remove heat from the air through evapotranspiration, reducing temperatures of the roof surface and the surrounding air. This paper reports the thermal performance of hybrid green roof system for a hot and humid subtropical climatic zone in Queensland, Australia. A thermal model is developed for the green roof system using ANSYS Fluent. Data were collected from two modelled rooms, one connected with green roof system and other non-green roof system. The rooms were built from two shipping containers and?installed at Central Queensland University, Rockhampton, Australia. Impact of air temperature on room cooling performance is assessed in this study. A temperature reduction of 0.95°C was observed in the room with green roof which will save energy cost in buildings. Only 1.7% variation in temperature was found in numerical result in comparison with experimental result.

气候变化下窑居建筑屋顶适宜性改造研究

调研发现陕北地区自2010年以来降水量开始呈现明显增加的趋势,而传统窑洞屋顶缺少良好的防水设计,易导致窑洞在经受暴雨时漏水甚至坍塌。村民采取在原屋顶上加建彩钢板的改造方式防雨,然而这种窑洞屋顶构造的自更新不仅未能充分解决屋顶防水问题,还在一定程度上破坏了窑洞村落的传统风貌。以陕北地区传统民居的典型代表窑洞为研究对象,通过调研测试与软件模拟分析窑洞屋顶加盖彩钢板构造对室内热环境的影响,发现加盖彩钢板能够提升屋顶的耐久度和防雨性能,但是不能改善室内热环境,并且不能充分融入到传统的乡村环境中。在此基础上提出了新型窑洞屋顶构造,以期进一步改善屋顶防水性能并延续传统民居建筑风貌,为后期窑居建筑更新改造提供参考。

混凝土屋面工程材料层变形与协同作用

屋面材料在各类影响因素作用下产生变形,防水层会受协同作用,进而影响防水有效性。材料层变形量主要受温度、湿度、荷载的影响,适合采用试验、解析式或有限元计算得到;材料间相对变形可基于构造、材料变形量进行组合;材料变形的协同作用包含变形量和变形率,适合引入不确定参数计算。材料层变形及其协同作用的机理、计算方法是开展防水有效性研究的基础。

耀雪冰雪世界项目施工难题及关键技术研究

以上海耀雪冰雪世界大型室内滑雪场项目为例,为保证质量、安全及建筑功能的实现,阐述了在整个项目施工过程中的难特点,并针对难题提出针对性的研究方向和对策,为类似冰雪场馆设施的建设提供了有价值的参考经验。

自然通风、冷屋顶与外遮阳对室内热环境改善效果实验研究

对自然通风、冷屋顶与外遮阳3种被动技术在夏热冬冷地区的综合隔热降温作用及对室内热环境的改善效果进行了测试分析。结果显示:当三者协同作用时,外遮阳可以遮挡太阳辐射,有效降低窗户的得热量,实验房间玻璃外表面温度较对比房间最高降幅达到7.6℃;高反射涂料的应用使屋顶表面降温幅度达到10.3℃,有效减少了屋顶的温差传热;自然通风系统成功诱导了连续并具有周期性波动的气流,并对埋管内空气有着良好的预冷效果;实验房间室内温度稳定在26.8~27.9℃之间,室内热环境得到了明显的改善。

厦门典型“平改坡”农宅室内热环境实测对比与分析

为改善农村人居环境和住房条件,厦门近年来将“平改坡”技术广泛运用于既有农宅的屋面改造。为定量分析“平改坡”对农宅室内热环境的影响效果,采取热环境实测与问卷调查的方法,选取厦门典型“平改坡”农宅与平屋顶农宅为测试对象,对比两种农宅顶层房间与坡顶通风层的热环境效应与热舒适需求。实测结果表明:“平改坡”增强了农宅顶层房间的保温隔热性能,对室内热环境具有积极影响,在过渡季与夏季分别降低顶层房间空气温度0.5~2.0℃、0.8~2.8℃,对顶层房间围护结构表面温度的影响程度为“平屋顶上表面>平屋顶下表面>顶层房间室内地面”。农宅“平改坡”后缩小了顶层房间中PMV的波动区间,在过渡季PPD减少4.7%,在夏季日间PPD减少0.3%但夜间PPD增加8.2%。坡顶通风层的室内热环境较差,可以通过优化构造材料、空间高度与通风形式的设计来提高“平改坡”屋顶的隔热性能,进而为提升夏热冬暖地区农宅的室内热环境品质并降低能耗提供参考。

海绵城市建设技术

海绵城市是一种综合性、多元化的城市生态系统,是以保护、修复和利用自然水循环系统为主要目标,其可实现城市的可持续发展。通过收集、过滤、回用和渗透等方式,合理利用雨水资源,降低洪涝灾害风险,减轻城市排水系统的压力。利用绿化和自然化手段,增加城市绿地面积和植被覆盖率,以提高城市的生态环境和空气质量。城市通过铺设透水铺装、建设绿色屋顶和垂直绿化等措施,提高了城市地表的透水性,促进自然水文循环,改善城市排水系统,通过建设雨水花园、湖泊等方式,提高了城市的抗洪排涝能力,缓解了城市洪涝灾害的风险。通过列举深圳市采用城市海绵技术建设的具体案例,印证了城市海绵技术带来的社会效益。

直立锁边金属屋面与复杂钢网架施工研究

以某滑雪场为研究对象,阐述钢网架施工流程及金属铝镁锰板屋面的构造节点、主要施工工艺流程及注意事项。对滑雪场屋面系统中防水和保温的节点做了施工深化,保证了保温聚氨酯的连续性、TPO柔性防水层及附加防水层的完整性,为同类型钢网架项目的施工提供了一定的参考。

