Proposal of a product model for the building trade

Like other industries, the building trade has had to face up to economic crisis. It is crucial for all the interacting parties to design and achieve new practices and methods, allowing them to improve performances as well as the quality of the object to be built, while reducing the costs of building projects. To achieve this, a multiple evolution of the building trade is necessary: a technical evolution which defines a process for improving performances, an organisational evolution which better structures the building project procedure and improves communication between the actors, and finally a human evolution which increases the practical and theoretical background of the parties involved. The research of Laboratoire d'Automatique et de Mécanique Industrielle et Humaine, Université de Valenciennes, particularly concerns the last two points, and aims to define a complete methodology to apply a concurrent engineering approach to the building trade. This methodology includes three stages: the definition of a building project procedure which integrates a concurrent approach, the establishment of a product model; and the design of an integrated computer system for the building trade.     

Application of information technologies in building design decisions

Research and development of a new sophisticated software environment to support building design decisions are presented. This new software, the Building Design Advisor (BDA), is intended as a research tool, teaching aid and, eventually, as a practical professional tool to facilitate both strategic and detailed decision-making throughout the design process from the early schematic phases of building design through to the detailed specification of building components and systems. BDA supports the integrated, concurrent use of multiple simulation tools and databases, while allowing output to support multicriterion judgement. BDA's ultimate aims are to address the data needs of whole building life cycle analysis: design, construction, commissioning, operation, performance and demolition. Cette communication presente les travaux de recherche et de developpement portant sur un nouvel environnement logiciel sophistique destine a faciliter la prise de decisions en matiere de concepts de construction. Ce nouveau ligiciel, denomme Building Design Advisor (BDA), est a la fois un outil de recherche, une aide pedagogique et, finalement, un outil professionnel pratique qui facilite le processus decisionnel strategique et detaille tout au long de la procedure de conception, des la premiere phase d'esquisse de conception d'un batiment jusqu'a la specification detaillee des composants et des systemes de ce batiment. Le BDA est compatible avec l'utilisation integree et simultanee de multiples outils de simulation et de bases de donnees et ses resultats sont compatibles avec des jugements multi-criteres. Les objectifs ultimes du BDA sont d'etudier les besoins en donnees du processus d'analyse du cycle de vie complet d'un batiment: conception, construction, mise en service, exploitation/performances et demolition.     

A green roof model for building energy simulation programs

A physically based model of the energy balance of a vegetated rooftop has been developed and integrated into the EnergyPlus building energy simulation program. This green roof module allows the energy modeler to explore green roof design options including growing media thermal properties and depth, and vegetation characteristics such as plant type, height and leaf area index. The model has been tested successfully using observations from a monitored green roof in Florida. A preliminary set of parametric tests has been conducted on prototypical 4000 m² office buildings in Chicago IL and Houston TX. These tests focus on evaluating the role of growing media depth, irrigation, and vegetation density (leaf area index) on both natural gas and electricity consumption. Building energy consumption was found to vary significantly in response to variations in these parameters. Further, this response depended significantly on building location (climate). Hence, it is evident that the green roof simulation tool presented here can serve a valuable role in informing green roof design decisions.     

Unsteady ceiling jet model for large building spaces

This study describes a method for predicting the performance of a ceiling jet in large building spaces. For applying this method to unsteady cases, the terms of the time differential used in the governing equations and the one-dimensional heat transfers to the ceiling are added to the Alpert′s theory. Moreover, some functions such as the friction force acting against the ceiling and the air entrainment rate are refined. In this method, the domains are divided into multiple control volumes by vertical concentric circular boundaries whose center axis is positioned on the fire source. The profile of the ceiling jet is assumed to be Gaussian, and hence, the average velocities, average gas temperatures, and height of the ceiling jet at each boundary are computed sequentially, considering the influence of the heat loss to the ceiling and the dilution by the air entrainment. In this study, the results of this prediction model are compared to Alpert′s and Heskestad′s practical correlations under steady conditions, and the basic performance of the model is confirmed. Then, the predictions of this model are compared with the measurements by performing a fire experiment in a large building space. The gas temperatures are slightly lower for the predicted results than for the measured data; however, the performance of the model is generally promising.     

