Sustainable Energy Technologies and Assessments 11 (2015) 114–125
Contents lists available at ScienceDirect
Sustainable Energy Technologies and Assessments
journal homepage: www.elsevier.com/locate/seta
Original Research Article
Investigations of life cycle climate performance and material life cycle
assessment of packaged air conditioners for residential application
Gang Li
Ingersoll Rand Residential Solutions, 6200 Troup Highway, Tyler, TX 75707, USA
Ingersoll Rand Engineering and Technology Center-Asia Pacific, Shanghai 200051, PR China
a r t i c l e
i n f o
Article history:
Received 19 May 2015
Revised 14 July 2015
Accepted 16 July 2015
Keywords:
Life cycle climate performance
Life cycle assessment
Packaged
Air conditioner
Material
Seasonal energy efficiency ratio
a b s t r a c t
A comprehensive investigation for life cycle climate performance (LCCP) and material life cycle
assessment (LCA) is performed under various influencing factors for the packaged conditioners. The
whole carbon dioxide equivalent (CO2-eq.) emissions during an air conditioner’s lifetime are evaluated
from the LCCP aspect. Results indicate that the seasonal energy efficiency ratio (SEER) rating has a large
influence on the emission variation, 13 SEER R410A has approximately a +3% CO2-eq. emission increase
when compared with the 13 SEER R22 in the area of Richmond, which is mainly caused by the direct
emission of annual leakage of high GWP R410A. The efficient 14 SEER R410A unit depicts a 9% reduction.
In general, as the climate is varied from cold to hot, the emissions are increased. Among the emission contributors, the energy consumption accounts for more than 70% of the total emissions, followed by annual
refrigerant leakage. Parameter analysis reveals that the refrigerant recovery rate has a larger effect on the
LCCP results than the cycle degradation coefficient, especially in the cold areas. In addition, the two
capacity air conditioner product has approximately a 13% emission reduction due to the better load
matching. Material LCA investigation shows that, in general, most of the material phase environmental
performance is decreased in 14 SEER air conditioners. This is because the addition of aluminum from
employing of the micro-channel heat exchanger. For a sustainable future, minimizing material use and
CO2-eq. emissions and maximizing energy efficiency should have been considered in its entirety.
Ó 2015 Elsevier Ltd. All rights reserved.
Introduction
Sustainability has become an alarming concern by increasing
the awareness that there are limits to the availability of
non-renewable resources, and there is the rising energy demand,
especially in the area of heating, ventilating, air-conditioning and
refrigeration (HVAC&R). To achieve a more sustainable future for
products in various applications, both the research institutes and
industry are taking more efforts to evaluate the environmental
burdens with various products. Based on the U.S. Department of
Energy (US DOE) [1], appropriately 70% of the households make
use of the central air-conditioning systems run by a conventional
external condenser or a heat pump. Therefore, the heating or
cooling systems/products in the buildings deserve the further
investigation to achieve better environmental impact. From the
environmentally life-cycle perspective, a manufacturer is usually
further challenged with strict design requirements, such as long
operational life, maximizing the energy efficiency, maximizing
the recyclable content, and minimizing the material use and CO2
E-mail address: gangli166@gmail.com
http://dx.doi.org/10.1016/j.seta.2015.07.002
2213-1388/Ó 2015 Elsevier Ltd. All rights reserved.
emissions, etc., to provide the most competitive products for the
application.
Currently there are limited studies regarding the in-depth environmental impact of residential buildings for cooling or heating
systems/products. One study [2] was performed for the life-cycle
energy, greenhouse gas emissions, and costs of a contemporary
2450 sq ft (228 m3) U.S. residential home (the standard home, or
SH). A functionally equivalent energy-efficient house (EEH) was
modeled that incorporated 11 energy efficiency strategies. These
strategies led to a dramatic reduction in the EEH total life-cycle
energy; 6400 GJ for the EEH compared to 16,000 GJ for the SH.
Life-cycle greenhouse gas emissions were 1010 metric tons CO2
equivalent for an SH and 370 metric tons for an EEH. However,
the estimated operating inputs such as the electricity for products
are directly mapped into model sectors for calculation without
considering various operating conditions under different
climates for the air conditioners and heat pumps. A study by
Heikkilä [3] compares the life cycle environmental impacts of
two air-conditioning systems for an office building in Sweden.
The difference in the form and source of the energy dominates
the relative environmental effects of the systems. Another study
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G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
Nomenclature
AHRI
AP
COP
EEH
GHG
SEER
SFP
air-conditioning, heating, and refrigeration institute
acidification potential
coefficient of performance
energy efficient house
greenhouse gas
seasonal energy efficiency ratio
smog formation potential
by Ochoa et al. [4] was conducted for the environmental impact for
improving a single family house and outlined a simple approach to
a life cycle analysis for residences. However, the following two
studies did not consider the effect of climate for products as well,
and this study by Ochoa et al. [4] was admitted their study was
limited in the life cycle assessment to the building environmental
impacts. There are many other similar studies. Therefore, based on
the literature review, there are few, limited in scope, and fragmented investigations with in-depth analysis for the environmental impact including the climate effect for residential applications.
To reveal the in-depth analysis, some powerful and necessary
tools evaluating the product environmental performance or impact
are briefly introduced here. One tool for is the web-based interactive life cycle climate performance (LCCP) modeling program for
residential heat pumps and air conditioners from reference [5].
