DC Energy Code: Net-Zero Mandate, Appendix Z, and Compliance Paths

The DC Energy Code sets binding efficiency requirements for nearly every building project in the District, from new construction and major renovations down to window replacements and HVAC upgrades. It is codified in Title 12-I of the DC Municipal Regulations and currently built on the 2015 International Code Council model codes and ASHRAE 90.1-2013, with DC amendments that often exceed the national baseline. The headline change on the horizon: by December 31, 2026, all new commercial construction and substantial improvements must meet a net-zero-energy standard.¹

When the Code Applies to Your Project

The code splits buildings into two tracks. Residential provisions govern detached one- and two-family homes, townhouses, and other residential buildings three stories or fewer. Commercial provisions cover everything else, including high-rise apartments, condominiums, offices, retail, and mixed-use buildings.¹

Coverage reaches well past new builds. Adding onto a building, performing a major renovation, replacing windows, swapping out HVAC equipment, or modifying the exterior shell all pull the work under the energy code. Even a change-of-occupancy permit can trigger compliance when the new use increases energy demand. In practice, almost any physical modification to a DC building has to move the structure closer to current efficiency standards.

The 2026 Net-Zero Mandate for Commercial Projects

The Clean Energy DC Building Code Amendment Act of 2022 (D.C. Law 24-177) rewrites commercial-scale construction rules. By December 31, 2026, the Mayor must finalize regulations requiring all new construction and substantial improvements of covered buildings to meet a net-zero-energy standard.¹ “Covered buildings” are those subject to the commercial energy code, so apartment complexes, condos, offices, and retail all fall in.

The law carries a backstop. If the Mayor misses the December 31, 2026 deadline, no building permit application submitted after that date can be approved unless the design complies with the most recent version of Appendix Z of the DC Energy Conservation Code.¹ Either way, Appendix Z becomes the floor.

Three restrictions sit at the center of the net-zero standard. On-site fossil fuel combustion is banned for providing thermal energy to the building, which effectively eliminates natural gas furnaces and water heaters in new covered buildings. Renewable energy must be generated on-site wherever feasible. Owners who procure offsite renewable energy cannot rely on unbundled renewable energy credits to meet the requirement.¹ The only carve-out allows fossil fuel combustion for backup power in buildings essential to public health and safety.

What Appendix Z Actually Requires

Appendix Z defines net-zero performance in numbers. The core metric is the Zero Energy Performance Index (zEPI), which compares a proposed building’s energy use to a baseline. A building must hit a zEPI of 30 or lower.²

Appendix Z also caps heating demand at 4.2 kBtu per square foot per year and cooling demand at 6.4 kBtu per square foot per year. These ceilings push designers toward high-performance envelopes, airtight construction, and efficient glazing before any mechanical system comes into play.²

Renewables close out the standard. A building must offset its projected annual energy use entirely with renewable sources. Before turning to offsite procurement, the project has to either meet at least 5% of total building energy consumption from on-site renewables or dedicate at least 25% of the total site area (including the building footprint) to photovoltaic arrays. Offsite procurement is limited to qualified Tier 1 renewable sources under the DC Renewable Portfolio Standard.²

Performance verification happens after move-in. Within 24 months of occupancy, the owner must submit documentation showing 12 continuous months of operation at no less than 90% occupancy where measured energy consumption equals or falls below the renewable energy associated with the building.² This is where designs that look fine on paper meet operational reality.

Compliance Paths for Projects Outside the Net-Zero Rule

Projects that don’t fall under the net-zero mandate have two routes to demonstrate they meet the code.

Prescriptive Path

The prescriptive path reads like a checklist. Every component of the building has to meet a specific value: insulation R-values for walls and roofs, U-factors for windows, efficiency ratings for HVAC equipment, lighting power density limits, and so on. No energy modeling, no trade-off calculations. If each piece hits its number, the building passes. This is the straightforward choice when the design already lines up with standard construction practice.

Performance Path

The performance path leaves room for design flexibility. Instead of meeting each component requirement, you use energy modeling software to calculate the building’s total projected energy use and compare it against a reference building designed to the prescriptive standard. If the proposed building performs at least as well, it passes, even where individual components fall short of prescriptive minimums. Commercial developers typically go this route when design goals conflict with rigid component rules.

Documentation You Need to Submit

Before filing for a permit, you need a documentation package that quantifies the building’s projected energy performance. Commercial projects use COMcheck and residential projects use REScheck, both free tools from the U.S. Department of Energy.³ You enter square footage, window-to-wall ratios, insulation R-values, and equipment efficiencies, and the software produces a compliance certificate.

Alongside those reports, submit detailed floor plans and architectural drawings with the thermal envelope clearly labeled. Call out efficiency ratings for boilers, air conditioning units, and water heaters, along with lighting power density for commercial spaces. Window glazing specifications, door U-factors, duct sealing details, and vapor barrier placement all need to appear on the plans. Missing or unclear information is the most common reason an application stalls in review. The responsible design professional must sign and stamp the compliance reports before they go in with the package.

