Research on the green retrofitting strategies of existing residential buildings in cold areas

Owing to global climate change and the energy crisis, there is an urgent need to enhance the energy efficiency and reduce the carbon footprint of existing residential buildings in cold regions. In this paper, the DeST software was used to simulate the energy consumption of Longhuhongting condominium in Lunan District, Tangshan City, as a case study. Relative to the baseline, increasing the external wall insulation thickness from 50 mm to 110 mm yields a 17.32 % reduction in the annual cumulative space-heating load, while an equivalent increment in roof insulation thickness delivers a 9.05 % improvement in energy-saving performance. The aluminum alloy hollow or low-e hollow glass window significantly reduces the heat load and achieves a maximum energy saving rate of 58.85 %, while reducing the cooling load by 48.2 %. Through combined simulation, the optimal scheme achieves an overall energy-saving rate of 38.39 % and an annual reduction of 61.69t CO 2 . While the scheme’s static payback period is 13.07 years, it remains feasible when considered alongside long-term environmental benefits and potential policy support.