Building Integration of Solar Energy. A Multifunctional Approach
Abstract: This thesis consists of two parts. The first part deals with building integrated solar energy, mainly from an architectural point of view. It is based on a literature review and discusses solar energy, the building as a system, the concept building integration (definition, motives, criteria, examples) and the relation between architecture and solar energy. The second part presents a novel design of a concentrating, hybrid PV/T system, which uses windows as the media in the integration of building and solar energy system. It is placed inside a window or a glazed facade, where the reflectors are used as moveable sunshades and internal insulation when closed. Since the system is involved in the building's thermal balance and daylight provision, the system is evaluated for its thermal properties and for its daylight obstruction. Measurements show that the window's U-value is reduced from 2.8 for the bare window to 1.2 W/m2K with closed reflectors, and simulations indicate a strong redistribution of the daylight with open reflector screens. The active thermal and photovoltaic performance has been measured for determining the concentrating system's optical efficiency. Long-term measurements of the thermal performance were also made during the summer of 2004. The results were used for creating models, simulating the system's performance, concerning PV/T yield, passive heat gains and thermal loss due to the varying optical performance and U-value of the open or closed reflectors. The simulations were used to privde an indication of a suitable control strategy, i.e. balance between open or closed mode of the reflectors, in respect for a maximal amount of daylight. It was suggested to generally keep the reflectors open at irradiance levels between 10 and 200 W/m2, which gives an open window 2800 hours of the year. This control strategy leads to an annual yield of 164 kWh/m2 of active solar heat and 50 kWh/m2 of photovoltaic electricity, window area. The annual net thermal transfer through the Solar Window is -78 kWh/m2.
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