Realistic and accurate room reverberation time (RT) extraction is very important in room acoustics. Occupied room RT extraction is even more attractive but it is technically challenging, since the presence of the audience changes the room acoustics. Recently, some methods have been proposed to solve the occupied room RT extraction problem by utilizing passively received speech signals, such as the maximum likelihood estimation (MLE) technique and the artificial neural network (ANN) scheme. Although reasonable RT estimates can be extracted by these methods, noise may affect their accuracy, especially for occupied rooms, where noise is inevitable due to the presence of the audience. To improve the accuracy of the RT estimates from high noise occupied rooms, adaptive techniques are utilized in this thesis as a preprocess ing stage for RT estimation. As a demonstration, this preprocessing together with the MLE method will be applied to extract the RT of a room in which there is significant noise from passively received speech signals. This preprocessing can also be potentially used to aid in the extraction of other acoustic parameters, such as the early decay time (EDT) and speech transmission index (STI). The motivation of the proposed approach is to utilize adaptive techniques, namely blind source separation (BSS) and adaptive noise cancellation (ANC), based upon the least mean square (LMS) algorithm, to reduce the noise level contained in the received speech signal, so that the RT extracted from the signal output generated by the preprocessing can be more accurate. Further research is also performed on some fundamental topics re lated to adaptive techniques. The first topic is variable step size LMS (VSSLMS) algorithms, which are designed to enhance the convergence rate of the LMS algorithm. The concept of gradient based VSSLMS algorithms is described, and new gradient based VSSLMS algorithms are proposed for applications where the input signal is statistically stationary and the signal-to-noise ratio (SNR) is zero decibels or less. The second topic is variable tap-length LMS (VTLMS) algorithms. VTLMS algorithms are designed for applications where the tap-length of the adaptive filter coefficient vector is unknown. The target of these algorithms is to establish a good steady-state tap-length for the LMS algorithm. A steady-state performance analysis for a VTLMS algorithm, the fractional tap-length (FT) algorithm is therefore provided. To improve the performance of the FT algorithm in high noise conditions, a convex combination approach for the FT algorithm is proposed. Furthermore, a new practical VTLMS algorithm is also designed for applications in which the optimal filter has an exponential decay impulse response, commonplace in enclosed acoustic environments. These original research outputs provide deep understanding of the VTLMS algorithms. Finally, the idea of variable tap-length is introduced for the first time into the BSS algorithm. Similar to the FT algorithm, the tap-length of the natural gradient (NG) algorithm, which is one of the most important sequential BSS algorithms is also made variable rather than fixed. A new variable tap-length NG algorithm is proposed to search for a steady-state adaptive filter vector tap-length, and thereby provide a good compromise between steady-state performance and computational complexity. The research recorded in this thesis gives a first step in introducing adaptive techniques into acoustic parameter extraction. Limited by the performance of such adaptive techniques, only simulated studies and comparisons are performed to evaluate the proposed new approach. With further development of the associated adaptive techniques, practical applications of the proposed approach may be obtained in the future.

This study investigates the potential savings in air conditioning energy and reductions in atmospheric pollutants in existing air conditioned mosques in Saudi Arabia. It aims to study in particular the improvements of passive cooling systems in existing mosques under three main headings of (1) the determination of (a) passive cooling systems' demand improvements and (b) the proposed measures for improvements, (2) their relative performances, and (3) their applications. Existing air conditioned mosques in city of Jeddah form the primary subject of this study, by surveying 48 existing air conditioned mosques' envelope, shading and night ventilation. Based on a better understanding of these passive cooling systems, combined with an analysis of the current economical, structural and constructional situations within existing air conditioned mosques, a coherent set of improvement measures have been proposed namely; (1) increase insulation values of mosques' fabric by adding various building and insulation materials for walls and roof, (2) increase shading by complete shading of windows and (3) increased night ventilation by ventilating the mosque for the whole night. A passive cooling evaluation method, appropriate to the measures defined, has been adapted to predict the potential savings in air conditioning energy, money and atmospheric pollutants. This manual method has been used to predict the various savings that can be achieved by applying these measures of improvements to nine case study mosques. A set of comprehensive tables showing the potential sayings in air conditioning energy, money and atmospheric pollutants emissions when applying these proposed measures for improving passive cooling systems in existing air conditioned mosques are produced. These tables can be used by the architects, by the mosques' management and by the Ministry of Awkaf (Endowment) who are responsible for mosque procurement and maintenance. Finally, the study has estimated the potential savings of these measures when applied to all existing air conditioned mosques in Jeddah and shown their relative contributions to reducing the national energy consumption and atmospheric pollutants emissions levels.

