Journal of Building Physics最新文献_第9页

Energy saving potential of phase change materials-enhanced building envelope considering the six Moroccan climate zones 考虑到摩洛哥六个气候区，相变材料增强建筑围护结构的节能潜力

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-04-22 DOI: 10.1177/17442591211006444

Amal Louanate, R. Otmani, K. Kandoussi, M. Boutaous, Daya Abdelmajid

Phase change materials (PCMs) show a good capability in absorbing massive heat when undergoing phase change, which have great potential to be incorporated into building envelopes to enhance indoor thermal comfort by preventing heat penetration into buildings and reducing energy requirements. In this work, a deep analysis of PCM enhanced-walls model has been conducted in six representative climate regions of Morocco: El Jadida, Fez, Marrakesh, Ifrane, and Errachidia. More in detail, numerical simulations were carried out to assess the thermal behavior and energy performance of a residential building integrated with four different PCMs. The results showed that the effectiveness and selection of PCMs strongly depend on local weather where they are applied, characteristics of HVAC systems, PCM layer thickness, and position. Furthermore, with reference to each climate zone, the appropriate PCM leading to the lowest annual energy consumption was identified. The findings show that PCMs are particularly suitable for Mediterranean climates, which a promising annual energy saving of about 41% was obtained. While, the lowest value was recorded in Errachidia city reveals that the integration of PCM has little effect in desert climate zone. As for the other climates considered, values of about 28% to 31% were achieved in the studied house model.

相变材料在相变过程中具有良好的吸热能力，在建筑围护结构中应用相变材料具有很大的潜力，可以防止热渗透到建筑内部，降低能耗，从而提高室内热舒适性。在本研究中，对摩洛哥六个具有代表性的气候区——贾迪达、非斯、马拉喀什、伊朗和埃拉奇迪亚进行了PCM增强墙模型的深入分析。更详细地说，进行了数值模拟，以评估与四种不同的pcm集成的住宅建筑的热行为和能源性能。结果表明，PCM的有效性和选择在很大程度上取决于应用地点的当地天气、暖通空调系统的特性、PCM层厚度和位置。此外，根据每个气候带，确定了导致最低年能耗的适当PCM。研究结果表明，pcm特别适合地中海气候，每年可节省约41%的能源。而埃拉奇迪亚城市的数值最低，说明在沙漠气候带，PCM的整合作用不大。至于考虑的其他气候，在研究的房屋模型中，价值约为28%至31%。

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引用次数: 17

Practical correlation for thermal resistance of 45° sloped-enclosed airspaces with upward heat flow for building applications 45°倾斜封闭空气空间的热阻与建筑应用中向上热流的实际相关性

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-04-22 DOI: 10.1177/17442591211009922

Hamed H Saber

Assessing the energy performance of building components with enclosed airspaces requires accurate determination of the thermal resistance (R-value) of the airspaces. The R-value of enclosed airspace depends on its size and orientation, direction of heat transfer through the airspace, and temperatures and emissivities of all surfaces that define the airspace. In previous studies, practical correlations were developed to determine the R-values for vertical enclosed airspaces, horizontal enclosed airspaces with upward heat flow and downward heat flow, and 30° and 45° sloped-enclosed airspaces with downward heat flow. However, to the authors’ best knowledge, there is no such practical correlations available to determine the R-values for wide ranges of dimensions and operating conditions for 30° and 45° sloped-enclosed airspaces with upward heat flow. This paper focused on the thermal performance of 45° sloped-enclosed airspaces with upward heat flow, and the predicted R-values were compared with the R-values provided in ASHRAE Handbook of Fundamentals at different conditions. The dependence of the R-value on the aspect ratio of the enclosed airspaces was also investigated. As well, considerations were given to quantify the potential increase in the R-value of enclosed airspace when a thin sheet having different values of emissivity on both sides was placed in the middle of the airspace. The results showed that depending on the value of the effective emittance and the thickness of the airspace, the R-value could be tripled by incorporating thin a sheet in the middle of the enclosed airspace. Finally, practical correlation were developed to determine the effective R-values of 45° sloped-enclosed airspaces with upward heat flow for wide ranges of aspect ratio, temperature difference across the airspace, mean temperature, and effective emittance. The results showed that the calculated R-values using this correlation were in good agreement with the predicted R-values.

