Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States.
Center for Industrial Ecology, Yale University, New Haven, Connecticut 06520, United States.
Environ Sci Technol. 2022 Apr 5;56(7):4565-4577. doi: 10.1021/acs.est.1c06474. Epub 2022 Mar 18.
Material efficiency (ME) can support rapid climate change mitigation and circular economy. Here, we comprehensively assess the circularity of ME strategies for copper use in the U.S. housing services (including residential buildings and major household appliances) by integrating use-phase material and energy demand. Although the ME strategies of more intensive floor space use and extended lifetime of appliances and buildings reduce the primary copper demand, employing these strategies increases the commonly neglected use-phase share of total copper requirements during the century from 23-28 to 22-42%. Use-phase copper requirements for home improvements have remained larger than the demand gap (copper demand minus scrap availability) for much of the century, limiting copper circularity in the U.S. housing services. Further, use-phase energy consumption can negate the benefits of ME strategies. For instance, the lifetime extension of lower-efficiency refrigerators increases the copper use and net environmental impact by increased electricity use despite reductions from less production. This suggests a need for more attention to the use phase when assessing circularity, especially for products that are material and energy intensive during use. To avoid burden shifting, policymakers should consider the entire life cycle of products supporting services when pursuing circular economy goals.
材料效率（ME）可以支持快速缓解气候变化和循环经济。在这里，我们通过整合使用阶段的材料和能源需求，全面评估了美国住房服务（包括住宅建筑和主要家用电器）中铜使用的 ME 策略的循环性。尽管更密集的使用空间和延长电器和建筑物寿命的 ME 策略减少了对初级铜的需求，但采用这些策略会增加通常被忽视的使用阶段在本世纪内占总铜需求的份额，从 23-28%增加到 22-42%。在本世纪的大部分时间里，房屋装修的使用阶段铜需求一直大于需求缺口（铜需求减去废料供应），限制了美国住房服务的铜循环性。此外，使用阶段的能源消耗可能会抵消 ME 策略的好处。例如，尽管生产减少，但较低效率冰箱的使用寿命延长会增加电力使用，从而增加铜的使用和净环境影响。这表明在评估循环性时，特别是对于使用过程中材料和能源密集型的产品，需要更加关注使用阶段。为了避免负担转移，政策制定者在追求循环经济目标时，应考虑支持服务的整个生命周期。
