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.