Multidisciplinary Optimization Research In Insulation Thickness Of Building Envelope Based On Cost

Using thermal insulation materials in the envelope of the building is one of the most effective energy-saving measures. However, the existing insulation thickness is determined by the energy conservation design standard without considering the life cycle of building. Based on the theory of life cycle assessment (LCA)of building, an improved economical optimum mathematical model of insulation thickness is developed, considering heat transfer of exterior wall under the actual climate, air-conditioning energy structure, cost of insulation materials, building life, performance of air-conditioning equipment, interest rate and so on.Calculating transient heat transfer trough wall using Frequency-Domain Regression (FDR) method and effect of moisture on heat transmission of envelope is also taken into account. Then, heat transfer is transformed into heat loads by Radiant Time Series Method (RTSM).Combining air-conditioning loads and the economical mathematical model of insulation thickness, a practical software for calculating optimum thermal insulation thickness of Building Envelope is developed, the software with friendly interface is convenient to be used. It can be used to identify the optimum thermal insulation thickness of various envelopes under the natural climate of different geographical positions. The results can be used as building envelope design standards, and provide reference data for energy-saving reconstruction of the old building.