Numerical Analysis on the Thermal Performance of a Lightweight Aluminum Standing-seam Roofing Structure with Experimental Validation

摘要

This paper reports an investigation result of the energy performance of a large-space building with the light-weight insulation roof structure.A computer simulation model for analyzing its dynamic building energy use is reported in the paper,and the thermal performance of a widely used roofing structure (R1) is evaluated accordingly.The developed model was validated by experimental results,and good agreement was found.The results indicate that the energy consumption for air conditioning of large-space buildings can be considerably reduced by employing lightweight roofs with polyurethane insulation (R2) compared with the buildings with currently used glass-wool insulation materials (R1).It was also found that the maximum heat flux of the lightweight metal roof at noon is 11.57W/m2,while the heat flux of south walls is 7.96W/m2;6.87W/m2 for east walls,6.42W/m2 for west walls,3.30W/m2 for north walls.The heat gain through the lightweight roof structure accounts for 32.03% of the total heat gains of the large-space building.Therefore,optimum design of a roof structure should be conducted.Four different roof structures are evaluated in this paper.It is found that the peak heat gain for R2 is 26200.94W,but 54129.77W for R1.The peak heat gain of R2 only accounts for 48.4% of that of the R1.Properly arranging insulation layers and selecting insulation material for such a building can significantly reduce heat gain through the roof,and hence reduce the space cooling load of a building and the design capacity of A/C systems accordingly.