Their findings confirm the affordability of building all-electric homes with the 2023 Stretch and Opt-In Specialized Codes in Massachusetts. In fact, all-electric homes are currently less expensive to build than those built with gas or as mixed-fuel (gas and electric) homes. Estimates of the cost of construction identify ductless, all-electric homes as the least expensive to build premiums compared to the 2022 Stretch Code can be fully offset by the MassSave all-electric incentive.
Initial cost estimates for construction under the 2022 Stretch Code requirements found that single family construction costs increased 1.8-3.0 percent, while multi-family Passive House construction was associated with a 2.8% overall increase. However, several large nonprofit builders of Passive House single-family and multi-family affordable housing note that as developers, engineers, and subcontractors become more familiar with Passive House construction requirements and techniques, incremental costs have declined and are expected to continue to decline.
Moreover, operational costs demonstrate a greater than 20% reduction in operational costs for single-family all-electric homes. Modeling energy savings for more energy efficient Passive House multi-family homes finds reductions in energy use of 40-60% or higher. However, increases in incremental costs for construction (dependent on local market supply and demand conditions) may impact the benefit of energy cost savings.
Adoption of the opt-in specialized code is essential to helping Massachusetts achieve statutory emissions reductions by requiring prewiring of new mixed-fuel home and avoiding higher cost future electrification retrofits,” says Justin Steil, one of the authors of the study. The opt-in specialized code requirement that new multifamily housing achieve Passive House standards will significantly reduce carbon emissions in those buildings, in addition to delivering health benefits to residents.