Probabilistic transition of condition: render facades

The service life of cement-rendered facades is closely related to the environmental conditions to which they are exposed. The probability distribution is determined for the degradation condition of render facades considering different environmental exposures. A sample of 100 render facades was subjected to meticulous fieldwork to determine their condition. The analysis focuses on the environmental factors that most influence the overall degradation of the facades, evaluated through the condition level. Probabilistic models based on Markov chains are developed to predict the evolution of facade deterioration according to exposure to outdoor environmental conditions. The proposed model provides data on the synergy between the degradation agents and the degradation condition of render facades, the average time of permanence in each degradation level, and indications of the effect of degradation on the durability of render that may be applied in the implementation and fine-tuning of maintenance procedures. A better understanding of the durability of render facades allows a more rational management of their maintenance, contributing to a reduction of their life cycle costs. The proposed stochastic model provides information that can be applied in the context of insurance policies, allowing an evaluation of the risk of failure of coatings.     

Serviceability of facade claddings

In the present world economic situation, the resources directed to the maintenance of buildings are very limited. Therefore, an increasing concern arises for the planning and prioritization of necessary maintenance works during buildings’ life cycle. The planning of maintenance action is achieved by predicting the moment when construction elements reach degradation levels that exceed acceptable standards. To be able to make such forecasts, crucial developments must be made regarding the methods to predict the serviceability of building materials and components. In this study, 444 facades located in the cities of Lisbon and Almada and the Algarve region (Portugal) are analysed based on in situ visual inspections. The approach proposed can be employed in various scopes of service life prediction and maintenance of constructions. This paper develops a priority hierarchy of maintenance actions for the claddings under analysis. The expertise acquired in buildings’ serviceability is very useful to support decision-making in the development of proactive maintenance strategies. The results reveal accurate outcomes in the correlation with the functionality and degradation parameters of facade claddings. The serviceability of the most common types of facades claddings (render, ceramic and paints) applied in Portugal is analysed.     

Quantifying environmental effects on cement-rendered facades: A comparison between different degradation indicators

The purpose of this research is to assess and quantify the environmental effects on cement-rendered facades in real-life service conditions. A holistic approach is proposed based on the assessment of the visual impact of the actual climatic environment that affects the aesthetic performance and durability of 19 cement-rendered facades located in Lisbon, Portugal. Different degradation indicators are presented and a deterioration path is identified, which points out to the possibility of modeling the overall degradation of facades in similar building and environmental conditions. Although the proposed method reflects the Portuguese building context, it can be easily adapted to other countries and expanded to include various cladding solutions, so that their remaining service life can be integrated in the existing commercial methodologies for service life prediction and asset management.     

Fire Performance of External Thermal Insulation Composite System (ETICS) Facades with Expanded Polystyrene (EPS) Insulation and Thin Rendering

External Thermal Insulation Composite System (ETICS) facades with expanded polystyrene (EPS) insulation and thin rendering are applied frequently in buildings. Considering high combustibility of EPS, with these facades concerns also arise regarding spread of a possible fire between neighbouring compartments of high-rise buildings. Fire tests of two large-scale facades were performed to study two parameters presumably influencing significantly the fires of such facades in real-life settings, i.e. incident heat flux upon the facade’s surface (IHFFS) and damage of the facade’s render (the latter being a consequence of poor or unfinished construction work, ageing or fire-induced thermal strain). The first facade was rendered fully and was exposed to moderately-fast increasing IHFFS. In the second (partially unrendered) facade case the IHFFS progressed faster. The facade flame body (temperatures and shape) was monitored by thermocouples, photo and video cameras. For detection of melting of EPS and internal burning, thermocameras were used within the facades areas outside the visible plume. In the plume zone, however, a group of thermocouples was embedded inside EPS and the shapes (plateaus and slopes) of the collected time-temperature graphs were observed for these purposes. The IHFFS imposed on the facades during fire testing were estimated by numerical calculations. In both cases the first pronounced render crack was evolved at the estimated average between-windows IHFFS of around 30 kW/m\(^2\) and was followed by internal burning of EPS. While the latter did not seem to spread across the facade for the fully-rendered facade, a fast fire spread was detected for the second specimen.     

