Hi folks,
I'm looking into lower-carbon pipe options for HVAC and plumbing. The MEP 2040 has slides from a Buro Happold study in 2020 showing PEX to be much lower in embodied carbon than copper, which is unsurprising. CPVC is also a lower-carbon option.
But PVC has its issues and neither PVC nor PEX are recyclable (especially if the PEX has an aluminum oxygen diffusion layer, which it needs in radiant heating/cooling applications).
We've published various pieces over the years about polyethylene and polypropylene alternatives that seem like win-wins: low carbon, relatively clean as plastics go, and recyclable. They claim to have lots of certifications and code approvals and to be competitive in terms of cost. My question is—is there some practical reason that they are not more widely used, other than the usual "we've never done it that way before" inertia problem? Is there a reason you, or your engineers, would be hesitant to specify them?
- Code Restrictions:
- Chicago still doesn’t allow PP-R and PE-RT for domestic (potable) water distribution or water service pipe.
- Corrosion Concerns
- For the Aquatherm PP-R piping there are corrosion /premature failure concerns when located downstream of copper piping in domestic hot water systems.
And finally, Kirk Pesta who has been with HED for 20 years in our Detroit office asnd who now co-leads mechanical across the firm with David said:- Plastic pipe cannot be used in air plenums unless it meets the 25/50 ratings of ASTM 84. Though Spears has a product that does meet ASTM E 84. Not sure if there are other manufacturers.
- Leaching of the chemicals in the domestic water system.
- Thermal expansion. Plastic pipe expands much more than copper or steel.
Hope this helps your gathering of input!