I am trying to help a project team in Boulder, Colorado consider a fugitive emissions requirement for a large student housing development:
Project must have a maintenance plan to monitor and reduce fugitive refrigerant emissions (from sources such as refrigeration, air conditioning, and fire suppression systems). The methodology for this maintenance plan shall follow the US EPA Greenhouse Gas Inventory Guidance Direct Fugitive Emissions from Refrigeration, Air Conditioning, Fire Suppression, and Industrial Gases.
It was borrowed from the ILFIâs Living Building Challenge. Does anyone know if meeting challenging and/or considered expensive? Also, any examples of similar projects meeting this requirement would be very much appreciated. Iâll ask the folks at ILFI the same question but I wanted to drop this question here as well.
When I was LEED EA TAG chair in 2023 I was digging for pre-req type refrigerant mgmt best practices to reference in LEED v5. If you look at the first draft thereâs no specific maintenance reference cited. If we can come up with a useful guide such as this EPA one youâve noted, then we can propose it in the second round of public comments or directly to the EA TAG.
As to hurdles and costs, I would say it is going to vary quite a bit from nothing to a lot. If youâre doing something at CU Boulder and tying into campus chilled water, you might have very little if any refrigerants on the project. But if youâre doing VRF with HPWHs then you could have refrigerant line sets running all over the building. And if it had any fire suppression or commercial refrigeration for food & bev, then youâre introducing more refrigerants and items to check. So without specifics itâs hard to state any issues the team would have.
Thank you. This is very helpful. I will report back to this forum what I gather over the next few weeks. This student housing project is a private development and has not yet been designed. There will not be a connection to campus infrastructure. I expect fire suppression and some limited commercial refrigeration for food and beverage.
A related follow up question: How reasonable would it be to pursue mechanical systems that are refrigerant free for student housing in this climate region?
Iâm not an MEP expert but I think it would be extremely unlikely to have a ârefrigerant freeâ mechanical system, particularly with the move to go all-electric for global warming systems (a fossil fuel boiler and natural ventilation could work for that program and climate, but I donât think it would be the best lifecycle carbon impact, at all).
I donât believe âzero GWPâ refrigerants exist, particularly at the scale â CO2 heat pumps (GWP=1) are starting to come on market for small residential hot water (probably not your scale).
Best resource I know about refrigerant leakage is the study PAE did for the city of Seattle: GHG Emissions Calculation Methodologies (seattle.gov). Good info on leakage for different system types and connections. My summary of best practice strategies would be to:
Chris your post got cut off apparently w/o listing any best practices.
The PAE paper is a good one. CIBSEâs TM 65 covers MEP A1-A5 and B1 and C1 modules. It provides UK-based leakage data. CIBSE is working with ASHRAE to publish a North American version which should have been out by now but is looking more like Sept. ASHRAE Std 228 has annualized leakage rates but is sourced from a single French study which actually cites a separate source from 2013. ASHRAE Std 240P is still TBD, but its prior two drafts have lifetime leakage calcs and defaults. ASHRAE Std 242P, of which Iâm a voting member, may skip B1 and C1 emissions and focus on just B6 and also skip B7 emissions, but thatâs not my preference. CARB has leakage rate estimations too. EPA GreenChill can give guidance on supermarket refrigeration.
As far as zero GWP refrigerants there are easily two: ammonia (R-717) and water (R-718). I havenât specâd a R-718 system and have not seen them in the US. Ammonia we do but mostly for ice plants such as NHL venues.
FYI: Iâm sitting in partially air-conditioned condo in Denver in a 1901 building in Cap Hill. Our main atrium stays cool at the ground floor but the top floors are indeed warmerâall w/o AC but the dwelling units are all spokes off this hub. My SW exposures need cooling. I wouldnât try to build a residential block in Boulder w/o cooling. If youâre not tied to the campus plant, then you can look at evap cooling, but if youâre trying to electrify the space heating, then youâll be installing heat pumps with refrigerants anyway. Keep in mind weâre also dealing with wildfire smoke at the moment and operable windows are useless during these events. So filtered fresh air of a MERV 13 should be must-have along with balanced ventilation for kitchen and toilet exhaust.
