Analysing the impact of reflectance distributions and well geometries on vertical surface daylight levels in atria for overcast skies

This study investigated the impacts of different diffuse reflectance distributions and well geometries on vertical daylight factors and vertical internally reflected components in atria. Two forms of reflectance distribution patterns of wall surface were examined: horizontal and vertical reflectance band variation. The square atrium models studied have a broader WI range of 0.25–2.0, which represent shallow, medium and high atria. Radiance, a powerful package based on backward ray tracing technique, was used for the simulations of vertical daylight levels. The results show that different reflectance distributions of square atrium walls do have an impact on the vertical daylight factors and vertical internally reflected components under overcast sky condition. The impact relates to the orientation of the band with different reflectance distributions on the wall. Compared with the vertical band surface, the horizontal band surface has a much more complicated effect. The horizontal distributions of the reflectances significantly affects the vertical daylight levels at the locations more than 30% atrium height on the wall. For an atrium with a height more than 1/2 the width, the effect tends to increase with the increasing well index. The vertical distributions of the reflectance, nevertheless, do not substantially take effect on the vertical daylight levels in atria except for some special reflectance distribution patterns.     

Comparative analysis of energy performance between courtyard and atrium in buildings

In this paper, the energy performance of a central atrium is investigated and compared with the energy performance of a courtyard with the same geometric proportions. The atrium and the courtyard design used for the analysis are square in plan and surrounded by the building on all four sides. The glazing type and percentage for the courtyard walls and atrium skylight are varied in the analysis. Weather data from four cities representative of climatic conditions of cold, temperate, hot-humid and hot-dry were used. The results show that, in general, the open courtyard building exhibits a better energy performance for the shorter buildings. As the building height increases, however, at some point the enclosed atrium exhibits a better energy performance. This “break even” point for the number of stories depends on different factors like glazing and climate parameters discussed above.     

Prospective techniques of effective daylight harvesting in commercial buildings by employing window glazing, dynamic shading devices and dimming control—a literature review

Over a few decades, daylighting has been perceived to possess good potential for energy conservation. In this perspective, there have been significant advances in research methodologies and technologies for optimizing energy consumption through daylight harvesting in commercial buildings. In light of this, a thorough understanding of the application of available technology is very important for daylighting practices for building energy management. The objective of this paper is to examine the status of published research on three key building parameters: window glazing area, dynamic shading devices, and daylighting controls playing a rule on energy conservation. This article may serve as a coherent literature survey that would provide better understanding of the subjacent issues and possibly rejuvenate research interest in this immensely potential field of energy engineering.     

Mathematical modeling and experimental study on vertical temperature distribution of hybrid ventilation in an atrium building

An extended Gebhart-Block model for large space buildings is proposed in this paper, which is used to predict the vertical temperature distribution of hybrid ventilation. Natural ventilation coupled with air-conditioning is described with a mathematical model. The indoor thermal environment formed by the air-conditioning and the natural ventilation can also be conducted for the potential analysis and optimal use of the natural ventilation. Experiments were carried out in an atrium building in Shanghai Research Institute of Building Sciences. This paper describes aforementioned model, and it is found that the calculation results implying this model agree well with the measurement data.     

Visitors' perceptions on the important factors of atrium design in shopping centers: A study of Gandaria City Mall and Ciputra World in Indonesia

Atriums as quasi-internal public spaces in shopping centers play an essential role as an identity provider and offer spatial orientation in shopping center architecture. This study aims to examine the significant factors of atrium design, which can provide a sense of place for shopping center visitors. The research was conducted with the sequential exploratory method, which involved a qualitative study, followed by a quantitative study. The objects of this research weret wo shopping centers located in the two largest cities in Indonesia, namely, Gandaria City Mall in Jakarta and Ciputra Worldin Surabaya. A total of 43 informants were a part of the qualitative data collection, and 350 respondents served as survey participants. The survey research shows that the design factors considered by visitors at the Gandaria City Mall are atrium legibility, atrium decoration, event decoration, social image and interaction, and event ambience, whereas the visitors at Ciputra World considered atrium legibility, socia limage and interaction, atrium ambience,and atrium decoration.     

