Evaluating the Circular Economy Performance of Construction and Demolition Waste Management in Taiwan: A DEA and Malmquist Index Approach

Construction and demolition waste (CDW) is a major industrial waste stream in Taiwan. Conventional indicators such as recycling rates and treated volumes describe throughput, without directly measuring how efficiently regional systems transform resource inputs into reusable products while limiting residual waste. This study evaluates regional CDW circular-economy performance using an input-oriented data envelopment analysis (DEA) framework and the Malmquist productivity index. The original database covered 19 geographic units for 2023–2025; excluding observations with all-zero outputs, the static DEA dataset contained 53 county-year observations for 18 counties and cities. A common pooled frontier was estimated using three inputs (CDW received, licensed treatment/reuse capacity, and estimated treatment cost) and three outputs (treated/reused CDW, recycled product output, and a reciprocal transformation of residual waste). For 2023–2025, the mean Charnes-Cooper-Rhodes (CCR) efficiencies were 0.509, 0.455, and 0.461 and mean Banker-Charnes-Cooper (BCC) efficiencies 0.639, 0.598, and 0.573, respectively. Input correlations were moderate ( r ≤0.578). Slack analysis identified frequent treated-/reused-output shortfalls and input excesses. While the Malmquist results reveal heterogeneous regional pathways, four zero or non-finite transitions, for Kaohsiung City and Taitung County, were treated as non-interpretable numerical cases rather than as substantive productivity declines. Because the processing and output statistics include non-CDW materials and carryover inventories, scores are interpreted as relative system-level operational benchmarks. These findings support scale matching, stronger waste-to-product conversion, and region-specific management interventions. Recycled product quantity is interpreted as an operational valorization indicator rather than as a complete measure of circularity, because product quality, substitution potential, and market acceptance remain important.