Building industry is one of the most influential economic sectors, which accounts for 10% of the gross domestic product (GDP) globally and 40% of the world energy consumption. To achieve the goal of sustainable development, it is necessary to understand the sustainability performance of building construction in the environmental, the economic and the social aspects. This study quantitatively evaluates impacts of building construction in the three aspects by using the recently developed life cycle sustainability assessment (LCSA) methodology, in which environmental life cycle assessment (ELCA), environmental life cycle costing (ELCC), and social life cycle assessment (S-LCA) are integrated. The scope of this research covers ‘cradle-to-site’ life cycle stages, from raw material extraction to on-site construction. Three life-cycle models are developed, namely the Environmental Model of Construction (EMoC), the Cost Model of Construction (CMoC), and the Social-impact Model of Construction (SMoC). EMoC is a comprehensive ELCA model that evaluates environmental impacts of building construction by considering eighteen impact categories. CMoC is an ELCC model that provides analyses on construction costs and externalities. SMoC is an innovative S-LCA model being able to quantify social impacts of building construction in thirteen social impact categories. The three models are then integrated into a newly proposed LCSA framework. In order to select an appropriate LCIA method for EMoC, the differences among existing life cycle impact assessment (LCIA) methods are investigated. It is found that LCIA methods are consistent in global impact categories, while inconsistent in regional impact categories. ‘ReCiPe’ is selected as the LCIA method to be used in EMoC. Midpoint and endpoint approaches of ‘ReCiPe’ can lead to different interpretations. Endpoint approach emphasizes on certain impact categories and can only be used when midpoint results are provided. A life cycle inventory is established for ready mixed concrete and precast concrete based on site-specific data from concrete batching plant and precast yard. EMoC is employed to compare environmental performance of precast and cast-in-situ construction methods. It is found that adoption of precast concrete can significantly improve environmental performance of building construction. SMoC suggests that adoption of precast concrete can have both negative and positive impacts on local employment. A case study is conducted to test the model performance. It demonstrates that environmental impacts of ‘cradle-to-site’ construction activities are mostly attributed to the material stage. The external cost due to carbon emission is about 2% of the total construction cost. Environmental-friendly on-site construction practices can significantly improve social performance of building construction. The major findings of this study are verified through interviews with the local experts in Hong Kong. These validation interviews confirm that the proposed LCSA framework and the developed models contribute to the building industry in Hong Kong. In particular, this study can be used as a supplementary to the building assessment scheme, HK BEAM Plus. Results from this study can improve the understanding of building sustainability. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

The pressure to reduce greenhouse gas (GHG) emissions has become increasingly obvious due to the need to alleviate the impact of climate change. As the second largest GHG emitter in the world, the building sector should play an active role in reducing GHG emissions. Particular attention should be directed to existing buildings not only because of the amount of emissions caused by inefficient buildings but also due to the existence of a variety of sustainable refurbishment solutions for different levels and stages of building refurbishment. The emission reduction performance of different sustainable refurbishment options may vary enormously as a result of different building design conditions. With the majority of residential properties being high-rise buildings, the most suitable sustainable refurbishment options for a sub-tropical city like Hong Kong are yet to be fully investigated. The opportunity to reduce emission may not be high without a tool to help the owners, occupants and consultants to assess the emission of different refurbishment solutions for multi-storey residential building. The aim of this research has been to develop a systematic decision tool to identify suitable sustainable refurbishment solutions for multi-story residential buildings in subtropical regions like Hong Kong and to calculate the CO2emission reductions of these solutions. The research began with a comprehensive literature review of the existing sustainable refurbishment approaches. The results of this literature review formed the basis for a preliminary screening according to local climate and buildings features. Interviews with experts and questionnaire surveys with residents were carried out in order to confirm the applicability of the proposed approaches. Then, based on a case study, this research established a set of methods, through literature review and energy simulation, to calculate the CO2 emission reductions achievable by sustainable refurbishment. With the setup of criteria for identifying applicable refurbishment solutions, method of calculation of CO2 emission reductions and parameter input/output and user interface design, a decision tool was developed for sustainable refurbishment. Finally, a series of interviews was conducted to validate the major research outcomes. In this study, a residential building is divided into two zones, the common area and those occupied by owners/tenants. This study further identifies possible sustainable refurbishment solutions for each area, which can provide stakeholders with a variety of options for launching sustainable refurbishment projects. Moreover, a theoretical framework for emission assessment, consisting of system boundary and calculation methods, is also proposed in this study, which can provide better calculation of emission reductions as a result of various sustainable refurbishment solutions. The most significant outcome of this project is a decision tool which can generate a set of sustainable refurbishment solutions and calculate CO2 emission reductions according to the architectural features input by users. With the function of identifying the approaches for reducing CO2emission, owners and occupants of existing residential buildings can minimize the CO2emissions of their properties through refurbishing some of the building components in a sustainable manner. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