双层幕墙建筑全生命周期评价

随着绿色建筑研究的深入,从全生命周期(LCA)角度评价建筑成为必然,这就要求对建筑物整个生命周期内各阶段消耗的资源和产生的环境负荷进行全面评估。该文以全生命周期的观点评价双层玻璃幕墙,提出双层幕墙的经济成本和环境效益的计算方法,并以杭州地区的应用为案例,分析双层幕墙建筑在该地的适用性。     

Solar control: A general method for modelling of solar gains through complex facades in building simulation programs

This paper describes a new general method for building simulation programs which is intended to be used for the modelling of complex facades. The term ‘complex facades’ is used to designate facades with venetian blinds, prismatic layers, light re-directing surfaces, etc. In all these cases, the facade properties have a complex angular dependence. In addition to this, such facades very often have non-airtight layers and/or imperfect components (e.g. non-ideal sharp edges, non-flat surfaces, …). Therefore building planners often had to neglect some of the innovative features and to use ‘work-arounds’ in order to approximate the properties of complex facades in building simulation programs. A well-defined methodology for these cases was missing. This paper presents such a general methodology.The main advantage of the new method is that it only uses measureable quantities of the transparent or translucent part of the facade as a whole. This is the main difference in comparison with state of the art modelling based on the characteristics of the individual subcomponents, which is often impossible due to non-existing heat- and/or light-transfer models within the complex facade.It is shown that the new method can significantly increase the accuracy of heating/cooling loads and room temperatures.     

Optimal operation of a south double-skin facade

There is an increasing demand for higher quality office buildings. Occupants and developers of office buildings ask for a healthy and stimulating working environment. Double-skin facades are appropriate when buildings are subject to great external noise and wind loads. A further area of application is in rehabilitation work, when existing facades cannot be renewed, or where this is not desirable. Double-skin facades have a special esthetic of their own, and this can be exploited architecturally to great advantage. However there are still relatively few buildings in which double-skin facades have actually been realized, and there is still too little experience of their behaviour in operation. In this matter, we choose to study a multistory double-skin facades behaviour. Simulations were realized with TAS software on the building proposed in the frame of the subtask A of the Task 27 (performance of solar facade components) of the International Energy Agency. Simulations were performed on the chosen building with and without double-skin facades. We decide to study eight types of days; and we analyze the double-skin facade behaviour for various operations. The thermal behaviours of the building with and without double-skin are compared. The study of these eight cases showed the importance of the dynamic use of the double-skin. The operation of this one must be obligatorily related to the climatic conditions as well external as interior and a bad operation of the double-skin could lead to catastrophic results.     

Modular responsive facade proposals based on semi-regular and demi-regular tessellation: daylighting and visual comfort

Responsive facades can reduce building energy consumption and control daylight and natural ventilation to improve user comfort. This study aims to develop alternative responsive facade systems based on semi-regular and demi-regular tessellations. For this purpose, first, the tessellation method used to generate responsive facades is introduced. Then, the geometric and parametric design principles and the movement capabilities of the proposed facade systems are presented. Finally, a set of analyses are performed to test and compare the performances of the facade systems based on daylight metrics and indoor glare comfort. This study contributes to the literature with the proposed facade systems that can adapt to changing environmental conditions, provide flexibility in shape control and simplicity in mechanism design, and improve building performance. The analysis results show that all the proposed facade systems provide the desired visual comfort and daylight levels at different configurations.     

以哈尔滨为例探究建筑外立面形象塑造意义

简述了建筑外立面与建筑形象的含义,以哈尔滨的城市建筑为例,针对目前建筑外立面形象塑造的现状,分析了影响建筑外立面设计的因素,并对建筑外立面形象塑造的意义及其发展趋势作了研究,为建筑的装饰设计提供了理论依据。     

Statistical models applied to service life prediction of rendered façades

An approach to the evaluation of the service life of rendered façades applying statistical tools is described. Using multiple linear regression analysis and artificial neural networks, mathematical models are established to estimate the degradation of this type of coating. To devise the models proposed, a sample of 100 rendered façades was subjected to meticulous field work to determine their condition. Some statistical parameters are used to evaluate the validity and efficacy of the models proposed. The service life of the sample of rendered façades is also evaluated, as estimated by the various models, and the result is expressed in histograms. The usefulness of these models to evaluate complex problems, such as the degradation phenomena of rendered façades, is thus demonstrated.     

