Energy and Power Engineering, 2013, 5, 253-257
doi:10.4236/epe.2013.54B049 Published Online July 2013 (
Heat Pump Technology Applies on Air-conditioners
Impact on Electric Power
Kun Liu, Xiaoyan Zhou, Hailang He
School of Electrical Engineering, University of Southwest Jiaotong, Sichuan, China
Received March, 2013
In recent years, power grid has been experienced in difficult times that there is a shortage of demand load among market,
and more and more black out exited that bothered residents’ normal life. With the increment of energy consumption and
power load, this problem will be more serious without any feasible solutions . Besides, the air conditioning system is the
largest residential energy consumer. In this report, a GSHP air conditioning system has been illustrated and compared
with the conventio nal air conditioning system currently used in Chengdu, Sichuan province, China. The benefits of us-
ing the GSHP system are not only on cost saving, but also energy saving and eco-friendly.
Keywords: GSHP; Air Conditioning; Energy Saving; Cost Saving
1. Introduction
Heat pump technology has been widely used on different
fields in most western countries for a long time, such as
in Norway, the United States of America and so on, but
this technique is still fresh to Chengdu, China, especially
in air-conditioner industry, which has proven to be the
most electricity consume electronic among the lives of
local residents. The whole world is walking at a high
speed of energy consumption[1].In this article, the analy-
sis of the heat pump air-conditione rs will be talked about
to determine whether it is a better system for the resi-
dents, the power company. The main aims of this project
is to determine whether the heat pump air-conditioner
system can consume less electricity when compared with
the conventional air-conditioners used in Chengdu, in
this situation, electric refrigeration heating air condition-
ers. If it is, how much electricity can be saved and how
much money customers can save by heat pump air-con-
2. Background
As the electricity energy is one of the most important
parts of energy resources, it plays a critical role in peo-
ple’s living standard and productivity. As the Interna-
tional Energy Agency mentioned[2], it has come to a
very dangerous situation for the lack of energy resources.
Nowadays, there is a crisis of energy shortage in the
world, especially the shortage of power resources. Ac-
cording to the concerning material record by the State
Grid Corporation of China (SGCC)[3], there were more
than 21 main large cities in China experienced black-out
because of the restriction of power, on the other words,
the lack of electricity offered by the power company in
2003, where Chengdu was one of these cities. This action
did a serious negative impact on the residents “living
standard and enterprises’’ normal production. Due to the
electricity survey report 2009 from the Sichuan power
grid. This big client occupied about 35% to 40% of the
total residential electricity consumption[4]. So if there is
a better solution which could make the residential
air-conditioner system consumes less electricity, there
will be a gr eat help to red uce the b urden from power g rid,
and make a contribution to the highlighted energy saving
2.1. Electrical Consumption in Residents’ Life
In recent years, as residents’ living standards improved,
the increment of the income of urban and rural residents,
and the update and popularize of all kinds of household
appliances, there is a remarkable rise of electricity con-
sumption by residents living, so is the proportion of total
electricity consumption. In 2007, residents’ electricity
consumption in Sichuan is 16098.38 GW/h, occupied
13.7% of the whole society total power consumption[5],
where the consumption from urban residents was
9044.97 GW/h, account for 56.19% of the sums Reasons
that caused by the rapid increment of the residents’ en-
ergy consumption are various, such as the rapid increase
in population; the increase of the household’s income
Copyright © 2013 SciRes. EPE
and the larger ownership of the electronic equipment.
Among the equipment, the significant one that leading to
the swift growth of electricity consumption could be
sharply increase of ownership of the air-conditioners in
2.2. Results Gained by Air Conditioning Energy
Saving Actions in Chengdu
Since 2003, because of the rising intension condition of
power supply in China[3],the Chinese government
started to promote electrical demand side management
(DSM). In 2004, the National Development and Reform
Commission (NDRC) and the State Electricity Regula-
tory Commission (SERC) issued jointly <Guidance for
strengthen the power demand side management> to sup-
port DSM action. In 2007, General Office of the State
Council released <Notification abou t strictly ex ecutio n of
air-conditioning temperature control standard in public
buildings > ([2007] NO.42) to regulate air-conditioning
saving management.
Chengdu government and power grid worked together
to organize a series of actions on cooling load demand
side management in summer to control the cooling load.
In order to reduce the energy burden, Chengdu power
grid en couraged th eir customer s to choose a new style of
air-conditioners to save more electricity with lower elec-
tricity price, this may help avoiding the appearance of
black out. This action has acquired preliminary achieve-
ments by some commercial customers, but met limited
excitement with residential customers[4].
3. Theory
In this section, all theories and applications will be ex-
pounded specifically. And heat pumps air-conditioners
are considered to replace conventional air-conditioners in
order to reduce the consumption of the electricity in the
Sichuan power market, the reduction of the energy con-
sumption will not only contribute to protect the power
grid to avoid black out, but also bring a financial benefits
to those customers for their electricity bills.