LCCP is a methodology that is used to assess the total global warming potential (GWP) impacts (both direct and indirect emissions),
expressed as carbon dioxide equivalent mass (kg-CO2 eq.), over
the lifetime of a particular refrigerant, piece of equipment or system with different climate inputs. It can be expressed as a summation of all sources of the direct and indirect source emissions. This
tool has the detailed input parameters for the use phase, including
various operating conditions based on ANSI/AHRI Standard
210/240 [6] with different climate conditions, cycle degradation
coefficient, various cities, etc. It will calculate the equivalent mass
of CO2 released into the atmosphere for different air conditioner
types. As mentioned before, there are few investigations that do
a complete and comprehensive work with covering one product
area in detail comparing various influencing parameters to achieve
the lowest environmental impact. Therefore, in the current study,
the LCCP investigation is performed comprehensively, from both
the direct and indirect emission aspects for the packaged 14
SEER air conditioners. In addition, there is a lack of material life
cycle assessment (LCA) analysis for the latest HVAC&R products
based on the recent component update from various environmental impacts from the literature review. Here the Ingersoll Rand’s
(IR) Screening LCA tool, which is followed the ISO 14000 series
standards [7–10], managed by PE, is used to evaluate the potential
environmental impacts from the material phase.
Therefore, in the current study the LCCP is used efficiently to
evaluate the environmental impact of the packaged air conditioners from a whole life cycle aspect, including both the direct
and indirect emissions. LCA tool can be efficiently utilized for the
material phase during the material production stage, which is a
small part for the indirect emissions. To show more detail about
the environmental impacts for material phase, it includes not
only the GWP, but also the acidification potential (AP), eutrophication potential (EP), ozone depletion potential (ODP), and smog
formation potential (SFP). The discoveries from the current study
are beneficial for the researchers, engineers and manufactures to
minimize the total environmental impact through maximum
efficiency and maintaining the maximum sustainability and
safety. It can be also beneficial for the researchers and engineers
HVAC&R
LCCP
ODP
EOL
EP
LCA
GWP
heating, ventilating, air-conditioning and refrigeration
life cycle climate performance
ozone depletion potential
end of life
eutrophication potential
life cycle assessment
global warming potential
to design the more efficient and convenient environmental
impact assessment tools.
Air conditioner unit performance
The system test conditions are shown in Table 1 [6].
The indoor unit capacity (Q) is determined using the mass flow
rate (mair) and the indoor air side enthalpy difference (Dh), as
shown in Eq. (1). The COP is determined as the ratio of the indoor
unit air capacity (Q) over the air conditioner total power (W)
including both the compressor and fan power, as shown in Eq. (2).
Q ¼ mair Dh
ð1Þ
COP ¼ Q =W
ð2Þ
The COP (or the further calculated SEER) and capacity from
cooling A are used for LCCP calculation, as shown in Figs. 1 and
2. Basically, there are three categories: 13 SEER R22, 13 SEER
R410A and 14 SEER R410A. The 13 SEER R410A and 14 SEER
R410A are the entry level Ingersoll Rand/Trane packaged air conditioner products. On April 24, 2014, the Department of Energy
(DOE) and the American Public Gas Association (APGA) reached a
settlement agreement on the implementation of the Federal
Regional Standards [11]. From this new standard, in 2015, the
U.S. DOE will increase the minimum federal standard for the air
conditioners in the southern U.S. (including Arizona) to 14 rated
seasonal energy efficiency ratio (SEER). The new standards are part
of a compromise among industry groups and environmental and
consumer advocates. This is resulting from a lawsuit brought
against DOE by the Natural Resources Defense Council in
2004 after the Bush administration attempted to reverse
air-conditioner efficiency standards set by the Clinton administration. Following this trend, the new 14 SEER R410A products are
designed and released. As seen from Fig. 1, the cooling capacity
for three categories is pretty close, while the total power consumption for the 14 SEER R410A is the lowest. As seen from Fig. 2, the 14
SEER R410A has the highest SEER value and the 14 SEER R410A in
general has the slightly lower cycle degradation coefficients than
the old 13 SEER R22 and 13 SEER R410A, which means for the most
part it can achieve the better thermal performance than others.
Table 1
ANSI/AHRI standard 210/240 test matrix.
Test
Indoor
Outdoor
Operating
D.B.
W.B.
D.B.
W.B.
Extended
condition
Cooling A
Cooling B
Cooling C
80 °F
67 °F
115 °F
NA
Steady state cooling
80 °F
80 °F
80 °F
67 °F
67 °F
657 °F
95 °F
82 °F
82 °F
NA
NA
NA
Cooling D
80 °F
657 °F
82 °F
NA
Steady state cooling
Steady state cooling
Steady state cooling, dry
coil
Cyclic cooling, dry coil
116
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
60000
-1
40000
5500
5000
4500
4000
30000
3500
20000
3000
2500
Air conditioner power (W)
50000
Cooling capacity (Btu h )
system transportation, component manufacturing, etc. A detailed
introduction can be found in literature [5]. The LCCP is calculated
in CO2-eq. emissions as follows:
6000
13SEER R22 capacity
13SEER R410A capacity
14SEER R410A capacity
13SEER R22 power
13SEER R410A power
14SEER R410A power
10000
2000
0
1500
2.0 Ton 2.5 Ton
3.5 Ton
3.0 Ton
4.0 Ton
5.0 Ton
Air conditioner unit
Fig. 1. Packaged air conditioner cooling A capacity and power consumption
performance.
Actually there are a series of tests including cooling A, cooling B
tests, etc., and only the cooling A performance is shown in Fig. 1.
To evaluate the air conditioner CO2 emissions, a series of such tests
from Table 1 are used for calculate LCCP.
LCCP model framework and material LCA model framework
LCCP model framework
LCCP is a cradle-to-grave analysis of the environmental impact at
all points in the life cycle chain, including the manufacturing of components, system operation and the end-of-life disposal. The LCCP
tool can be found via reference [5]. This framework relies on four
main modules: (1) the core open-source LCCP calculation methodology, (2) the system performance model, (3) the load model, and (4)
standardized reference data sets for emissions and weather. These
modules interact with each other via standardized communication
interfaces that describe the data input–output process.
