A Bayesian Network approach to the evaluation of building design and its consequences for employee performance and operational costs

A Bayesian Network approach has been developed that can compare different building designs by estimating the effects of the thermal indoor environment on the mental performance of office workers. A part of this network is based on the compilation of subjective thermal sensation data and the associated objective thermal measurements from 12,000 office occupants from different parts of the world. A Performance Index (Π) is introduced that can be used to compare directly the different building designs and furthermore to assess the total economic consequences of the indoor climate with a specific building design. In this paper, focus will be on the effects of temperature on mental performance and not on other indoor climate factors. A total economic comparison of six different building designs, four located in northern Europe and two in Los Angeles, USA, was performed. The results indicate that investments in improved indoor thermal conditions can be justified economically in most cases. The Bayesian Network provides a reliable platform using probabilities for modelling the complexity while estimating the effect of indoor climate factors on human beings, due to the different ways in which humans are affected by the indoor climate.     

A practical approach to in-situ evaluation of surface-treated structures

This paper describes the result of a field evaluation carried out to ascertain the effectiveness of hydrophobic and consolidating treatments applied to the surfaces of three historic buildings and monuments in the UK. The surface treatments were 7–18 years old at the time of testing. The field trials were carried out using a simple but practical suite of complementary and wholly non-destructive test methods. The methods, procedures and criteria used for assessing the performance of surface treatments used were developed from an EC sponsored laboratory and site test programme carried out on stones representing those used in the construction of monuments across Europe. This approach has been shown to provide useful, early warning information to owners of historical or modern structures, which will enable them to make an informed decision regarding when to treat a deteriorated surface or the need to re-treat an already treated but subsequently weathered surface. The results obtained suggest that the treatments applied on some of the tested structures have deteriorated to the extent that it is now time to consider re-treatment.     

A performance-based approach to project assignment and performance evaluation

Project assignment and performance evaluation have been addressed as two important and separate research issues in project management. This paper develops a new performance-based approach for integrating the project assignment and the performance evaluation processes in a project-based organization. An objective-oriented preference-based assignment process is developed to assign a project to a project manager. An optimal project assignment model is developed to maximize the total weighted contribution value of all new projects to the organizational objectives. An efficiency-based evaluation process is developed using data envelopment analysis to measure the relative performance efficiency of the completed projects and of the project managers. The approach provides a proactive mechanism for facilitating objective-focused management of projects. The outcomes of an empirical study conducted provide managerial insights in assigning projects to project managers and in evaluating the performance efficiency of both projects and project managers.     

Building signatures: A holistic approach to the evaluation of heating and cooling concepts

A sustainable and environmentally responsible building concept aims at a high workplace comfort, a significantly reduced heating and cooling demand, a high-efficient plant system, and the use of renewable energy sources to condition the built environment. This paper presents a comprehensive analysis of the heating and cooling concepts of 11 low-energy buildings in terms of energy use, efficiency and occupant thermal comfort. All buildings investigated employ environmental energy sources and sinks – such as the ground, ground water, rainwater and the ambient air – in combination with thermo-active building systems. A limited primary energy use of about 100 kWh_prim/(m²_neta) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, a comprehensive long-term monitoring in high time resolution was carried out for two to five years, with an accompanying commissioning of the building performance. Measurements include the useful heating and cooling energy use, auxiliary energy use for the hydraulic system, as well as end and primary energy use, occupant thermal comfort and local meteorological conditions. A new methodology is proposed for a holistic approach to the evaluation of heating and cooling concepts, which not only considers the occupants thermal comfort, but also the useful energy consumption and the efficiency of the generation, distribution and delivery of heating and cooling energy.     

Galloping stability of triangular cross-sectional bodies: A systematic approach

One of the classical aeroelastic instabilities of slender structures is galloping, which can be characterized as a low-frequency, large-amplitude normal to the flow oscillations phenomenon. In this paper, the transverse galloping stability of triangular cross-section bodies has been systematically analyzed (up to now, most of the effort in galloping oscillation research has been concentrated on bodies with square or rectangular cross-sections). To perform such analysis, first, the Glauert–Den Hartog criterion for galloping instability was used through wind tunnel static tests. Then, another series of wind tunnel dynamic tests was realized to determine the transversal cross-section displacements as a function of the incident wind velocity. The results from these dynamic tests are in very good agreement with the results obtained from the static ones. Finally, information on the flow morphology needed for the physical interpretation of the results was obtained by measuring the pressure distribution along the body surfaces.     