Evaluation of buoyancy-driven ventilation in atrium buildings using computational fluid dynamics and reduced-scale air model

This research focuses on developing a reliable methodology for predicting the performance of buoyancy-driven ventilation in atrium buildings during the design stage using both computational fluid dynamics (CFD) and scale model tests. The results show several features. First, the agreement between CFD simulation and measurement results in the heated zone is better with rng k–? and zero-equation turbulent schemes; whereas, in the atrium space, the laminar and zero-equation CFD models provide better results. Second, the external ambient temperature has a larger effect on the temperature distribution in the atrium space than the thermal load inside the building. Third, the position of the stack openings that create a direct ventilation path can improve the internal thermal environment. The size of the stack openings also affects the temperature distribution in the atrium space. Lastly, due to the small temperature difference in hot and humid climates, a buoyancy-only ventilation strategy is not very effective in such a situation. That is, when a low-rise atrium building is situated in a hot and humid environment, additional efforts such as wind-driven ventilation, wind-buoyancy ventilation or mechanically driven ventilation will be necessary to achieve the thermal comfort desired.     

多因素下居民室内天然气泄漏扩散数值模拟

住宅天然气的意外泄漏会对居民造成重大威胁.利用CFD方法模拟分析典型住宅天然气泄漏的燃爆区域影响因素等扩散规律,重点评价了自然通风对减少爆炸风险的作用,并通过实验对模拟结果进行了验证.模拟结果表明:易燃云在空间上部堆积并蔓延到相邻的房间,自然通风是防止天然气积聚、降低泄漏风险的有效方法.     

控制因素指导下的肌理操作--以莱州云峰山文化旅游产业区规划设计为例

肌理是城市空间形态的重要表征,本文以莱州云峰山文化旅游产业区规划设计为例,从肌理操作的角度,阐述提炼原有肌理的空间模式,结合控制因素的用地规划,剖析原有肌理重塑等思考成果,深入探索了肌理操作的模式和可行性。     

不排水条件下黏性土地基承载力系数N_c值的计算与工程应用

为了使黏性土地层地基承载力计算和基坑稳定性分析能够考虑基础形状和深度影响,给出了一个计算地基承载力系数N_c值的近似解析计算方法,可以把不同形状和埋深基础的承载力统一在一个公式中计算。如果对塑性区深度作适当调整,可以使计算结果非常接近试验值和现场数据的调查结果。依据该方法,可证明地基承载力计算时采用的N_c值与基坑稳定性分析时采用的N_c值是同一的。基于该方法,可以使Terzaghi的抗隆起稳定分析方法能够考虑围护结构插入深度的影响;同时,文章也给出了一个浅基础承载力系数的近似估算方法。     

Reliability based determination of material partial safety factors for cast iron beams in jack arched construction exposed to standard and natural fires

Cast iron beams were extensively used in many 19th century structures, especially in fireproof flooring systems (such as jack arch). Many such structures are still in use today and it is important that they fulfil the current requirements of fire resistance when there is a change of use. These structures are out of scope of modern design codes and old design codes do not provide guidance for fire resistance design. Furthermore, cast iron is a brittle material weak in tension, and there are many uncertainties in its mechanical properties at ambient and elevated temperatures due to material flaws. It is necessary to quantify the probability of structural failure and to introduce safety factors to reduce the probability of structural failure in fire to an acceptable level. This paper presents the results of a detailed study whose purpose is to derive appropriate safety factors to achieve different levels of reliability, for fire safety design of cast iron beams. In this study, a fibre analysis method has been used to calculate the moment capacity of four different types of cast iron cross section. Using randomized stress-strain-temperature relationships, based on variability of the different governing parameters (under tension: maximum stress, 0.2% proof stress, corresponding strains at maximum stress (strength) and failure; under compression: Young's modulus, proportional limit, 0.2% proof stress and the maximum stress), the probability distribution of moment capacity has been calculated. Based on the criterion of cast iron beam failure not exceeding probabilities of 10⁻¹, 10⁻² and 10⁻³, material safety factors of 1.5, 3.0 and 5.0 respectively have been obtained.