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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.

Energy Benefit in Tidal Power Schemes' by Helen Suckling Abstract Predictions of energy output from a barrage in the Severn Estuary can be made by using a mathematical model describing the operation of the barrage linked to one of tidal flow. Estimates of the likely energy production from such a barrage have been made using a flat surface model of the estuary which incorporates real machinery operating characteristics. The flow through the barrage can be controlled optimally in order to obtain the greatest amount of energy from the tides. The energy predictions made by using the flat surface model are examined using a hydrodynamic model of flow in the estuary. A simple one-dimensional hydrodynamic model of the tidal flow in the Severn Estuary is presented. The area of the estuary under consideration is that which lies between approximately Berkeley in Gloucestershire and 11 fracombe on the North Devon coast. The only open boundary is assumed to be the seaward boundary. No account is taken of flow into the estuary from rivers. Finite amplitude shallow water wave equations, together with a representation of bottom friction, are used to describe the tidal behaviour in the estuary. The crosssectional topography of the estuary is assumed to be a rectangle. The boundary conditions are that there is no flow through the landward boundary and the water level at the seaward boundary is a known function of time. The equations are solved numerically as a system of ordinary differential equations. A simple Runge-Kutta method is used. The mqdel is used to obtain predictions of the level and time of high and low tide at certain points along the estuary. The results are compared with those obtained by using another, but more complex, onedimensional model. In the region of computation, the accuracy of the results of the two models are comparable. The effect of varying both the coefficient of friction and the form of the friction term is examined. The effect of linearizing the governing equations is also studied. A model of a tidal power barrage, sited between Weston-super-Mare and Cardiff, is then incorporated into the hydrodynamic model. The operation 'of the barrage is determined by using an open loop control, obtained by using a flat surface model of the estuary. The extent to which hydrodynamic effects may modify the energy predictions made by the flat surface are examined. variation of the time at which generation is allowed to start is found to affect the amount of energy predicted by the hydrodynamic model. The costate equations, which are necessary for the solution of the optimal control problem are derived, but the solution of these equations is not presented

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This study examines the effects of 10 years of river regulation on the sediments and sediment transport processes within the gravel-bedded River North Tyne. The North Tyne was regulated following the closure of Kielder dam in 1981. Since 1984, the releases from Kielder reservoir have been dominated by the generation of hydro-electricpower. The work combines a long term review and re-survey of pre-regulation sediment and bathymetric databases, with measurements of contemporary sedimentological and sediment transport processes. This has involved the application of a range of techniques designed to characterise the bed morphology and sediments. These included two new techniques for determining the structure and strength of gravel-bed surfaces. The results of these surveys revealed subtle changes in the grainsize composition of riffle sediments, characterised by an increase in the frequency of coarse particles at the surface, and the accentuation of bed structure and particle compaction. This has resulted from a process of hydraulic winnowing sustained as a result of the high shear stresses experienced on riffles during the passage of the hydropower release wave. Direct measurements of sediment transport using a range of tracing and trapping techniques identified a sediment flux divergence between riffles and pools. During rising discharges, sediments are selectively restrained by bed structure on riffles, whilst pool sediments become competent in the order pool-head, mid-pool, pool-tail. This generates a queuing system for sediments culminating at high discharges in the evacuation of the pool-tail to the downstream riffle. The presence of bed structure on riffles presents a surface of higher particle entrapment probability; the net result of which is lower particle velocities over riffles than in pools, and a subsequent choking of riffles with pool sediments. The interaction of the regulated flood waves and the riffle-pool morphology produces riffle degradation and pool-tail aggradation, although at rates much lower than in a neighbouring regulated river. Hydropower releases retard the rates of aggradational channel change caused by the reduction of flood magnitude. However, historical evidence suggests that catchment sediment supply is variable through time, and should new supplies be accessed, major channel changes should be anticipated, particularly at the tributary junctions. The results of this study have direct implications for the management of game fisheries in regulated rivers, and for understanding the relationships between flood waves and sediment transport in morphologically diverse channels.

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The thesis includes a literature survey of small hydraulic turbines, incorporating a historical review. The possible role of "micro hydros" in generating power in various parts of the world, and particularly in Iran, is discussed. The theory of turbo machinery, particularly with regard to axial flow turbines, is presented next. This is followed by some details on the design of guide vanes, runner blades and draft tube of axial flow turbines, these components being usually regarded as areas which have major impact on the performance of hydraulic turbines. The next chapter gives the details of the test circuit that was constructed. This could provide water volume flow rates of up to 0.15 m3/s at heads of up 25m. The two dynamometers that were used could adsorb pores to up to 25 kw and 50 kw respectively. An existing micro-turbine, the Agnew turbine, was selected for examination and possible improvement. The first possible improvement was the introduction of guide vanes upstream of the turbine runner (this inclusion necessitated a second support for the main shaft). It was found that this gave significant improvements - efficiency raised by over 20% in some cases. The domain of high efficiency working was considerably extended. It was observed that instability (with fall in power output) could occur after a period of running. This seemed to be associated with an accumulation of air bubbles at the highest point in the casing of the machine. Introduction of a vent from this point was found to relieve this problem and ensure stable operation.