Optimal method to achieve energy
efficiency in residential buildings in
different climate regions of China
Yuxin Wang
Master of Science Thesis
KTH School of Industrial Engineering and Management
Energy Technology EGI_2016-086 MSC
Division of Heating and Ventilation
SE-100 44 STOCKHOLM
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Master of Science Thesis EGI_2016-086 MSC
Optimal method to achieve energy efficiency
in residential buildings in different climate
regions of China
Yuxin Wang
Approved
Examiner
Supervisor
Jaime Arias Hurtado
Peter Kjaerboe
Commissioner
Contact person
Sammanfattning
Genom att energin är begränsad i världen och att byggsektorn kräver en mycket stor andel så är arbetet
att effektivisera i denna sektor ett av de viktigaste målen i denna bransch.
Syftet med detta arbete är att finna en bra, effektiv, och billig metod för att snabbt nå målet med
energieffektivitet för Kinas bostäder.
Beaktat att Kina är ett stort land indelas det i flera delar med olika klimat för att med större säkerhet nå
rätt. Ett typhus har antagits i beräkningarna för fem olika klimatzoner. Programmet Designbuilder har
använts och data för isolering och ventilation i ett basfall, ett fall med bättre skal d v s U-värden och ett
med värmeåtervinning diskuterats vilka tar längre tid att genomföra och kräver större investering men
ändå är lönsamma. Dessa kan förordas med statligt stöd.
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Abstract
Due to the energy shortage situation of the world and building sector occupies the most significant
particle of total energy consumption, promoting the energy efficiency in the buildings has become one
of the most urgent goals for energy develop the profession.
The purpose of this project is to look for the most reasonable method, which is efficient and can be
carried out in a short term with a lower investment, to reach the goal of energy efficiency in residential
buildings in China.
Considering that China is a vast territory country, the whole mainland is separated into five parts
according to the various climate types in order to research accurately. A base building has been modeled
in five climate zones at the same time. The software Designbuilder is used to simulate the base scenario,
the building envelope improved scenario and the HVAC system improved scenario. The final suggestion
is given according to the comparison of these three scenarios.
Besides, some other technologies have been given in the thesis. These methods would take a longer time
period or more investment, but still are good choices for residential buildings energy efficiency. They
should be promoted in the future by the government support.
Keywords
Energy efficiency, Residential buildings, Climate zones, Building envelope, HVAC
system, Energy consumption
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Table of Contents
Sammanfattning....................................................................................................................................... 2
Abstract ................................................................................................................................................... 3
Glossary of Terms.................................................................................................................................... 6
List of Tables ........................................................................................................................................... 7
List of Figures ......................................................................................................................................... 9
1
Introduction ..................................................................................................................................... 10
1.1
1.2
2
Background ...............................................................................................................................11
1.1.1
Current situation of building energy efficiency in China .........................................11
1.1.2
Regional areas.......................................................................................................... 12
1.1.3
Standard modelling selection ................................................................................... 14
1.1.4
Status of urban residential building energy consumption ........................................ 15
1.1.5
Status of heating energy consumption in northern urban area ................................. 18
Objectives ................................................................................................................................ 20
Methodology ................................................................................................................................... 20
2.1
The Standard Building ............................................................................................................. 20
2.2
Modelling................................................................................................................................. 22
2.3
Energy efficiency technologies ................................................................................................ 29
2.4
2.5
2.6
2.3.1
Introduction of energy efficiency technologies ....................................................... 29
