EPA Refrigerant Mandates and the Impact on Multifamily Construction

Josh Biehler, PE
Lead Mechanical Engineer
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As a result of EPA mandates, the refrigerant currently being used in split system air conditioners (R-410a) is being phased out and replaced with two new refrigerants with lower environmental impact: R-32 and R-454b.

When Do the Changes take effect?

Per the EPA1:

  • Equipment manufactured or ordered pre-Jan. 1, 2025, can be installed until Jan. 1, 2026, with old refrigerants.
  • Existing equipment can remain as-is and be charged with old refrigerant.
  • Replacement parts for existing air conditioners can still be manufactured.

To summarize, if you have existing equipment or have already charged the refrigerant for the equipment installed in a new building, you can repair it and recharge it. If you’re looking to future-proof new construction to account for the new EPA guidelines or account for installation of systems containing either of the R-410a replacements sooner than later, there are changes you’ll need to make to your building to account for the hazard level of the refrigerant. Best practices for these new refrigerants are spelled out in the 2022 edition of ASHRAE 152.

Where Will I Need Pipe Shafts3?

Piping that penetrates two or more floor/ceiling assemblies needs to be enclosed within a fire-rated shaft enclosure as it travels vertically within the building.

When will I need to ventilate the Pipe Shafts?

Refrigerant pipe shafts containing A2L refrigerant need to be naturally or mechanically ventilated, and both R-410a replacements are A2L refrigerants, so a ventilated shaft is required whenever a shaft for refrigerant piping is required.

Naturally ventilated shafts shall have a pipe/duct/conduit not less than 4” in diameter that connects to the lowest point of the shaft and extends to the outdoors.

Mechanically ventilated shafts shall have a minimum velocity based on the cross-sectional area of the shaft. Ventilation shall either be continuous or activated via refrigerant detector with sampling tube/detector located where refrigerant will accumulate.

What if I Don’t Want a Pipe Shaft4?

Only piping that penetrates 2 or more floor/ceiling assemblies requires a shaft, so taking more consideration to outdoor condensing unit/heat pump placement is also an option. For example, placing at least the top floor of a 3-floor building’s outdoor units on the roof would allow for keeping all the refrigerant piping in the building without needing shafts.

Another option that allows for piping to not require a shaft is to route the piping outside of the building in a pipe chase at the building’s exterior and enter the building at the floor the piping serves, or enter where the piping will only pass through a single floor/ceiling assembly.

KLH’s Recommendation

It’s understood that space within the interior of a multifamily building is at a premium – being sensitive to that fact and taking into account maintenance and utility costs, KLH’s recommendation is to route the piping outside of the building up to within one floor of its indoor destination.

This piping will need to be protected by mounting it outside of the area of foot travel, and it will need travel vertically within an enclosure that is open at the top and bottom so as not to trap moisture and to give the refrigerant an escape path of least resistance to vent outside of the building if it were to leak.

If an enclosure exterior to the building is not feasible, KLH recommends utilizing naturally ventilated refrigerant pipe shafts.


Josh Biehler, PE
Lead Mechanical Engineer

Patrick Fernbach, PE, WELL AP
Principal | Director of Mechanical Engineering


  1. https://www.epa.gov/climate-hfcs-reduction/frequent-questions-phasedown-hydrofluorocarbons#restrictions-technology
  2. ASHRAE 15-2022, Safety Standard for Refrigeration Systems
  3. ASHRAE 15-2022, section
  4. ASHRAE 15-2022, section

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