评估具有封闭空气空间的建筑构件的能源性能需要精确确定空气空间的热阻(r值)。封闭空域的r值取决于其大小和方向、通过该空域的热传递方向以及定义该空域的所有表面的温度和发射率。在以往的研究中，建立了实用的相关性来确定垂直封闭空气空间、水平封闭空气空间(向上热流和向下热流)以及30°和45°倾斜封闭空气空间(向下热流)的r值。然而，据作者所知，对于30°和45°倾斜封闭的向上热流空气空间，没有这样的实际相关性可以确定大范围尺寸和操作条件下的r值。本文以热流向上的45°倾斜封闭空气空间为研究对象，将预测的r值与ASHRAE基础手册中提供的不同条件下的r值进行了比较。研究了r值与封闭空间宽高比的关系。此外，还考虑了在封闭空域中间放置两面发射率值不同的薄板时，如何量化封闭空域r值的潜在增加。结果表明，根据有效发射度的大小和密闭空间的厚度，在密闭空间中间加入薄板可以使r值增加三倍。最后，在宽宽比、空域温差、平均温度和有效发射度范围内，建立了实际关联，以确定热流向上的45°倾斜封闭空域的有效r值。结果表明，利用这种相关性计算的r值与预测的r值吻合较好。

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引用次数: 0

CLT construction without weather protection requires extensive moisture control 没有天气保护的CLT建筑需要广泛的湿度控制

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-04-09 DOI: 10.1177/1744259121996388

L. Olsson

This study examines how cross-laminated timber (CLT) constructions, including joints, connections and attachment points, are affected by precipitation during construction. The case studies are based on moisture content measurements and material sampling as well as microbiological analysis during the structure’s construction stage. The study does not include remediation control. The field measurements show microbiological growth in all buildings and almost all floor structures that were investigated. Of a total of 200 measuring points analysed, half had mould growth and around a third had moderate or extensive growth. The moisture content measurements for one of the locations with the largest percentage of elevated or high moisture content was at the top of the floor structure in the bottom gap between timbers in the CLT top layer. This is one example of several materials or construction components where there is limited possibility of dry out. Based on the outcome, it would appear difficult, or impossible, to avoid the appearance of microbial growth during construction with CLT without weather protection. Previous studies indicate that microbiological analysis of CLT is extremely rare in both laboratory and field studies, which implies that there are obvious shortcomings in the scientific work. The fact that mould growth is often invisible needs to be disseminated, especially in practical studies. However, there seems to be a good level of awareness in the literature that theoretical studies often conduct mould growth risk evaluations. There do not appear to be any moisture safety assembly methods or solutions for CLT construction that do not have weather protection or a declaration of the critical moisture conditions for CLT products.

本研究考察了交叉层压木材(CLT)结构，包括接缝，连接和附着点，在施工过程中如何受到降水的影响。案例研究基于结构施工阶段的水分含量测量和材料取样以及微生物分析。该研究不包括补救控制。实地测量显示，在所调查的所有建筑物和几乎所有地板结构中都有微生物生长。在分析的总共200个测量点中，一半有霉菌生长，大约三分之一有中度或广泛的生长。含水率升高或高含水率百分比最大的位置之一是在CLT顶层木材之间底部间隙的地板结构顶部。这是几种材料或建筑部件干燥可能性有限的一个例子。根据结果，在没有天气保护的CLT施工期间避免微生物生长的出现似乎是困难的，或者是不可能的。以往的研究表明，CLT的微生物学分析在实验室和现场研究中都极为罕见，这意味着科学工作存在明显的不足。霉菌生长往往是看不见的，这一事实需要传播，特别是在实际研究中。然而，在文献中似乎有一个很好的认识，理论研究经常进行霉菌生长风险评估。似乎没有任何湿度安全组装方法或解决方案的CLT结构，没有天气保护或CLT产品的关键湿度条件的声明。

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引用次数: 5

Hygrothermal performance of cool roofs with reflective coating material subjected to hot, humid and dusty climate 热、湿、多尘气候下反射涂层冷屋顶的湿热性能

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-04-09 DOI: 10.1177/17442591211001408

