This thesis reports the results of research into the modelling and simulation of solar water and space heating for Cyprus, and the investigation of the factors concerning the optimisation of such systems. Further a number of design criteria, which can be used by consultants and designers of solar heating systems, have been established. Five solar heating system configurations have been modelled using the component models of the TRNSYS programme. They concern thermosyphon solar water heating systems, active solar water heating systems, solar space heating systems, combined solar water and space heating systems and solar assisted heat pump systems for space and water heating. These models are used to simulate the thermal performance of the systems and investigate their cost effectiveness under the weather and socioeconomic conditions of Cyprus. The results of the simulations have been used to identify the optimum design criteria for such systems in the Cyprus environment. The design criteria that have been established are concerned mainly with the solar collector and the storage tank and they are key design factors for a solar heating system. The design factors include the collector orientation and tilt angle, the collector to load factor which relates the collector surface area to the annual thermal load, the storage factor which relates the capacity of the storage tank to the collector size, the collector water flow flux, which relates the water flow rate through the collector with the collector area, and other criteria, which concern the auxiliary heat supply and the heat exchangers. For space heating systems, in addition to the above factors, a new design criterion is introduced, the collector to floor area factor, which relates the collector area to the building floor area, while for domestic hot water systems, the collector to consumer factor is used to specify the collector surface area needed for each hot water consumer in the building. This work has resulted in the publication of four papers in refereed International Journals and the presentation of three other papers at International Conferences. A list of publications is included in the Appendices.

ABSTRACT : THESIS PART ONE. The thermal performances of two schools with central atria, and a typical primary school class- base, were assessed using the SERI-RES computer model. ABSTRACT : THESIS PART TWO. To improve the modelling of sunlight and daylight, measured values of solar radiation, recorded at one minute intervals, were used to examine the relationship attributed to Lui A Jordan(1960), between the fraction of the solar radiation which is received on a horizontal surface, and the equivalent diffuse fraction,

In this paper , analytical techniques are developed for evaluating the performance of passively heated buildings. As most buildings use conservatories to enhance their performance , the direct gain types having attached conservatories are considered in detail. The complexity of the problem is minimized by ensuring all equations are developed from first principles. Auxilliary energy predictions for space heating by the method is in close agreement with monitored data for three occupied houses in Milton Keynes in England.

The performance of three types of passive solar feature has been studied; fifteen Roof-Space Collectors on an estate of low energy houses at the Milton Keynes Energy Park, 101m2 of Thermosyphoning Air Panels at a county primary school in Nazeing, Essex, and three Thermosyphon Solar Water Heaters installed on a group of three terraced cottages at Cranfield, Bedfordshire. Each of these passive solar features was monitored intensively for at least one heating season using dedicated data-acquisition systems. The maximum specific annual solar contributions to the auxiliary space/water heating systems were 128 kWh/M2 , 78 kWh/M2' and 104 kWh/M2 respectively. The corresponding payback periods were 25,37 & 21 years respectively, on replication.

The thesis presents analytical and experimental methods of studying various aspects of the optical and thermal performance of a transwall passive solar system. Some of these methods are applicable to other solar systems. Two ray-tracing techniques, 1-dimensional and 3-dimensional, are presented for an accurate calculation of the optical properties of a transwall module with its outside glass plate(s). These techniques calculate not only the reflected, absorbed or transmitted fractions of the incident radiation but also the spectrum of the transmitted radiation. This information is required for a better assessment of the transwall system as an illuminating source and as a thermal system. Both techniques are applied to a particular transwall module with one outside glass plate and the importance of various features of the incident solar radiation (such as spectrum, angular variation, polarization, etc.) are discussed. The difficulties associated with the nature of the diffuse solar radiation coming from the sky, or the ground , are overcome by employing a discretization method in which the continuous diffuse radiation is divided into discrete pencils of radiation. An analytical thermal model of a passive solar system is presented and its verification is established by using a test-box containing a full size transwall module. The outcome of this verification is satisfactory given the uncertainties of the optical and thermal properties of the various elements of the test-box. The success of the analytical modelling depends on accounting for the 3-dimensional solar radiation field outside and inside the passive solar system. The methods developed, accompanied by the two ray-tracing techniques, allow for an accurate distribution of the total incident radiation among the semitransparent elements and the external and internal surfaces of any passive system. The method of distributing the solar radiation among the internal surfaces of an enclosure is applied to the convex parallelepiped enclosure of the test-box and, as additional example of the method, also applied to the non-convex enclosure of a typical glasshouse with E-w transwalls. The phenomenon of the natural convection of a fluid inside a transwall module induced by the absorption of radiation is predicted by a numerical method, first introduced by Patankar. Examples of the temperature, pressure and velocity fields of three transwall modules filled with distilled water under the irradiance conditions of 400 to 500 W/m2 are presented. By introducing the effective conductivity concept the complicated phenomenon of the fluid convection inside the module is simplified to a conduction phenomenon. This is also necessary for the long term-days or months - analytical modelling of the total transwall passive system because the numerical prediction of the former phenomenon requires an excessive amount of computer time. The calculation of the effective conductivity is obtained by employing an analytical approach which makes use of the data collected from the application of the numerical method, mentioned above. Values of the ratio of the effective conductivity to the conductivity of the still water are calculated at two interfaces inside the water of four different transwall modules. Measurements of the temperature and the velocity at certain points in a small transwall module irradiated by a solar simulator have been performed to support some of the numerical predictions.

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