DE Building Energy Code

Building Energy Code

Administered by Delaware Department of Natural Resources

AI summary · 7/12/2026

Delaware requires all new homes built after January 1, 2026, to be designed as zero net energy capable, meaning they must be energy-efficient enough to use zero energy if you add on-site solar or similar generation. Your home must meet the 2024 IECC standards, which cover insulation, windows, HVAC systems, and other efficiency features enforced by your local building official during construction and inspection.

Delaware's 2024 IECC (residential) and ASHRAE 90.1-2022 (commercial) codes, effective April 11, 2026, are mandatory statewide and enforced locally. You can use COMcheck and REScheck tools to demonstrate compliance, and all new residential construction must achieve zero net energy capable status by 2026, requiring careful design of the building envelope and systems to minimize energy demand.

Delaware's Energy Code is administered by the State Energy Office under DNREC and reviewed every three years for updates to IECC and ASHRAE standards. The 2024 IECC and ASHRAE 90.1-2022 became effective April 11, 2026; local code officials in each county and municipality enforce compliance. State law (SB 59) mandates zero net energy capable design for all new residential buildings after December 31, 2025, and commercial buildings after December 31, 2030, with agricultural structures exempt as determined locally.

Program details

Program ID
1827
Last updated
5/21/2025

Eligibility

Sectors
commercial residential
Technologies
comprehensive measures/whole building

Program summary

NOTE: Much of the information presented in this summary is drawn from the U.S. Department of Energy’s (DOE) Building Energy Codes Program and the Building Codes Assistance Project (BCAP). For more detailed information about building energy codes, visit the DOE and BCAP websites.

On May 2014, Delaware updated its energy code to 2012 IECC with amendments for residential sector and ASHRAE 90.1-2010 with amendments for the commercial sector. The Delaware specific amendments to the energy code can be accessed on the regulation webpage. These codes are effective starting November 2014 following a six month grace period.

The Delaware Energy Code is reviewed by the State Energy Office every three years for potential updates to the most recent version of the International Energy Conservation Code (IECC) and ASHRAE Standard 90.1. The compliance with the building code is mandatory statewide, with exception for agricultural structures as determined by the local government. The codes are enforced on the local level by the code officials within the county or municipality.

SB 59, signed in July of 2009 requires the Delaware Energy office to establish programs to promote construction of zero net energy homes. The law requires all new residential buildings constructed after December 31, 2025, and all new commercial buildings constructed after December 31, 2030 to be zero net energy capable. To be qualified as net zero energy capable, the building must be energy efficient enough that the building would consume zero energy if the building owner chose to install on-site generation.

In June 2020, the Division amended the Regulations by adopting the 2018 International Energy Conservation Code and the ASHRAE 90.1 2016 Energy Standard for Buildings Except Low Rise Residential Buildings. These codes become effective on December 11, 2020.

Contact & resources

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