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Indoor air pollution is a persistent problem found not only in buildings but . also in transportation vehicles, aircrafts and many other confined spaces. Photocatalytic air cleaning devices, in combination with source control and ventilation appears to be a promising method to reduce volatile organic compounds (VOCs) levels, which are among the most abundant indoor air pollutants. A major challenge this technology faces, is poor catalyst illumination efficiency. In general, effective photon utilization is a critical factor in determining the economic feasibility of a particular photocatalytic reactor design. A deficient use of light within a photocatalytic reactor will inherently lead to high operational costs, which in turn, will prevent the reactor to be implemented especially in cases in which catalyst activity is low. Consequently, the analysis of the radiation field in photocatalytic reactors is an essential step towards the optimization of photocatalytic air cleaners. This study focuses on the analysis and optimization of the geometry and radiation field in a multi-plate photocatalytic reactor (MPPR) irradiated by cylindrical UV lamps orthogonal to the plates, a reactor virtually not studied before. The MPPR aims to provide not only high light utilization, but also low pressure drop while treating large volumes of air. The MPPR presents a large photocatalyst surface area as well as a modular design, which facilitates scale up. All these characteristics could make the MPPR a costeffective alternative for indoor air remediation. The optimum design was validated by the oxidation of toluene in a humidified air stream. In addition, the performance of the reactor was evaluated with close to real concentrations using mixtures of trichloroethylene, ethanol, acetone, hexane and toluene.

Nowadays, issues regarding building stock are highly important in the quest to reduce overall UK energy consumption and finding prime targets for cuts in carbon emissions. Of all the main consumers of energy, the fact how occupants use and operate the building plays a crucial role. Therefore, it is necessary to have a thorough understanding of the occupant response to environmental controlling systems in buildings because the building should be designed not only to satisfy comfort requirements but also to be used with a low input of energy. This research can be seen as an attempt to explore such issues. It examines various environmental issues such as motivating forces and influential effects related to the occupant control behaviour with special attention to the usage of those simple, easy-to-use and robust means that the occupant is able to see and almost immediately experience the results of the actions. Two naturally ventilated buildings in Sheffield were selected as the study cases. Their architectural features were examined, including environmental situation, occupant identification and architectural speciality. Both buildings' blinds (shading rolls) and windows were recorded by photograph twice a day for 16 months continuously. At the same time, the outside hourly weather parameters and inside physical parameters were collected. A questionnaire survey and a face-to-face interview were also carried out in order to investigate the thermal, visual and acoustic comfort sensation and an indication of the motivating forces for manual control obtained. From a sustainability perspective, the study has provided knowledge that enables designers to anticipate how a design encourages that the sustainable interaction between the occupant operation behaviour, building components and/or systems, and conversely, avoid built conditions where occupant interaction may cause sustainable penalties. This understanding may well lead to the building using less energy to maintain comfort. The study could also provide opportunities for decision makers to understand the current situations of the buildings that were selected as case studies. The result of this research may be used as a work-base for successful improvement and give confidence to embark on the design of naturally ventilated buildings.

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Natural ventilation has the potential to provide good indoor air quality, thermal comfort for occupants, and can also save energy and reduce CO2 emissions. Computational fluid dynamics (CFD) offers detailed information about indoor flow patterns, air movement, temperature and local draught distribution in buildings, so it has unique advantages as an efficient and cost-effective tool for optimum design in a complex built environment. This thesis shows the use of CFD to simulate the coupled external and internal flow field around a 6m cubic building with two small openings. To study both wind driven and combined wind and buoyancy driven cross ventilation through a full-scale cubic structure, un-structured grid CFD and a steady envelope flow model were applied to calculate mean ventilation rates. To validate the CFD results, full-scale experiments were undertaken under various weather conditions in England. For wind driven ventilation RANS model predictions were proved reliable when wind directions were near normal to the ventilation openings, i.e. 0o~30o. However, when the fluctuating ventilation played a more dominant role than the mean flow (90o) RANS models were incapable of predicting the total ventilation rate. Improved results may be expected by applying more sophisticated turbulence models, such as LES, weighted quasi-steady approximations, or unsteady envelope flow models. In the thesis experience on the modelling of combined wind and thermal effects is outlined and feedback is provided to CFD code developers to enable further improvements for building ventilation studies. The full-scale field testing data from this study is valuable for comparison with wind tunnel results and validation of CFD applications.