The advantages of information management through building information modelling

As building information modelling (BIM) is positioned by governments and construction professionals as a solution to the problems in the construction industry, research is needed into the benefits BIM actually confers. The focus here is on the effectiveness of BIM as a medium for communicating information within a construction team. A case study of an offsite precast concrete fabrication facility was conducted. At the time of the study, the facility was supplying precast units for four public sector projects, and using four information management systems: e-mail, a construction project extranet tool, an Enterprise Resource Planning system and a new BIM-based system. The flow of information through the four media was measured and visualized as the projects progressed. This quantitative measurement of information flow was combined with qualitative data from interviews with facility staff. It was found that the introduction of the BIM-based system diverted information flow through the building model and away from the extranet system. The use of e-mail was largely unaffected. BIM allowed considerably more accurate, on-time and appropriate exchange of information. It is concluded it is possible to quantify some of the benefits of BIM to information management. This research paves the way for future research into the management of more construction project information linked more closely to building models.     

Development and application of a road product model

Product modeling is not a new technology any more, but its use in construction industry is still very rare, even more in the area of road design, construction and maintenance. The paper presents the evolution of a road product model, PMC, from its early concepts in 1993 to the latest implementations and applications. It explains the basic structure of the model and compares the PMC with other existing road models. Some software modules based on the latest version of the PMC road product model are presented. Further the paper presents experiences and findings of a case study, where the model and the relevant software has been tested. The paper concludes with a discussion on effectiveness of the PMC and suggests next steps for a broader acceptance of the presented technology.     

A comprehensive model for streamlining low-energy building design

Building designers are often limited in their ability to reduce the environmental impact of buildings, due to a lack of information on the environmental performance of building components as well as inconsistencies in the way in which this information is derived. Whilst numerous tools exist to help facilitate the low-energy building design process, these typically require large investments of time and money that are often beyond those available within any particular project. This paper describes an approach for streamlining the design process to reduce building life cycle energy consumption. Building assemblies are ranked based on an assessment of the life cycle energy requirements associated with their use within a building. This facilitates early stage assessment, negating the need for a resolved design before the relative energy requirements of alternate design solutions are known. Previous work assessed the initial and recurring embodied energy as well as the operational energy requirements for heating and cooling associated with the use of a range of building assemblies, using a simplified house model. This paper presents a sensitivity analysis of variations to the floor area, shape and orientation of this model, to test the reliability and applicability of the ranking approach across a broad range of circumstances. It was found that these variations did not influence the ranked order of the assemblies in terms of their life cycle energy requirements. Thus, the ranking of assemblies appears to provide an appropriate approach for streamlining the selection of construction elements during the building design process.     

A generic model of Exergy Assessment for the Environmental Impact of Building Lifecycle

A generic model of Exergy Assessment is proposed for the Environmental Impact of the Building Lifecycle, with a special focus on the natural environment. Three environmental impacts: energy consumption, resource consumption and pollutant discharge have been analyzed with reference to energy-embodied exergy, resource chemical exergy and abatement exergy, respectively. The generic model of Exergy Assessment of the Environmental Impact of the Building Lifecycle thus formulated contains two sub-models, one from the aspect of building energy utilization and the other from building materials use. Combined with theories by ecologists such as Odum, the paper evaluates a building's environmental sustainability through its exergy footprint and environmental impacts. A case study from Chongqing, China illustrates the application of this method. From the case study, it was found that energy consumption constitutes 70-80% of the total environmental impact during a 50-year building lifecycle, in which the operation phase accounts for 80% of the total environmental impact, the building material production phase 15% and 5% for the other phases.     

Development of a customer focused strategy in speculative house building

The UK housing industry has been slow to adopt new working practices which have brought improvements in product quality and customer focused operations to many sectors of manufacturing industry. Instead, the dominant business driver has been land and house price inflation, with the market characterized by pronounced boom-and-bust cycles. Reports on the sector often have highlighted the need for research and action aimed at bringing about fundamental changes in its operations, both to satisfy social needs and benefit the companies in the industry. This paper examines the drivers needed for implementing new customer focused business processes in the sector. Of particular importance is the development of a product strategy based on an understanding and analysis of the market. Results are presented from a large market survey that was carried out, and their implications for the industry are discussed.     