The LCCP, expressed in terms of the greenhouse gases (GHGs)
consists of the direct and indirect global warming impacts. The
direct emissions are mainly from the refrigerant leaks. The indirect
emissions mainly include the emissions from system operation,
20
1.2
13SEER R22
13SEER R410A
14SEER R410A
16
1.1
1.0
0.9
0.8
12
0.7
-1
-1
SEER (Btu h W )
14
10
0.6
13SEER R22 Cd_c
13SEER R410A Cd_c
14SEER R410A Cd_c
8
0.5
0.4
6
0.3
4
0.2
2
0.1
0
0.0
2.0 Ton 2.5 Ton
3.0 Ton
3.5 Ton
4.0 Ton
Cycle degradation coefficient
18
5.0 Ton
Air conditioner unit
Fig. 2. Packaged
performance.
air
conditioner
SEER
and
cycle
degradation
coefficient
Emtotal ¼ Emdirect;ref
leak
þ Emdirect;others þ Emindirect;elec
þ Emindirect;others
ð3Þ
Emdirect,ref leak is the direct emission from refrigerant leaks;
Emdirect,others is direct emissions from the additional sources:
atmospheric reaction products of refrigerant, manufacturing,
transport & service leakage, accidents, and EOL refrigerant emissions; Emindirect,elec is the indirect emission from system operation;
Emindirect,others is indirect emissions from additional sources: chemical production of refrigerant and transport, material manufacturing and recycling, system assembly. Both the direct emissions
and indirect emissions are reported in terms of CO2-eq. emissions,
considering the carbon content of the fuel utilized in each process
and during system operation. The load model is used to determine
the hourly load values which are required by the system performance model. In turn, the system performance model, using the
weather data, calculates the hourly energy consumption of the system. The hourly consumption is then multiplied by the hourly
emission rate for the electricity production, obtained from the
standardized reference datasets for the location-specific emissions,
to obtain the hourly emission due to the energy consumption of
system. The default values for the hourly emission rate for
specified locations within the USA are obtained from Deru et al.
[12]. Some building energy modeling tools such EnergyPlus [13]
can be used to determine both the hourly load and energy
consumption.
The default weather data available in the LCCP tool is based on the
Typical Meteorological Year (TMY) data from the National Solar
Radiation Database [14]. These datasets include the dry-bulb temperature, dew-point temperature, and the relative humidity for all
8760 h of the year. The tool has 47 built-in cities with the ability of
adding additional user defined cities. The default GWP values used
in the LCCP tool are obtained from the IPCC Fourth Assessment
Report (AR4) [15] and are based on the 100 year time horizon
(GWP100).
LCCP model input data
The most important data is the power consumption and the
capacity performance data. In addition, there are other emission
inputs assumed: annual leakage rate 5%, EOL refrigerant loss 15%,
service leakage rate 5%, and accident leakage 0.3%. The back up
heat fuel data is set as the default values in the LCCP tools. The
model can simultaneously analyze various products for CO2-eq.
emissions.
LCCP model output data
After the input data has been set into the model, the tool provides the output results including LCCP values, details of the direct
and indirect emissions for different cities. The model can also be
used to make the prediction for LCCPs under different influencing
parameters.
Material LCA model framework
Ingersoll Rand’s (IR) Screening LCA tool, managed by PE, is used
to reflect IR’s product portfolio to provide the directional decision
support based on a variety of the environmental performance metrics. The calculation is closely follow ISO 14040:2006 and ISO
14044:2006 LCA guidelines. It can also be beneficial to enable
the user to perform the quick and easy scenario analyses of new
product design concepts based on the incomplete and high-level
117
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
material information. It uses best-case, worst-case, and most-likely
modeling assumptions to establish three data points per design
option: (1) lower bound = best case, (2) PERT estimate = (best
case + 4 times most likely + worst case)/6, and (3) upper bound = worst case. PERT estimate is performed for the current study. The
input is the material type with corresponding weight information
for the air conditioner unit, and the output is the environmental
performance metrics, including AP, EP, GWP, ODP, and SFP.
LCCP results and discussion
Effect of air conditioner size and climate for LCCP investigation
Fig. 3 through Fig. 5 show the LCCP values of three categories for
seven US cities, Minneapolis, Boston, Richmond, Los Angeles, San
Antonio, Phoenix, from cold to warm climate zones. Regarding 13
SEER R22, as shown in Fig. 3, from the 5.0 Ton air conditioner to
the 2.0 air conditioner, CO2-eq. emissions are decreased sharply.
It can also be found that when the climate is varied from cold areas
(such as Minneapolis and Boston) to hot areas (such as Phoenix),
the CO2-eq. emissions are increased. While for the area of Los
Angeles, since the balmy and comfortable weather itself makes
the cooling demand decreased greatly, the total emission is lowest
among all areas in Fig. 3. It can also be found that the direct CO2-eq.
emission is approximately 20% in cold areas of Minneapolis and
Boston, while it is approximately only 5% in the hot area of
Phoenix. Similar conclusions can be drawn from Figs. 4 and 5 for
13 SEER R410A and 14 SEER R410A, respectively. To make the fair
LCCP comparison for the three categories, the area of Richmond is
chosen to reveal their performance metrics, as shown in Fig. 6.
250000
Indirect
Direct
150000
-21%
-30%
-33%
-48%
-46%
5.0 Ton 13SEER R22
4.0 Ton 13SEER R22
3.5 Ton 13SEER R22
3.0 Ton 13SEER R22
2.5 Ton 13SEER R22
2.0 Ton 13SEER R22
-20%
-30%
-35%
-48%
-57%
200000
-19%
-25%
-25%
-41%
-46%
-20%
-28%
-29%
-45%
-51%
50000
-20%
-29%
-31%
-47%
-54%
100000
-20%
-29%
-30%
-46%
-53%
LCCP emissions per lifetime (kg CO2-eq.)
CO2-eq. emission composition:
0
Minneapolis
Boston
Richmond Los Angeles San Antonio
US cities
Cold
Phoenix
Hot
Fig. 3. Packaged 13 SEER R22 air conditioner LCCP.
