A Summary of the 2017 Peer Review
An independent peer review was conducted on EPA's Vintaging Model (VM) in 2017. The VM
simulates the transition from ozone depleting substances (ODS) to alternative processes and
chemicals in several industrial sectors in the United States. The VM is used to evaluate and report
banks1 and emission trends for ODS and ODS substitutes to support policy and regulatory anal-
ysis. As a result of the peer review, some updates were completed in 2018 and others, requiring
further research and information, will be considered in future updates of the VM.
The VM estimates emissions from six industrial
¦	Refrigeration and ¦ Cleaning Solvents
Air Conditioning	¦ Aerosols
¦	Foam Blowing Agents ¦ Sterilants
¦	Fire Suppression
Within these sectors, there are 66 independently
modeled end-uses.
EPA's Vintaging Model was developed in the 1990s
as a tool for estimating the annual chemical emis-
sions from industrial sectors that have used ODS in
their products. The VM estimates the emissions of
various ODS substitutes reported in the U.S. Greer
house Gas (GHG) Inventor and submitted annually
to the United Nations Framework Convention on C||
mate Change (UNFCCC).
Under the Montreal Protocol on Substances that
Deplete the Ozone Layer (Montreal Protocol) and
the Clean A:r Act Amendments of 1.990, the United
States is phasing out production and consumption
of ODS including chlorofluorocarbons (CFCs), hal-
ons, carbon tetrachloride, methyl chloroform, and
hydrochlorofluorocarbons (HCFCs). As a result of
the ODS phaseouts the affected industrial sectors
transition to other chemicals. As these industries
have moved toward ODS alternatives, the VM is a
tool for estimating the rise in consumption and
emissions of these alternatives and the decline of
ODS consumption and emissions.
The model requires information on the market
growth for each of the end-uses, a history of the
market transition from ODS to alternatives, and the
characteristics of each end-use such as market size
or charge sizes and loss rates. As ODS are phased
out, a percentage of the market share originally filled
by the ODS is allocated to each of its substitutes.
'The "bank" of an ODS or ODS substitute is the cumulative difference between the chemical that has been consumed in an
application or sub-application and that which has already been emitted.
Refrigeration arid Foam Blowing	Fire	Aerosols	Sterilants	Cleaning
Air Conditioning	Agents	Suppression	Solvents

The VM is a "bottom-up" model named for its
method of tracking an inventory of the in-use
stocks and emissions from annual "vintages" of
new equipment containing ODS and ODS substi-
tutes that enter into service. It models the con-
sumption of chemicals based on estimates of the
quantity of equipment or products sold, serviced,
and retired each year, and the amount of the
chemical required to manufacture and/or maintain
the equipment. Emissions are estimated by apply-
ing annual leak rates, service emission rates, and
disposal emission rates to each population of
equipment. By aggregating the emission and con-
sumption output from the different end-uses
within each sector, the model produces estimates
of total annual use and emissions of each ODS and
major ODS substitutes from 1985 through 2050.2
As a bottom-up model, the VM produces results in
mass, ozone depletion, and carbon dioxide equiv-
alent terms.
The VM synthesizes data from a variety of sources,
including data from EPA's ODS Tracking System, the
Greenhouse Gas Reporting Program, information
from submissions to EPA under the Significant New
Alternatives Policy (SNAP) program, and published
sources such as documents prepared by the Mon-
treal Protocol's Technology and Economic Assess-
ment Pane' and the U.S. Department of Energy. EPA
also coordinates extensively with numerous trade
associations and individual companies. The VM is
regularly updated to incorporate up-to-date market
information, including equipment stock estimates,
leak rates, and sector transitions.
An independent peer review of EPA's VM was con-
ducted by a contractor in 2017 for six specific VM
end-use groups: fire suppression, motor vehicle air
conditioning (MVAC), unitary air conditioning (AC),
refrigerated transport, large retail food, and con-
struction foam. A list of 15 candidate peer reviewers
were identified through known industry contacts,
grey literature, and EPA stakeholder meetings.
Reviewers were selected independently, consistent
with the guidelines of the EPA Peer Review Hand-
book, and based on the following criteria:
¦	Well-known, respected subject matter experts
with expertise in one of the end-uses/sectors se-
lected for peer review,
¦	No association with the VM, and
¦	Interest and availability.
The peer reviewers were provided with two tech-
nical summaries (i.e., an overview of the methodol-
ogy for calculating emissions and consumption
within the selected sector, and an overview of the
assumptions for calculating emissions and con-
sumption for the selected end-use) and an individ-
ualized letter indicating the charge questions. The
peer reviewers provided written responses to the
peer review coordinator. The comments received
were used to identify potential updates to the VM.
Seven peer reviewers responded to the peer review
across four end-use groups: fire suppression,
MVACs, unitary AC, and refrigerated transport.
Several updates in the refrigeration and AC and fire
suppression sectors in response to peer review
comments were implemented into the VM in March
2018 for inclusion in the publication of the 1990-
2016 U.S. Greenhouse Gas Inventory. The remaining
updates were implemented in August 2018.
Unitary AC
The VM has three unitary AC end-uses: 1) residential
unitary AC, 2) small commercial unitary AC, and 3)
large commercial unitary AC.
2 See Annex 3.9 of the U.S. GHG Inventory for the detailed methodology and assumptions of how the VM estimates the use
and emissions of ODS and ODS alternatives.

