TRANSITIONING TO LOW-GWP ALTERNATIVES
in Motor Vehicle Air Conditioning

Background
This fact sheet provides current information on low global
warming potential (GWP)1 alternative refrigerants to high GWP
hydrofluorocarbons (MFCs) for use in motor vehicle air conditioning
(MVAC) systems. MFCs are powerful greenhouse gases (GIHGs)
with GWPs hundreds to thousands of times more potent per
pound than carbon dioxide (C02); however, more low-GWP
alternatives are becoming available.
Globally, approximately 80% of MFCs are emitted in the
refrigeration, air conditioning (AC), and MVAC sectors, with the
remainder accounted for by the foam-blowing, aerosols, fire
suppression, and solvents sectors. While developed nations have
historically accounted for the majority of global HFC emissions,
total HFC emissions in developing nations are projected to
quadruple by 2030. This rapidly increasing rate of HFC emissions
is largely driven by the increased demand for refrigeration and
AC, particularly in the tropical climates of much of the developing
world, and the transition away from ozone depleting substances
(ODS). Emissions from MVAC systems occur as HFCs are released
to the atmosphere throughout the lifecycle of equipment—i.e.,
during operation, servicing, and at end of life.
Figure 1. Global HFC Emissions in 2020 by Sector
MVAC
13%
Aerosols,
Solvents,
Foams,
and Fire Ext,
21%
Other Ref
12%
Commercial
Ref
26%
Global HFC Emissions: 1,084 MMT C02 Eq.
Global HFC Emissions in MAC: 137 MMT C02 Eq.
Source: Estimates based on U.S. EPA (2013).
MVAC Systems
MVAC systems are used to cool passenger
compartments of motor vehicles, including cars,
vans, and trucks.2 MVAC system components
are located in the vehicle engine compartment
and ventilation system and charged during
vehicle manufacture. The main components are connected
by flexible refrigerant lines. Table 1 lists the typical capacity,
refrigerant charge, and annual leak rate for MVAC systems.
Table 1. Typical MVAC System Characteristics
System Location
Vehicle Market
Capacity
(kW)
Refrigerant
Charge (kg)
Annual Leak
Rate (%)
Engine compartment and ventilation
system
Cars, vans, and trucks
3-5
CO
CD
1
CD
2-10
Source: LJNEP (2015b).
1	GWP is a measure of a substance's climate warming impact compared to CO?,
2	AC systems for ships are not addressed by this fact sheet. AC on ships is provided by chillers and other large commercial AC systems.

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TRANSITIONING TO LOW-GWP ALTERNATIVES in Motor Vehicle Air Conditioning
Global MVAC Market Growth
Motor vehicle AC is a large IH C consuming sector in developing nations and is expected to dramatically increase, especially in rapidly
emerging economies where new vehicle sales have been growing significantly and AC is becoming a standard vehicle feature. Between
2005 and 2015, for example, sales of new vehicles grew at an average annual rate of 16% in China and 10% in India. Studies predict that the
estimated number of MVAC units in developing countries will dramatically increase from 200 million units in 2010 to 1 billion units by 2050.
Improved Servicing and End-of-Life Practices
Refrigerant emissions from MVAC equipment occur during
operation (i.e., system leaks), servicing (i.e., due to loss of
refrigerant during connection and disconnection of refrigerant
lines), and end-of life (i.e., equipment disposal). Emissions could
also occur if the MVAC system is otherwise compromised, such
as during an automobile accident.
Small amounts of refrigerant can be lost due to leakage during
the use of the MVAC system based on the characteristics
of joints and gaskets. Operational losses typically increase
throughout the lifetime of the equipment due to wear and
vibrations.
During servicing events and end-of-life, the extent of refrigerant
losses depends on various factors including the existence of
and compliance with refrigerant recovery laws, the technical
efficiency of refrigerant recovery equipment, and the proficiency
of technicians' service practices. Often MVAC systems are
serviced by do -it-yourself (DIY) owners rather than professional
technicians, which can lead to increased refrigerant emissions
during the charging procedure, as well as from the release of
unused refrigerant remaining in the refrigerant can (known as the
"heel") or due to a lack of leak repair on the part of the DIY user.
Improvements in the technologies and practices associated with
the use of MVAC refrigerants by manufacturers, technicians,
and consumers; the introduction of alternative refrigerants
and technologies; implementation of refrigerant recovery laws
arid standards; and market/policy drivers that provide financial
incentives for recovery may help to offset most HFC refrigerant
emissions from MVAC systems.
HFC Alternatives and Market Trends
Some MVAC systems in use contain ozone depleting refrigerant
CFC-12, which is being phased out globally under the Montreal
Protocol. Almost all new units sold today contain III C 134a
which is thousands of times more potent than C02 on an equal
mass basis. A number of lower GWP alternative refrigerants
are available and currently in use or under development for use
in new MVAC systems—including CO,, IliO l/3-'1yf, and HFC-
152a. These alternatives are described in Table 2.
Table 2. GWPs and Global Use Status of Low-GWP MVAC Refrigerants3
Refrigerant
GWP"
Flammability
Classification0
Cars, Vans,
and Trucks
FIFC-152a
124
2
n+
H F0-1234yf
4
2L
~+
R-744 (CO.)
1
1
~+
a ~ = Available now, ~ = Under development, + = U.S. EPA SNAP-approved,
subject to use conditions
b GWP values are from IPGC Fourth Assessment Report (2007) and U.S. EPA (2015c).
'¦ Refrigerants are classified by flammability according to ASHRAE Standard 34 and
ISO 817 A classification of 1 represents no flame propagation; 2 represents lower
fiammabiiity; 2L represents lower flammability with a maximum burning velocity of <10
cm/s; and 3 represents higher flammability.
4 HFOs (hydrofluoroolefins) are unsaturated i-IFCs (i.e., containing a carbon-carbon double bond).

