San Antonio Energy Code Multifamily: 2021 IECC, Local Amendments, and When to Study First

If you are building multifamily inside the City of San Antonio, the most common mistake starts with a headline: "San Antonio adopted the 2024 codes." It did, for the building, residential, mechanical, plumbing, fuel gas, existing building, fire, and pool codes. The energy code was left out of that cycle. San Antonio still enforces the 2021 International Energy Conservation Code with local amendments, and it has its own submittal and inspection playbook in Development Services Information Bulletins 221 and 167. Teams get caught when they design to a 2024 IECC they assumed came along with the 2024 building code, copy an Austin or Dallas package, or find out about the energy letters and commissioning report at Certificate of Occupancy.

This page is the San Antonio 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, and Dallas 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 San Antonio Right Now

Per the City of San Antonio Development Services Codes and Ordinances page, City Code Chapter 10 (Building-Related Codes), and the ordinances behind it (primary sources; confirm with the City before you file):

• Chapter 10, Article X (Energy Conservation Code), Section 10-91 adopts the 2021 International Energy Conservation Code, both the commercial and residential provisions, with San Antonio amendments in Section 10-92.
• Ordinance 2022-11-10-0875, passed November 10, 2022, adopted the 2021 International Code Council codes, including the IECC, with local amendments. It took effect February 1, 2023.
• Ordinance 2025-01-30-0075, adopted January 30, 2025, moved San Antonio to the 2024 editions of the building, residential, mechanical, plumbing, fuel gas, existing building, fire, and pool codes, effective May 1, 2025. The same Chapter 10 keeps the 2021 edition of the IECC.
• The City's own page says it directly: the IECC was excluded from the 2024 cycle and is currently under the 2021 codes.
• For commercial buildings, Information Bulletin 221 (Commercial 2021 IECC Submittal Requirements, revised September 2026) lists ASHRAE 90.1-2019 as the ASHRAE option alongside the 2021 IECC paths.

That puts San Antonio closer to Houston and Dallas (2021 IECC with ASHRAE 90.1-2019 options, each with its own amendments and process) than to Austin, which moved to the 2024 IECC and ASHRAE 90.1-2022 on July 10, 2025. Statewide Texas still sits on a 2015 IECC floor for many jurisdictions. Use the City's pages and bulletins as the source of truth for your filing date, not a blog summary.

Residential vs Commercial Split for Multifamily

IB 221 and IB 167 draw the line the same way the 2021 IECC does. Group R-2, R-3, and R-4 buildings three stories or less above grade plane use the residential provisions. Taller apartment buildings, and the nonresidential portions of any building, use the commercial provisions.

• Mixed-use and podium projects. IB 221 says the appropriate section of the IECC applies to each part, with residential and commercial submittals as appropriate for each portion. Retail, amenity, lobby, corridor, and parking areas follow commercial documentation even when the team thinks of the job as "apartments."
• Apartment units inside a commercial-provisions building. IB 221 sends the residential energy compliance forms for apartment buildings and individual dwelling units to the permit record through the BuildSA portal under IB 167.

That split decides whether you are looking at residential envelope tables, testing, and an ERI or ENERGY STAR path, or a commercial package with COMchecks, commissioning, and possibly whole-building modeling. Confirm it with San Antonio plan review before anyone models.

San Antonio Commercial Paths and the IB 221 Package

IB 221 makes the design team pick one compliance path, and the entire building and MEP design must comply under that same path. The City reviews under the path you declare:

1. 2021 IECC prescriptive. Sections C402 through C406 and C408, with the envelope shown by the R-value method (C402.1.3), the U-factor method (C402.1.4), or the component performance alternative (C402.1.5, COMcheck). Prescriptive submittals must show the C406 additional efficiency packages chosen to reach 10 points (five points for interior finish-outs).
2. 2021 IECC total building performance (C407). An annual energy cost report showing less than 85 percent of the standard reference design, with a third-party compliance report.
3. ASHRAE 90.1-2019. Prescriptive (Section 5.5), Energy Cost Budget (Section 11), or Performance Rating Method (Appendix G), each with its mandatory provisions and functional performance testing called out on the plans.

The permit package also needs an Energy Summary Sheet inside the plans (path chosen, efficiency packages, and where the required information lives), mechanical and lighting COMchecks that match the drawings (plus an envelope COMcheck if you use the component performance method), and commissioning and testing plans that will later line up with the preliminary commissioning report.

Before Certificate of Occupancy, IB 221 says up to ten energy inspections may be placed on the permit. They are cleared by Commercial Energy Compliance Systems Letters from the architect, engineer, contractor, installer, commissioning agent, or owner's agent, plus a Preliminary Report of Commissioning submitted to the City where commissioning applies (for example, mechanical systems with cooling capacity of 480,000 Btu/h or more, combined service water and space heating of 600,000 Btu/h or more, and automatic lighting controls). Commissioning may be performed by a Texas licensed architect or engineer or by a certified commissioning agent. Thermal envelope testing applies too: Group R and I occupancies follow the dwelling and sleeping unit enclosure testing in C402.5.2.