Combined, the unitary AC end uses are projected to
contribute 26% of total ODS substitute emissions in
2020 on a global warming potential (GWP)-
weighted basis.3
In response to peer review comments, updates to
the unitary AC end-uses in 2018 included:
¦	Updated 1999-2016 sales estimates and 2017-
2030 growth rates for residential and commer-
cial unitary AC systems to reflect updated ship-
ment data from the Air Conditioning, Heating,
and Refrigeration Institute (AHRI) and align with
projected household growth rates.
¦	Reduce charge sizes for residential unitary AC
systems according to new values provided by
peer reviewers.
¦	Reduced annual loss rates for residential and
commercial unitary AC systems entering the
market in 2006 or later and disposal loss rates
for residential and commercial unitary AC sys-
tems in 2015 to represent improved systems
and practices.
The VM has two light-duty MVAC end-uses—light
duty cars (LDC) and light duty trucks (LDT). Com-
bined, the MVAC end-uses are projected to contrib-
ute 14% of total ODS substitute emissions in 2020
on a GWP-weighted basis.
In response to peer review comments, updates to
the MVAC end-uses in 2018 included:
¦	Updated sales projections of LDCs and LDTs in
2021-2025 to be consistent with the sales esti-
mates from EPA's Proposed Determination of
the Appropriateness of the Mode/ Year 2022-
2025 Light-Duty Vehicle Greenhouse Gas Emis-
sions Standards under the Midterm Evaluation:
Technical Support Document.
¦	Reduced the annual servicing loss rate for
LDCs and LDTs from 3.1%, reaching 2.7% by
2013, to accurately reflect the reported decrease
in the amount of refrigerant required for servic-
ing shown by the 2013 and 2016 Mobile Air
Conditioning Society Field Surveys.
Refrigerated Transport
The VM has six refrigerated transport end uses:
road transport; intermodal containers; merchant
marine, naval, and fishing vessels; reefer ships; vin-
tage (i.e., older-style) rail transport; and modern rail
transport. Combined, the refrigerated transport
end-uses contribute 5% of total ODS substitute
emissions in 2020 on a GWP-weighted basis.
In response to peer review comments, updates to
the road transport and intermodal container end-
uses in 2018 included:
¦	Removed refrigerant transition to CO2 in road
transport and added a transition from R-404A to
R-452A starting in 2017.
¦	Updated the annual loss rate to 15% for all HFC
road transport vintages starting in 2000.
3 Estimated emissions come from VM version VM IO file v-M. 03.16.18, the version that was used for reporting to the UNFCCC
in 2018.

Fire Suppression
The VM has two fire suppression end uses: 1) hand-
held "streaming" applications (e.g., portable fire ex-
tinguishers) and 2) installed "flooding" systems
(e.g., fixed systems protecting enclosed spaces).
Combined, the fire suppression end-uses are pro-
jected to contribute 2% of total ODS substitute
emissions in 2020 on a GWP-weighted basis.
In response to peer review comments, updates to
the fire extinguishing end-uses in 2018 included:
¦	Updated replacement ratios for total flooding
agents, assuming a weighted average between
Class A and Class B values.
¦	Updated growth rates of the total flooding
market from 1996 through 2030 to reflect real-
world growth trends in the technology market.
¦	Implemented suggested changes to the market
transitions for the total flooding and streaming
¦	Increased the lifetimes of the total flooding
(20 to 33 years) and streaming end-uses (12 to
24 years).
¦	Reduced annual loss rates for total flooding
agents over time to represent improved systems
and practices.
Together, the implemented updates to the fire sup-
pression, MVAC, unitary AC, and refrigerated
transport end-uses in response to the peer review
increased fluorinated greenhouse gas (F-GHG)
emissions, excluding ODS, on average by 0.2 per-
cent on a GWP-weighted basis between 1994 and
2003 and decreased emissions on average by 11
percent between 2004 and 2030. Prior to 1994, F-
GHG emissions did not change. On a GWP-
weighted basis, consumption of F-GHGs increased
by an average of 1.5 percent in 1994 through 2005,
but decreased on average by 7 percent between
2006 and 2030.
Figure 1: Comparison of United States F-GHG Consumption and Emissions from VM Peer Review Updates
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990 2000 2010 2020 2030
2000	2010	2020	2030
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Office of Air and Radiation (6205T)
September 2018