Verification tests of a mirror box type artificial sky without and with building scale model

A mirror box type artificial sky for simulating the CIE standard overcast sky has been designed and constructed, while the verification method has been developed and tested. Ratio between the mirror height above the workplane and the room length is 60:133 or 0.451, whereas the ratio between the mirror height above the workplane and the room width is 5:9 or 0.556. Taking the CIE standard overcast sky as reference, indoor illuminance ratios at various elevation angles relative to the zenith is found to be more consistent than luminance ratios. The largest error of illuminance and luminance ratios are respectively 10% and 43%, obtained at 0° elevation angle. Horizontal workplane illuminance values are on average 11,400lx, with illuminance uniformity U₀ and U₁ of respectively 0.92 and 0.86. Based on test results with a building scale model, four out of nine measuring points inside the model have small errors, four have medium error, and one has a large error of 25%. Most of the obtained errors are within the tolerable range of ±21% from the ideal values. Based on the conducted tests, the constructed mirror box type artificial sky is considered appropriate to be utilized for its purpose.     

Optimisation of solar-optical and thermal properties of buildings incorporating solar panels, emulating traditional Chinese building style

A building-integrated solar energy system, based on the traditional Chinese building (e.g., pagoda) - buildings with roofing at intermediate levels (known as eaves) - was investigated, with regard to providing for heating and cooling demands. A number of building parameters, related to energy exchange - solar absorptivity of the exterior wall, level of glazing, etc. - were optimised to minimise demand, and the orientation and tilt of the panels were selected to provide maximum energy at the times of maximum demand. Each parameter was investigated for a range of locations, in order to identify trends, which could then be applied to other locations. In most cases, solar power was sufficient to meet the cooling demands. For a number of locations, solar power provided some, but not all, of the heating loads.     

A graphical method of presenting property rights,building types,and residential behaviors: A case study of Xiaoxihu historic area,Nanjing

One of the main reasons for the decline of urban historic areas in China is the co-existence of multiple property rights. It also deeply affects conservation and regeneration practice. This paper aims to propose a graphical method that illustrates the association between property rights, space, and resident behavior. Based on typological maps and justified graphs, a three-step method was proposed to visualize the relationships between these three elements. The final graph and quantitative data were used to observe the evolution of the courtyard building from a diachronic perspective, as well as to compare the residential behavior in different types from a synchronic perspective. The results show that following the subdivision of property rights, the building layout become more diverse due to various illegal additions, while the residential behavior within different building types tends to be consistent. Moreover, the study observed the traditional Chinese courtyard buildings’ adaptability. The findings contribute to understand the evolution of Chinese urban historic areas and internal motivation, and provide guidance for the conservation and regeneration practice.     

A systematic procedure to study the influence of occupant behavior on building energy consumption

Efforts have been devoted to the identification of the impacts of occupant behavior on building energy consumption. Various factors influence building energy consumption at the same time, leading to the lack of precision when identifying the individual effects of occupant behavior. This paper reports the development of a new methodology for examining the influences of occupant behavior on building energy consumption; the method is based on a basic data mining technique (cluster analysis). To deal with data inconsistencies, min-max normalization is performed as a data preprocessing step before clustering. Grey relational grades, a measure of relevancy between two factors, are used as weighted coefficients of different attributes in cluster analysis. To demonstrate the applicability of the proposed method, the method was applied to a set of residential buildings’ measurement data. The results show that the method facilitates the evaluation of building energy-saving potential by improving the behavior of building occupants, and provides multifaceted insights into building energy end-use patterns associated with the occupant behavior. The results obtained could help prioritize efforts at modification of occupant behavior in order to reduce building energy consumption, and help improve modeling of occupant behavior in numerical simulation.     

A personalized measure of thermal comfort for building controls

A personalized measure for thermal comfort has been applied for use in combination with smart controls for building automation. Using data from a field study, we first show the superiority of personalized measures for thermal comfort compared to standard non-adaptive methods. Based on this knowledge we describe a methodology, using logistic regression techniques, to convert user votes to a probability of comfort. We also describe the interface used to collect the votes. We show that, for a given subject, our thermal profile converges against the probabilities found in the field study. As a case study we implemented the measure in a control algorithm to control the shading devices. The results clarify the mode of action and also show the effectiveness of the method.     

A primer on the building economics of climate change

Climate change will entail new conditions for the construction industry. Knowledge about the implications of climate change on the built environment will be of the utmost importance to the industry in years to come. A building is a ‘long lasting’ durable asset that is changed over time due to exogenously imposed strains and by actions. The built environment has an expected lifetime varying from 60 to more than 100 years. Hence, the building economics of climate change should be treated within a dynamic analytical framework that explicitly allows for changes in the information sets over time. The building stock of the future consists of the building stock of today and of new construction. In the future, parts of the present building stock will be adapted to changes in the environment, while some parts will be kept as they are. Analysis of how building stock is affected by future climate change should handle this diversity. This can be done through the use of a putty-clay model. Uncertainty of what kind of climate regimes will prevail in the future enhances the profitability of actions that increase future flexibility. Hence, the real option approach to building economics is utilized.     

