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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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A thesis submitted to the Faculty of Science, in fulfilment of the requirements for the degree of Doctor of Philosophy. University of the Witwatersrand, Johannesburg May 23, 2016 / Amongst the major technological challenges of the twenty rst century is the harvesting of renewable energy sources. We studied the solar cell performance of the ternary compounds AgAlX2 (X = S, Se and Te) and AgInS2 as promising materials for meeting this challenge. Structural, electronic and optical properties of the compounds were investigated by means of the density functional theory and many body perturbation theory. Using cohesive energy and enthalpy, we found that among six potential phases of AgAlX2 and AgInS2, the chalcopyrite and the orthorhombic structures were very competitive as zero pressure phases. We predicted a low pressure-induced phase transition from the chalcopyrite phase to a rhombohedral phase. For the chalcopyrite phase, we found that the tetragonal distortion and anion displacement were the cause of the crystal eld splitting. The bandgaps from the general gradient approximation PBEsol were underestimated when compared to experiment and accurate bandgaps were obtained from the hybrid functioanl HSE06, the meta-general gradient approximation MBJ and GW approximation. Optical absorption from the Bethe-Selpeter equation indicated the presence of bound exciton in AgAlX2. We estimated the solar cell performance of the compounds using the Shockley and Queisser model and the spectroscopy limited maximum e ciency approach. We found that apart from AgAlS2, the estimated theoretical e ciency of the other compounds was greater that 13 %.

University of Macau / Faculty of Science and Technology. / Department of Electrical and Computer Engineering

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.

Thesis. 1977. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Includes bibliographical references. / by John I. Meyer, Jr. / M.Arch.A.S.

The performance of unheated solar buffer zones (SBZs) or sunspaces in relatively high latitudes' locations has become increasingly controversial. Conceived as simultaneously saving energy and providing amenity, the latter characteristic has provided the user with the opportunity and/or aspiration to negate the former - by heating a sunspace during winter either directly, or by opening it up as an extended heated part of the dwelling. Scotland has been host to passive solar projects promoting the use of small sunspaces where 'opening up' is a greater risk than directly heating. 'Opening-up' signals a change from 'indirect' to 'direct' solar gain with the heated volume partially extended. Within this context, this work examines the relevant aspects of a small sunspace as a passive solar technique by posing three questions from which answers are to be sought. 1. How useful and usable are the sunspaces ? 2. To what extent are occupants' interventions affecting energy saving ? 3. What is the energy 'worth' of the two sunspaces? The vehicle for this work is the CEC Solar Energy Demonstration Project at Easthall, Glasgow, where 36 thermally sub-standard flats built in the 1960s have been retrofitted with each flat having two sunspaces on opposite facades to tackle the issue of random orientation, and a common stairwell functioning as a shared thermal buffer space. The author's close acquaintanceship with a relatively large sample of occupants over a monitoring period of two years, taken in conjunction with data from questionnaires, interviews, diaries and personal observations, has enabled a substantive 'cause and effect' analysis. The findings confirm the likelihood of user intervention negating optimum performance, especially in spring and autumn, and in association with particular household types and characteristics. Nevertheless, the mean space heating load was approximately 30% lower than it would have been for the equivalent dwelling adjusted to the same internal temperature and ventilation rate, but without the front and rear sunspaces; and winter performance vindicates the role of sunspaces in providing good air quality at a relatively low running cost. The work sets aside the issue of life-cycle, pay-back analysis since, in general terms, this is dependent firstly on how much of the cost of sunspaces is written off as necessary floor area or improved amenity, and secondly on variable costs of a complementary energy-efficient package. However, on the assumption that these factors may be favourable, the work concludes with broad design recommendations based on the research findings; in particular recognising the dominance of the 'heat recovery' rather than 'solar' mode of operation of sunspaces.

Solar heating systems are a proven technology which can significantly reduce the amount of fossil fuel needed to meet the heating reuqirements of homes. The southern part of Australia represents the region which requires considerable heating and experiences significant levels of sunshine during the winter period. However existing solar heating systems are not a viable technology due to practical, aesthetic and cost factors. A novel concept for a solar heating system has therefore been proposed which attempts to address these factors.

<p>Almost all the domestic water in Brazil is heated with an electrical heater directly by the end consumer. A typical heater has an effect of 5 400 W and when the whole population takes a shower in the evening it causes big peaks in the electrical grid. This consumption peaks could be reduced by simple and cheap solar collector system. </p><p>Different system technologies and the most important parts of a solar collector system are described in the technical background. In Lajeado almost every system is a self-circulated system because of the simplicity and the lower costs. </p><p>Solar cooling as an alternative to the vapor compressor chillers has been studied. The cooling demand is biggest when the sun shines; this makes the sun perfect as a source to cooling. The ab- and adsorption chillers as a method in the future have been discussed in this paper; however it has only been studied briefly because small scale chillers using the technology can not be found on the market yet. </p><p>A number of different systems have been dimensioned after the existing conditions of Lajeado, the town where the project has been carried out in. Prizes and costs for both installation and materials come from the local solar collector supplier. With this as a background; several systems for various hot water demands has been dimensioned and costs and repayment time been calculated. A study of all the systems shows that, if the hot water demand increases and the systems get bigger, the profitability grows and the repayment time becomes shorter, down to three years. In almost every case the repayment time was under eight years, which makes solar heating attractive and the profit is good for the southern Brazil.</p>