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Climate is a major determinant in building design. There has been a long standing need by designers and architects, as well as engineers, in Saudi Arabia for easy access to hourly climatic data. Such data are essential for many passive and active solar applications, including the simulation of the energy performance of building designs. A major contribution of the present study lies in the development of a Reference Year representative of the climate in Saudi Arabia. This reference year compensates the scarcity and inadequate climatic data presently published in Saudi Arabia. It also provides substantial data base of climatic variable for use in simulation programs, not only for Saudi Arabia, but also for similar hot-arid regions. The present study also bridges the gap, currently observed in literature and research, concerning the energy performance of internal shading devices. These devices, and in particular curtains and blinds, are quite common features in our living spaces. T he effects such devices have on the energy balance of indoor spaces and the comfort of occupants, can be assessed by the simplified design tools developed in the present study. The characteristics of two samples (a domestic curtain and a low-e coated blind) have been measured using outdoor test rooms at the "Passys" test site. Results have indicated that the blind is more effective than the domestic curtain. The blind can reduce the transmission coefficient of double glazed fenestration by 11%, and can reduce the solar heat gain factor by 34%. In comparison, the curtain reduces the fenestration heat transmission coefficient and solar heat gain factor by 8% and 29% respectively. Results from the simulation programs "ESP" and "Curtain" have been compared with measured parameters. The analysis have provided confidence in such tools. This thesis has been structured to be of value to architects. The effort put forward in the layout and presentation of the thesis provide a readable and easy to understand research material. The reviews, results, and analysis covered in this thesis would be useful for further research.

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The aim of this thesis was to investigate and challenge current thinking regarding the sensitivity of the thermal performance of active solar water heating systems to the control strategy employed, with particular attention to the effect of the control temperature differential settings between the solar absorber plate and the solar store at which the circulating pump is switched on and off (dTon and dToff). A mathematical analysis suggested that the performance should be more sensitive to the above parameters than is generally believed. The theoretical appraisal also suggested a relationship for the ratio dTon/dToff required for stable pump control. Measured data from a large-scale solar heating field trial were carefully correlated with the predictions of a computer model. The calibrated model was then used to carry out a sensitivity analysis into the effect of altering the control criteria. The results have shown that, contrary to current thinking, the long-term thermal performance of the system is significantly impaired by the use of a pump switch-on criterion (dTon) higher than 6°K, and that the sensitivity to this parameter increases with increasing dTon. The results have also revealed that the heat losses throughout the system are five or six times higher than theoretical calculations based on the insulation manufacturers' specifications predict. This is not an isolated result, but has been experienced on other monitored installations, and the implication is that the quoted figures for insulation performance (which are derived from tests under tightly controlled laboratory conditions) are extremely difficult to achieve in practice. It is argued that the above two observations are linked, and that a high switch-on criterion leads to significant amounts of collectable solar radiation being wasted as the collector absorber plate loses heat to the surrounding air without reaching a temperature sufficient to turn the circulating pump on. The effect of the control settings on pump switching stability was also investigated, and, whilst the point at which instability occurred did not agree precisely with the theoretical value, the general relationship between the ratio dTon/dToff and the number of pump switching cycles per year supported the mathematical hypothesis. The discrepancy was attributed to the difficulty of measuring the collector overall heat loss coefficient, U1, precisely. For the installation under study it was found that a value of dTon/dToff above 8 would ensure stable pump control. Interpreting optimum performance in terms of both annual solar energy output and pump switching stability, the combination of all the above results led to the general recommendation that a pump switch-on setting of 4-6°K with a switch-off setting of 0.1-0.5°K should be employed to achieve optimum performance of a solar water heating system utilising flat plate solar collectors in the UK. The switch-on criterion of 4-6°K can be achieved reasonably easily by the use of standard, inexpensive controllers and nickel-based temperature sensors. However, such controllers are not capable of consistently resolving temperature differentials to the degree required to meet the switch-off criterion of 0.1-0.5°K over the full operating temperature range. For large installations, therefore, the use of high quality controllers with calibrated platinum resistance thermometers as temperature sensors will prove cost-effective and is strongly recommended.

Transparent semiconducting oxide films of ITO have been deposited using screen printing techniques for fabricating heterostructure solar cells. The ITO material used is a readymade combination of organometallic compounds of indium and tin, dissolved in a suitable organic vehicle to make a screenprintable ink or paste. The paste is then printed onto substrates in the desired configurations. The effect of various firing temperatures, from 450°C to 650 °c, on the film properties were observed. The sheet resistances, Ra, changed as the firing temperature varied. Ra values could be decreased by annealing the films in an inert gas or in vacuum conditions. An annealing temperature of 300°C seemed to be optimum for annealing the ITO films. This decreased the sheet resistance by a factor of more than ten. The lowest sheet resistance of the ITO films was about 290 n/sq, measured during annealing under vacuum conditions at a temperature of 300 °C. This gradually increased up to about 1 Kn/sq after the film was aged for a few days in a laboratory atmosphere. The solar cell structures of ITO/p-Si and ITO/Sn/p-Si were made in this research. The first structure suffered from an excessive oxide interfacial layer thickness and it was abandoned. The second structure was then made to overcome the problems resulting from the interfacial oxide. The Sn layer was produced by using evaporation prior to the screen printing of ITO. The thickness of the Sn layer was about 100 nm. After evaporation, screen printing methods were used to complete the heterostructure solar cell. The best typical values of these cells are, open circuit voltage, V~= 0.360 Volt, short circuit current density, Jsc= 16.4 mA/cm2 with fill factor, FF = 0.34 and efficiency, 1) = 2.5% under 80 mW/cm2 simulated illumination, where this illumination is equivalent to air mass 2, (AM2).

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