2.3.2
Major research subjects ........................................................................................... 29
Sample cities ............................................................................................................................ 29
2.4.1
Selection of sample cities ........................................................................................ 29
2.4.2
Basic information of sample cities .......................................................................... 30
Base scenario ........................................................................................................................... 35
2.5.1
Changchun ............................................................................................................... 36
2.5.2
Beijing ..................................................................................................................... 37
2.5.3
Shanghai .................................................................................................................. 38
2.5.4
Guangzhou ............................................................................................................... 38
2.5.5
Kunming .................................................................................................................. 39
Envelope improved scenario.................................................................................................... 40
2.6.1
Changchun ............................................................................................................... 42
2.6.2
Beijing ..................................................................................................................... 43
2.6.3
Shanghai .................................................................................................................. 44
2.6.4
Guangzhou ............................................................................................................... 44
2.6.5
Kunming .................................................................................................................. 45
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2.6.6
2.7
3
Payback time............................................................................................................ 46
HVAC system improved scenario ............................................................................................ 48
2.7.1
Changchun ............................................................................................................... 48
2.7.2
Beijing ..................................................................................................................... 49
2.7.3
Shanghai .................................................................................................................. 50
2.7.4
Guangzhou ............................................................................................................... 50
2.7.5
Kunming .................................................................................................................. 51
Result .............................................................................................................................................. 52
3.1
Comparison of the same technologies in different cities ......................................................... 52
3.1.1
Envelope improved scenario.................................................................................... 52
3.1.2
HVAC system improved scenario ............................................................................ 53
3.2
Comparison of two technologies in the same city ................................................................... 54
3.3
Comprehensive comparison..................................................................................................... 56
4
Discussion ....................................................................................................................................... 57
5
Conclusion ...................................................................................................................................... 57
Bibliography .......................................................................................................................................... 59
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Glossary of Terms
GHG
Green House Gas
UNEP
United Nations Environment Programme
HVAC
Heating, Ventilating and Air Conditioning
tce
Tons of standard coal equivalent
EU
European Union
kgce
Kilogram of standard coal equivalence
CHP
Combine heat and power generation
DHW
Domestic Hot Water
VAV
Variable Air Volume
Yuan
Chinese Yuan, RMB
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List of Tables
TABLE 1-1 THE GRAPHIC SYMBOL OF FIGURE 1-1 .................................................................................................. 12
TABLE 1-2 AVERAGE TEMPERATURE OF DIFFERENT CLIMATE ZONES ...................................................................... 13
TABLE 1-3 THERMAL DESIGN REQUIREMENTS IN DIFFERENT REGIONS ................................................................... 14
TABLE 1-4 RESIDENTIAL BUILDING CATEGORIES DIVIDED BY FLOORS .................................................................... 14