Ground source heat pump systems are based on the
shallow geothermal of rock and earth mass, ground water
and surface water as resources for both heating and
cooling[6]. This is a new central air conditioning system
that depends on renewable resources for both heating and
cooling and can meet the achievement of “energy saving
and emission reduction”.
3.1. The Components and Features of GSHP
Ground source heat pumps are consisting of water-source
heat pump unit which can provide cooling or heating to
the buildings, a shallow geothermal heat exchanging
system and a central air conditioning system in the inte-
rior of the buildings. There are three types of GSHP due
to the different heat transfer medium, they are Ground
water heat pumps, Surface water heat pumps, and Buried
pipe Ground source heat pumps. Heat pump units can
also divide into two types by methods of operation,
screw heat pump units and water switch heat pump u nits.
In this project, air-conditioners are used for the central
air-conditioning system for the whole community, there-
fore screw heat pump units is more suitable than the
other one for cooling and heating[7]. This system fea-
tures characteristics as shown below[6]:
Ground source heat pump technology is a technol-
ogy with high efficiency energy saving, non-pollution,
and low cost of the operation which relies on shallow
geothermal resources for both cooling and heating. Not
only for air conditioning, can it also supp ly hot water for
residents living. It has been referred as the “Green air
conditioning technology” in the 21st Century. Currently,
there are two types of GSHP in air conditioning market,
they are grou nd wa ter technolo g y and bu r ied p ip e g rou nd
source technology.
Ground source heat pump has the ability to reduce
the emission of greenhouse gas sharply. As most of the
resources are coming from the underground soil when
the GSHP system generates heating in winter, less than
half resources are generated by electricity. Hence it can
be used instead of a heating boiler, so that there could be
approximately 70% of greenhouse gas emission reduced
for the environment. Moreover, there is no need for any
special geothermal field or geothermal water to apply for
the system, normal soil (over -3.5) can meet the tech-
nical operation conditions of GSHP. Meanwhile, it will
not pollute and deplete the underground wa ter.
GSHP uses renewable resources; there is no re-
source exhaustion problem for this technology.
High efficiency but low cost. For heating, the coef-
ficient of performance (COP) could reach at most of 5.0,
but this of the normal boiler is only between 0.7 and 0.9,
70% of energy can be saved and there is also about half
reduction of the operation cost. For cooling, the conven-
tional electrical refrigeration air-conditioners spend 40%
of energy more than GSHP, which could make the elec-
trical bill more expensive. Hence, there is an economical
benefit while using GSHP.
3.2. Economic Efficiency and Energy
Conservation of GSHP
Ground source heat pump can work together with
an energy storage device to realize propose of electricity
load shifting suggested by the power grid company. A
battery can store electricity during the off-peak time,
which is at a very low price compare with peak time. In
this situation, customers can save much money on elec-
Copyright © 2013 SciRes. EPE
K. LIU ET AL. 255
tricity bill and the power grid gets protected at the same
During the summer time, units can recover heat
from condenser by the heat recovery switch, heating liv-
ing water for free. Furthermore, the tropical island effect
can be avoided by not using the cooling tower for the
The COP of GSHP can be very high compared with
conventional air-conditioners. COP of GSHP for heating
can reach 5.0 at most and even achieve 6.0 for cooling,
where conventional system can only reach up to 3.5.The
method to calculate Coefficient of Perfo rmance[6]: COP =
Q / W,
Where Q: delivered heat; W: electricity consumption
of the heat pump. To determine the benefits that obtain
by a GSHP system could come after by following proc-
3.3. Previous GSHP Air-conditioning Case in
In 2005, Long Jin community had been selected to be the
first residential community to use the GSHP system for
the air-conditioning. Due to the limited conditions of
itself, only two buildings can apply for the GSHP central
air conditioning system. Residents in these two building s
can choose either GSHP system or conventional split
type air-conditioners.According to the feedback re-
port[8],customers received a 40% less electricity bill on
operation cost of GSHP compared with conventional
systems. Especially when the temperature was over 35,
the gap between these two systems became larger, up to
Overall, customers who chose Ground source heat
pump as air-conditioners saved 2424 (Yuan) than customers
who consisted using conventional air-conditioners for a
year. As the capital cost of GSHP air-conditioners is
8000 (Yuan) more than conventional air-conditioners, so
the GSHP’s customers recovery cost after 3 years and a
half.End-users can make this goal by changing their
electricity consumption patterns in several approaches
such as adjusting their air-conditioners level[9].
4. Figures and Tables
In this section, the operation cost of GSHP air-condi-
tioners and conventional spilt-type electric refrigeration
and heating air-conditioners will be discussed here. These
two systems should operate under all conditions below:
1) For the GSHP system, equipment will operate 90
days in summer (from mid-June to mid-September) and
60 days in winter (From mid-December to mid-Febru-
2) Air-conditioners will start to work at 11 am until 21
pm, ten hours working every day. This system should
continuo usly wor k ev en in the peak time; he nc e ther e is a
four-hour peak demand.
