Quick answer. Philadelphia enforces the 2021 energy code with its own local amendments, in effect for all permit applications from July 1, 2026. New homes need a blower door test at 3.0 ACH50 or lower on the prescriptive path. Unlike the rest of Pennsylvania, Philadelphia requires a duct leakage test even when the ducts are inside the insulated envelope, and it requires an additional energy efficiency package. Test reports must reach the building official before final inspection.
Local Energy Audits is based in Philadelphia and tests for builders across the city. Book a test online or call (888) 213-3975.
How Philadelphia differs from the rest of Pennsylvania
| Requirement | Pennsylvania statewide | Philadelphia |
|---|---|---|
| Blower door limit, prescriptive path | 3.0 ACH50 | 3.0 ACH50 |
| Duct test when ducts are entirely inside the envelope | Not required | Required, limit 8.0 CFM25 per 100 sq ft |
| Additional energy efficiency package | Not required | Required |
| High-efficacy lamps | 90% | 100% |
| Lighting controls | Not adopted | Interior and exterior controls required |
| Who oversees testing | The local code official decides whether a third party is required | A special inspection under the city building code, by a third party |
The city did this by declining to adopt several of the state’s amendments, so the original 2021 code text applies in Philadelphia for those sections.
Timeline
- January 1, 2026: the 2021 codes took effect.
- Through June 30, 2026: L&I accepted applications under either the 2018 or 2021 edition.
- June 12, 2026: the Mayor signed Bill 250644, the city’s local energy code amendments.
- July 1, 2026 onward: every permit application must comply with the 2021 codes and the local amendments.
Permits that expire and are resubmitted are reviewed under the 2021 codes.
Blower door test requirements
Philadelphia did not change the state’s air leakage limits.
| Compliance path | Maximum air leakage |
|---|---|
| Prescriptive, including the UA trade-off (REScheck) | 3.0 ACH50 |
| Performance or Energy Rating Index | 5.0 ACH50, or 0.28 CFM per sq ft of enclosure area |
| Attached homes, multifamily units, and homes of 1,500 sq ft or less | May instead meet 0.30 CFM per sq ft of enclosure area |
The test is run to ASTM E779, ASTM E1827 or ANSI/RESNET/ICC 380, after all penetrations of the building envelope have been sealed.
Duct leakage test requirements
Every duct system is tested, to ANSI/RESNET/ICC 380 or ASTM E1554, at rough-in or after construction.
| Condition | Maximum total leakage |
|---|---|
| Rough-in, air handler installed | 4.0 CFM25 per 100 sq ft of conditioned floor area |
| Rough-in, air handler not yet installed | 3.0 CFM25 per 100 sq ft |
| After construction | 4.0 CFM25 per 100 sq ft |
| All ducts and air handlers entirely inside the thermal envelope | 8.0 CFM25 per 100 sq ft |
The only exception is for ducts that serve a ventilation system and are not tied into the heating or cooling ducts.
The additional energy efficiency package
Philadelphia kept the 2021 code’s requirement for efficiency beyond the base code.
- Prescriptive path: install one of five package options.
- Performance path: install one of the options, or show an annual energy cost at or below 95% of the reference design.
- Energy Rating Index path: has its own added requirement.
The five options:
- Enhanced envelope performance
- More efficient HVAC equipment
- Reduced energy use in water heating
- More efficient duct distribution
- Improved air sealing with efficient ventilation
Testing is a special inspection
Philadelphia Building Code section B-1705.21 makes both tests a special inspection.
- Envelope air leakage testing must verify the maximum allowed leakage rate.
- Duct leakage testing must verify the maximum allowed duct leakage.
- A written report of each test goes to the building official before final inspection.
Confirm with L&I whether your tester needs a special inspection license for this category.
Who can perform the tests
L&I’s most recent published guidance (February 2025) required a third party holding one of these certifications:
- RESNET-certified HERS Rater
- RESNET-certified Rating Field Inspector
- BPI Building Analyst
- BPI Infiltration and Duct Leakage
- BPI Energy Auditor
- BPI Envelope Professional
Under that guidance, only the two RESNET credentials qualified for the air barrier visual inspection, which is done before the walls are closed in.
Ori Rosenkrantz of Local Energy Audits holds the BPI Infiltration and Duct Leakage certification, which is on that list.
Need a third-party tester in Philadelphia?
Blower door and duct leakage tests for builders, with the written reports that are due before final inspection.
What L&I needs from you
- The air barrier checklist, completed before close-in.
- The blower door and duct leakage results, on L&I’s air and duct leakage form, before final inspection.
- The HVAC equipment certification form.
- On the performance paths, the final compliance report.
Form names change, so check L&I’s current forms before you submit. Ask about report timing when you book.
Frequently asked questions
Is Philadelphia’s energy code different from the rest of Pennsylvania?
Yes. It is built on the same 2021 code, but Philadelphia requires duct testing in every case, an additional efficiency package, and stricter lighting, and it treats testing as a special inspection.
Do I need a duct leakage test in Philadelphia if all my ducts are inside the envelope?
Yes. The limit in that case is 8.0 CFM25 per 100 square feet of conditioned floor area. Elsewhere in Pennsylvania no test is required for that layout.
What blower door result do I need in Philadelphia?
3.0 ACH50 or lower on the prescriptive path. On the performance or Energy Rating Index path the tested result can be as high as 5.0 ACH50 if the overall design complies.
When did Philadelphia’s new energy code take effect?
All permit applications received on or after July 1, 2026 must comply. Between January 1 and June 30, 2026, L&I accepted either edition.
Who can do blower door and duct testing in Philadelphia?
A third party with a RESNET or BPI certification that L&I accepts. Because testing is now a special inspection, confirm the current requirements with L&I before you book.
What is the additional energy efficiency package?
An upgrade beyond the base code that every new home must include. On the prescriptive path you choose one of five options, covering the envelope, HVAC equipment, water heating, ducts, or air sealing with ventilation.
When are the test reports due?
Before final inspection. The air barrier checklist is due earlier, before the walls are closed in.
Does a three-story rowhouse follow these rules?
Yes. One- and two-family homes and townhouses of three stories or fewer follow the Philadelphia Residential Code, whose energy chapter mirrors these requirements.
Sources
- Philadelphia City Council: Bill 250644 (certified copy)
- Philadelphia L&I: Code Bulletin B-2501, Implementation of 2021 International Codes
- Philadelphia L&I: 2021 I-Code Local Changes
- Philadelphia L&I: 2021 I-Code transition materials
- Philadelphia Building Code, Section 1705
- Philadelphia L&I: Energy Code Enforcement (February 2025)
- 2021 International Energy Conservation Code, Chapter 4 (Residential)
This page summarizes the code for builders and is not legal advice. Confirm the details of your project with the Department of Licenses and Inspections.
Code requirements elsewhere: Pennsylvania · New Jersey · Delaware
Our services: Blower door testing · Duct leakage testing