No description available.

This research has introduced a new concept, 'stiffness/strength corrector', which more accurately models variation in masonry properties at various locations (zones) within a masonry wall panel. Derivation of these correctors was based on a closer mapping of the laboratory experimental results to those obtained from a non-linear finite element analysis of full-scale masonry panels subjected to a uniformly distributed lateral load. In this research only one panel, which was tested in a previous research, was used as the "base panel" and correctors for new panels with and without openings with various boundary conditions were derived by matching similar regions and zones between the new panel and the base panel. The research has also derived the concept of zone similarity between the base panel and any new panel. It was discovered that the types of panel boundaries surrounding specific regions within the two panels govern zone similarity. At first, a manual method for matching zone similarity was proposed based on careful visual inspection to identify similar regions within the two panels. It was found that this method is difficult to implement as the user needs to have a deep knowledge of the behaviour of the panel to be able to accurately locate similar regions/zones. As it was established that the zone similarity was mainly related to the panel boundaries, this knowledge was used to derive appropriate rules for matching zone similarity. These rules were implemented in a cellular automata model which was able to automatically locate similar zones between the base panel and a new panel and assign appropriate corrector values to zones within the new panel. The stiffness/strength corrector values were used to, modify global material properties of the panel. A specialised non-linear FEA program for masonry panels was used to analyse a number of panels provided by CERAM with modified rigidities or tensile strength values. Comparison of results with laboratory experimental values shows that with this new method an average 18% improvement in the prediction of failure load, in comparison with the non-linear FEA results with smeared masonry properties, was possible. The failure patterns for the majority of panels with or without openings, having various sizes and boundary conditions, were much closer to the experimental results. The results of case studies using the new method clearly show that the proposed method is a much better representation of the true behaviour of the masonry panels which models variation in masonry properties and the boundary effects more accurately. The corrector values for any type of new panel are derived from a single base panel in which there was not sufficient data available at different locations on the panel, particularly near the panel boundaries. Thus, in some cases it uses a crude approximation of the boundary types to establish corrector values for a new panel. If sufficient data points were available more accurate results would have been possible to achieve.

This work concerns the in situ measurement of thermal conductivity and thermal diffusivity of building materials, so as to provide improved data for the estimation and prediction of energy efficiency in buildings. Thermal data sources and measurement methods currently used by industry to inform building design were found to give flawed values for the thermal properties of materials as found in situ. A transient measurement technique, carried out by means of a thermal probe, and used in various other industries, was investigated as an alternative, relatively non-destructive, rapid and economic means of obtaining representative results. An analysis of the literature associated with the technique's history, theory and practice was carried out. Four strands of scientific research were undertaken: traditional thermal probe solutions were assessed; computer simulations were used to model probe behaviour while avoiding practical, experimental error; laboratory based measurements were carried out with materials of known and unknown thermal properties using varied parameters, including moisture content; an apparatus was developed for fieldwork, and in situ measurements were carried out on real buildings, using novel analysis routines. Results for thermal diffusivity values achieved by the thermal probe method were found to be unreliable. Representative thermal conductivity values were achieved for structural materials with varied moisture content, both in controlled laboratory environments and in situ under diverse environmental conditions, which had not previously been achieved. Heat losses from the probe open end and the material adjacent to it were shown to currently prevent reliable values being obtained for building insulation materials. The thermal probe technique was successfully transferred from laboratory to in situ measurements. It was shown that various calibration factors reported in the literature could not be relied upon to transfer successfully between material types. A significant cause of error in the measurement of insulation materials was identified and a guarded probe was proposed to overcome this. The technique was shown to provide much improved thermal conductivity data for structural building materials, whether as samples or in situ, with the potential to expand this success to insulation materials in the future.