TABLE 1-5 THE CHINESE PHASE OUT OF INCANDESCENT LAMP CIRCUIT DIAGRAM................................................. 17
TABLE 2-1 AREA RATIO OF WINDOWS TO WALLS ON DIFFERENT DIRECTIONS ......................................................... 21
TABLE 2-2 BASIC INFORMATION OF THE WALL OF THE STANDARD BUILDING ......................................................... 24
TABLE 2-3 DETAILS OF 200MM CONCRETE WALL ................................................................................................... 24
TABLE 2-4 DETAILS OF THE WINDOWS IN THE STANDARD BUILDING ...................................................................... 26
TABLE 2-5 THE SCHEDULE OF LIGHT SYSTEM ........................................................................................................ 26
TABLE 2-6 DESIGN INDOOR TEMPERATURE IN HEATING CASE ................................................................................ 27
TABLE 2-7 DESIGN PARAMETERS OF INDOOR CLIMATE IN COOLING CASE .............................................................. 27
TABLE 2-8 PARAMETERS OF STANDARD BUILDING................................................................................................. 28
TABLE 2-9 SAMPLE CITIES ..................................................................................................................................... 29
TABLE 2-10 CLIMATE OF CHANGCHUN .................................................................................................................. 31
TABLE 2-11 CLIMATE OF BEIJING........................................................................................................................... 32
TABLE 2-12 CLIMATE OF SHANGHAI ...................................................................................................................... 33
TABLE 2-13 GUANGZHOU CLIMATE ....................................................................................................................... 34
TABLE 2-14 KUNMING CLIMATE ............................................................................................................................ 35
TABLE 2-15 CALCULATED VALUES OF EXISTING WALL ........................................................................................... 36
TABLE 2-16 TOTAL ENERGY CONSUMPTION OF CHANGCHUN – BASE SCENARIO .................................................... 37
TABLE 2-17 ENERGY CONSUMPTION BY CATEGORIES OF CHANGCHUN – BASE SCENARIO ...................................... 37
TABLE 2-18 TOTAL ENERGY CONSUMPTION OF BEIJING – BASE SCENARIO............................................................. 37
TABLE 2-19 ENERGY CONSUMPTION BY CATEGORIES OF BEIJING – BASE SCENARIO .............................................. 38
TABLE 2-20 TOTAL ENERGY CONSUMPTION OF SHANGHAI – BASE SCENARIO ........................................................ 38
TABLE 2-21 ENERGY CONSUMPTION BY CATEGORIES OF SHANGHAI – BASE SCENARIO .......................................... 38
TABLE 2-22 TOTAL ENERGY CONSUMPTION OF GUANGZHOU – BASE SCENARIO .................................................... 39
TABLE 2-23 ENERGY CONSUMPTION BY CATEGORIES OF GUANGZHOU – BASE SCENARIO ...................................... 39
TABLE 2-24 TOTAL ENERGY CONSUMPTION OF KUNMING – BASE SCENARIO ......................................................... 39
TABLE 2-25 ENERGY CONSUMPTION BY CATEGORIES OF KUNMING – BASE SCENARIO ........................................... 40
TABLE 2-26 TYPICAL PHYSICAL PROPERTIES OF XPS ............................................................................................. 41
TABLE 2-27 THE PERFORMANCE OF IMPROVED EXTERNAL WALL ........................................................................... 42
TABLE 2-28 TOTAL ENERGY CONSUMPTION OF CHANGCHUN – ENVELOPE IMPROVED SCENARIO .......................... 42
TABLE 2-29 ENERGY CONSUMPTION BY CATEGORIES OF CHANGCHUN.................................................................. 43
TABLE 2-30 TOTAL ENERGY CONSUMPTION OF BEIJING – ENVELOPE IMPROVED SCENARIO .................................. 43
TABLE 2-31 ENERGY CONSUMPTION BY CATEGORIES OF BEIJING .......................................................................... 43
TABLE 2-32 TOTAL ENERGY CONSUMPTION OF SHANGHAI – ENVELOPE IMPROVED SCENARIO .............................. 44
TABLE 2-33 ENERGY CONSUMPTION BY CATEGORIES OF SHANGHAI ..................................................................... 44
TABLE 2-34 TOTAL ENERGY CONSUMPTION OF GUANGZHOU – ENVELOPE IMPROVED SCENARIO .......................... 44
TABLE 2-35 ENERGY CONSUMPTION BY CATEGORIES OF GUANGZHOU.................................................................. 45
TABLE 2-36 TOTAL ENERGY CONSUMPTION OF KUNMING – ENVELOPE IMPROVED SCENARIO ............................... 45
TABLE 2-37 ENERGY CONSUMPTION BY CATEGORIES OF KUNMING ...................................................................... 45
TABLE 2-38 THE COST OF INSTALLING XPS INSULATION ....................................................................................... 46
TABLE 2-39 THE PRICE OF RESIDENTIAL ELECTRICITY IN CHANGCHUN ................................................................. 47
TABLE 2-40 THE PRICE OF RESIDENTIAL ELECTRICITY IN BEIJING .......................................................................... 47
