Inversion Study On Heat Conductivity Of Building Envelope

In accordance with the requirement for the detection of feature and energy conservation of building envelope, Inversion study on heat conductivity of building envelope provides theoretical support and requirement for the application of the software.In a certain condition of the building envelope, model and boundary conditions were confirmed. The control-volume-based numerical method was presented to deal with the procedure of heat transfer in a multilayer wall. The harmonic mean method was used to deal with discontinuity of material properties of the multilayer wall. The effective thermal conductivity was calculated by the compound method. Genetic Algorithm and Levenberg-Marquardt method were used to identify the thermal conductivity of building envelope. The composition with the genetic algorithm and the Levenberg-Marquardt method were programmed. It indicates that, the genetic algorithm and the Levenberg-Marquardt method are both suitable for the inverse problem of heat condition in transient state on heat conductivity of numerical schemes utilizing. The calculation results are approximately equal to the experiment result. The calculation speed of genetic algorithm is slow and the genetic algorithm needs high-powered computer configuration, which are the rub of the research. The calculated result by genetic algorithm shows that the accuracy of this method is high, and the method is not limited to initial value and it can overcome the effect of the measured error . The speed of the Levenberg-Marquardt method is fast but the result is inaccurate compared with genetic algorithm, and it can't overcome the effect of the measured error and initial value.A fast and accurate software for calculating heat conductivity of building envelope has been developed. The software uses C++ language. It can calculate heat conductivity of building envelope on the condition the you enter the parameter such as boundary conditions, physical parameters, physical dimension, Spatial Lag and time step. This software is not only applied to this example but also simply applied to identify conductivity of different structures and different material of complex structures. This software is a sub module of the chief platform which serves for a nation-support project for heat conservation effect on-line assessment and diagnosis emulation. It offers vital information for estimating the capability of heat conversation of the building envelope, and also provides substantial support for future studies.