Investment analysis and policy recommendation on energy-saving renovation of exterior walls in boreal regions of China

The purpose of this paper is to analyse the economic and environmental benefits of investing in external wall insulation for an existing building with a comprehensive consideration of the initial investment, insulation material performance and construction techniques. The economic benefits are further estimated based on a techno-economic method with a sensitivity analysis of the initial investment, energy prices and discount rate. The results show that the total annual heating load savings are 1,229,072 KWh, equivalent to about 442.47 million kJ, and that the total heating cost savings are 21,668 Y{stroke}. Further, the annual cooling load savings are found to total 30,625 KWh, and the cooling cost savings are calculated to be 15,313 Y{stroke}. This paper's economic analysis arrives at two important conclusions. First, because the investment cannot be paid back in a reasonable timeframe, no private sector will be tempted to carry out energy-saving projects in buildings at the current technology level. Second, renovation projects undertaken in China's cold regions can affect heating loads in winter much more than cooling loads in summer. We also analyse the environmental gains by considering energy consumption and carbon emission reductions. In this paper, the annual carbon emission reductions of the project are estimated at 563.3 tons, the sulphur dioxide emission reductions at 1.83 tons, the nitrogen oxides emission reductions at 1.59 tons and the dust emission reductions at 1.18 tons. As such, external wall thermal insulation has a significant effect on energy saving. We hope this paper contributes to the promotion of a nationwide energy-saving programme for buildings in China.