Selection of Building External Windows in Different Climatic Zones Based on LCA

The area of building external windows is about 30% of the total area in building envelope, but the energy loss of the external windows accounts for over 50% of the building energy. Building external windows is the weakest parts of insulation performance in building envelope. Based on the method of life cycle assessment (LCA), this article deeply surveys and analyzes the resource consumption, energy consumption and pollutant emissions of bridge-cut-off aluminum alloy windows, unplasticized polyvinyl chloride (PVC-U) windows and aluminum-wood composite windows. This article calculates five main environmental impacts of functional unit (per m2) for the three products including the non-renewable resource consumption, energy consumption, greenhouse effect, acidification and eutrophication. The results show that to meet local design standard for energy efficiency and to achieve the same energy-saving effect, the environmental impacts of different climate zones in external windows from low to high are in the following order: unplasticized polyvinyl chloride (PVC-U) windows with 70 series (4 or 5 cavity), aluminum-wood composite windows with 68 series, un-plasticized polyvinyl chloride (PVC-U) windows with 60 series (3 cavity), bridge-cut-off aluminum alloy windows (55-58 series, the height of PA66 from 14.8mm to16.8mm), and bridge-cut-off aluminum alloy windows (65-70 series, the height of PA66 from 22mm to 35mm). This research provides domestic basic data for building external windows and green building.