Optimising the installation costs of renewable energy technologies in buildings: A Linear Programming approach

This paper demonstrates how Linear Programming (LP) can be applied to assist in the choice of renewable energy technologies for use in buildings to meet CO₂ emissions reduction targets. Since there are many possibilities for combining different renewable technologies, the capital costs associated with the installation of one or more renewables can vary widely. In terms of capital investment the preferred solution will be the one at least cost, and LP provides an effective way to find this minimum through the so-called “objective function”. This project has used “lp_solve”, a free-source Mixed Integer Linear Programming solver that has been embedded in a Microsoft Excel application called Carbon emissions And Renewables for Building OPtimisation Toolkit (CARB-OPT) developed by RES Ltd in collaboration with London South Bank University (Renewable Environmental Services Ltd. (RES) is the environmental consultancy of Long and Partners Engineering Group. RES is currently involved in a Knowledge Transfer Partnerships (KTP) project in conjunction with the Faculty of Engineering, Science and the Building Environment (ESBE) at London South Bank University). This paper reports the application of this LP optimisation process for an office building case study with four alternative combinations of renewables. The process showed the technology mix that would lead to the smallest investment needed to comply with UK Building Regulations requirements and regional planning targets. In addition, the process offers a robust methodology to test the impact that the key assumptions may have upon the optimum solution.     

A socio-technical approach to post-occupancy evaluation: interactive adaptability in domestic retrofit

Understanding the process of domestic retrofit is important for learning and innovation. This is particularly the case for low carbon retrofits such as those undertaken under the UK's Retrofit for the Future (RftF) programme, with its aim to achieve an overall 80% carbon reduction by 2050. Current post-occupancy evaluation (POE) research has both theoretical and methodological limitations with implications for technical and behavioural research in the built environment. Drawing on relevant ideas and concepts from social practice theory and science and technology studies, principally prefiguration (constraints/enablement), black-boxing, heating and cooling practices, this paper demonstrates how the relationship between buildings and people could be reconceptualized as mutually constitutive and co-evolving through a process of ‘interactive adaptation’. The concept of ‘interactive adaptation’ is explored through a novel approach to integrating physical and social data collected from a sample of dwellings selected from the RftF programme. Analysis yields insights into the influences and pathways of interactive adaptation resulting from retrofit technology and practices. The implications of these insights for policy-makers, the research community and practitioners are discussed: end-use energy demand policy needs to be informed by a socio-technical approach.     

A neuro-fuzzy computational approach to constructability knowledge acquisition for construction technology evaluation

This paper describes a methodology for constructability knowledge acquisition of construction technologies. The methodology combines a neuro-fuzzy network-based approach with genetic algorithms. The combination of fuzzy logic with learning abilities of neural networks and genetic algorithms may allow for automatic acquisition of constructability knowledge from training examples and for providing understandable explanations for the reasoning process. The proposed methodology can provide a mechanism to trace back factors causing unsatisfactory construction performance and the necessary feedback to construction engineers for technology innovation. An application example is provided to demonstrate the capabilities of the proposed methodology.     

A process approach in measuring quality costs of construction projects: model development

One of the most effective tools for evaluating the success of a quality management programme is the measurement of quality costs (prevention, appraisal and failure costs). The application of the concept of quality costs originated in the manufacturing industry in the early 1950s. As increasing attention has been given to improving the overall quality in the construction process since the early 1980s, the application of total quality management (TQM) practices in the construction industry has gained much popularity. A systematic approach is needed for measuring quality costs, especially in the construction industry, due to the great number and complexity of activities involved in a typical project. This paper describes how a simple methodology can be used to capture quality costs in construction projects. Pre-existing models for capturing construction quality costs, by Davis, by Abdul-Rahman, by Low and Yeo and by others, recognize quality cost components but do not address the causes or sources of unwanted deviations. This paper proposes an alternative approach, based on the process cost model and in conformance with BS6143 (1992), which is thought to better facilitate the fundamental goal of TQM, i.e. continual process improvement. A number of professionals involved in construction quality management were interviewed and responded favourably to the practicality of the proposed framework in the construction context.     

