This How Housing Matters article explains how energy efficiency upgrades can boost low-income multifamily properties’ net operating incomes, save low-income households money on energy bills and improve environmental outcomes—making investments in these upgrades a triple win. But narrow operating margins, competing repair priorities and misaligned incentives between landlords and tenants can lead property managers to miss opportunities for energy efficiency upgrades. This evidence roundup highlights why policymakers and funders should continue to push housing providers, utility companies and intermediary organizations to bolster their efforts to bring energy efficiency upgrades to both subsidized and unsubsidized multifamily rental housing.