250000
-20%
-25%
-37%
-49%
-59%
Indirect
Direct
5.0 Ton 13SEER R410A
4.0 Ton 13SEER R410A
3.5 Ton 13SEER R410A
3.0 Ton 13SEER R410A
2.5 Ton 13SEER R410A
2.0 Ton 13SEER R410A
150000
-20%
-25%
-31%
-49%
-57%
200000
-18%
-23%
-23%
-42%
-48%
-19%
-24%
-26%
-46%
-53%
50000
-19%
-24%
-29%
-48%
-55%
100000
-19%
-24%
-27%
-47%
-54%
LCCP emissions per lifetime (kg CO2-eq.)
CO2-eq. emission composition:
0
Minneapolis
Cold
Boston
Richmond Los Angeles San Antonio
US cities
Fig. 4. Packaged 13 SEER R410A air conditioner LCCP.
Hot
Phoenix
118
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
250000
-16%
-31%
-37%
-52%
-59%
Indirect
Direct
200000
150000
-18%
-32%
-37%
-52%
-58%
5.0 Ton 14SEER R410A
4.0 Ton 14SEER R410A
3.5 Ton 14SEER R410A
3.0 Ton 14SEER R410A
2.5 Ton 14SEER R410A
2.0 Ton 14SEER R410A
-20%
-26%
-28%
-44%
-50%
-19%
-29%
-32%
-48%
-54%
50000
-18%
-31%
-35%
-50%
-57%
100000
-19%
-30%
-34%
-50%
-56%
LCCP emissions per lifetime (kg CO2-eq.)
CO2-eq. emission composition:
0
Minneapolis
Boston
Richmond Los Angeles San Antonio
US cities
Cold
Phoenix
Hot
Fig. 5. Packaged 14 SEER R410A air conditioner LCCP.
100000
Richmond, Virginia
Indirect
Direct
75000
3.0 Ton
-12%
+3%
-12%
3.5 Ton
-1%
-13%
+5%
-9%
+2%
-5%
50000
-1%
13SEER R22
13SEER R410A
14SEER R410A
-7%
+1%
LCCP emissions per lifetime (kg CO2-eq.)
CO2-eq. emission composition:
25000
0
5.0 Ton
4.0 Ton
2.5 Ton
2.0 Ton
Air conditioner
Fig. 6. Packaged SEER rating air conditioner LCCP comparison.
Basically, 13 SEER R410A has approximately a +3% CO2-eq. emission increase as compared with the 13 SEER R22, which is mainly
caused by the direct emission of annual leakage of refrigerant.
GWP value for refrigerants R22 is 1810, and R410A is 2088, with
approximately a 10% increase as compared with R22 (R22 is mainly
phased out due to the ODP issues). Therefore, a higher CO2-eq.
emission can be achieved for 13 SEER R410A. It can also be found
that the 14 SEER R410A depicts a 9% reduction as compared with
the 13 SEER R22. Possible explanation is that the new 14 SEER
R410A adopts the more efficient scroll compressor, and has the
reasonable thermostatic expansion valve (TXV) setting, and
uniform refrigerant flow line distribution in the coil for better heat
transfer.
It is necessary to reveal the CO2-eq. emission contributors to
have a deep understanding about the product LCCP, as shown in
Fig. 7. Three product categories are compared at the city of
Boston, Richmond and Phoenix. In the cold city of Boston, 13
SEER R410A has a +6% CO2-eq. emission increase when compared
with the 13 SEER R22 and the 14 SEER R410A depicts a 9% reduction. Among the contributions for 13 SEER R22, the energy consumption, the main indirect emission, consumes 70% of the total
emissions. The annual leakage, the main direct emission, has 21%
of the total emissions. Direct emissions from refrigerant loss end
of life (EOL) and service leakage make the contributions of 4.0%
and 4.0%, respectively. The total direct emission is approximately
29%. From the discussion in this paragraph, the emission due to
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
LCCP contributors, Boston, Massachusetts 3 Ton
110%
70%
60%
50%
40%
30%
20%
10%
13 SEER R22 Boston, Massachusetts, BSL
80%
14 SEER R410A Boston, Massachusetts, BSL -9% BSL
90%
13 SEER R410A Boston, Massachusetts, BSL +6% BSL
100%
Emissions - Charge
Emissions - Materials and Recycling
Indirect Emissions
Emissions - Service
Emissions - EOL
Direct Emissions
Emissions - Annual Leakage
Emissions-Energy Consumption
0%
(a) Boston, Massachusetts
LCCP contributors, Richmond, Virginia
3 Ton
13 SEER R22 Richmond, Virginia, BSL
13 SEER R410A Richmond, Virginia, BSL +3%
BSL
14 SEER R410A Richmond, Virginia, BSL -12% BSL
Emissions - Service
Emissions - EOL
Emissions - Annual Leakage
Emissions-Energy Consumption
(b) Richmond, Virginia
LCCP contributors, Phoenix, Arizona
3 Ton
14 SEER R410A Phoenix, Arizona, BSL -11% BSL
13 SEER R22 Phoenix, Arizona, BSL
13 SEER R410A Phoenix, Arizona, BSL -2% BSL
Emissions - Charge
Effect of air conditioner system energy consumption reduction for
LCCP investigation
This section further reveals the detailed effects of energy
consumption reduction for product CO2-eq. emissions with location set to be Boston, Richmond, Phoenix, from cold to hot areas.
As discussed in Effect of air conditioner size and climate for LCCP
investigation, the energy consumption is the largest contributors
for CO2-eq. emissions. Therefore, its variation will heavily influence
the LCCP results. As shown in Eq. (4) for energy consumption LCCP
calculation, tlifetime is the product lifetime (15 years), xlocation is the
emission rate for the location city, Whr is the hourly energy consumed, and there are totally 8760 h for 1 year.