Data modelling and the application of a neural network approach to the prediction of total construction costs

Neural network cost models have been developed using data collected from nearly 300 building projects. Data were collected from predominantly primary sources using real-life data contained in project files, with some data obtained from the Building Cost Information Service, supplemented with further information, and some from a questionnaire distributed nationwide. The data collected included final account sums and, so that the model could evaluate the total cost to the client, clients' external and internal costs, in addition to construction costs. Models based on linear regression techniques have been used as a benchmark for evaluation of the neural network models. The results showed that the major benefit of the neural network approach was the ability of neural networks to model the nonlinearity in the data. The ‘best’ model obtained so far gives a mean absolute percentage error (MAPE) of 16.6%, which includes a percentage (unknown) for client changes. This compares favourably with traditional estimating where values of MAPE between 20.8% and 27.9% have been reported. However, it is anticipated that further analyses will result in the development of even more reliable models.     

Landscape impact analysis: a systematic approach to landscape impacts of policy

A method for analysis of landscape impacts and for presentation in visual terms was developed by the author and has been applied in Sweden and Norway to policy analysis. The method has successively been developed into a generalized method of landscape impact analysis of policies, programmes and plans — Landscape Impact Analysis (LIA). This deals with the interaction of human and natural systems and the resulting landscape. The method uses scenario techniques as a way of solving the problems of lack of specificity of policy, a problem which seems underestimated in the development of strategic environmental assessment. The paper describes the main steps of the method and shows examples of the application of the method to changes in Norwegian agricultural policy.     

A model approach to assess the long-term trends of indirect photochemistry in lake water. The case of Lake Maggiore (NW Italy)

A model-based approach is here developed and applied to predict the long-term trends of indirect photochemical processes in the surface layer (5 m water depth) of Lake Maggiore, NW Italy. For this lake, time series of the main parameters of photochemical importance that cover almost two decades are available. As a way to assess the relevant photochemical reactions, the modelled steady-state concentrations of important photogenerated transients (^•OH, ³CDOM* and CO₃^-•) were taken into account. A multivariate analysis approach was adopted to have an overview of the system, to emphasise relationships among chemical, photochemical and seasonal variables, and to highlight annual and long-term trends. Over the considered time period, because of the decrease of the dissolved organic carbon (DOC) content of water and of the increase of alkalinity, a significant increase is predicted for the steady-state concentrations of the radicals ^•OH and CO₃^−•. Therefore, the photochemical degradation processes that involve the two radical species would be enhanced. Another issue of potential photochemical importance is related to the winter maxima of nitrate (a photochemical ^•OH source) and the summer maxima of DOC (^•OH sink and ³CDOM* source) in the lake water under consideration. From the combination of sunlight irradiance and chemical composition data, one predicts that the processes involving ^•OH and CO₃^−• would be most important in spring, while the reactions involving ³CDOM* would be most important in summer.     

A systematic evaluation of accelerating indoor airflow simulations using cross-platform parallel computing

With new advances in computer hardware and software, users now have widespread accessibility to multicore devices inside personal computers making it feasible for fast indoor airflow simulations. Some exciting preliminary results of a cross-platform parallel computing framework OpenCL using specific hardware were reported. However, those results are largely based on two hypotheses: 1. OpenCL code on all devices will generate the same results; 2. On the same device, running in parallel with multiple processors will be faster than running in sequential with a single processor. This study attempted to evaluate these two hypotheses by systematically studying the accuracy and computing speed of OpenCL for indoor airflow simulations. A Fast Fluid Dynamics (FFD) code was selected as an exemplar indoor airflow simulation program. To compare the cross-platform ability of OpenCL, the evaluation was performed using four Graphics Processing Units (GPUs) and five Central Processing Units (CPUs) from three manufacturers, with different degrees of computing capability and mounted on two operating systems. The test subjects were evaluated using four case studies consisting of various indoor airflows. A sequential FFD code programmed in C and a Computational Fluid Dynamics (CFD) program were first used to perform the case studies and generate numerical benchmarks. The comparison of the numerical simulation results with experimental data showed that CFD and FFD can predict the studied flows with averaged relative errors of 9.99% and 11.30%, respectively. Afterwards, the accuracy and speedup of the OpenCL code was compared with numerical benchmarks. Although the OpenCL code on the CPUs generated identical numerical results, the OpenCL results from the GPUs were slightly dissimilar. This is likely due to varying interpretations, by the manufactures, of an Institute of Electrical and Electronics Engineers standard. Depending on the hardware, the speedups of the OpenCL code varied from 0.7 to 4.2 times on the CPUs and 5.1–129.3 times on the GPUs. The slowdown of computing speed happened when running OpenCL on a two-core CPU in a Windows Operating System using the Boot Camp on a Mac computer. Finally, a separate study on the relationship between speedup and global work size showed that a speedup of 1139 can be achieved when using an AMD FirePro W8100 GPU.     

