No description available.

No description available.

A district cooling system (DeS) is a.scheme for centralised cooling energy distribution which takes advantage of economies of scale and load diversity. . A cooling medium (chilled water) is generated at a central refrigeration plant and then supplied to a district area, comprising multiple buildings, through a closed-loop piping circuit. Because of the substantial capital investment involved, an optimal design of the distribution piping . configuration is one of the crucial factors for successful implementation of a district 1'. cooling scheme. Since there. exists an enormous number of different combinations of the piping configuration, it is not feasible to evaluate each individual case using an exhaustive approach. This thesis exammes the problem of determining an optimal distribution piping configuration using a genetic algorithm (GA). In order to estimate the spatial and temporal distribution of cooling loads; the climatic conditions of Hong Kong were investigated and a weather database in the form of a typical meteorological year (TMY) was developed. Detailed thermal modelling of a number of prototypical buildings was carried out to determine benchmark cooling loads. A novel Local Search/Looped Local Search algorithm was developed for finding optimal/near-optimal distribution piping configurations. By means of computational . experiments, it was demonstrated that there is a promising improvement to GA performance by including the Local Search/Looped Local Search algorithm, in terms of both solution quality and computational efficiency. The effects on the search performance of a number of parameters were systematically investigated to establish the most effective settings. In order to illustrate the effectiveness of the Local Search/Looped Local Search algorithm, a benchmark problem - the optimal communication,spanning tree (OCST) was used for comparison. The results showed that the Looped Local Search method developed in this work was an effective tool for optimal network design of the distribution piping system in DCS, as well as for optimising the OCST problem.

Due to the fact that the worldwide energy consumption caused by cooling devices in buildings has been increasing steadily and also the fact that the pressure has been rising to provide this cooling energy with environmentally friendly technology, solar powe.re~ DEC-systems (Desiccative and Evaporative Cooling) have begun capturing increasing interest over the past few years. , However, up to now little experience has been gained in the operation of these systems and thus currently little information is available about the performance, the efficiency, the control strategy and the best component choice. This lack of knowledge has resulted in a low rate of acceptance of, this technology so far. The studies presented in this thesis serve as a contribution to the advancement of DEC technology by providing fundamental knowledge about the operation and attainable performance of these systems. A comprehensive study of desiccant wheels was undertaken which provides detailed information about the operation and the achievable dehumidification performance of this component. A detailed simulation model for desiccant wheels was developed and verified with measured data from a desiccant wheel test plant. Additionally, two commercially used DEC-systems (one in a public library in Spain and the other in a plastics processing factory building in Germany) were monitored for the purposes of evaluating the performance of these systems and resolving existing problems in their operation and control strategies. In spite of the generally positive validation of the planned and expected cooling performances in both cases, the monitoring also showed that there are considerable possibilities· for improvement, especially with the regulation of the system.

The focus of this thesis is the performance modelling of shading devices with regard to daylight illumination and thermal effect in non-domestic buildings - offices, classrooms based on real time-varying conditions. The research is centred in quantifying the impact of external shading devices on energy demand for electric lighting, heating and cooling. The Unix-based Radiance lighting simulation program as the engine, and a nodal thermal model processing irradiation inputs, have been used. An adaptation of suitable calculation approaches and the development of custom-written data analysis programs have been also performed on this behalf. The thesis begins with a literature. review of current practice in modelling buildings particularly examining the daylight and thermal modelling approaches used. Daylight assessment tools and shading systems are also looked at. A formulation of a novel hybrid dynamic lighting thermal model using the daylight coefficient approach and Radiance, combined with a simple thermal model has been developed. A range of external shading devices are reviewed and computer models developed in order to simulate their lighting and thermal performance. These models use, as input, real time-varying meteorological data and hence predict the internal illuminance distribution and incoming irradiation through the window-shading device system. Automated models obtaining heating and cooling loads from possible scenarios where thermal loads are linked to daylight-linked electric controls are used. The validity of the use of these modelling programs in combination is compared against an existing validated computer model. The results of energy consumption for electric lighting, heating and cooling are organized and presented to easily compare and rate the performance of different shading options, facade orientation and climates. The results show a significant influence of shading device design upon some visual environment comfort parameters as well as upon energy consumption for electric lighting. As regards of thermal loads, it is shown that the influence of shading can be considerable if coupled with control switching strategies. It is expected that this study and the methodologies proposed should be useful to architects, building designers and developers, particularly those requiring research based on precise modelling techniques or parametric studies. It may also be of use to developers of such as shading devices, since it can assist them in their research on improving the characteristics of their products. Abstract

No description available.

No description available.

