Arlington TX Energy Code Multifamily: 2021 IECC, Green Building Standards, and When to Study First

If you are building multifamily inside the City of Arlington, Texas, the code edition is the easy part. The City enforces the 2021 International Energy Conservation Code with local amendments, adopted by City Council on November 1, 2022 and required for permit applications starting January 1, 2023. The part that catches teams is newer. On September 16, 2025, Council passed Ordinance 25-075, which adds Green Building Performance Standards for Multi-Family and Mixed-Use Development on top of the building code. For covered projects, that means at least a 10% improvement over the IECC baseline, net-zero ready (solar- and battery-ready) infrastructure, all-electric HVAC and appliance infrastructure, and SEER 16 or better HVAC. Teams get caught when they price a plain 2021 IECC package, copy a Dallas or Fort Worth filing, or assume an older approval keeps them out.

This page is the Arlington Energy Code door for multifamily developers. For the statewide Texas commercial code path (the 2015 IECC floor, ASHRAE pairings, and why mid-rise is not HERS-first), see ASHRAE COMcheck Texas multifamily. For the Texas study door, see energy code feasibility study Texas. Other Texas city doors already live: Houston Energy Code multifamily, Austin Energy Code multifamily, Dallas Energy Code multifamily, San Antonio Energy Code multifamily, Fort Worth Energy Code multifamily, El Paso Energy Code multifamily, and Corpus Christi Energy Code multifamily. Program, testing, and modeling context: ENERGY STAR Multifamily New Construction, blower door testing for multifamily buildings, and multifamily energy modeling.

What Code Applies in Arlington Right Now

Per the City of Arlington Building Codes page and the City's adopted ordinances (primary sources; confirm with the City before you file):

• On November 1, 2022, City Council adopted the 2021 International Building, Energy Conservation, Residential, Existing Building, and Swimming Pool and Spa Codes (Ordinance 22-055, Construction Chapter, Article I), plus the 2021 Fire, Mechanical, Plumbing, and Fuel Gas Codes and the 2020 National Electrical Code in companion ordinances. Permit applications have had to comply since January 1, 2023.
• The 2021 IECC is adopted with Arlington deletions, amendments, and addenda in Construction Chapter Section 1.04. Read the amendments for your filing, not a generic 2021 IECC summary.
• Ordinance 25-075 added Subsection H to Section 1.04, the Green Building Performance Standards for Multi-Family and Mixed-Use Development. It took effect September 16, 2025, with enforcement delayed 30 days to October 16, 2025 under Texas Local Government Code Section 214.218. The City lists it as adopted but not yet codified.

That puts Arlington on the same 2021 IECC edition as Houston, Dallas, San Antonio, and El Paso, ahead of Fort Worth and Corpus Christi (2015 IECC), and behind Austin (2024 IECC since July 10, 2025). What sets Arlington apart is the multifamily overlay, not the edition.

Who the Green Building Standards Cover

Ordinance 25-075 applies to:

• New construction of multifamily and residential mixed-use developments.
• Conversions: an existing structure that needs substantial reconstruction to change from a commercial use to multifamily or residential mixed-use.
• Existing multifamily that needs substantial reconstruction as part of a single project.

Substantial reconstruction means demolishing or rebuilding 50% or more of the gross floor area, or removing, replacing, or structurally altering 50% or more of the exterior walls and roof assembly. Interior renovations, maintenance, and repairs under those thresholds are out.

The definitions are broad. Multifamily residential means a site with three or more dwelling units in one or more buildings, condominiums included. Mixed-use residential means residential uses are at least 65% of the total square footage. Garden-style, townhome-style, mid-rise, and podium jobs can all land inside it.

There is one timing carve-out. A project approved by City Council through a Planned Development Development Plan for RMF-22 uses, a Multi-Family Development Plan, or a Mixed-Use Development Plan before September 1, 2025 is exempt until September 1, 2030. After that date, any permit is subject to the standards. A pre-2025 approval buys time, not a permanent pass.

What the Standards Require (Energy and Beyond)

The ordinance lists enhanced standards by topic. The energy items supplement Sections 403 and 406 and Appendix CB of the 2021 IECC:

• Minimum 10% improvement over IECC baseline performance.
• Net-zero ready infrastructure (solar- and battery-ready).
• All-electric HVAC and appliance infrastructure.
• High-efficiency HVAC, SEER 16 or higher.

The same ordinance also sets non-energy items that touch the energy design and the budget:

• Indoor environmental quality: minimum MERV 13 filtration, ASHRAE 62.2 compliant ventilation, VOC limits, and STC/IIC of at least 50 for walls, floors, and ceilings.
• Water: toilets at or below 1.0 gpf, showers at or below 1.5 gpm, faucets at or below 1.0 gpm, rainwater or graywater reuse readiness, and smart irrigation controllers.
• Roofing: high-albedo roofing (SRI of at least 78 low-slope, at least 29 steep-slope), on-site stormwater mitigation, and UL 2218 or FM 4473 Class 4 hail resistance.
• Construction: at least 75% construction and demolition waste diversion and an indoor air quality management plan during construction.
• Transportation: 1 bicycle space per 5 units, and EV parking at 1.5 charging stations plus 2.5 EV-ready spaces per 10 dwelling units, for a site total of 40% EV-ready or EV-installed spaces.
• Safety (CPTED): uniform lighting at entries, walkways, and parking, full cut-off fixtures at 1.0 footcandle minimum, and clear landscaping and boundaries.

The ordinance says the most recently adopted Arlington building codes and amendments are the baseline, and where a future code conflicts, the most stringent rule controls. Treat these as path facts. Ask Arlington plan review how it wants the 10% improvement shown for your building type before anyone models.

