| The survival and development of human society is inseparable from energy.However, the contradiction between current global energy supply and demand isgrowing, which becomes one of the most important factors restricting the developmentof global economy. Building is the main consumer of energy, and its energy saving haslong been the focus of scholars. China has a vast territory and distinct regional climates,so building energy conservation technology also needs to be adjusted according to localconditions. Tibetan Plateau has the most abundant sunlight in China and even in theworld. And Tibet is a special area where only heating is required and cooling is not. Theecological environment in Tibet is very fragile, which is easy to be damaged anddifficult to recover. So the study on passive solar buildings in this region is verysignificant.Public buildings have high energy consumption per unit area, thus hugeenergy-saving potential. This thesis focuses on public buildings in Lhasa to study howto use solar energy resources to reduce energy consumption while improving the indoorthermal comfort in public buildings. Firstly, an office building in Lhasa was taken as anexample, of which the indoor thermal environment and energy consumption weresimulated using DeST. The impact of each factor on building heating energyconsumption has been ranked using orthogonal design.Then, taking this office building as an example, the impact of the envelope thermalperformance on indoor thermal environment and total heating load has been studied.The optimal indicators for energy efficiency design of office building envelope in Lhasaare derived as follows:①Building orientation: Buildings in Lhasa should be southoriented, and the main heating room should be south oriented. When constrained bytopography or other factors, the orientation of the building should be±30°from south;②Exterior walls: Southern external walls of office buildings in Lhasa should use thickwalls (such as240mm wall and370mm wall) with wall heat transfer coefficient K≤2.0W/(㎡K) and no insulation. Northern external walls should be insulated and heattransfer coefficient should be≤0.9W/(㎡K), with insulation of eastern and westernexterior walls taken into consideration;③Exterior windows: Northern and southernexterior windows are advised to use common double glazing with high transmittance ofsunlight and moderate cost;④Window-wall ratio: Window-wall ratio of southern exteriors should be≥0.4; Window-wall ratio of the northern exteriors should be≤0.2;⑤Roof: Lhasa is drought and lack of rain throughout the year, with intense solarradiation, so inverted roof is advisable and roofing heat transfer coefficient should be nogreater than0.7W/(㎡K).Lastly, field test of indoor thermal environment and heat transfer coefficient ofsouth oriented exterior was carried out in this office building. Results showed that in themorning, the south oriented rooms only need about1hour’s air conditioning in theheating season. Afterwards, indoor thermal environment can meet the requirementsusing solar radiation and no active heating. The temperature of north oriented rooms islower, which means the insulation needs to be strengthened. The measured heat transfercoefficient of southern exterior wall was1.77W/(㎡K). Results of the field test areconsistent with the conclusions of the above theoretical analysis.This thesis has analyzed the factors affecting energy consumption of officebuildings in Lhasa and has derived the optimal indicators for energy-efficient design,which would provide theoretical reference for future energy-saving design of bothnewly constructed and reconstruction projects. |
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