TA-23-C073 – Going Beyond Business as Usual: Finding Deeper Cost and Carbon Savings in Multifamily Energy Efficiency Programs

Multifamily retrofit programs are typically structured to incentivize minimum improvements, rather than encourage high-performance, deeper energy retrofits. Given the increasingly ambitious targets set by building performance standards, it is important to leverage these programs to implement deep energy retrofits. This paper examines the energy, cost and carbon impacts of deep energy retrofits (DERs) versus “business as usual” retrofits (BAUs) in existing multifamily buildings. An energy model representing a typical existing multifamily building in Cincinnati, Ohio was developed. A series of retrofits were then modeled that meet the minimum performance threshold required to receive financial incentives. These measures included changes to the building envelope, domestic hot water (DHW) systems and HVAC systems to represent a BAU approach to retrofits. These same retrofit measures were then modeled using high-performance design criteria to represent a DER approach and compared to the BAU results. Our results indicate that the envelope and DHW system DERs provided modest energy, cost, and carbon savings compared to the BAUs. In contrast, the HVAC system DER, which involved electrification using a heat pump, produced much greater energy savings, but increased costs and provided only modest carbon savings compared to the BAU. Overall, the results show that the benefits of DERs vary by retrofit type and performance metric and that implementing DERs as a combined package is the best strategy for maximizing their potential benefits and minimizing their drawbacks.