Submitting the Permit and Getting Reviewed

Building permit applications run through the Department of Buildings, which operates an online portal. You need a verified account to upload COMcheck or REScheck files, drawings, and supporting documents.

Review track depends on project size. Projects of 10,000 square feet or more get a “green review” that evaluates both the Energy Conservation Code and either the Green Building Act or the Green Construction Code. Projects under 10,000 square feet get a narrower “energy review” limited to the Energy Conservation Code.⁴ Larger projects take longer, especially during high-volume periods. Track status online and respond quickly to examiner comments to keep the timeline from slipping.

Permit and Green Building Fees

Fees scale with project type and size. For new construction and additions, the permit fee is $0.03 per cubic foot of construction, plus a 10% enhanced fee surcharge. Alterations and repairs use a sliding scale tied to construction value: projects valued between $1,001 and $1 million pay $30 plus 2% of value, while projects over $1 million pay $10,030 plus 1% of total construction cost, each with the 10% surcharge on top.⁵

A separate Green Building Fee stacks on top. For new construction, that’s $0.002 per square foot. For alterations valued between $1,001 and $1 million, the Green Building Fee is 0.13% of construction value. For alterations over $1 million, it’s $1,300 plus 0.0065% of the value above $1 million.⁵ Small alterations under $500 start at $36.30 including the surcharge, so the fee burden scales sharply with project size.

Field Inspections and the Certificate of Occupancy

Once the permit is issued, construction does not run on the honor system. Inspectors visit at specific milestones to confirm the work matches the approved plans. Inspections are typically scheduled before walls are closed and systems are concealed, because that’s the only point when insulation, duct sealing, and vapor barriers can actually be seen.⁶ Failing an inspection can bring a stop-work order or force you to open finished work for re-examination.

Schedule inspections through Tertius, the Department of Buildings’ online marketplace. You can either request that DOB handle inspections at no additional cost or hire a certified third-party agency from the Tertius database. Third-party agencies must be DOB-approved, and their findings go to the Department of Buildings for the official record.⁷ Once all inspections pass and the final energy verification is filed, the District issues the Certificate of Occupancy.

Exemptions and Special Cases

Not every project triggers the full weight of the code. Temporary structures, including trailers and modular spaces, are exempt from the net-zero energy standard under the Green Building Act. Additions under 10,000 gross square feet do not need to request an exemption from the net-zero standards; the Department of Buildings has determined they fall outside the requirement automatically.⁸

Historic landmarks get accommodation, not a blanket pass. Interior spaces designated as registered historic landmarks are excluded from interior lighting power calculations, so lighting in those spaces doesn’t count against the building’s overall lighting power allowance.⁹ Beyond that specific carve-out, historic properties generally still need to comply to the extent feasible when they’re renovated. If you’re working on a landmarked building, expect to negotiate details with both the Department of Buildings and the Historic Preservation Office.

What Non-Compliance Costs

During construction, failing an energy code inspection can trigger a stop-work order that halts the project until the deficiency is corrected. If insulation or mechanical systems are already concealed, you may have to open them up for re-inspection. Proper staging avoids both outcomes.

For existing buildings, the District uses a separate schedule of civil infractions with escalating fines under its Building Energy Performance Standards program. Implementing a compliance measure that threatens occupant health or safety is the most serious violation, with fines starting at $2,000 for a first offense and climbing to $16,000 for a fourth or subsequent offense. Failing to submit a required compliance pathway selection to the Department of Energy and Environment carries fines from $1,000 to $8,000 on the same escalating scale. Failing to submit required reports, energy audits, action plans, or documentation to buyers before a building sale draws fines from $500 to $4,000 per offense. Each violation repeats, so an owner who ignores multiple reporting requirements can accumulate substantial liability quickly.

A Note on Existing Buildings

The energy code governs construction and renovation work. Operational energy performance for existing buildings is handled under a separate program, Building Energy Performance Standards (BEPS), established by the Clean Energy DC Omnibus Amendment Act of 2018. BEPS applies to privately owned and DC-owned buildings over 10,000 square feet, with compliance rolling out in three six-year periods. Starting in calendar year 2025, all privately owned buildings over 10,000 square feet must benchmark their energy use, with reports due by May 1, 2026.¹⁰ If you own an existing building of any significant size, BEPS obligations run on their own track in parallel with any construction work governed by the energy code.

1
D.C. Law Library. D.C. Law 24-177 – Clean Energy DC Building Code Amendment Act of 2022
2
Department of Energy and Environment. District of Columbia Energy Conservation Code Appendix Z
3
U.S. Department of Energy. REScheck
4
Department of Buildings. Energy and Green Building Process
5
Department of Buildings. Building Permit Fee Schedule
6
Department of Energy. Building Energy Code Compliance
7
Department of Buildings. Third-Party Program
8
Department of Energy and Environment. Green Building Act Exemption Application Guidelines
9
Department of Buildings, District of Columbia. 2017 District of Columbia Energy Conservation Code
10
DC Sustainable Energy Utility. Building Energy Performance Standards (BEPS) and Benchmarking