TABLE 2-41 THE PRICE OF RESIDENTIAL ELECTRICITY IN SHANGHAI ..................................................................... 47
TABLE 2-42 THE PRICE OF RESIDENTIAL ELECTRICITY IN GUANGZHOU ................................................................. 47
TABLE 2-43 THE PRICE OF RESIDENTIAL ELECTRICITY IN KUNMING ...................................................................... 47
TABLE 2-44 THE PAYBACK TIME OF EACH DWELLING ............................................................................................ 48
TABLE 2-45 TOTAL ENERGY CONSUMPTION OF CHANGCHUN – HVAC IMPROVED SCENARIO ................................ 48
TABLE 2-46 ENERGY CONSUMPTION BY CATEGORIES OF CHANGCHUN – HVAC IMPROVED SCENARIO .................. 49
TABLE 2-47 TOTAL ENERGY CONSUMPTION OF BEIJING – HVAC IMPROVED SCENARIO......................................... 49
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TABLE 2-48 ENERGY CONSUMPTION BY CATEGORIES OF BEIJING – HVAC IMPROVED SCENARIO .......................... 49
TABLE 2-49 TOTAL ENERGY CONSUMPTION OF SHANGHAI – HVAC IMPROVED SCENARIO .................................... 50
TABLE 2-50 ENERGY CONSUMPTION BY CATEGORIES OF SHANGHAI – HVAC IMPROVED SCENARIO ...................... 50
TABLE 2-51 TOTAL ENERGY CONSUMPTION OF GUANGZHOU – HVAC IMPROVED SCENARIO ................................ 50
TABLE 2-52 ENERGY CONSUMPTION BY CATEGORIES OF GUANGZHOU – HVAC IMPROVED SCENARIO .................. 51
TABLE 2-53 TOTAL ENERGY CONSUMPTION OF KUNMING – HVAC IMPROVED SCENARIO ..................................... 51
TABLE 2-54 ENERGY CONSUMPTION BY CATEGORIES OF KUNMING – HVAC IMPROVED SCENARIO ....................... 51
TABLE 3-1 ENERGY SAVING IN THE ENVELOPE IMPROVED SCENARIO .................................................................... 52
TABLE 3-2 ENERGY SAVING IN THE HVAC IMPROVED SCENARIO ........................................................................... 53
TABLE 3-3 ENERGY SAVING DIFFERENCE BY TWO METHODS .................................................................................. 55
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List of Figures
FIGURE 1-1 TOTAL ENERGY CONSUMPTION OF THE WORLD IN 2014 ..................................................................... 10
FIGURE 1-2 CHINA CLIMATE ZONES MAP .............................................................................................................. 13
FIGURE 2-1 SCHEME OF METHODOLOGY ................................................................................................................ 20
FIGURE 2-2 LAYOUT PLAN OF MODEL DWELLING ................................................................................................... 21
FIGURE 2-3 BUILDING OUTLOOK ............................................................................................................................ 22
FIGURE 2-4 BUILDING BLOCK ................................................................................................................................ 23
FIGURE 2-5 BUILDING BLOCK – TOP VIEW ............................................................................................................ 23
FIGURE 2-6 STRUCTURE OF 200MM CONCRETE WALL ............................................................................................ 25
FIGURE 2-7 CONDENSATION ANALYSIS OF 200MM CONCRETE WALL ...................................................................... 25
FIGURE 2-8 SAMPLE CITIES ................................................................................................................................... 30
FIGURE 2-9 STRUCTURE OF EXISTING EXTERNAL WALL ......................................................................................... 35
FIGURE 2-10 XPS EXTRUDED POLYSTYRENE ......................................................................................................... 40
FIGURE 2-11 IMPROVED EXTERNAL WALL .............................................................................................................. 41
FIGURE 3-1 COMPARISON OF DIFFERENT CITIES – ENVELOPE IMPROVED SCENARIO ............................................... 53
FIGURE 3-2 COMPARISON OF DIFFERENT CITIES – HVAC IMPROVED SCENARIO ..................................................... 54
FIGURE 3-3 ENERGY CONSUMPTION IN DIFFERENT CITIES ..................................................................................... 55
FIGURE 3-4 THE PERCENTAGE OF ENERGY SAVED BY TWO SCENARIO ..................................................................... 56
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1 Introduction
With the social development and the improvement of science technology, energy consumption
increasing sharply in order to meet the requirement of human comfortable. Besides, the building sector
occupies the most significant part of total energy consumption. At the same time, the building sector is
the largest contributor to global GHG emission (United Nations Environment Programme, 2016). The
data collected by UNEP shows that buildings use about 40% of global energy, 25% of global water, 40%
of global resources, and they emit approximately 1/3 of GHG emissions (United Nations Environment
Programme, 2016). Therefore, achieving energy efficiency in existing buildings has become one of the
most urgent task for the world, especially for the energy workers.