A direct approach for the evaluation of the conventional modes within the GBT formulation

This paper proposes a new approach for the evaluation of the conventional modes, i.e. rigid, distortional, local and Bredt shear-modes, to be used in the framework of the Generalised Beam Theory (GBT) for the analysis of thin-walled members. The new method identifies a set of conventional modes in a single step cross-sectional analysis and for any type of cross-section, i.e. open, closed and partially-closed ones. The algorithm differs from that of the classical GBT, which requires a two-step evaluation procedure, consisting of an initial choice of the vector basis and its successive orthogonalization. The method is based on a definition of a new quadratic functional, whose steady condition leads to an eigenvalue problem, and directly generates the sought orthogonal basis, here found using a finite-element approach. The accuracy of the proposed method is validated by means of two numerical examples, one dealing with a lipped C-section and one with a partially-closed profile. It is shown that the conventional modes derived with the proposed approach are identical to those determined with the classical two-step procedure, thus limiting the computational effort required in their identification.     

浅谈DB总承包合同框架设计

DB总承包模式在国际工程领域已经被较为广泛地应用，而目前我国对该模式的应用仍处于刚起步阶段，各方面理论尚处于探索阶段。参照现代合同设计原则，并考虑到DB总承包合同文本的特殊性，提出了进行DB总承包合同框架设计的一些问题，在此基础上，提出了DB总承包合同框架的设计图，旨在为以后进一步的研究做一铺垫。     

Fixing the contract after the contract is fixed: A study of incomplete contracts in IT and construction projects

This paper aims to increase our understanding of collective outcomes by exploring both micro- and macro-level strategies for dealing with problems arising from incomplete contracts. By combining theories dealing with risk-sharing under various degrees of uncertainty (financial incentives and long-term relationships) with respect to social influence tactics involved in negotiations concerning additional work and changes, a useful framework was created. Case data regarding Swedish interorganizational development projects from both the construction and IT industries are used to illustrate the theoretical arguments. Findings indicate that social norms and the work-related values and attitudes of key negotiators significantly affect project outcomes. Efforts to increase the sophistication of financial incentives and long-term arrangements (e.g., standardized routines concerning risk-sharing and collaborative initiatives) do not seem to pay-off.     

监理违约责任若干问题

对监理的履约，违约行为方式以及监理违约责任的适用归责原则进行了较为深入的研究，探讨了现行法律法规存在的问题，并就相关问题提出了自己的看法。     

A systematic approach towards the structural behaviour of a lightweight deck–side shell system

Lightweight structures are increasingly used for high-speed ships. This paper presents a systematic approach to analyse the structural behaviour of a lightweight deck–side shell system using high strength steel. An analytical model of the deck–side shell system was first given, which includes the effects of stiffeners for the deck and side shell, the support conditions of the centreline girder (CL-girder), the influence of transverse beams, and the interaction between the side shell and the lightweight deck as parts of problems to the solution. By changing several geometric parameters, the sensitivity of both overall and local stress and deflection for the deck–side shell system was investigated. The different geometric parameters analysed comprise the influence for variation in the thickness of the web for transverse beams, longitudinal stiffeners and the CL-girder, the thickness of lower flange for the transverse beam and, the thickness for the panel. Furthermore, the influence of the lightweight deck and loads from the deck above on the side shell, the effects of the side shell and loads from top deck on the deck, the support conditions for the CL-girder, and the influence of deck loads on the eigenmodes were also analysed. By evaluating the results obtained from FE simulation, the support conditions of the CL-girder, the thickness of the panels and the lower flange of the transverse beams were found to be the most relevant parameters affecting both the stress and the deflection distribution of the structure. The dynamic characteristics of the structure were also analysed. The FE analysis concerning buckling of the structure was present. The results enable naval architects and structural engineers to design new extreme lightweight deck structure more reliable and economical. And some suggestions for future research are also given.