Committee on the Environment

 View Only

Community HTML

ALBION DISTRICT LIBRARY BY PERKINS + WILL IS A 2018 COTE TOP TEN RECIPIENT. IMAGE: DOUBLESPACE PHOTOGRAPHY

Quick Links

Who we are

The Committee on the Environment (COTE®) is an AIA Knowledge Community working for architects, allied professionals, and the public to achieve climate action and climate justice through design. We believe that design excellence is the foundation of a healthy, sustainable, and equitable future. Our work promotes design strategies that empower all AIA members to realize the best social and environmental outcomes with the clients and the communities they serve.

Enjoy our latest on COTE news (and follow us on X and LinkedIn). 

To learn about the Framework for Design Excellence (formerly the COTE Top Ten Measures), click here.

Check out COTE's history and timeline. 

Starting a local COTE or sustainability group and need some guidance? Check out the AIA COTE Network Resources here.

A big thank you to our 2024 sponsors: 
Founding sponsors: Building Green
Premier sponsors: Sherwin-Williams
Sustaining sponsors: GAF Roofing, Milliken, Andersen Windows,
BlueScope Buildings
Green sponsors: EPIC Metals
Allied sponsors: TLC Engineering, Sierra Pacific Windows

  • 1.  Global Warming Potential (GWP) in Heat Pump Refrigerants?

    Posted 12-28-2020 04:55 PM

    I need some advise on selecting the type of heating system for a small new home that will be all-electric.

    I am wondering about the common refrigerants used in small scale residential heat pumps and the concern about the GWP.

    Does anyone know the real world impact of this in terms of leakage? If the system is sealed and properly installed, does it leak over time?

    As far as I can tell, most of the common refrigerants in small scale residential systems have a GWP of around 1100-1400 (such as R-410A used in a Mitsubishi mini-split).  I know there is one company (Sanden) that makes an air-to-water heat pump that uses CO2 itself with a GWP of 1,but it involves some bulky equipment and produces a certain amount of noise, and vibration, which in a dense urban environments (like SF) is not easy to accommodate. Plus it involves a more costly water based radiant system, storage, etc. 

    A small mini-split system has somewhere between 2-4 lbs of refrigerant. My rough math indicates that a 1 lb leak of refrigerant equals driving about 1500 miles so want to be careful to consider the trade offs of the air-to-water using CO2 (using Sanden) or a more typical refrigerant system.

    I appreciate the perspective of the group. 



    ------------------------------
    Troy Kashanipour
    Troy Kashanipour Architecture
    San Francisco CA
    ------------------------------


  • 2.  RE: Global Warming Potential (GWP) in Heat Pump Refrigerants?

    Posted 01-04-2021 09:10 AM

    2 years ago just installed a 4 zone mini split into an 1100 sf 1920's bungalow in Sacramento.  It is very quiet, performs well, and my energy costs are the same as my old gas wall mounted space heater bill even with AC.  The biggest issues relative to leakage is with the installer.  Not all fully comply with CA regulations for refrigerant capture.  Adding shutoff valves on the line sets at the internal and external unit will reduce chances of leakage if maintenance is required at a later date as you can more easily isolate components.  You can expect 25 years or better of service life in our climate.  Buy from quality manufacturers and pay attention to coastal conditions as salt can quickly compromise the exterior coils.

    You can do a co2e comparison of the old fossil fuel system and you will likely find that the full loss of refrigerant is much less than that of the fuel used if you stuck with gas, especially if you are adding PV and seeking a near or zero net energy solution.



    ------------------------------
    James R. Deane, AIA, CDT, LEED AP, PMP
    Senior Supervising Architect
    WSP
    ------------------------------



  • 3.  RE: Global Warming Potential (GWP) in Heat Pump Refrigerants?

    Posted 01-05-2021 09:15 AM
    Great response, James. I watched a decade or so ago as an HVAC tech let old refrigerant bubble through a bucket of water and out into the atmosphere. Nowadays any shop in Massachusetts that sells refrigerant is required to have recovery equipment and document recovery of old refrigerant so maybe it is not as much of a problem as it was. Like all technologies, heat pumps come with potential for bad installations, slip-shod enforcement, and of course plenty of hype as to their performance and benefits. It is our job to sift through and try to make conservative estimates and realistic assessments. So many green architects get caught up in the race to be the greenest that they don't look as closely as they should at the reality.

    ------------------------------
    James Carr AIA
    James Carr, AIA architecture & design
    Brookline MA
    ------------------------------



  • 4.  RE: Global Warming Potential (GWP) in Heat Pump Refrigerants?

    Posted 01-07-2021 10:47 AM
    Well put, Mr Carr, and if the members of this profession won't do this, who will?




    Nick Peckham, FAIA
    Principal Architect • Peckham Architecture
    mobile: (573) 489-0901 • phone: (573) 777-4444
    email: nick@peckhamarchitecture.com
    2009 North Country Club Drive
    Columbia Mo, 65201
    www.peckhamarchitecture.com
       
    The content of this email is confidential and intended for the recipient specified in message only. It is strictly forbidden to share any part of this message with any third party, without a written consent of the sender. If you received this message by mistake, please reply to this message and follow with its deletion, so that we can ensure such a mistake does not occur in the future.













  • 5.  RE: Global Warming Potential (GWP) in Heat Pump Refrigerants?

    Posted 01-07-2021 10:47 AM
    Boy, James (Carr), you really can be a tiresome scold! What does that even mean, "So many green architects..."? Utter nonsense!
    Anyway, apologies to all. Carry on!
    :-)

    ------------------------------
    James Carr AIA
    James Carr, AIA architecture & design
    Brookline MA
    ------------------------------