H. Saber

The measurements for the short-wave solar reflectivity of a Reflective Coating Material (RCM) with various cleaning operations that were obtained in a previous study were used in this study to conduct numerical simulations in order to assess the moisture and energy performance of cool and black roofs when they were subjected to the weather conditions of Saudi Eastern Province and Kuwait City. The results of the numerical simulations showed that black roofs always work with less moisture than cool roofs. Because the highest relative humidity in the different components of the black and cool roofs was well below 80%, there was no risk of condensation and mold growth in these roofs. For both weather conditions of Saudi Eastern Province and Kuwait City, the results showed that installing cool roofs have resulted in increasing the heating energy loads in relation to black roofs. Conversely, the results showed that the decrease in the cooling energy loads due to installing cool roofs were typically much greater than the increase in the heating energy loads. As such, cool roofs have resulted in net energy savings in relation to black roofs. Replacing black roof by cool roof in Saudi climate, the results showed that the annual energy savings in the total energy load was 25% and 34% as a result of installing cool roof with RCM at no cleaning and weekly homemade cleaning, respectively. Additionally, replacing black roof by cool roof in Kuwaiti climate, the results showed that the annual energy savings in the total energy load was 23% and 31% a result of installing cool roof with RCM at no cleaning and weekly homemade cleaning, respectively.

在本研究中使用了在先前的研究中获得的反射涂层材料(RCM)的各种清洁操作的短波太阳反射率的测量值来进行数值模拟，以评估冷屋顶和黑色屋顶在沙特东部省和科威特市的天气条件下的水分和能源性能。数值模拟结果表明，黑色屋面在较低湿度条件下工作。由于黑色和凉爽屋顶的不同组成部分的最高相对湿度远低于80%，因此这些屋顶没有凝结和霉菌生长的风险。对于沙特东部省和科威特市的两种天气条件，结果表明，安装冷屋顶导致了相对于黑色屋顶增加的热能负荷。相反，结果表明，由于安装冷屋顶，冷却能量负荷的减少通常远大于加热能量负荷的增加。因此，与黑色屋顶相比，冷屋顶节省了净能源。在沙特气候条件下，用冷屋顶代替黑色屋顶，结果表明，在不清洁和每周自制清洁的情况下，安装带有RCM的冷屋顶，每年的总能源负荷节能分别为25%和34%。此外，在科威特气候条件下，用冷屋顶代替黑色屋顶，结果表明，在不清洁和每周自制清洁的情况下，安装带有RCM的冷屋顶，每年的总能源负荷节能分别为23%和31%。

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引用次数: 5

Influence of wall composition on moisture related degradation of the wall surfaces in Hagia Sophia, Istanbul 伊斯坦布尔圣索菲亚大教堂墙体成分对墙面水分相关退化的影响

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-03-01 DOI: 10.1177/1744259121996017

Etsuko Mizutani, D. Ogura, T. Ishizaki, M. Abuku, Juni Sasaki

Over the past 10 years, our research team has holistically studied the environmental aspects of the conservation and restoration of the Hagia Sophia, which is suffering from severe degradation of its wall paintings, including the exfoliation of wall paintings and inner finishing materials, mainly due to salt crystallisation. In the present study, we investigated the influence of environmental factors and wall composition on the hygrothermal behaviour in the structure, such as moisture accumulation and evaporation within the walls, which significantly affect salt crystallisation. The differences in distribution of high moisture content at second cornice are depending on the azimuth, and the high correlation between high moisture content and deterioration severity is significant. A two-dimensional numerical model of the simultaneous transfer of heat and moisture considering the measured material physical properties and wall composition of the exedra wall is developed to quantitatively investigate the influence of environmental factors on moisture accumulation. Numerical results show that infiltrated rainwater tends to accumulate because the original builders used connection mortar, which has a much larger moisture diffusivity than that of modern mortar, and the accumulated water at the bottom of the wall is difficult to drain owing to the shape of the wall. In the northwest exedra, the influence of wind-driven rain on water accumulation is similar to that of runoff rainwater from the upper roofs, which probably causes deterioration over a wide area. In addition, the effect of the deterioration suppression measure by the re-covering of the outer surfaces of the west wall in 2013 is verified, and an appropriate suppression measure against water permeation is examined using a numerical model.