Emindirect;elec ¼ tlifetime
can also be found that the indirect emission of materials and recycling is only a small part of the total emissions. In addition, Boston,
Richmond and Phoenix, from cold to hot, are compared for three
product categories for total emissions. The 13 SEER R410A shows
a +6% increase, +3% increase, and 2% reduction as compared with
the 13 SEER R22, respectively. The 14 SEER R410A shows a 9%, 12%,
and 12% reduction as compared with the 13 SEER R22, respectively.
This is because the indirect emission has an increasing weighing
factor for the total emissions, from the cold city of Boston
(70%), to Richmond (80%) and the hot city of Phoenix (90%).
Emissions - Charge
Emissions - Materials and Recycling
Emissions - Materials and Recycling
8760
X
W hr xlocation
Emissions - EOL
Emissions - Annual Leakage
Emissions-Energy Consumption
(c) Phoenix, Arizona
Fig. 7. Packaged SEER rating air conditioner LCCP contributors.
energy consumption takes approximately 70%. Therefore, more
attentions should be paid for energy efficiency improvements. It
ð4Þ
n¼0
The investigation of energy consumption reduction on LCCP
results is shown in Fig. 8. For all three cities, results reveal that
the CO2-eq. emissions are decreased. The direct emissions nearly
remain constant and only the indirect emissions are decreased
greatly as the energy consumption reduction is increased. From
Fig. 8, with the energy consumption reduction of 5%, 10% and
15%, the LCCP is decreased by approximately 4%, 8%, and 12% as
compared with the baseline 14 SEER R410A, respectively. Energy
consumption, as the main LCCP contributors, with reasonable
and efficient COP strategies, will lead the heavy CO2-eq. emission
reductions. Energy efficiency can be improved with more efficient
compressor, uniform coil refrigerant distribution, etc.
Effect of air conditioner refrigerant recovery rate for LCCP
investigation
As shown in Eq. (5) for refrigerant leakage at the EOL LCCP
calculation, mref is the amount of the refrigerant charge GWP, the
GWP value for refrigerants (R22 with 1810, R410A with 2088),
xref,EOL is the percentage of refrigerant lost at end of life.
Emdirect;ref EOL ¼ mref GWP xref;EOL
Emissions - Service
119
ð5Þ
The effect of refrigerant recovery rate on LCCP is investigated by
varying it in four rates (82%, 85%, 88% and 91%), as shown in Fig. 9.
Results showed that for the area of Phoenix the three categories
have the negligible effects on total emissions. Actually, the variation of LCCP results is within 1%. This result can be easily explained
from the CO2-eq. emission contributors. The refrigerant leakage is
the main contributor for direct emissions and it is approximately
only 5.0% of the total emissions for the area of Phoenix. With the
refrigerant recovery rate change from 82% to 91%, the total
emission variation is within 1%. Since all three categories are the
packaged products, the weight of refrigerant effect is quite small
as compared with the energy consumption for CO2-eq. emissions.
While for the city of Boston and Richmond, the variation of LCCP
results can be high of approximately 13% and 8%, respectively.
The refrigerant leakage is the main contributor for direct emissions
and it is high with approximately 25% and 15% of the total
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
Indirect
Richmond, Virginia
Phoenix, Arizona
-5%
Boston, Massachusetts
3.0 Ton Air conditioner
-9%
Direct
125000
100000
13SEER R22
13SEER R410A
14SEER R410A
25000
0
-8%
-6%
-9%
-4%
50000
-12%
75000
-3%
LCCP emissions per lifetime (kg CO2-eq.)
150000 CO -eq. emission composition:
2
-14%
120
-5 -10 15
)0
) 0 -5 ) -10 ) -15
) 0 -5 ) -10 ) -15
)
,% % )
,% % )
),% % )
on tion, n,% n,%
on ion, ion,%on,%
on ion, ion,%on,%
i
i
i
t
t
t
t
o
t
ti tio
mp p
mp p pt pti
mp p pt pti
su um mp mp
su um um m
su um um m
on ns su su
on ns s su
on ns s su
(C (Co Con Con
(C (Co (Con(Con
(C (Co (Con(Con
(
(
Energy Consumption Reduction
Fig. 8. Effect of air conditioner energy consumption reduction on LCCP.
LCCP emissions per lifetime (kg CO2-eq.)
150000 CO -eq. emission composition:
2
Direct
125000
Boston, Massachusetts
3.0 Ton Air conditioner
+1%0%-1%-2%
Indirect
Richmond, Virginia
Phoenix, Arizona
100000
13SEER R22
13SEER R410A
14SEER R410A
75000
50000
+4% 0% -4%-8%
+6%0%-6%-13%
25000
82
%
85
%
88
%
91
%
82
%
85
%
88
%
91
%
88
%
91
%
82
%
85
%
0
Rerfigerant Recovery Rate
Fig. 9. Effect of air conditioner refrigerant recovery rate on LCCP.
emissions, respectively. Therefore, for air conditioners in cold
areas, the refrigerant recovery rate cannot be neglected for
CO2-eq. emission reductions.
Effect of air conditioner cycle degradation coefficient for LCCP
investigation
This section further investigates the LCCP results for the effect
of cycle degradation coefficient. Usually the air conditioners cycle
off and on at part-load conditions to meet the load. Because of
startup losses, the capacity and efficiency are lower at part-load
conditions. The SEER procedure accounts for part-load losses with
a cyclic degradation coefficient (Cd). The transient startup behavior
can be expressed with degradation coefficients. Usually low Cd
indicates high-efficient system performance. The normalized efficiency degradation, i.e. the part load factor (PLF), can be expressed
in Eq. (6), it is the function of the part load ratio (PLR). DOE-2 [16]
includes several correlation curves that predict the energy use of
systems under the part load conditions. DOE-2 simulates systems
on an hour-by-hour basis, therefore the correlations are intended
to predict the part load energy use (and efficiency) as a function
of the (PLR) for each hour, where PLR is the ratio of the hourly load
over the available capacity.
