In June 2026, ICF Consulting published a report titled "Cost of Energy Efficiency Changes in New Housing: 2009 to 2015 or 2024 IECC," which calculated the incremental upfront construction costs of moving from the 2009 IECC to 2015 IECC and 2024 IECC for residential buildings. The report estimates the incremental upfront costs for compliance with the 2024 IECC compared to the 2009 IECC to be between $2,566 and $8,320, depending on the climate zone, foundation type, and whether a home uses gas or is all-electric. The report does not calculate any savings or costs after construction, such as energy bill savings, maintenance costs, mortgage payments, etc. The report mentions that the actual upfront costs of newer energy codes may be even lower than the estimates because of two factors: 1) tighter building envelopes allow for smaller HVAC units, saving upfront costs, and 2), builders may already exceed certain code requirements when building to a 2009 IECC (such as furnace efficiency), making the jump to 2024 IECC requirements not as significant in cost. The full report can be found here.