San Antonio Amendments Multifamily Teams Miss

Section 10-92 changes several 2021 IECC sections that hit apartment buildings directly:

• Separate electric meters (C405.6). Each dwelling unit in a Group R-2 multifamily building shall have a separate electrical meter.
• EV capable parking (C409). San Antonio adds an EV capable section for buildings outside the residential EV ready section: reserved panel space and capacity for one future 40-ampere breaker for every two spaces, sized to 5 percent of the total required parking spaces, labeled "For Future EV."
• Energy monitoring threshold (C405.12). San Antonio raises the energy monitoring trigger from 25,000 to 100,000 square feet of gross conditioned floor area, and raises the R-2 and tenant space exception from 5,000 to 10,000 square feet.
• Roof reflectance and hot water circulation (C402.3, C404.6.1). Steep-slope roofs above cooled space need a minimum reflectance of 0.35 or SRI of 29, and hot water circulation pumps need demand-based or timer plus return-temperature controls.
• Residential third-party verification (R402.4.1.1, R402.4.1.2). Where the residential provisions apply, an approved third party inspects the envelope components, and air leakage testing is done by an approved third party to a maximum of 5.0 air changes per hour or 0.28 cfm per square foot of dwelling unit enclosure area at 50 Pa, under any compliance path.
• Climate zone 2 edits. San Antonio amends the climate zone 2 rows: ceiling insulation of R-38 instead of R-49 in Table R402.1.3, and a maximum Energy Rating Index of 59 instead of 52 in Table R406.5. A radiant barrier is added for new dwellings (R402.6, with exceptions), and the residential lighting section (R404) is repealed.

Treat those as path facts, not a design checklist. The adopted Chapter 10 text and the City's bulletins are the numbers to design against.

Low-Rise Apartments: Testing, Batches, and the State ENERGY STAR Path

For residential-provisions buildings, IB 167 (Residential Energy Inspection Forms, revised April 4, 2025) lists four compliance paths: prescriptive or UA alternative, performance, and ERI under the 2021 IECC, plus an EPA ENERGY STAR path allowed by Texas Health and Safety Code Chapter 388. On that state path, the Energy Rating Index must be 57 or lower on or after September 1, 2025, and 55 or lower on or after September 1, 2028. If you use the ERI or ENERGY STAR path, the certificate or report has to be uploaded showing you hit the target.

IB 167 also spells out batch testing for R-2, R-3, and R-4 buildings: units are tested separately with an unguarded blower door to 0.30 cfm per square foot of testing unit enclosure area at 50 Pa. Buildings with fewer than eight testing units test every unit. With eight or more, the greater of seven units or 20 percent are tested, including a top floor unit, a ground floor unit, and the largest unit, and two more units are tested for each failure. No Certificate of Occupancy issues until the required units pass, and one set of energy compliance documents can cover the whole building.

Proof From ECC Studies (Method, Not San Antonio Invoices)

ECC does not publish a San Antonio or Texas dollar-per-square-foot average, and we do not have a San Antonio 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 San Antonio lists in IB 221. 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 commercial-code outcomes, not San Antonio invoices. They show the order: lock the path, rank the packages, then document the winner.

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 a San Antonio price.

Common Mistakes on San Antonio Multifamily Energy Filings

• Assuming the 2024 IECC came with the 2024 codes. San Antonio adopted the 2024 building-related codes effective May 1, 2025, but kept the 2021 IECC.
• Copying an Austin package. Austin is on the 2024 IECC and ASHRAE 90.1-2022. San Antonio lists ASHRAE 90.1-2019 and the 2021 IECC paths.
• Copying a Dallas package. Dallas runs a signed compliance path form and certificate from a City-registered third-party energy provider. San Antonio runs the IB 221 Energy Summary Sheet, energy letters, and commissioning report.
• Mixing paths across the building. IB 221 requires the entire building and MEP design to comply under the same chosen path.
• Leaving commissioning to the end. The commissioning and testing plans go in at plan review, and the preliminary commissioning report has to reach the City before Certificate of Occupancy.
• Forgetting the R-2 meter and EV lines. Separate dwelling unit meters and EV capable panel capacity are San Antonio amendments, not model-code defaults.
• Buying COMcheck or ERI hours before the path is locked. The study should settle residential vs commercial, which IB 221 path you will declare, and the ERI or performance target, then the paperwork follows.

When to Study First

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

1. Confirm the permit address is inside the City of San Antonio and on the energy code in force for your filing date (2021 IECC with Chapter 10 amendments since February 1, 2023)
2. 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)
3. Pick one path for each commercial portion: IECC prescriptive with 10 C406 points, C407 total building performance at less than 85 percent, or ASHRAE 90.1-2019 prescriptive, Energy Cost Budget, or Appendix G
4. For residential portions, pick the path (prescriptive, performance, ERI at 59, or the state ENERGY STAR path at 57 through August 31, 2028, then 55) and plan batch testing with the third-party verification San Antonio requires
5. Model envelope and HVAC packages side by side against that path, including ENERGY STAR Multifamily New Construction where you plan to enroll
6. Write the Energy Summary Sheet, COMchecks, and commissioning and testing plans against the locked plan, then line up the energy letters, testing, and preliminary commissioning report for Certificate of Occupancy

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 San Antonio energy code for multifamily is the 2021 IECC with Chapter 10, Article X amendments, effective February 1, 2023, and still in force after the City moved its other codes to the 2024 editions on May 1, 2025. Commercial portions pick one IB 221 path (2021 IECC prescriptive, C407 performance, or ASHRAE 90.1-2019), file an Energy Summary Sheet with COMchecks and commissioning plans, and clear energy inspections with letters and a preliminary commissioning report. Residential portions add third-party verification, batch testing, and an ERI or state ENERGY STAR target. This is the San Antonio city-code door, not the statewide Texas code-path page, not the Houston, Austin, or Dallas city doors, and not the Texas study door. Lock the split, the path, and the targets first, then buy the paperwork that matches the plan.