Economic feasibility and energy-cost benefits of power recuperation systems in ultra-low-energy buildings

The rapid expansion of ultra-low-energy buildings in China has increased interest in power recuperation systems that recover otherwise wasted electrical and mechanical energy from elevators, ventilation equipment, heat pumps, and other building services. However, evidence concerning the economic feasibility and energy-cost benefits of these systems remains limited. This study evaluates the effects of power recuperation technologies on building energy consumption, operating expenditure, and investment returns in China. A panel dataset covering ultra-low-energy residential and commercial buildings across 30 Chinese provincial-level regions from 2015 to 2025 is constructed using building energy-monitoring records, electricity tariffs, climatic conditions, building characteristics, and regional economic indicators. A propensity-score-matched difference-in-differences model is employed to estimate the causal effect of power recuperation system adoption, while building and year fixed effects are used to control for unobserved heterogeneity and common temporal shocks. The analysis is supplemented by system generalized method of moment's estimation to address potential endogeneity between technology adoption and building energy performance. Economic feasibility is assessed through annual energy-cost savings, discounted payback period, net present value, internal rate of return, and sensitivity to electricity prices, capital costs, climatic zones, and building-use intensity. The econometric results indicate that power recuperation systems significantly reduce electricity consumption and annual operating costs, with stronger effects in high-rise commercial buildings, buildings located in regions with higher electricity tariffs, and facilities characterized by intensive elevator and ventilation use. The estimated economic returns are sensitive to initial investment costs and system utilization rates, although most installations remain financially viable under medium- and long-term operating scenarios. Regional heterogeneity analysis further shows that eastern and northern Chinese cities achieve comparatively greater financial benefits because of higher energy prices, denser building utilization, and longer equipment operating periods. The study concludes that power recuperation systems can improve both the energy efficiency and lifecycle economic performance of ultra-low-energy buildings in China. Targeted subsidies, performance-based incentives, standardized energy monitoring, and region-specific technology deployment strategies could accelerate their adoption in China's low-carbon building sector.