Designers are considered to be in a unique position to make a significant contribution to the health and safety of those involved in construction work. However, despite the introduction of the Construction (Design and Management) Regulations-almost two decades ago, there appear to be no clear indication which point to a marked improvement in health and safety through design. Existing research has, in the main, concentrated on how designers should think about what they do rather than looking at how designers actually work. This thesis is written from the viewpoint of the designer and aims to enter into their world to discover what issues they face and how they look to resolve or process ~I .A these issues when faced with the demand to consider health and safety during the design process. This study is based on a collection of primary and secondary data. Primary data in the form of interviews were collected from design engineers-those, considered to be a homogenous group fitting the description of designers, as defined under the CDM regulations. Secondary data in the form of literature was used to develop and nest the grounded theory. The Grounded Theory research method has been used to identify the main concern of the substantive population under study and to develop a theory of explanation that describes the processing of health and safety aspects during the design process. The output from this study is a theory that describes the basic social process of Balancing as the prime mover for the design engineer's behaviour where there are two main elements involved in this process: Limiting and Framing. The notion of the design microcosm helps to explain why different design engineers will produce different design options, even when the same processes are being undertaken by individual design engineers. It also acts as the stabilising force during the balancing process and is core to the creation of the WobBall- the product or consequence of Balancing. Three group types of design engineers are identified: the Giver, the Receiver and the Doer. These group types exhibit particular tendencies towards the Balancing of health and safety during the design process. This study offers a new way of looking at how health and safety is being perceived and dealt with by designers; and suggests new ways of designing for and managing the framing of health and safety. It offers a conceptual theory of Balancing for a healthier and safer frame to designing with which to extend current understanding.

When it becomes necessary to use mechanical energy in buildings, it would be expected that the amount used should not only correspond to the density of spatial utilisation but also the occupancy patterns, or vice versa – that vacancy patterns should produce corresponding reductions in energy use. Empirical evidence suggests that this is not always the case. This research aimed to find out if patterns of interior space organisation and/or utilisation have corresponding patterns of energy consumption, and if planning and/or utilisation programming strategies can enable energy savings. Although this study acknowledges that space planning is related to user organisations, it is not about such relationships. Previous research alludes to the following factors as potential determinants of energy use, but their quantitative degree of influence is not well understood: properties of interior construction elements; environmental interaction/autonomy between spaces; circulation configuration; layout density; activity relationships; and temporal factors of space use. The influence of these factors on energy is examined by quantitative analysis, which matches different plan regimes and environmental systems against different occupancy regimes. The wider target is buildings that experience varied patterns of occupancy, but the focus here is on office, laboratory, and library building typologies, by way of examples. The quantification is by computer simulation using established software packages (TAS, Lightscape, and Flovent) and Excel spreadsheets developed for this work. Further investigations in selected case study buildings involve first monitoring spatial utilisation and the corresponding running environmental systems. The data are then used to quantitatively evaluate the performance of the existing layout against hypothetical options on the existing ‘shell and core’ of each building. A conceptual approach for energy saving, which is partly based on the findings of the parametric and empirical studies, is then formulated and tested in some of the case study buildings. The thesis demonstrates that: different patterns of spatial, activity, and systems organisation have corresponding patterns of energy use; and that significant energy savings can be achieved in a best practice ‘shell and core’ through the right match of space plans with space use patterns – with potentially higher savings in a wasteful shell. It also demonstrates that adopting approaches that dynamically adjust to the temporal diversity of space use can also enable significant savings. One such approach is proposed and promising directions for further research are suggested.

The thermal behaviour was investigated of three offices positioned in three buildings built in different periods, one academic institute built in 1920 and two modem commercial buildings in London. The buildings chosen for this study are the Rockefeller Building, which is part of University College London (UCL), Portman House in Oxford Street and the Visa Building in Paddington. Due to the lack of specific information related to the structure of the buildings such as windows, doors, building dimensions and other information that would allow the use of physical models, in this project black-box linear and non-linear mathematical models were used. Data relating to room temperature, hot and chilled water temperature, air flow and temperature from air handling units and outside temperature were collected for one year, from the actual building management systems (BMSs) installed in these buildings. The main assumption of the model development in the three buildings was that although occupancy, computers, printers etc cause an additional internal heat gain, their impact is in part indirectly included in the model. The primary objective of the analysis was to identify the inputs (independent variables) that gave good models for the prediction of room temperature for a certain period. Consequently, the process of input selection and period of validity in obtaining models that give good thermal prediction (within the same period) were the key points in season subdivision. The first part of the analysis applied the following linear parametric mathematical models to the three office buildings selected: Box Jenkins (BJ), autoregressivem oving averagew ith exogenousi nput (ARMAX) and output error (OE) structure. The project then deals with non-linear mathematical models. The same inputs selected and assumptions made with linear analysis were used to build, in turn, models with feedforward backpropagation (FFBP), non-linear autoregressive mathematical models with parallel arrangement (NARX) and series-parallel arrangement (NARXSP). The research presented in this project is related to developing models for three real offices positioned in three different buildings whereas previous researchers have applied these models mainly to experimental rooms and HVAC plants, with the purpose of fault detection and diagnostics. Furthermore, in the past, research on thermal model development has been related to one office or HVAC plant, and for a limited period of time (a few weeks or months). In contrast, this study undertakes an overall analysis of thermal model development for three offices and for a period of one year, where the process of input selection is given priority to obtain good models. Thus, previous studies have not utilized these two types of models for such a long period of data collection nor related them to three different buildings. Finally, model development and then validation were pursued utilizing the same week, different weeks and different days (where the first part of the data in each case was used for model estimation and the following part for model validation). This was one within the period that the models gave good results for the prediction of room temperature. The best mathematical models (linear and non-linear) that predict the room temperature, in terms of the inputs selected, has been determined for each season. The procedures for how to choose the best models are based on the following techniques: final prediction error (FPE for linear models), mean squared error (mse for non-linear models), and model fits and errors between measurements and simulated model output. Overall, the results related for the prediction of room temperature with non-linear models, are better than those obtained with linear models, as a result of comparison between models' errors, FPE and mse obtained with linear and non-linear models.