在过去的10年里，我们的研究团队对圣索菲亚大教堂的保护和修复进行了全面的环境方面的研究，圣索菲亚大教堂的壁画正遭受严重的退化，包括壁画和内部装饰材料的剥落，主要是由于盐结晶。在本研究中，我们研究了环境因素和壁面组成对结构中湿热行为的影响，如壁面内的水分积累和蒸发，这对盐结晶有显著影响。第二檐口高含水率分布的差异取决于方位，高含水率与劣化程度高度相关。为了定量研究环境因素对水分积累的影响，建立了考虑被测材料物理性质和外壁组成的热湿同步传递二维数值模型。数值计算结果表明，由于原施工人员使用的连接砂浆具有比现代砂浆大得多的水分扩散系数，并且由于墙体形状的原因，墙体底部积聚的水分难以排出，使得入渗雨水容易积聚。在西北地区，风力降雨对雨水积累的影响与上层屋顶径流雨水的影响相似，可能会导致大面积的恶化。此外，验证了2013年西墙外表面复盖抑制劣化措施的效果，并通过数值模型探讨了适当的抑制渗水措施。

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引用次数: 1

WITHDRAWAL— Accidental Duplicate Publication – Editorial volume 41 no 1 (September) 撤回-意外重复出版-编辑第41卷第1期(9月)

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-03-01 DOI: 10.1177/1744259120964188

引用次数: 0

Corrigendum to “The role of water in the behavior of wood” “水在木材性能中的作用”的勘误表

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-03-01 DOI: 10.1177/1744259121989175

引用次数: 0

Factors affecting the performance of ventilation cavities in highly insulated assemblies 影响高度绝缘组件通风腔性能的因素

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-03-01 DOI: 10.1177/1744259121995221

Klaus Viljanen, Xiaoshu Lü, J. Puttonen

The article presents experimental studies of typical Finnish highly insulated (HI) envelopes with thermal resistance values (R value) for the wall and roof inside the ventilation cavity between 7.7 and 8.1 m2K/W and 13 m2K/W, respectively. The conditions in the ventilation cavities were studied by using typical and increased R values for the exterior part of the cavity, which were 0.18 m2K/W and 1.57 m2K/W in the walls, and 0.13 m2K/W and 2.13 m2K/W for the roof. With higher exterior R values of 1.57 m2K/W and 2.13 m2K/W, the cavity temperature increased only after closing the inlet gap of the cavities. If the cavity inlet was closed, the restriction of the outlet gap from 20–25 mm to 10 mm had no significant effect on the temperatures. A closed ventilation inlet resulted in increased absolute humidity in the cavity, which indicates that the restriction of cavity ventilation should be made with care to avoid impairing the drying-out ability. The computational analysis showed that the optimal air change rates in the wall and roof cavities of HI structures were 4–40 1/h and 20 1/h, respectively. The conventional 22-mm-thick wood cladding enables safe cavity conditions in HI walls if the vapor barrier is vapor tight and other moisture sources are low. A lower heat flux and additional heat loss caused by cloudless sky at night support the observation that HI roofs have a higher moisture risk. In HI roofs, a conventional exterior R value of 0.13 m2K/W should at least be increased to the range of 0.3–0.4 m2K/W, which is achieved, for example, by a 20-mm-thick mineral wool board under the roofing. The use of mold-resistant materials in the ventilation cavity is recommended to mitigate the possible ramifications of the moisture behavior of HI roofs.

本文对芬兰典型的高绝热(HI)围护结构进行了实验研究，其通风口内墙体和屋顶的热阻值(R值)分别在7.7 ~ 8.1 m2K/W和13 m2K/W之间。采用典型的外腔R值(墙体R值分别为0.18 m2K/W和1.57 m2K/W，屋顶R值分别为0.13 m2K/W和2.13 m2K/W)和增大后的R值对通风腔内的条件进行了研究。当外部R值分别为1.57 m2K/W和2.13 m2K/W时，腔体温度只有在关闭入口间隙后才会升高。当空腔入口关闭时，出口间隙从20-25 mm限制到10 mm对温度没有显著影响。封闭的通风入口会增加空腔内的绝对湿度，这表明应谨慎限制空腔通风，以免损害干燥能力。计算分析表明，HI结构的最佳换气量分别为4 ~ 401 /h和201 /h。传统的22毫米厚的木材包层可以在蒸汽屏障是气密的和其他湿气源较低的情况下，在HI墙壁中提供安全的空腔条件。较低的热通量和夜间无云的天空造成的额外热损失支持了HI屋顶有较高受潮风险的观察。在高强度屋顶中，传统的0.13 m2K/W的外部R值至少应该增加到0.3-0.4 m2K/W的范围，例如，在屋顶下使用20毫米厚的矿棉板可以实现这一目标。建议在通风腔中使用防霉材料，以减轻HI屋顶潮湿行为的可能后果。

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引用次数: 3

A methodology for hygrothermal modelling of imperfect masonry interfaces 不完善砌体界面的湿热建模方法

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-02-16 DOI: 10.1177/1744259121989388