PLF ¼ 1 C d ð1 PLRðT amb ÞÞ
ð6Þ
PLR ¼ Q loading =Q available
ð7Þ
121
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
Indirect
13SEER R22
13SEER R410A
14SEER R410A
Richmond, Virginia
Phoenix, Arizona
Direct
125000
Boston, Massachusetts
-1.5%
3.0 Ton Air conditioner
100000
75000
-1.5%
50000
-1.5%
LCCP emissions per lifetime (kg CO2-eq.)
150000 CO -eq. emission composition:
2
25000
as
el
in
e
-0
.0
2
-0
.0
4
-0
.0
6
B
B
as
el
B
as
el
in
e
-0
.0
2
-0
.0
4
-0
.0
6
in
e
-0
.0
2
-0
.0
4
-0
.0
6
0
Cycle Degradation Coefficient
Fig. 10. Effect of air conditioner cycle degradation coefficient on LCCP.
LCCP emissions per lifetime (kg CO2-eq.)
150000 CO -eq. emission composition:
2
3.0 Ton Air conditioner
Indirect
Direct
125000
Boston, Massachusetts
Richmond, Virginia
Phoenix, Arizona
-12%
100000
13SEER R22
13SEER R410A
14SEER R410A
75000
50000
-14%
25000
-14%
gl
e
Tw Spd
o
ca
p.
Si
n
e
Tw Sp
o d
ca
p.
Si
n
gl
Si
ng
le
Tw Sp
o d
ca
p.
0
Single Speed vs Two Capacity
Fig. 11. Effect of two capacity air conditioner on LCCP.
As shown in Fig. 10, with the value of 0.06 decreased for the Cd
values, the CO2-eq. emission is decreased by 1.5%. For air
conditioners, the refrigerant recovery rate has larger influence than
the Cd on the CO2-eq. emission reductions.
Effect of air conditioner two capacity unit for LCCP investigation
All the air conditioner LCCP result discussed above is the single
speed type. The two capacity air conditioner unit was developed
for better loading match at part-load conditions. As shown in
Fig. 11 for the effect of two capacity unit LCCP investigation, the
14 SEER two capacity air conditioner product from Ingersoll
Rand/Trane has approximately a 13% CO2-eq. emission reduction
as compared with the current 14 SEER R410A air conditioner (single speed). Basically, the two capacity unit has the higher efficiency
at part-load conditions. In addition, it has the better comfort
condition due to the better load matching (few cycles and less
temperature and humidity swing). Furthermore, due to the fewer
compressor cycles, it can achieve the higher reliability performance. To explore the reason in detail, Fig. 12 shows the two
capacity operation illustration as compared with the single speed
air conditioners. The illustrations show profiles of various parameters, such as the high stage capacity, low stage capacity, energy
efficiency ratio (EER) or COP, and the single speed capacity. All
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
60000
122
26
Single speed capacity
High stage capacity
Energy efficiency ratio (Btu h-1W-1)
Cooling capacity (Btu h-1)
Loading
High stage
continuous
Cycling between
high& low stage
Low stage capacity
Cycling on
low stage
High frequency
temp. range
75
T1
T2
High stage EER
T3
11
6000
Low stage EER
105
Ambient temperature (°F)
Fig. 12. Packaged two capacity air conditioner operation condition.
illustrations show the progress of the performance over a range of
the ambient temperatures. For the convenience of readers,
customers and manufactures, the English unit system is used other
than the International units. The magnitude of parameters is not
identified exactly at the axis, as the illustrations are meant to
merely facilitate the understanding of operation conditions of the
two capacity air conditioners.
As shown in Fig. 12, when the loading is at the low ambient
temperature zone (T1–T2), the low stage capacity is utilized for
cycling; while for the single speed air conditioner, the capacity
used is much higher than the low stage capacity and the excessive
cooling capacity (shaded area in the figure) is wasted. When the
loading is in the temperature ozone from T2 to T3, which is the high
frequency temperature range, the two capacity air conditioner unit
is cycling between the high stage and low stage. If the rough
assumption is made that two capacity air conditioner unit cycling
in such temperature ozone matches the loading well, the shaded
area indicates the excessive cooling capacity is wasted for the single speed air conditioner operation. As to the ambient temperature
zone above T3, the two capacity unit operates at the continuous
high stage, which is close to the operation of single speed air
conditioner. In general, the shaded areas show the wasted cooling
capacity for single speed air conditioner (high frequency temperature range: T2–T3), which indicates that excessive CO2-eq.
emissions could be produced as compared with the two stage air
conditioner unit. Therefore, with a better match with the loadings,
the two capacity unit has lower CO2-eq. emissions as compared
with the single speed air conditioner unit.
supplied by the vapor compression cycle and furnace is supplied
by the gas combustion). The product of air conditioner only provides the cooling. It can be also observed that the 14 SEER R410A
air conditioner shows a slightly higher CO2-eq. emission than the
14 SEER R410A heat pump. This difference can be explained with
the refrigerant charge amount. For the ANSI/AHRI Standard
210/240 test, the refrigerant charge amount for heat pumps is usually a littler lower than that of the air conditioner because the heat
pump should meet both the cooling and heating rating test and the
charge amount cannot be large enough. While for air conditioners,
since it only provides cooling, the refrigerant charge amount can be
large enough to make the cooling capacity more satisfied. As a
result, for the CO2-eq. emission with cooling purpose, the slightly
lower refrigerant in heat pumps makes less contribution than that
of air conditioners. From Fig. 14, it can be observed that in cold
areas the heat pumps can achieve a 220% increase for CO2-eq.
emissions as compared with air conditioners, while furnace has a
710% high increase. While the increase can be reduced in hot areas
since the heating demand is decreased.
To reveal more details about the packaged air conditioners, the
micro-channel heat exchanger, which has been investigated by
researchers widely [18,19], is employed for most 14 SEER R410A
air conditioners. It can reduce the refrigerant charge and make
the system more efficient with uniform refrigerant flow line
distribution in the coil for better heat transfer. In addition, the high
efficient Trane unique outdoor unit spine fin coils (Fig. 15) are also
employed for better air-refrigerant heat transfer.
