Effect of natural ventilation on transmission load of building external walls and optimization of insulation thickness

Abstract

The effect of natural ventilation on yearly transmission load and optimum insulation thickness of different orientation external walls is studied in this paper. In addition, the effects of insulation location and life-cycle cost analysis (LCC) model on optimum insulation thickness are also investigated. The research is performed for four cities in hot summer and cold winter zone in China. Expanded Polystyrene (EPS) is selected as the insulation material. A FORTRAN code developed by an implicit finite difference method is applied to calculate yearly cooling and heating transmission loads. A LCC method, which is according with the reality, is applied to determine optimum insulation thickness. Results show that insulation location almost has no effect on total yearly transmission load while natural ventilation plays a significant role in reducing the yearly cooling transmission load for all orientation walls. Moreover, it is found that natural ventilation results in obvious decrease of optimum insulation thickness and different LCC models lead to significant distinction in optimum insulation thickness. Research indicates that the effect of orientation on optimum insulation thickness cannot be ignored. At last, a sensitivity analysis on optimum insulation thickness is carried out and the results show that insulation price is the most sensitive factor.

Keywords

• optimum insulation thickness
• natural ventilation
• cooling and heating transmission loads
• life-cycle cost analysis (lcc)
• sensitivity analysis