The map below (Enerdata Offices, 2015) shows the total energy consumption all over the world,
Figure 1-1 Total Energy Consumption of the World in 2014
From the figure, reducing energy consumption in China is an urgent goal. (Enerdata Offices, 2015) The
Chinese government has already made policies formulating and implementing the green building action
plan, promoting the building energy efficiency from planning, regulations, technologies, standards,
designs and other aspects. According to the 12th Five-Year Plan, which was made in 2011, new buildings
should implementation of building energy efficiency standards strictly, and the standard implementation
rate should be improved. Advancing in existing residential heat metering system and energy-saving
renovation in north China, coming into force the energy saving greenhouse engineering, transforming
the old heat supply networks, implementing heat metering charging and carrying out energy
consumption quota management. Encouraging retrofitting existing residential buildings in the hotsummer and cold-winter area. To promote renewable energy and building integrated application, extend
the use of new energy-saving building materials and recycled building materials, continue expanding
bulk cement. To strengthen the construction of public building energy efficiency supervision system,
consummate the energy audit, energy efficiency publicity, motivate energy efficiency reform and
operation management. Study on the construction and use of life cycle management system, strict the
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management of building demolition. To strengthen the city lighting management, strictly prevent and
correct the excessive decoration and lighting. (The Central People's Government of the People's
Republic of China, 2011)
Comparing with the EU countries, they propounded a series policy during 2003 to 2003 such as The
European Energy Performance of Buildings Directive (EPBD)(2002), Intelligent Energy - Europe
(IEE)(2003), etc. China was focusing on measurement management, while new goals are better to set as
improving the energy efficiency technology.
To achieving the goal of reducing the building energy consumption, various types of methods, such as
using heat pumps or improving the HVAC systems, can be used. While, not all methods need to be used
at the same time. There would have an optimization choice or a terrific combination can be found for
buildings. The reduction of energy use in the built environment through optimizing building energy
efficiency is a strategic research challenge (Chwieduk, 2003). This thesis is dealing with a standard
model of a Chinese building and focus on finding out a top selection by scientific analyzation and
consultant.
1.1 Background
1.1.1 Current situation of building energy efficiency in China
Sustainability is comprehensive therefore a complex subject (Ragheb, El-Shimy, & Ragheb, 2015).
Achieving energy efficiency is an important step of promoting a sustainable world. As one of the largest
countries, which have a great number of buildings, China has already recognized that some
improvement measures should be introduced to cut down the energy consumption, which is caused by
buildings. The process of promoting energy-saving technology has become one of the most crucial
technologies in China. Hence, China has been developing and improving building energy efficiency
policies since 1980’s (Shui & Li, 2012).
In 2011, the total energy consumption in China was 3.75 billion tce (National Bureau of Statistics of the
People's Republic of China, 2014), and the total building energy consumption (except for biomass
energy) is 0.756 billion tce (Building Energy Conservation Research Center, 2015). Thus, building
sector contributes 19.5% of total energy consumption in China.
According to Chinese government documents, by 2015, the implementation rate of new green buildings
in the urban area should achieve to 20%, the area of new green buildings is suggested reach 300 million
square meters, completed 300 million square meters of existing residential building heating metering in
northern area (General Office of the State Council, 2014).
Among all branches of energy consumption, the intensity of heating energy consumption in northern
cities and towns is relatively large. To improve the heating system would be the dominating measure to
achieve building energy efficiency in northern heating region consequently. In 2013, energy
consumption of heating in northern cities and towns was 0.181 billion tce, occupied 24.0% of total
building energy consumption (Building Energy Conservation Research Center, 2015). During 2001 to
2013, building area of the northern heating region has increased from 5 billion m2 to 12. The rate of
growth is 1.5 times while the heating energy consumption rose less than one time (Building Energy
Conservation Research Center, 2015). The main reasons of the energy consumption reduction are the
improvement of building envelope insulation, the rapid increase of the proportion of efficient heat source
application, and the amelioration of heating system. Although China has already made a great progress
in northern heating energy efficiency, the increase of energy consumption significantly lower than
residential gross floor area, China still need to continue improving measures and policies in order to
pushing against a better result.
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Excluding heating energy consumption in northern district, total residential building energy
consumption in China 2013 is 0.185 billion tce, separated energy using terminals as air conditioning
systems, household electric appliances, hot tap water and etc. the average growth of household energy
consumption intensity approximately 50% since 2001 (Building Energy Conservation Research Center,
2015). With the improvement of people’s living standard, the requirement on living comfortable is
becoming higher and higher. Some districts who are located along Yangtze River basin and even
southern starts to use heating devices to get a warmer indoor climate.
1.1.2 Regional areas
China is a vast territory country, 9.6 million square kilometres land covering a variety of climate zones.
To simplify the research work, the Chinese government made a code separate total landing area into
different regions and define them.
