Thermal properties optimization of envelope in energy-saving renovation of existing public buildings

Abstract The shape factor and windows-to-wall ratio are different from building to building. How to design the thermal properties of building envelope affects energy-saving renovation economy of existing public buildings. The limited heat consumption per unit volume and equivalent heat transfer coefficient of external windows and wall were proposed based on the prescription of China national standard “Design standard for energy efficiency of public buildings”(GB50189-2005) for envelope design. Mathematical model on economical thermal insulation thickness of building envelope and thermal properties optimizing of envelope were built considering the impact of house orientation, windows-to-wall ratio and types of windows. The model is verified to be feasible by an existing public building in Shenyang. The variation of windows-to-wall ratio for different orientation leads to the different economical thermal insulation thickness of building envelope and payback period. The project optimization design for envelope renovation could be determined by the technical and economic analysis considering the impact of house orientation, windows-to-wall ratio, types of insulation materials and windows.