3) All system holds a full load operation rate at 0.6.
4) The utilization rate for summer and winter is 0.8
and 0.7 respectively.
The operation fee can be calcula t ed by this e quat io n:
Operation Cost = (L * P * T+ L * Ps * N) *D * O * U
Where, L represents power input load;
P represents the electricity price at peak time;
Ps represents the standard electricity price;
T represents the system working time at peak load;
N represents the rest operation time;
D represents the working days of system;
O represents the full load operatio n rate;
U represents the system utilization rate.
Referring to the running output of this programming,
we can get that operation fees in both summer and winter
for these two systems as shown in “Table 4.1”.
As shown above, it can be clearly seen that the annual
operation cost of conventional system is much expensive
than GSHP system, customers will spend 130,440 Yuan
(about 0.027 Yuan per square meter per day) more for
the conventional system every year.
Besides, The power input of the GSHP system is less
than 1000 kW, in this situations, the air conditioning
system only requires a 1000 KV transformer. But the
conventional system asks for more power to operate,
hence only one 1000 KV transformer is not satisfied the
maximum demand; therefore, there could be a big dif-
ference between the costs of the power supply system
and maintenance fees for these two systems.
From “Table 4.2”, it shows that for the power supply
system, for the initial investment of the GSHP system,
there will be 300,000 Yuan less than conventiona l system
for the power supply system; and in the following ten or
even twenty years, there will also b e 50,000 Yuan less in
maintenance cost each year.
The total cost of these two systems can be seen in
Table 4.3 ”. This cou ld be a distin ctly comparison be tween
GSHP system and conventional system.
The economic trend of these two systems can be seen
in “Figure 4.4”.
Table 4.1. Annual operation cost for both systems.
Annual Operation GSHP system Conventional system
Summer 241,520 342,900
Winter 209,630 238,690
Annual total cost (Yuan)451,150 581,590
Per square meters cost
(Yuan) 0.094 0.121
Copyright © 2013 SciRes. EPE
Table 4.2. Capital cost of air conditioning power supply
(Yuan) GHSP system Conventional system
1000KV transformer r equired 1 2
Cost of transformer 300,000 600,000
Maintenance fees(per year) 50,000 100,000
Capital cost saved 300,000
Maintenance cost saved 50,000
Table 4.3. Total cost for GSHP system and conventional
Cost items GSHP system Conventional system
Equipment capital cost 5,315,000 3,840,000
Power supply system
equipment cost 300,000 600,000
PS system maintenance
cost (per year) 50,000 100,000
Operation cost (per year) 451,150 581,690
In “Figure 4.4”, it can be seen that in the first five
years, the cost of GSHP is higher than conventional sys-
tem, but when both system work in the middle of the
fifth year, the GSHP system begins to show its’ own
economic advantage. Suggest both systems have 20 years
lifetime, customers who choose the GSHP system only
pay 14,783,000 Yuan in total, but customers still consist
using the conven tional air conditioning system will spend
more than 18,000,000 Yuan. With the latest survey for
the lifetime of split-type electric refrigeration and heating
air-conditioner is normally five to seven years. So after
this period of time the air-conditioners should be replac-
ing by new systems, this will cause a large increment of
the capital cost of conv entional system.
Besides, with the GSHP system, plenty of electricity
can be saved under the operation of this system when
compared with the conventional system. In this case, the
reduction of power demand from customers will decrease
the instability factor which could give a dangerous im-
pact on the power grid.
According to “Figure 4.5”, each year, there can be
more than 0.4425 GW/h energy consumption saved by
the GSHP system when compared with the currently
conventional system. Assuming run both systems for 20
years, there will be approximately 8.85 GW/h consump-
tion saving operating under the GSHP system. This sig-
nificant number will give a great help for Power Com-
pany to offer a stable network to the public.
5. Conclusions
This Article has suggested a newly GSHP technology
applied on the air conditioning system to replace the
conventional split-type electrical refrigeration and heat-
ing air-conditioners. For power grid, GSHP system can
reduce 0.4425 GW/h energy consumption every year,
leave totally 8.85 GW/h free electricity away in the mar-
ket in 20 years. Under the circumstances, it vigorously
protect the power grid, brings a more stable and reliable
power system for the market.
Figure 4.4. Economical effects of both systems in 20 years.
Figure 4.5. pow e r consumption of both systems.
6. Future Work
There is a system called “ice storage air conditioners”
existed in the market, but this technology does not have
the heating function, so would it become more efficien t if
it do have both heating and cooling functions in the fu-
ture? Whether this system can save more energy and cost
with a reliable and stable market?
That is what I want to go furthermore if I have more
time and resources.
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