BuildingsLife: a building management system

The financial resources available for infrastructure maintenance and rehabilitation are always limited, which creates a need for efficient resources' management and for the ability to predict maintenance actions throughout the infrastructure's service life. In the context of bridges, management systems have been developed and are already implemented around the world. A much larger variety of maintenance problems and a reduced number of buildings per owner mean that building management systems (BdMSs) are still quite rare. Actually, efficient methods for the service life prediction of building materials still need to be developed. This paper discusses the service life prediction methods used in building components based on deterministic, stochastic or engineering methods. The architecture of a recently developed BdMS – BuildingsLife – is presented, where the service life analysis of components is based on an initial statistical analysis of anomalies obtained from the inspection of in-use buildings. This method analyses the corresponding degradation through the use of deterministic and stochastic models.     

Thermal behaviour of a ventilated double skin facade in hot arid climate

Modern Movement in architecture has resulted in a large number of high-rise buildings with glazed facades which increase the energy load of the buildings. To combat this phenomenon in colder climates, architects have turned to using double skin facades. These facades comprise of: a completely transparent external facade; an internal skin; and an air layer between the two. Research on the performance of double skin facades mostly considers cold and moderate climates. In addition, data collection is normally based on simulations, rather than actual field measurements. In this paper a building with double skin facade was monitored for 2 weeks in summer and 2 weeks in winter in the hot arid climate of Iran, in order to observe the behaviour of the facade both in hot and cold conditions. Additionally, simulations were performed on the case study building with and without double skin facade, to assess the effectiveness of the facade. The results revealed that the temperature difference between the outer skin, the inner skin and the cavity can significantly save heating energy in winter. To reduce the cooling loads in summer it is essential to introduce additional techniques such as night ventilation and installation of shading devices for the cavity.     

Natural ventilation in a double-skin facade

Double-skin facades are assuming an ever-greater importance in modern building practice. There is an increasing demand for higher quality office buildings. Occupants and developers of office buildings ask for a healthy and stimulating working environment.Double-skin facades are appropriate when buildings are subject to great external noise and wind loads. A further area of application is in rehabilitation work, when existing facades cannot be renewed, or where this is not desirable. Double-skin facades have a special aesthetic of their own, and this can be exploited architecturally to great advantage.However, there are still relatively few buildings in which double-skin facades have actually been realized, and there is still too little experience of their behavior in operation.In this matter, we choose to study the natural ventilation in multi-storey double-skin facades. Simulations where realized with TAS software on a building proposed in the frame of the subtask A of the Task 27 (performance of solar facade components) of the International Energy Agency, Solar Heating and Cooling Program.We decide to study a sunny summer day; and we analyze the double-skin facade behavior for various conditions: impact of the double-skin orientation and impact of the wind orientation and the degree of wind protection.     

工业建筑的艺术化表达——广州市粮食储备加工中心项目设计

以广州市粮食储备加工中心项目为实例,通过对粮食仓储加工类工业建筑外立面处理方式的研究,探讨在工业建筑立面设计中强化企业形象的可能性,将企业形象通过艺术化的表达应用在工业建筑的立面设计中,并由此提出在工业建筑创作时应持的态度。     

开洞矩形截面超高层建筑局部风压风洞试验研究

基于一栋立面上有多个开洞的矩形截面超高层建筑的刚性模型表面压力测量风洞试验结果,分析了矩形截面超高层建筑在长边立面上不同开洞工况下建筑各表面平均风压系数和最不利风压系数的变化规律。试验结果表明:当建筑长边迎风时,开洞使得背风面洞口附近的平均风压系数绝对值增大,但迎风面上的平均风压系数变化很小;当建筑短边迎风时,开洞对洞口附近的平均风压系数和最不利正风压系数均只有微弱影响,但对其最不利负风压系数却有很大影响,特别是中部开洞,将使其周围的最不利负风压系数增大一倍以上;开洞对短边立面上的最不利风压系数不产生明显的影响。为有结构开洞的高层建筑洞口附近的围护结构设计提供了参考数据。     

Wind-driven rain on the facade of a monumental tower: Numerical simulation,full-scale validation and sensitivity analysis