Building climate zoning system in China is divided into two levels: primary level division is divided
into five categories, and the secondary division is divided into 20 areas (Ministry of Construction of the
People's Republic of China, 1993). The main indexes are the average temperature in January and July,
and the average relative humidity on July. The auxiliary indexes are annual precipitation, the number of
days of the daily average temperature lower than or equal to 5 ℃ and the number of days of the daily
average temperature higher than or equal to 25 ℃.
Figure 1-1 shows the climate zones system in China (China Architecture Design & Research
Group(CAG), 2005). Table 1-1 below is the Graphic symbol of Figure 1-2
Table 1-1 the graphic symbol of Figure 1-1
Severe cold region
Cold region
Hot-summer and cold-winter region
Hot-summer and warm-winter region
Temperate region
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Figure 1-2 China Climate Zones Map
The average temperature of different climate zones in January and July can be found in Table 1-2 below.
The data is collected from Standard of climatic regionalization for architecture, which was published
by the ministry of construction of the People’s Republic of China in 1993.
Table 1-2 average temperature of different climate zones
Regions
Average temperature (℃)
January
July
Severe cold region
≤ -10
≤ 25
Cold region
-10 ~ 0
18 ~ 28
Hot-summer and cold-winter region
0 ~ 10
25 ~ 30
Hot-summer and warm-winter region
＞ 10
25 ~ 29
Temperate region
0 ~ 13
18 ~ 25
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Due to the different climate feature in different region, the requirements of heating and cooling has to
be considered separately according to regions, as shown in the table below (Ministry of Construction of
the People's Republic of China, 1993), when design or transformation of construction.
Table 1-3 Thermal design requirements in different regions
Regions
Requirement for winter heating
Requirement for summer cooling
Severe cold
Have to be fully considered
Do not have to be considered
Cold
Need to be considered
Proper consider in partial area
Hot-summer & cold-winter
Proper consider
Need to be considered
Hot-summer & warmwinter
Do not have to be considered
Have to be fully considered
Temperate
Do not have to be considered
Proper consider in partial area
1.1.3 Standard modelling selection
During the year of 2001 to 2013, a plenty of people relocate to urban areas from rural areas, urbanization
rate grows from 37.7% to 53.7% (National Bureau of Statistics of the People's Republic of China, 2014).
The rapid urbanization lead to the uprush of urban residential floor area, because of the shortage of urban
land area per capita, the urban residential building has become one of the most extensive architectural
forms. Thus, as the most commonly urban residential building, the department has been chosen as the
pilot building style.
The residential buildings can be divided into 4 categories according to the floors, as shown in the
following table (Ministry of housing and urban & rural development of the people's Republic of China,
2011).
Table 1-4 residential building categories divided by floors
Name
Number of layers
Low layer buildings
1~3
Multilayer buildings
4~6
Upper layer buildings
7~9
Top layer buildings
10 and above
Although those better-developed cities like Beijing, Shanghai, Guangzhou and etc. have lots of top layer
buildings, the sort of multilayer still are the most commonly residential buildings in China.
The building specifications have clear regulation in relative codes. For each dwelling unit, which
composed of a bedroom(s), living room (hall), kitchen and bathroom, its size should not be less than
30m2, the story height of residential buildings is appropriate 2.8m (Ministry of housing and urban &
rural development of the people's Republic of China, 2011), besides, Chinese residential buildings
always composed of 4 units which have 2 families on each floor per unit. Since the average residential
area per person in China is approximately 30 m2, and the average number of persons per household in
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China is 3.35 (National Health and Family Planning Commission, 2015), the area of each dwelling
should be around 100m2.
According to the data above, the standard building, which would be used for modelling is a 6-floor
apartment building that has 8 families, which can be separated into 4 units, on each floor. On the basis
of Chinese building habits, the apartment would be located on north and south direction.
The area of each dwelling is 105.48m2, the length on north and south direction of each dwelling is 10.4m,
and the length on east and west direction is 12.6m.