Numerical simulations of wind-driven rain on building envelopes based on Eulerian multiphase model

A numerical simulation approach for evaluation of wind-driven rain (WDR) on building envelopes is presented based on Eulerian multiphase model. Unlike existing methods, which are generally on the basis of Lagrange frame to deal with raindrop motions by trajectory-tracking techniques, the present approach considers both wind and rain motions and their interactions under Euler frame. By virtue of the Eulerian multiphase model, the present method could significantly reduce the complexity in evaluations of WDR parameters, simplify the boundary condition treatments and is more efficient to predict transient states of WDR, spatial distributions of rain intensity, impacting rain loads on building surfaces, etc. A numerical example shows that the simulation results by the present method agree well with available experimental and numerical data, verifying the accuracy and reliability of the WDR simulation approach based on the Eulerian multiphase model. It is also demonstrated through the validation example that the present method is an effective tool for numerical evaluations of WDR on building envelopes.     

Energy efficient surfaces on building sandwich panels—A dynamic simulation model

The choice of building envelope is critical for the energy performance of buildings. The major part of the energy used by a building during its lifetime is used for maintaining a suitable interior thermal climate under varying exterior conditions. Although exterior heat radiation properties (i.e. total solar reflectivity and long wave thermal emissivity) have been well accepted to have a large impact on the need for active cooling in warmer climate, the effect of a reduced thermal emissivity on interior surfaces on the building thermal energy flux is rarely studied. This paper addresses the sensitivity of the thermal energy flux through a sandwich panel, by systematically varying the surface thermal emissivity (both interior and exterior) and total solar reflectance of exterior surface, for three geographical locations: southern, middle and northern Europe. A model is introduced for calculating the effect of both interior and exterior optical properties of a horizontal roof panel in terms of net energy flux per unit area. The results indicate potential energy saving by the smart choice of optical properties of interior and exterior surfaces.     

A combined CFD-HAM approach for wind-driven rain on building facades

Numerical heat-air-moisture (HAM) transfer models are increasingly being used to study the hygrothermal performance and the durability of building facades. One of the most important boundary conditions for HAM simulations is wind-driven rain (WDR). Due to the complexity of WDR, however, the current HAM models generally incorporate it in a very simplified way. Recent research has shown that CFD can provide quite accurate estimates of the spatial and temporal distribution of WDR on building facades. Therefore, in this paper, a combined CFD-HAM approach is presented. It consists of implementing catch-ratio charts resulting from CFD simulations into the HAM model. Within the model, these charts are used to convert the standard meteorological input data (wind speed, wind direction and horizontal rainfall intensity) into WDR distribution records that are used as boundary condition for the actual HAM simulations. The combined approach is demonstrated for a simplified wall model. It is shown that the accuracy of the HAM-simulation results is to a large extent determined by the time resolution of the meteorological input data and by the data-averaging technique used for these data. Some important guidelines for accurate HAM analyses with WDR are provided.     

The impact of information on perceived air quality--'organic' vs. 'synthetic' building materials

As indoor air quality complaints cannot be explained satisfactorily and building materials can be a major source of indoor air pollution, we hypothesized that emissions from building materials perceived as unfamiliar or annoying odors may contribute to such complaints. To test this hypothesis, emissions from indoor building materials containing linseed oil (organic) and comparable synthetic (synthetic) materials were evaluated by a na?ve sensory panel for evaluation of odor intensity (OI) and odor acceptability (OA). The building materials were concealed in ventilated climate chambers of the CLIMPAQ type. When information was provided about the identity and type of building material during the evaluation, i.e. by labeling the materials in test chambers either as 'organic' or 'synthetic', the OI was significantly lower for all the 'organic' materials compared with evaluations without information. Similarly, OA was increased significantly for most 'organic' samples, but not the 'synthetic' ones. The major effect is probably that OA is increased when the panel is given information about the odor source. PRACTICAL IMPLICATIONS: As providing information about the source of odors can increase their acceptability, complaints about indoor air quality may be decreased if occupants of buildings are well informed about odorous emissions from the new building materials or new activities in their indoor environment.