Wind-driven rain (WDR) is one of the most important moisture sources that affect the hygrothermal performance and the durability of building facades. The facades of the Dutch monumental building St. Hubertus show severe deterioration caused by WDR. Assessment of the amount and intensity of WDR falling onto the facades is necessary as input for numerical heat-air-moisture (HAM) transfer models to analyse the causes of the moisture problems and the impact of remedial measures. In this study, a numerical simulation method based on Computational Fluid Dynamics (CFD) is used to predict the amount of WDR impinging on the south-west facade of the tower of the building. The paper focuses on the numerical simulation results, the validation of these results and their sensitivity to two parameters: the level of geometrical detailing of the computational building model and the upstream terrain aerodynamic roughness length. Validation is performed by comparison of the numerical results with a dataset obtained from on-site WDR measurements. It is shown that the CFD simulations provide fairly good predictions of the amount of WDR impinging on the south-west facade of the tower, except for the lower part. It is also shown that the local effects of geometrical facade details are significant and can yield differences in WDR exposure up to 40%, while their effect at other positions is negligible. Finally, the sensitivity of WDR simulations to the upstream aerodynamic roughness length is discussed.     

双幕墙长矩形建筑风荷载特性的试验研究

以节能、生态为理念的双幕墙围护体系已逐步应用于高层办公建筑中。由于双幕墙之间存在通风廊道,因此对于双幕墙建筑有三个受风表面,即外层幕墙的内表面和外表面以及内幕墙的外表面,这使得风载取值变得复杂,目前也无规范可依。本文通过对杭州市某双幕墙办公楼的风洞试验研究,探讨了双幕墙建筑内、外层幕墙的风载取值问题;研究了门厅大跨挑篷风压分布特征,当风从侧面吹向挑篷时,挑篷上、下表面风载与普通屋盖挑篷相同,而当风从正面吹向挑篷时,挑篷上表面出现正风压,并对此现象进行了分析;文中针对该建筑物长宽比较大的特点,比较了大长宽比矩形建筑风载体型系数与规范给出的正方形建筑风载体型系数:当风沿建筑物长向流动时,采用规范给出的正方形建筑风载体型系数是可行的,当风沿建筑物进深方向流动时,其两侧及背风面的负压比正方形的大。     

Responsive envelope tessellation and stochastic rotation of 4-fold penttiles

This paper reports on the design and control of a responsive envelope based on the rotation of tessellated components. The study investigates responsive and dynamic approaches for building facades and envelopes to regulate solar shading, light control, views and thermal gain within the building. It is well known that near real-time visual output from computational simulation can significantly impact the prediction of dynamic building-environment interactions and lead to the development of smart, adaptable, net zero energy buildings. To address these motivations, this paper reports the development of an experimental simulation of a responsive envelope based on using a 4-fold penttile scheme. The simulation is developed using a novel pentagonal approach involving component (tile) design, tessellation and control methods. The paper further elaborates on the geometry and control aspects of the facade subdivision and presents the results of applying this tessellation geometry to a building envelope shading study based on facade components with rotation. Finally, it tests the “responsiveness” to multiple performance metrics by applying a non-deterministic exploration method for the stochastic rotation of individual panels. The sophisticated evaluation of alternative envelope configurations for a set of performance criteria require a tighter computational coupling between modelling and control of dynamic geometry.     

A low environmental impact anidolic facade

The building of the Solar Energy Laboratory (LESO) of the Swiss Federal Institute of Technology of Lausanne was erected in 1981 to allow “in situ” testing of experimental solar facades. In 1998, the building was the object of a significant restoration and a new southern facade was designed and built following the principles of sustainable development. This article describes the principles that guided this work, and presents the results obtained with regard to energy consumption, flow of matter, daylight, comfort and, lastly, a detailed life cycle assessment analysis: the various environmental impacts related to the construction, exploitation and maintenance of the facade are presented and discussed.     

Service life prediction of exterior cladding components under standard conditions

An empirical method was developed for the prediction of the service life of building components, based on an evaluation of their actual performance and on the identification of failure mechanisms affecting their durability. The service life of exterior components subjected to normal service conditions is predicted. Four types of exterior claddings are exemplified: cementitious mortar, synthetic rendering, ceramic mosaic, and wet‐fixing stone cladding. The proposed prediction models yield high degrees of fit to the data (R ² in the range of 0.86 to 0.93 at a 0.0001 level of significance). Life cycle costs (LCC) analysis – following service‐life prediction results – leads to the conclusion that maintenance and replacements costs account for 10–80% of initial capital costs. Synthetic rendering exhibited the highest LCC effectiveness, reflecting durability and low capital costs. The method can be used for planning preventive maintenance, evaluating economic implications of failures, and planning service life.