Not available / text

Not available / text

Quantitative characterization of hydraulic conductivities of aquifers is of fundamental importance to the study of groundwater flow and contaminant transport in aquifers. A conditional approach is used to represent the spatial variability of hydraulic conductivity. Briefly, it involves using qualitative and quantitative geologic borehole-log data to generate a three-dimensional (3D) hydraulic conductivity distribution, which is then adjusted through calibration of a 3D groundwater flow model using pumping-test data and historic hydraulic data. The approach consists of several steps. First, classify the lithological information obtained from geologic borehole-logs into representative texture categories; second, establish a quantitative correlation between laboratory measured corescale hydraulic conductivities and texture; third, generate a 3D hydraulic conductivity distribution using a genralized kernel-estimator method; fourth, upscale the core-scale hydraulic conductivity values such that the vertically averaged value at each location matches the field-scale value estimated from pumping tests; and fifth, use hydraulic data to calibrate the 3D field-scale distribution to account for regional-scale characteristics. The approach is applied to a trichloroethene (TCE) contaminated large-scale Superfund site. Based on the good agreement between simula.tions and observations, the results are considered reasonable and realistic. A number of nonideal processes and factors may contribute to the decreasing contaminant removal rate observed at the site. Most of the quantitative analyses of nonideal transport behavior have been conducted using data collected from column or small-scale field experiments. Studies extending such analyses to regional-scale contaminant transport are rare. In this study, a fully 3D transport model is developed to evaluate the effects of various processes/factors on the regional-scale nonideal TCE transport. Based on the analyses, it is found that while large-scale heterogeneity of hydraulic conductivity and ratelimited desorption have significant impacts on TCE transport and cause some nonideal behavior, their impact is not sufficient to account for the extensive tailing exhibited by the observed concentrations in the groundwater entering the treatment plant. Rate-limited dissolution of immiscible liquid appears to be the most likely primary cause of the extensive nonideal transport behavior observed at the site. The impact of the nonlinear sorption and the local-scale heterogeneity on TCE removal appears to be insignificant.

A comprehensive Ultrapure Water (UPW) simulator program has been developed to model each unit process in UPW systems, including the entire dynamic system in real time. The program estimates the removal efficiencies for contaminants generated in semiconductor processes and in municipal water supplies. Calculations are performed using flow balance and concentration profile determinations at each unit process throughout the system. Simulator validation occurred using existing industrial facilities. Spent rinsewater (SRW) recycling in semiconductor facilities has been shown to provide significant UPW quality improvements. Contrary to many perceptions, this recycling is not a compromise to the quality, but an improvement. Benefits to the cost, reliability, and environmental improvements have also been identified. Processing risks have also been identified as the use of UPW with even minute quantities of contaminants, in particular the organic contaminants, could cause process problems. The simulator has been shown to be quite capable of predicting the impact on UPW quality due to excursions in SRW quality from semiconductor processes. Photolithography is a primary semiconductor process where organic photoresist is removed from wafers with corrosive chemistries. SRW is contaminated with both organic residues and corrosive chemicals. Ozonated UPW has recently become an alternative chemical for photoresist removal. A single-wafer tool was fabricated out of quartz designed for various processes. With direct observation of the wafer possible. Ultraviolet light experiments were also performed, directing light through the quartz, process solution, and onto the wafer. Experimental procedures were developed to study the effects of turbulence, wafer pretreatment, in-situ process treatments, and vibration on the kinetics and mechanism of photoresist removal by ozonated UPW. Data was obtained to determine which oxidation pathway was dominant; direct ozone, or indirect oxidation through radical formation. Intermediate products were determined using Fourier Transform Infrared Spectroscopy. Two distinct mechanisms were observed: film dissolution via a uniform sheeting method, and a non-uniform vapor-phase bubble mechanism where film dissolution occurred underneath the bubble. Models were developed that describe the film removal under both mechanisms. The uniform sheeting model describes typical process conditions in current tools. This model was validated and found in good agreement with experimental data.

Taxonomic differences exist between Thyasira gould! and T. flexuosa both in conchological features and in the soft parts, perhaps the best of these differences are those concerning the sperm which are easily seen even in badly curated specimens. The occurrence of a population of T. gouldi within Loch Etive on the west coast of Scotland extends the known distribution of this arctic bivalve considerably further south. The development is nonpelagic and this, associated with the non-synchronized reproductive activity , means that independence is gained from plankton blooms and other external triggers allowing the characteristic dense but patchy populations to be built up. Salinity and sediment particle size both limit the distribution of T. souidi within L. Etive, the VI naturally occurring sediment is altered by the inhabi tants of the area into a sediment vlhich is better suited to the needs of T. gouldi. Asynchronized breeding, slow growth rate, longevi ty of life and 10\'1 adul t mortality all combine to give a characteristic bimodal population, the modes of which do not appear to shift with time. A method is described whereby an indication of both the mean state of the population and the state of the individual can be obtained for any period of the year. The biochemical composition varies with size and time of the year as well as with gonad state. Dry weight fluctuations are, however, not entirely explained by variations in the stage of gonad development as seasonal variations in the amount of somatic tissue do exist. Thyasira gouldi is one of the Lucinaceans infected by the much modified copepod parasite Axinophilus thyasirae. The life cycle and infective stage of this parasite are described as is the external morphology of the nauplius copopedite and adult. The reproductive system of both the male and the female are also described. The first infected parasite is always female and only rarely does more than one female reach maturity within anyone host even though up to five parasites may be present. The parasite has been shown to affect the biochemical composition of the host, reducing the amount of each of the components present, but tending to reduce the amount of nitrogenous material in preference to the amount of carbohydrate. VII The parasite affects the gonad of the host resulting in castration probably as an indirect effect of 'food robbing'. The interference to the host's food supply by the parasite is thought to be so great as to reduce the host to starvation levels of food,

Not available / text

published_or_final_version / Urban Studies / Master / Master of Social Sciences

published_or_final_version / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning