PASSIVE SOLAR ENERGY DESIGN OF BUILDING IN SINGAPORE : SOLAR INDUCED VENTILATION CUM WATER HEATING SYSTEM

Abstract

This thesis deals with passive solar energy design of building in Singapore emphasizing on solar induced ventilation cum water heating system. The focus of the study is to develop a hybrid system of solar induced air ventilation cum water heating in a low rise residential house. This system incorporates a cheap collector as a solar roof on the building with a stack attached to it. It has the objective of achieving both thermal comfort through induced air ventilation created in the building and generating hot water at the same time. Climatic data have been collected from various sources and presented in visual forms to bring out the dominant patterns of the Singapore climate. These were used as background materials for the experimental model and also served as a guide to the design of passive solar energy buildings in Singapore. Availability of world energy sources was discussed while the importance of solar energy as an alternative was highlighted. Consumption of energy in Singapore was also analysed and the patterns of electricity consumption were identified. Thermal comfort design parameters in Singapore were studied. Solar energy availability and its application in Singapore were also discussed. Since passive solar energy design in Singapore is relatively new, all passive solar energy design strategies applicable to Singapore were identified and discussed. Ventilative cooling was highlighted as one of the effective passive solar design strategies in Singapore. Mechanism of air ventilation to achieve thermal comfort was also discussed with illustrations of air flow patterns due to different interior and exterior design features of buildings. A full scale experimental model of the system with an 2 effective collector area of 7.04m was set up above the airwell of a terrace house. Inlet air duct from the system was placed in the bedroom to induce air ventilation for the improvement of thermal comfort. Outlet air ducts which acted as 'stack' were attached to the space frame tower. Improvement in the thermal comfort levels through induced air ventilation was measured and studied. The readings were further compared with thermal comfort conditions when there were no induced air ventilation. From the experiment, it shows a difference of 0.5 to 1.0 PMV value on the comfort level range due to improved thermal condition in the room through induced air ventilation. A microcomputer based data-logging system with software programs were developed for the experiment to record and process various parameters for analysis. Automatic recordings were made for all three different system configurations namely, both induced air ventilation cum water heating; the induced air ventilation; and the water heating. Graphs, charts and tables were drawn from the readings to explain the working of the system. Main points to be analysed were listed so that they would not be obscured by detailed analysis. Overall higher efficiency was observed in the induced air ventilation cum water heating operation with an optimum system efficiency of 82.6% at stack height of 2.55 m in this experiment. From the results, it is concluded that the solar induced ventilation cum water heating system is a workable and practical proposition. The cost study of the system 2 indicated an overall cost of $370.00/m which is half of the cost of the conventional solar hot water collector. A prototype of a low rise residential house was designed and a model to a scale of 1:50 was constructed to study the architectural implication. It was found to be an attractive and practical proposition.