M. Gutland, S. Bucking, M. S. Quintero

Hygrothermal models are important tools for assessing the risk of moisture-related decay mechanisms which can compromise structural integrity, loss of architectural features and material. There are several sources of uncertainty when modelling masonry, related to material properties, boundary conditions, quality of construction and two-dimensional interactions between mortar and unit. This paper examines the uncertainty at the mortar-unit interface with imperfections such as hairline cracks or imperfect contact conditions. These imperfections will alter the rate of liquid transport into and out of the wall and impede the liquid transport between mortar and masonry unit. This means that the effective liquid transport of the wall system will be different then if only properties of the bulk material were modelled. A detailed methodology for modelling this interface as a fracture is presented including definition of material properties for the fracture. The modelling methodology considers the combined effect of both the interface resistance across the mortar-unit interface and increase liquid transport in parallel to the interface, and is generalisable to various combinations of materials, geometries and fracture apertures. Two-dimensional DELPHIN models of a clay brick/cement-mortar masonry wall were created to simulate this interaction. The models were exposed to different boundary conditions to simulate wetting, drying and natural cyclic weather conditions. The results of these simulations were compared to a baseline model where the fracture model was not included. The presence of fractures increased the rate of absorption in the wetting phase and an increased rate of desorption in the drying phase. Under cyclic conditions, the result was higher peak moisture contents after rain events compared to baseline and lower moisture contents after long periods of drying. This demonstrated that detailed modelling of imperfections at the mortar-unit interface can have a definitive influence on results and conclusions from hygrothermal simulations.

湿热模型是评估与水分相关的腐烂机制风险的重要工具，这些机制可能会损害结构完整性，建筑特征和材料的损失。在砌体建模时，有几个不确定的来源，与材料特性、边界条件、施工质量以及砂浆和单元之间的二维相互作用有关。本文研究了砂浆-单元界面的不确定度，如发际裂纹或不完美的接触条件。这些缺陷将改变液体进出墙体的速率，阻碍砂浆和砌体单元之间的液体输送。这意味着，如果只对散装材料的特性进行建模，那么壁面系统的有效液体输送将是不同的。给出了一种将该界面建模为断裂的详细方法，包括断裂材料特性的定义。该建模方法考虑了砂浆-单元界面上的界面阻力和平行于界面增加的液体输运的综合影响，并可推广到各种材料、几何形状和裂缝孔径的组合。建立了粘土砖/水泥砂浆砌体墙的二维DELPHIN模型来模拟这种相互作用。模型暴露在不同的边界条件下，模拟湿润、干燥和自然循环天气条件。这些模拟结果与不包括裂缝模型的基线模型进行了比较。裂缝的存在增加了润湿阶段的吸附速率和干燥阶段的解吸速率。在循环条件下，降雨事件后的峰值水分含量高于基线，而长时间干燥后的水分含量较低。这表明，砂浆-单元界面缺陷的详细建模可以对湿热模拟的结果和结论产生决定性影响。

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引用次数: 4

Model of thermal buoyancy in cavity-ventilated roof constructions 空腔通风屋面结构热浮力模型

IF 2 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Journal of Building Physics

Pub Date : 2021-02-10 DOI: 10.1177/1744259120984189

T. Säwén, M. Stockhaus, C. Hagentoft, Nora Schjøth Bunkholt, P. Wahlgren

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

木制屋顶建筑通常通过屋顶护套下的空气腔通风，以从建筑中除去热量和水分。这种通风的驱动力是风压和热浮力。风驱动通风已经得到了广泛的研究，而浮力流动的预测模型还不发达。在本研究中，提出了一种新的分析模型来预测通风屋顶结构中由热浮力引起的气流。该模型为顶板施工提供了计算空腔瑞利数的方法，并将空腔瑞利数与风量进行了关联。将模型预测结果与实验和数值研究结果进行了比较，研究了不同空腔设计和倾角对通风屋顶中不同热负荷下空气流速的影响。在80多个不同的测试设置中，分析模型被发现在可接受的范围内复制实验和数值结果。增加屋顶总高度、空腔高度和给定建筑的太阳能热负荷的影响是增加通过空腔的空气流速。平均而言，对于类似的测试设置，分析模型预测的空气流速比数值研究中发现的高3%，比实验研究中发现的低20%。所提供的模型可用于预测不同设计的空腔内的空气流速，并量化建议的屋顶设计变化的影响。研究结果可作为屋面结构防潮安全性评估的依据。

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引用次数: 5