1.1.4 Status of urban residential building energy consumption
The data collected by building energy conservation research Centre of Tsinghua University shows the
trend of urban residential building energy consumption during 1996 to 2011 (Building Energy
Conservation Research Center, Tsinghua University, 2013),
Urban residential building energy
consumption(billion tce)
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Year
Figure 1-3 Yearly changing of urban residential building energy consumption
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Urban residential building energy
consumption per household except for
district heating, kgce/(household*year
700
600
500
400
300
200
100
0
1996199719981999200020012002200320042005200620072008200920102011
Year
Figure 1-4 Trend of urban residential building energy consumption per household except
for district heating
The energy consumption was more or less steady during 1996 to 2000, With China's sustained rapid
economic development and the increasing residents income, the living standard of residents improve
gradually, the ownership rate and usage rate of various types of home appliances increased substantially.
Besides, energy using patterns of residents in China has changed as well. Various reasons leading the
energy consumption surged.
The totally urban building energy consumption can be divided into six main sections as district heating,
air conditioning, household electric appliances, domestic hot water, cooking, and lighting.
1.1.4.1
District heating
District heating part would be discussed in detail afterward.
1.1.4.2
Air conditioning
Citizens always use air conditioners for cooling in summer, and some of the people living in south China
use air conditioners to warm the room in winter. The appliances like radiant heaters, electric oil heaters,
electric heating boxes and electric blankets always are used to warm in south China as well.
At present, the prevalence rate of air conditioning in the urban residential building is very high. While
fission air conditioning is locating in the dominant position in China, household central air conditioning
still needs to be expanded. The prevalence of household central air conditioner is no higher than 5%,
even in the new high-grade residential building in Beijing (Building Energy Conservation Research
Center, Tsinghua University, 2013). The totally residential electric consumption on the air conditioner
is 52.0 billion kWh, amount to 16.03 million tce, accounting for 10.4% of total residential energy
consumption in 2011 (Building Energy Conservation Research Center, Tsinghua University, 2013).
1.1.4.3
Household electric appliances
The total electric appliances consume 110.6 billion kWh of electric, amount to 34.07 million tce,
accounting for 22.2% of total residential energy consumption in 2011 (Building Energy Conservation
Research Center, Tsinghua University, 2013).
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1.1.4.4
Household hot water
The main types of water heater are electric water heater and gas water heater, district heating and solar
water heater are auxiliary types. The energy consumption of water heater is around 14.53 million tce in
2011, accounting for 9.5% of total energy consumption (Building Energy Conservation Research Center,
Tsinghua University, 2013).
1.1.4.5
Cooking
The energy consumption of cooking is 47.7 million tce in 2011, accounting for 31.1% of total energy
consumption (Building Energy Conservation Research Center, Tsinghua University, 2013).
1.1.4.6
Lighting
The energy consumption of lighting is 92.2 billion kWh, amount of 28.4 million tce, accounting for 18.5%
of total energy consumption (Building Energy Conservation Research Center, Tsinghua University,
2013). Improving the energy efficiency is an effective method to reduce the energy consumption in
China because the lighting efficiency still has a large space can be increased.
The National Development and Reform Commission & the Ministry of Commerce & the General
Administration of customs & the State Administration for Industry and commerce & the State
Administration of quality supervision & General Administration of China issued the Chinese phase out
of incandescent lamp circuit diagram jointly on November 11th in 2011.
Table 1-5 The Chinese phase out of incandescent lamp circuit diagram
Phase
Term
Target product
Rated
power
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Implement
Comment
1
11-01-2011
to 09-302012
2
Since 10-012012
Gradual
incandescent
lamps
≥
100W
Ban the
import and
sale
--
3
Since 10-012014
Gradual
incandescent
lamps
≥60W
Ban the
import and
sale
--
4
10-01-2015
to 09-302016
5
10-01-2016
Publish the
announcement and
circuit diagram
Transition period
Mid-term evaluation and follow-up policy adjustment
Gradual
incandescent
lamps
≥15W
Ban the
import and
sale
The eventually banned
goal products and time,
and whether it is
prohibited to produce
depends on mid-term
evaluation result
The Chinese phase out of incandescent lamp circuit diagram (The National Development and Reform
Commission & the Ministry of Commerce & the General Administration of customs & the State
Administration for Industry and commerce & the State Administration of quality supervision & General
Administration of China, 2011) plays an important role of controlling the electric consumption on
lighting part.