It will be important to know what is the meaning of âmaintenance planâ. If it is a âregularâ checking, for e.g. every quater or every month, not real time, then the expense can be a person going around with a hand held detector to find out if there are leakages. However, if requires âreal timeâ detection, then devcies, e.g. pressure differential sensors may be required to real time checking system pressures. Than can be more expensive on first cost, pending on how many systems you have. Or, if the maintenance plan is to track the among of refrigerant purchase every year (to replenish the fugitive refrigerant) only, the cost of monitoring can be lowered.
Luke do you know of a good source to describe the real time detection? All I can think of off the top of my head is ASHRAE Std 15-2022 due its updates to deal with A2L refrigerants outside of the typical refrigeration machinery rooms.
Aaronâs link to the EPA mgmt practice describes the latter (Simplified) Material Balance Method for tracking replaced charge lost via service contracts or in-house logs.
For real time, the conventional method is to measure typically a space with ppm of refrigerant. There are online material, including specifications and details, e.g. University of Michigan information:
The above is obviously more difficult if VRF is used in a building with refrigerant piping. Btw, one way is to use hybrid VRF, so only water indoor to avoid refrigerant piping.
Gas Pressure Detection in real time can be another way to alarm if there is potential leakages. Real time pressure signal is transmitted by measuring the pressure difference between interior and exterior of the system. This test is also only âqualitativeâ to know whether the system leaks and will need additional test to find out where is the leakage.
Going back to Chris & Jamyâs comments about Zero GWP Refrigerants - I would like to argue that CO2-based systems are reaching the scale needed for multifamily midrise projects. Some of my teammates at Introba (formerly Integral) published this paper on the topic 3 years ago - these are no longer that ânovelâ (CO2 Air Source Heat Pumps for Domestic Hot Water, located here: Research â Vienna House). And this wasnât just studied - hereâs a blog post from a few months ago from that same project showing the selected system (the Waterdrop) being built and getting ready for install ; A Cutting-Edge Zero-Carbon Hot Water Plant Is in the Works for Vienna House â Vienna House
In Canada where I am, we generally look to the refrigerant leakage rates defined in LEED; (2%/year and 10%/end of system life) but the CIBSE TM65 ones work too (agreed that there arent enough studies to definitively say which rates are the closest to reality). I am hopeful ASHRAE 240p will provide the market with clarity there.
In case youâre looking for more resources about refrigerants, Louise Hamot (also a colleague) published " Refrigerants & Environmental Impacts: A Best Practice Guide" a few years ago:
These are all great responses. The more lines the more refrigerants that can escape from VRFs system. I donât think youâd do an underfloor air distribution in a residensce hall either. Iâd recommend reaching out to our fellow cote friend, George george.reilly@burohappold.com. He has strong expertise in this matter even if they arenât the eor.
Aaron,
It is possible to eliminate refrigerants for space conditioning while also reducing life-cycle carbon. This paper: Redirecting compares life-cycle carbon with and without heat pumps. They find that a âfabric firstâ approach that emphasizes very low envelope losses and does not include a heat pump results in lower life-cycle carbon than less aggressive insulation with a heat pump. The study was done in the UK, and we seem to prefer more AC in the US. However, natural ventilation and ground loop cooling are capable of keeping indoor temperatures comfortable in the summer without refrigerants.
Further, one can forego conventional mechanical heating and cooling equipment entirely by using ambient energy instead. There are examples of homes in CO that achieve this goal (Redirecting). Such homes are usually occupied by knowledgable residents who manually open/close windows for ventilation cooling, install/remove sun shades to avoid overheating, etc. For student housing, automatic control could be a better option, but operating the building could also be a valuable teaching opportunity.
Heat pump water heaters (HPWHs) are in general not appropriate for Colorado, because they take heat out of the space that they are in. This results in increased heating requirements if the HPWH is in the conditioned space, as well as if it is in an adjacent space that thermally communicates with the conditioned space. HPWH are good for climates for which cooling is the largest load, which is not the case in CO . Solar thermal water heaters use no refrigerants, and are 10 - 100 times more efficient than HPWHs in terms of electricity used to heat water.
With zero refrigerants for space conditioning and water heating, a large part of the problem is solved!
) GWP refrigerants, I was happy to see in the NYT this article about a new MF condo in Brooklyn that is using QAHV electric hot-water pump with CO2 refrigerants. It is happening!: