Development of a Passive Solar Simulation Technique Using Small-Scale Models.

In order to investigate the thermal simulation of a full-sized passive solar building using scale models, a simplified base line unit (6' x 6' x 7' inside dimensions) along with several half and quarter scale units were used in testing the adequacy of the scaling relationships. The experimental program involved both indoor and outdoor tests of the scaled units with various types of passive solar systems--including direct gain, water wall, thermosiphon air collector systems, moveable insulation, and multi-zone. This research has shown that small-scale models can be used as predictive tools for the more complex passive solar systems now in common use. Important factors in this direct comparative thermal scale modeling technique have been identified: (1) Interior thermal mass plays a significant role in thermal scaling in the aspect of time lag. The difficulty in scaling volumetric air mass ratio can be overcome by introducing thermal mass; (2) The edge and corner heat-loss ratio difference plays an important role in scaling due to the transition from two dimensional to a three dimensional heat transfer. Statistical analyses of the data can be used to establish adjustment factors; (3) The temperature stratification (temperature gradation) due to the scaling has been identified: the smaller the model, the more temperature stratification exists; (4) The time scaling variable can be eliminated in both conductive and convective scaling if one satisfies the scaling factors as discussed; (5) Convective heat distribution systems using natural convection can be simulated with a small-scale model by providing an appropriate opening area ratio between the prototype and scale model while maintaining identical time lag between the prototype and scaled model. The opening area ratio has been identified. All tests were done under identical micro-climate and site conditions at the Building Technology Laboratory of the University of Michigan. These initial test results have accomplished an essential logical step towards the establishment of a thermal scaling technique prior to full-scale building simulation. All the analyses of the test results suggest that it is quite feasible to simulate the thermal performance of full-scale passive buildings whose thermal features are more complex than those reported in this study.PhDArchitectureUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/158564/1/8204577.pd