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TRANSITIONING TO LOW-GWP ALTERNATIVES in Motor Vehicle Air Conditioning
HFO-1234yf
•	In use in certain models of cars, vans, and trucks in 40
countries, including Member States of the European Union
(EU), the United States, Japan, China, Saudi Arabia, Turkey,
Israel, and the United Arab Emirates
•	Cooling performance and fuel use is comparable to
HFC-134a
•	Under evaluation for secondary loop systems in a
demonstration project in India
•	Suitable for systems where safety regulations permit use of
a lower flammability refrigerant
Carbon Dioxide (C02, R-744)
•	High pressure refrigerant being considered by automobile
manufacturers; systems operate at 5 to 10 times higher
pressure than other passenger vehicle AC systems
•	Global car manufacturers developing C02 MVAC systems for
passenger vehicles
•	Cooling performance, energy efficiency, and fuel use
comparable to HFC-134a systems in temperate climates;
efficiency may drop in hotter climates
HFC-152a
•	Prototype systems are under evaluation globally, including a
joint project with an Italian and German OEM using a double
loop system
•	Under evaluation for secondary loop systems in a
demonstration project in India
•	Good energy efficiency and cooling performance, but
requires additional safety requirements and system changes
compared to standard HFC-134a systems due to flammability
Alternative Technologies
In support of the movement to improve the efficiency of
vehicles and reduce overall GHG emissions, alternative MVAC
technologies are under development, often in parallel with
advances in alternative car propulsion technologies (e.g., hybrid,
all-electric vehicles), including:
•	Phase change material (PCM) technology stores cold in the
evaporator of the MVAC system that can be released when
the compressor is not running (e.g., in hybrids)
•	Secondary loop systems allow the safe use of mildly
flammable refrigerants (e.g., HFC-152a and HFO-1234yf) as
the entire refrigerant loop is located in the engine
compartment, rather than in the air distribution system
that is connected to the passenger compartment
•	Reversible heat pump systems operate to provide both
heating and cooling in the vehicle's passenger compartment
•	Sorption heating and cooling is based on the re-use of
waste heat (e.g., exhaust gas or cooling jacket) and also
offers opportunity of long-term thermal storage
•	Thermoelectric heating and cooling uses couples of
material that generate electric energy to operate as heat
pumps providing active cooling or heating
Case Study: Secondary Loop Systems to Replace HFC-134a in MVACs
A demonstration project financed by the Climate and Clean Air Coalition (CCAC) is currently evaluating the use of HFC-152a and HFO-1234yf
refrigerants in secondary loop MVAC systems. The project—which is being conducted by TATA Motors Limited (India), MAHLE (Germany),
and the Institute for Governance and Sustainable Development (IGSD)—aims to reduce refrigerant consumption and emissions while
increasing fuel efficiency of MVACs. HFO-1234yf and HFC-152a are listed as acceptable for use in MVACs (subject to use conditions) by the
U.S. EPA's Significant New Alternatives (SNAP) program, and qualify under the European Union F-Gas regulations as acceptable with GWP
less than 150.
Secondary loop systems offer a design solution that allows the safe use of mildly flammable refrigerants while optimizing energy efficiency
in high ambient temperature climates, because the refrigerant is contained in components located in the engine compartment, rather
than in the air distribution system (which is connected to the passenger compartment). Energy efficiency is increased by engaging the
compressor during deceleration to lower the temperature of the coolant and then delivering that cold to the passenger compartment when
needed by controlling the pump and fan. The thermal ballast also maintains passenger comfort with "stop/start" systems that turn off the
engine during short stops in traffic and restarting the engine when traffic moves.
Based on results from the demonstration vehicle, the use of these low-GWP refrigerants in the secondary loop technology can significantly
reduce GHG emissions from MVACs in several ways: first, any leaked refrigerant has a lesser climate impact due to its lower GWP
than HFC-134a; second, the amount of refrigerant required in the primary loop of a secondary loop system is much less than that of a
conventional direct expansion system (20% less for HFO-1234yf and 40% less for HFC-152a), meaning that significantly less refrigerant will
be leaked overall; and third, life-cycle leak rates are significantly lower than conventional MVAC systems due to use of shorter hoses, fewer
fittings, and integrated components.

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TRANSITIONING TO LOW-GWP ALTERNATIVES in Motor Vehicle Air Conditioning
Future Outlook
Together, the suite of known alternative chemicals, new
technologies, as well as better process and handling practices,
can significantly reduce HFC use in both the near- and long-term.
Many countries are transitioning to lower-GWP alternatives in
MVAC applications while satisfying the various international
energy efficiency, safety, and environmental standards. The
equipment manufacturers and chemical producers for the MVAC
industry are continuing to work on developing new alternatives
that can be marketed worldwide. Although much work remains
to fully develop and adopt some of these low-GWP alternatives
and some unknowns still remain, the affected industries have
proven through the ODS phaseout that they can move quickly to
develop low-GWP alternatives that protect the environment.
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TRANSITIONING TO LOW-GWP ALTERNATIVES in Motor Vehicle Air Conditioning
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08$ SNAP
AN	SIGNIFICANT NEW ALTERNATIVES POLICY
PRO^°
EPA-430-F-15-029 • www.epa.gov • December 2016

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