Material LCA results and discussion
Effect of air conditioner, furnace and heat pump for LCCP investigation
Air conditioner material composition
This section makes the comparison of the packaged air
conditioner, furnace and heat pump for CO2-eq. emissions. The
air conditioner and furnace have the same cooling capacity and
the furnace has the additional natural gas for backup heat output.
As shown in Fig. 13, from cold area to hot area, the cooling demand
increases while the backup heat decreases. It can also be found that
the heat pump shows larger emissions as compared with the air
conditioner, and the furnace shows the largest emissions,
especially in cold areas. The packaged heat pump product has been
systematically investigated by Li [17]. For the products of heat
pump and furnace, they include both the cooling (supplied by
vapor compression cycle) and heating sector (heat pump is
The material categories regarding the 3 Ton air conditioners are
shown in Fig. 16. The 13 SEER R22 air conditioner and the 13 SEER
R410A air conditioner are assumed to have the similar material
composition. It can be found that the carbon steel (47%),
aluminum (10%), ferrous (17%) are the main materials for the
13 SEER air conditioner unit. The 14 SEER air conditioner unit
has a 4% weight increase due to the increasing amount of 22 lbs
for the material of aluminum. The micro-channel heat exchanger,
which is mainly made of the aluminum and employed in the 14
SEER air conditioners, is the main contributor for material increase
of aluminum.
123
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
LCCP emissions per lifetime (kg CO2-eq.)
250000 CO -eq. emission composition:
2
225000
Cooling
3 Ton
HP heating Backup heat
200000
Boston, Massachusetts
13SEER R22 Air conditioner
13SEER R410A Air conditioner
14SEER R410A Air conditioner
14SEER R410A Heat pump
14SEER R410A Furnace
Richmond, Virginia
Phoenix, Arizona
175000
150000
125000
100000
75000
50000
25000
0
Packaged Product Type
Fig. 13. Effect of air conditioner, furnace and heat pump for LCCP investigation for energy demand.
CO2-eq. emission composition:
225000
Direct
3 Ton
13SEER R22 Air conditioner
13SEER R410A Air conditioner
14SEER R410A Air conditioner
14SEER R410A Heat pump
14SEER R410A Furnace
Indirect
200000
175000
Boston, Massachusetts
Richmond, Virginia
Phoenix, Arizona
+3%
+32%
150000
125000
100000
50000
25000
+100%
+330%
75000
+220%
+710%
LCCP emissions per lifetime (kg CO2-eq.)
250000
0
Packaged Product Type
Fig. 14. Effect of air conditioner, furnace and heat pump for LCCP investigation for direct and indirect emissions.
Outdoor coil
Fig. 15. Spin fin.
124
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
Acidification Potential (AP)
Material Composition
Carbon steel
Ferrous
Rubber
0
Stainless steel
Non-ferrous
Refrigerant
50
100
150
Aluminum
Compression molding
PWB electronics
Copper
Injecon molding
Wiring electronics
Carbon steel
Ferrous
Rubber
Stainless steel
Non-ferrous
Refrigerant
Copper
Injecon molding
Wiring electronics
13 SEER unit, BSL
13 SEER unit, BSL:1.94E+02 kg H+ moles-eq.
14 SEER unit, BSL+4%BSL
14 SEER unit, BSL-3%BSL
200
250
300
350
400
450
0%
20%
60%
80%
100%
Fig. 19. Air conditioner material AP distribution.
Fig. 16. Air conditioner material composition.
Global Warming Potential (GWP100)
Stainless steel
Non-ferrous
Refrigerant
40%
Acidification Potential (AP) Distribution
Unit Material Composition (lbs)
Carbon steel
Ferrous
Rubber
Aluminum
Compression molding
PWB electronics
Aluminum
Compression molding
PWB electronics
Eutrophication Potential (EP)
Copper
Injecon molding
Wiring electronics
Carbon steel
Ferrous
Rubber
Stainless steel
Non-ferrous
Refrigerant
Aluminum
Compression molding
PWB electronics
Copper
Injecon molding
Wiring electronics
13 SEER unit, BSL:6.8810E+02 kg CO2-eq.
13 SEER unit, BSL:9.53E-02 kg N-eq.
14 SEER unit, BSL+9%BSL
14 SEER unit, BSL+5%BSL
0%
20%
40%
60%
80%
100%
120%
Global Warming Potential (GWP100) Distribution
0%
20%
40%
60%
80%
100%
120%
Eutrophication Potential (EP) Distribution
Fig. 17. Air conditioner material GWP distribution.
Fig. 20. Air conditioner material EP distribution.
Ozone Depletion Potential (ODP)
Carbon steel
Ferrous
Rubber
Stainless steel
Non-ferrous
Refrigerant
Aluminum
Compression molding
PWB electronics
Copper
Injecon molding
Wiring electronics
13 SEER unit, BSL: 6.35E-06 kg CFC 11-eq.
14 SEER unit, BSL+11%BSL
0%
20%
40%
60%
80%
100%
120%
Ozone Depletion Potential (ODP) Distribution
Fig. 18. Air conditioner material ODP distribution.
Air conditioner material environmental performance metrics
Figs. 17–21 show the air conditioner material environmental
performance metrics. These figures can be helpful in understanding the overall results and in identifying hot-spots that drive the
environmental performance profile. Fig. 17 shows the GWP-also
known as the Product Carbon Footprint (PCF) – based on IPCC
2007 characterization data for a 100 year time horizon. It can be
found that 14 SEER unit shows a 9% increase due to the addition
of material of aluminum. It should be noted that here only the
material phase is performed for environmental performance
assessments, and the refrigerant leakage and recycle are not considered here since they are investigated in the LCCP. Fig. 18 shows
the ODP distribution. ODP is a measure of air emissions that contribute to the depletion of the stratospheric ozone layer.