Residential vs Commercial Split for Multifamily

The 2021 IECC draws the line by building type and height. Group R-2, R-3, and R-4 buildings three stories or less above grade plane fall under the residential provisions. Taller apartment buildings, and the nonresidential portions of any building, fall under the commercial provisions, where the 2021 IECC commercial chapter or its ASHRAE 90.1-2019 alternative applies.

• Mixed-use and podium projects. Retail, amenity, lobby, corridor, and parking areas follow commercial documentation even when the team thinks of the job as "apartments."
• Garden-style and townhome projects. Three stories or less usually lands on the residential provisions, with envelope tables, blower door and duct testing, and a prescriptive, performance, or ERI path.

Either way, the Green Building Standards sit on top. The 10% improvement is measured against the IECC baseline, so the split decides which baseline, which software, and which reports you will need.

Low-Rise Apartments: Paths and Testing

Arlington sits in Tarrant County, climate zone 3A (warm, humid) in the 2021 IECC, the same zone as Dallas and Fort Worth. Where the residential provisions apply, plan the air leakage and duct tests, and the tester, before framing. A failed test on an occupied schedule is the most expensive kind. Under the overlay, the HVAC is all-electric and at least SEER 16, so heat pump sizing, duct location, and ventilation (ASHRAE 62.2 with MERV 13 filtration) should be decided together, not one trade at a time.

Proof From ECC Studies (Method, Not Arlington Invoices)

ECC does not publish an Arlington or Texas dollar-per-square-foot average, and we do not have an Arlington energy-code invoice to present as your number. We cite other studies as proof of method, and we label them that way.

On our 267-unit Cromwell, CT study (CS68), two buildings up to six stories (272,036 square feet) were filed on IECC commercial provisions using ASHRAE 90.1-2019 Appendix G, the same ASHRAE year that pairs with the 2021 IECC Arlington enforces. The recommended all-electric tier came in at about $35.23 per square foot net and captured a $1,500 per unit Energize CT incentive ($400,500). Those are Connecticut outcomes, not Arlington invoices. They show the order: lock the path, rank the packages, then document the winner, which is exactly what an all-electric, better-than-code requirement calls for.

On a 112-unit Revere, MA study (CS57), a seven-story mixed-use building kept dwelling units on a Massachusetts Stretch HERS path and still called for a COMcheck report for all common and support areas, plus ASHRAE 62.1 ventilation calculations and lighting power density calculations. The recommended ductless package landed at about $42.52 per square foot net. Those are Massachusetts outcomes. We cite them as proof that mixed-use paperwork splits before modeling hours, not as an Arlington price.

Common Mistakes on Arlington Multifamily Energy Filings

• Pricing a plain 2021 IECC package. Covered projects must beat the IECC baseline by at least 10%, be all-electric, and use SEER 16 or better HVAC.
• Assuming small jobs are out. Multifamily under the ordinance starts at three dwelling units, and mixed-use counts once residential is 65% of the square footage.
• Reading the 2030 exemption as permanent. Projects approved before September 1, 2025 are exempt only until September 1, 2030.
• Missing a conversion or gut rehab. Commercial-to-residential conversions and multifamily projects over the 50% reconstruction thresholds are covered.
• Copying a Dallas or Fort Worth filing. Dallas shares the 2021 IECC and climate zone 3A but not Arlington's overlay. Fort Worth is still on the 2015 IECC.
• Treating the overlay as energy only. MERV 13, STC/IIC 50, water fixtures, cool and Class 4 roofing, EV parking, and lighting all land on the same drawings.
• Buying COMcheck or ERI hours before the path is locked. The study should settle residential vs commercial, IECC vs ASHRAE 90.1-2019 for commercial areas, how the 10% improvement is shown, and the testing plan, then the paperwork follows.

When to Study First

Settle the Arlington path before anyone buys REScheck, COMcheck, ERI, or whole-building modeling hours:

1. Confirm the permit address is inside the City of Arlington and on the 2021 IECC with Section 1.04 amendments for your filing date
2. Check whether Ordinance 25-075 applies (new multifamily or mixed-use, conversion, or substantial reconstruction) and whether a pre-September 1, 2025 approval exempts you until September 1, 2030
3. Lock the residential vs commercial split (three stories or less for Group R-2 / R-3 / R-4 on the residential provisions, and commercial documentation for nonresidential areas)
4. For each commercial portion, pick 2021 IECC commercial or ASHRAE 90.1-2019, and agree with plan review how the 10% improvement over baseline will be documented
5. Model all-electric envelope, window, and HVAC packages side by side for climate zone 3A, at SEER 16 or better, including ENERGY STAR Multifamily New Construction where you plan to enroll
6. Produce the COMcheck reports, performance models, and test results against the locked plan

That comparison is what a free feasibility study produces. For the Texas study method, see energy code feasibility study Texas. For how modeling works on apartment buildings in general, see multifamily energy modeling. If the path is already chosen and you need COMchecks, modeling, inspections, or testing, see ECC services.

Bottom Line

The Arlington energy code for multifamily is the 2021 IECC with local amendments, adopted November 1, 2022 and required since January 1, 2023. Since October 16, 2025, Ordinance 25-075 adds Green Building Performance Standards for new multifamily and mixed-use, conversions, and substantial reconstruction: at least 10% better than the IECC baseline, net-zero ready, all-electric, SEER 16 or better, plus ventilation, water, roofing, waste, EV, and lighting items, all in climate zone 3A. This is the Arlington city-code door, not the statewide Texas code-path page, not the Houston, Austin, Dallas, San Antonio, Fort Worth, El Paso, or Corpus Christi city doors, and not the Texas study door. Lock the split, the baseline, and the overlay first, then buy the paperwork that matches the plan.