No description available.

Carbon dioxide emissions reduction in the domestic sector in the UK has been increasingly in focus in recent years. Reducing carbon emissions for both operational and embedded building energy will contribute to lowering the overall emission levels. This study aims to investigate the potential contribution of thermal energy storage systems in the UK’s domestic buildings. It also aims to investigate multiple thermal energy storage technologies and their integration into zero-carbon buildings. The research process is conducted in two phases: building energy simulation, and thermal energy storage modelling. Building energy simulation phase investigates energy performance of a single family zero-carbon house located in the UK. This simulation is performed to generate hourly thermal energy performance and calculate potential energy generated from on-site renewable sources. The energy simulation is conducted using HTB2, a computer based tool. The results show a total of 4158 kWh thermal demand while energy generation from renewables reached 6200 kWh. Although the generation exceeds demand, the simulated model requires an extra 1724 kWh of energy supply from the grid. The extra energy supply from the grid is a clear indication of an existing mismatch between energy demand and on-site energy generation. The second phase of this research is conducted by creating a calculation model for the thermal energy storage system. This model is used to determine the performance of different thermal energy storage systems under the operational loads of the zero-carbon house. This step determines the thermal energy storage system contribution in energy demand reduction by shifting load peaks. Furthermore, this step compares the performance between different storage technologies in terms of thermal energy capacity, volumetric storage, storage medium, and annual performance. The final modelling in this study shows performance difference between different TES technologies. While thermochemical energy storage systems achieved higher energy storage capacities with lower volumes than sensible heat storage and PCM systems, all systems were able to reduce demand from grid energy. The annual energy performance of artificial thermochemical sorption materials like zeolite 13X have the ability to achieve zero-grid demand with low requirement of storage volume compared to other material types tested in this study.

This research aims to empirically examine whether continuity during the transformation process of the physical/built environment helps to sustain people’s satisfaction with life by bridging two previously independent fields of research: typo-morphology and sense of place (SoP). The former concerns the transformation process of the built environment, in paarticular continuity of urban form, represented through typological process which was theorised by the Italian Typological School. The latter is an important indicator of life satisfaction. The research proposes a mixed methodology combining typological analysis and SoP assessment, which then is applied in the Turkish context with seven selected cases of housing development in Ankara which were developed in different periods of the city’s development since the late 19th century. Each period features distinctive socio-economic, political and cultural conditions that have shaped different building types or urban types. Regarding the mixed methodology, a typological frame of a set of spatial characteristics is established against which types are defined at the building, street and neighbourhood scales. Then, spatial characteristics of the building, street and neighbourhood types of the seven cases are compared in a chronological order to identify continued and partly continued (thus in typological process), or discontinued transformation. Regarding SoP assessment, firstly, a conceptual SoP model consisting of ten indicators is proposed and interview questions for the residents of the seven housing developments are developed accordingly. Then, 20 residents from each housing development are interviewed to assess their degree of satisfaction with each indicator using a 7-point Likert scale. The research did not intend to measure SoP in its absolute value but to monitor SoP in a comparative perspective. By aligning the SoP scores with the corresponding typological changes at the three scales, the research reveals that SoP is weakened during the transformation process from the traditional types to the contemporary types. It proves that changing housing typology is one of the factors affecting SoP although the degree of its impact is not entirely clear compared to that of socio-economic and demographic factors. The results demonstrate that continuity over time at the building scale helps to maintain SoP at least at the moderate level; while mutations at the street and neighbourhood scales cause dramatic decreases of the SoP scores over time. Furthermore, the degrees to which physical changes affect SoP are different at different place scales. In detail, physical changes at the street scale affect SoP the most, followed by changes at the neighbourhood scale. Changes at the building scale affect SoP the least. The study also clarifies those spatial characteristics that contribute positively to SoP and therefore should be sustained in contemporary development in the cultural context. For example, functional zoning of the houses clearly defining the individual and shared spaces, gradual transition between public streets and the private building entrances, building accesses from pedestrianised/traffic-calmed streets, having clear boundaries of housing clusters, clear separation of public and private spaces, neighbourhood design prioritising pedestrians and integrated street network centralising open spaces and encouraging social interaction. Such characteristics are mainly relevant to the design of public spaces at the street and neighbourhood scales. In sum, this thesis has established a methodological framework for SoP assessment during the process of typo- morphological transformation. The framework can be applied to other Turkish cities or is relevant to other cultural contexts. The methodology has not only shed some light on the definition of typological process, but also contributed to the lesser extended literature on measuring SoP and understanding the impact of spatial characteristics on SoP.