Depletion of the ozone leads to higher levels of UVB ultraviolet rays
reaching the earth’s surface with detrimental effects on humans
and plants. Similarly, it can be found that the 14 SEER unit shows
approximately an 11% increase due to the addition of material of
aluminum. Fig. 19 shows the AP distribution, which is a measure
of emissions that cause acidifying effects to the environment. The
acidification potential is a measure of a molecule’s capacity to
increase the hydrogen ion (H+) concentration in the presence of
water, thus decreasing the pH value. Potential effects include fish
mortality, forest decline and the deterioration of building materials. The 14 SEER unit has a larger amount of aluminum than the
13 SEER unit. However, it has less amount of copper. The larger
amount of copper for the 13 SEER unit, which is mined in most sulfuric ones, is one of the main contribution for AP. Therefore, the 14
SEER unit shows approximately a 3% reduction due to the reduction of material of copper. Fig. 20 shows the EP distribution.
Eutrophication covers all potential impacts of excessively high
levels of macronutrients, the most important of which nitrogen
(N) and phosphorus (P). Nutrient enrichment may cause an undesirable shift in species composition and elevated biomass production in both the aquatic and terrestrial ecosystems. In the aquatic
ecosystems increased biomass production may lead to the
depressed oxygen levels, because of the additional consumption
of oxygen in the biomass decomposition. Similarly, the 14 SEER
unit shows approximately a 5% increase due to the reduction of
the material of aluminum. Fig. 20 shows the SFP distribution. SFP
is a measure of emissions of precursors that contribute to ground
level smog formation (mainly ozone O3), produced by the reaction
of VOC and carbon monoxide in the presence of nitrogen oxides
under the influence of UV light. Ground level ozone may be injurious to the human health and ecosystems and may also damage the
crops. It can be also made the conclusion that the 14 SEER unit
shows approximately a 7% increase due to the reduction of material of aluminum. In general, because of the addition of aluminum,
the material phase environmental performance may be decreased.
From the use phase with LCCP analysis, with the micro-channel
G. Li / Sustainable Energy Technologies and Assessments 11 (2015) 114–125
Smog Formation Potential (SFP)
Carbon steel
Ferrous
Rubber
Stainless steel
Non-ferrous
Refrigerant
Aluminum
Compression molding
PWB electronics
Copper
Injecon molding
Wiring electronics
13 SEER unit, BSL: 3.04E+01 kg O3-eq.
14 SEER unit, BSL+7%BSL
0%
20%
40%
60%
80%
100%
120%
Smog Formation Potential (SFP) Distribution
Fig. 21. Air conditioner material SFP distribution.
heat exchanger employed efficiently in the 14 SEER unit, the total
emissions during a product’s lifetime is decreased greatly.
Therefore, for a sustainable future for products in various applications, it is acceptable with proper material phase CO2-eq. emission
increase to decrease the total emissions during a product’s lifetime.
For future perspective, minimizing material use and CO2-eq. emissions and maximizing energy efficiency should have been considered in its entirety.
Conclusions
Comprehensive LCCP and material LCA investigations are
detailed from various influencing parameters for the packaged air
conditioners. Several conclusions are drawn as follows:
(1) The SEER rating for air conditioner systems performs a large
influence on lowering the CO2-eq. emissions. The 13 SEER
R410A has approximately a +3% CO2-eq. emission increase
when compared with the 13 SEER R22 in the area of
Richmond, which is mainly caused by the direct emission
of annual leakage of refrigerant. It can also be found that
the 14 SEER R410A depicts a 9% reduction. Possible explanation is that the new 14 SEER R410A adopts the more efficient
scroll compressor, and has the reasonable TXV setting, and
uniform refrigerant flow line distribution in the coil for better heat transfer.
(2) In general, for all three categories, when the climate is varied
from cold areas (such as Minneapolis and Boston) to hot
areas (such as Phoenix), the CO2-eq. emissions are increased.
Due to the comfortable weather itself, balmy area such as
Los Angeles, has the lowest emissions. Among the contributors for CO2-eq. emissions, the energy consumption accounts
for more than 70% of the total emissions, followed by the
emissions from the annual refrigerant leakage. Therefore,
more attentions should be paid for the energy efficiency
enhancements.
(3) When the energy consumption is decreased by 5%, 10% and
15% as compared with the baseline 14 SEER R410A, the corresponding LCCP is decreased by 4%, 8%, and 12%, respectively. Energy consumption, as the main LCCP contributor,
with reasonable and efficient COP strategies, can lead heavy
CO2-eq. emission reductions. The refrigerant recovery rate
has larger influence than the Cd on the CO2-eq. emission
reductions, especially in the cold areas. Basically, the two
capacity unit has the better comfort condition due to the
better load matching (few cycles and less temperature and
humidity swing). Furthermore, due to the fewer compressor
cycles, it can achieve the higher reliability performance.
125
Therefore, the 14 SEER two capacity air conditioner product
has approximately a 13% CO2-eq. emission reduction as
compared with the current 14 SEER R410A air conditioner
(single speed).
(4) The LCA investigation shows that the carbon steel (47%),
aluminum (10%), ferrous (17%) are the main materials
for 13 SEER air conditioner unit. The 14 SEER air conditioner
unit has a 4% weight increase due to the increasing amount
material of aluminum. The employing of the micro-channel
heat exchanger (as the evaporators), which is mainly made
of aluminum and employed in 14 SEER air conditioners, is
the main contributor for material increase of aluminum. In
general, most of the material phase environmental performance is decreased in the 14 SEER air conditioners due to
the addition of aluminum. For a sustainable future, minimizing the material use and CO2-eq. emissions and maximizing
the energy efficiency should have been considered in its
entirety.
Acknowledgments
No funding support. The author would like to express the deepest appreciation to Z. Li and P. Li for their endless love, support, and
encouragement during the uncertainty of career path.
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