基于现代材料的装配式建筑防渗漏解决方案研究

本研究聚焦装配式建筑防渗漏问题,分析了渗漏路径、结构变形及施工工艺带来的挑战。利用现代材料,如高效防水隔热外墙保温系统、弹性防裂涂料及膜材料、全新屋面防水材料等,分别针对外墙、屋面、窗户和门窗提出创新解决方案。通过创新链接搭接技术、改进接缝处理与密封技术,并结合实际案例分析,证实了综合应用现代材料的防渗漏方案可降低渗漏风险,提升装配式建筑抗渗漏能力,为其稳定性和室内环境舒适性提供有力保障,推动装配式建筑发展。

居住小区空间载体的微气候调节作用及其落位原则

室外立体空间拓展和绿化设施配置不仅可有效补充地面绿量,还能够调节住区微气候,营造舒适活动空间。参照重庆地域特征,建立下沉花园和屋顶花园两类空间载体,并细分为8种设计模式;借助ENVI-met和Ray Man软件开展室外微环境和人体舒适度模拟,进而依据对热风环境和生理等效温度热感觉累计时长的改善程度,提出空间载体落位原则。研究结果拟丰富住区室外立体空间规划内容,为引导室外活动设施的空间选位和规划实践提供支撑。

架空隔热屋面的研究进展及发展趋势

屋面热工性能的提升对于降低室内空调采暖能耗和改善室内热舒适性具有重大意义,该文详细介绍建筑节能领域的架空隔热技术的研究进展及发展趋势,分析不同架空隔热技术的隔热原理及对室内热舒适度的影响,对传统与新型架空隔热屋面的研究进展分别进行阐述。传统架空隔热屋面具有改善隔热的优势,但其结构未将优势达到最大化,目前学者们在此基础上广泛研究各类新型架空隔热屋面,意在从结构优化、使用新型材料、复合型屋面等方式进一步提高架空隔热屋面的热工性能。该文还对光伏与架空隔热结合的光伏架空隔热屋面相关研究进行重点讨论和比较,光伏架空隔热屋面具有改善屋面隔热性能和利用太阳能为建筑供电的两种优势。在当前中国倡导绿色发展,加快能源结构转型的背景下,新型光伏架空隔热屋面更符合建筑节能和光伏建筑一体化的发展趋势。

基于无人机技术的建筑围护结构热工缺陷测试方法研究

建筑围护结构热工性能是降低建筑能耗、实现建筑低碳的关键因素之一。现阶段建筑围护结构热工性能的测试主要是以点代面,即选取典型位置进行热工缺陷测试代表整体的热工性能,难以真实地评价围护结构整体热工性能。当前我国建筑以中高层建筑为主,传统手持红外热像仪测试中高层建筑围护结构外墙、外窗、屋顶的热工性能难度极大且准确性差、成本极高。通过多旋翼无人机搭载红外热像仪进行中高层建筑围护结构外墙、外窗、屋顶的热工性能测试,可实现建筑围护结构周期性巡检。研究认为:无人机不受地形和建筑高度限制、成本低,目前我国无人机技术成熟,具备大规模应用基础;在高度较低位置无人机搭载红外热像仪与手持红外热像仪测试精度一致,在较高位置无人机搭载红外热像仪测试精度远超手持红外热像仪测试精度;无人机搭载红外热像仪在中高层建筑围护结构、建筑屋顶测试上优势明显;无人机搭载红外热像应以建筑物体量的大小选择设备距外墙的拍摄距离,在10~40 m范围内测试结果一致性较好;通过无人机搭载红外热像仪测试数据可合成围护结构整体热像图,能够全面地分析建筑围护结构整体热工性能;建筑物围护结构整体热工性能缺陷测试和分析,需结合可见光照片进行;建筑整体围护结构热工性能测试数据处理量大、缺少专用软件,缺陷分析识别需要人员水平较高;无人机飞行时噪声较大,应合理选择测试时段或采用低噪声机型,避免扰民。

装配式混凝土夹芯拱形屋盖性能分析

【目的】为切实降低建筑碳排放,满足“双碳”发展背景下建筑业的发展要求。【方法】通过对一种新型装配式混凝土夹芯拱形屋盖进行分析,探讨该结构的空间构形特点,研究空间曲面夹芯拱形板的力学性能、热工性能及装配施工技术。【结果】研究表明,装配式混凝土夹芯拱形屋盖力学性能好、承载能力高,夹芯保温层能够有效改善热工性能,屋盖单元的预制生产、装配施工方便。【结论】根据建筑结构设计分析方法,研究了混凝土夹芯拱形屋盖的关键装配施工技术,并提出了优化策略和建议。本研究可为我国寒冷采暖地区装配式建筑的发展提供借鉴。

高层建筑屋顶球体结构节能材料研究

简要介绍了某高层建筑屋顶球体结构设计,其墙体保温材料选择沫玻璃一体化板,窗户采用Low-E玻璃,分别对这两种材料的导热性能、防火性能、耐久性能、吸湿性能进行了测试,并与其他材料进行了对比分析。由测试结果可知,泡沫玻璃一体化板和Low-E玻璃的各项性能均符合绿色节能要求,并优于其他材料。

屋面轻质保温材料的防水性能

研究了以水泥、生石灰为胶凝材料,以粉煤灰为填料,以膨胀珍珠岩为保温原料,加入防水剂、憎水剂,制成集保温与防水为一体、一次施工完成的新型屋面保温防水板.该板抗压强度1.6MPa,导热系数0.13 W/m.K,密度562 kg/m3,吸水率5%.