Sustainability is one of the most important challenges of our time. In the 21st century, it has become a central issue for debate about development at local, national and international levels. The concept of sustainability is now seen as an integral part of policy reforms in many countries because of the potential for detrimental impacts of certain practices on the environment and society. Within the construction sector, there is a growing interest in the ethos of sustainable development. However, it is unclear if most countries in western Africa share the same inclination, owing to the particular development needs and the challenges that these countries face. This present research explores the extent to which the construction companies in Nigeria takes into account and apply sustainability principles in project management activity, with the view to developing a strategy for change to improve sustainability practices. The present research was conducted through case studies to increase our understanding of the current situation. Nine projects from three multinational construction companies were selected for study in four main geopolitical zones in Nigeria to ensure the diverse social-cultural and geographical demographic areas were represented. Data was collected through a combination of survey, interviews and documents to acquire comprehensive evidence for the research. This research was conducted in two stages; first, a survey was conducted to gain broad insight into the current practices and the ambition of the participating company to improve sustainability performance. A total of 204 questionnaires were studied using descriptive statistical analytical techniques. The outcome of the survey, guided the series of semi-structured interviews with 31 representatives of the middle and senior-management team from three different stakeholders groups – the clients, contractors and regulatory institutions. The interviews were designed to get an in-depth insight into the rationale for the current practices, as well as the barriers and opportunities for promoting a sustainable construction approach. Interview data were coded and analysed using Nvivo 10 data management software.

This research explored the adoption and implementation of Sustainable Construction (SC) at the strategic and operational levels by construction firms in Nigeria. It is argued that developing countries (DCs) stand to gain immensely from the pursuit of efficiency in resource utilization, energy, reducing waste and pollution and consideration for local communities which are central concerns of sustainability. Literature indicates that while the sustainability agenda offers advantages for DCs, its adoption and implementation is more prevalent in the developed world. Questions then arise as to whether SC offers any business opportunities and lessons to construction firms in DCs on sustainable built assets. While numerous publications exist prescribing SC strategies seemingly deemed suitable for DCs, very little known about sustainability in the context of Nigerian Construction. Many of these strategies are normative and prescriptive with little empirical evidence gathered within local contexts to support them. This thesis argues that firm-level adoption of SC would be the outcome of a complex relationship between the firm’s understanding of SC, its capacity and capabilities and the characteristics of the local context. This relationship was studied through an exploratory multi-case study of three Nigerian firms. Multiple sources of data were used including interviews, observations and archival records. Transcripts of the interviews were analysed using thematic coding. The analyses indicate that there is a very limited business case for SC with numerous barriers in the Nigerian context. Firstly, SC awareness of is low across various stakeholders, resulting in low demand and capabilities for sustainable buildings. Secondly, the firms have more pressing issues to deal with in the NCS. Currently, clients remain the single driver of SC identified in this context. It is recommended that at this early stage of SC, the Government plays a more active role in stimulating the adoption of SC in the NCS.