1.1.5 Status of heating energy consumption in northern urban area
Energy consumption in the northern region is relatively large, accounting for more than 40% of the total
urban construction energy consumption (Shui & Li, 2012). The large proportion of the energy
consumption in this branch is because of the usage of district heating system.
Due to the coal-based energy in China, combined heat and power generation and coil fired boiler
dominance the heating resources. Meanwhile, the clean energy has becoming more and more because
of the national policy. The urban heat source proportion is showed as below (Lin, 2014).
-18-
Gas boiler Others
2%
8%
CHP
42%
CHP
Coil fired boiling
Coil fired boiling
48%
Gas boiler
Others
Figure 1-5 Proportion of Heating Resources
The form and proportion of various heat sources in typical cities can be described by the bar graph
below (Building Energy Conservation Research Center, 2015).
100%
90%
80%
Others
70%
Industrial Waste Heating
60%
Gas Heating
50%
40%
Scattered small coal-fired boiler
30%
District coal fired heating
20%
CHP
10%
0%
Figure 1-6 Proportion of Various Heating Sources in Typical Cities
The most seriously polluted heating form, coal-fired heating still dominate a large proportion of Chinese
heating style, hence, this phenomenon can become one of the breaches to solving the problem of energy
efficiency in North China.
-19-
1.2 Objectives
Due to the atmosphere that is getting worse in China, and the building energy consumption contributes
to the total energy consumption a lot. Looking forward to the approach to achieve building energy
efficiency has become one of the most important industries in China nowadays. However, applying all
of the existing methods in constructions in not only unreliable but also uneconomical. The objective of
this project is to find out the optimal method or combined approaches to achieve the goal of building
energy efficiency in different regions of China.
Obviously, optimal choices of different regions are related to the climate, economical level, living habit
of inhabitants and so on. Thus, a standard building would be set and be modelled in different regions
separately.
2 Methodology
In order to make sure the difference of energy efficiency between areas, the history data would be
collected to work out the status of energy consumption, then figure out energy efficiency scheme and be
compared side by side.
During the whole process, the software Designbuilder would be used to set up building modelling and
energy analyzation.
The steps by the whole process should be as below:
Step 1
Set up the standard building
Step 2
Building the modeling in Designbuilder
Step 3
Concluding common means of energy efficiency
Step 4
Select sample cities in different areas
Step 5
collecting data of energy consuption in sample cities
Step 6
Simulation the base senario in Designbuilder
Step 7
Simulation the energy efficiency senario in Designbuilder
Step 8
Result
Figure 2-1 Scheme of methodology
2.1 The Standard Building
According to the chapter 1, the area of each dwelling is 105.48m2, the length on north and south direction
of each dwelling is 10.4m, and the length on east and west direction is 12.6m.
-20-
Figure 2-2 Layout plan of model dwelling
The standard building, which would be used for modelling is a 6-layer apartment building that has 8
families, which can be separated into 4 units, on each floor. Due to the story height of residential
buildings is appropriate 2.8m (Ministry of housing and urban & rural development of the people's
Republic of China, 2011), the additional value of cooling and heating load should be calculated when
the height of the layer is more than 3.0m (Ministry of Construction of the People's Republic of China,
1993). The height of each layer of standard building is designed as 3.0m. On the basis of Chinese
building habits, the apartment would be located on north and south direction.
For the area of windows, the standard GBT50176-1993 Thermal design code for civil building (Ministry
of housing and urban & rural development of the people's Republic of China, 2011) has the following
tips.
Table 2-1 Area ratio of windows to walls on different directions
Orientation
Area ratio of windows to walls
North
≤ 0.25
East & West
≤0.3
South
≤ 0.35
-21-
Thereby, the ratio of windows to walls on the standard building can be set to 0.25 on the north, east &
west and south separately. The average area ratio of windows to walls of the whole standard building is
0.25.
In previous years, residential buildings were always built by brick walls, and the thick of brick walls
were depends on where the building located in. 240mm thick brick walls are always be used in the
temperate region, the walls of server cold region are always 490mm, and 370mm walls can be found in
other area of China. While, since China has come to an energy efficiency age, the brick walls are going
out of sight step by step. In the new buildings, the most common external wall is the 200mm concrete
wall, which added by thermal insulation. Therefore, the 200mm concrete wall has been chosen as the
external wall of standard building, and the thermal insulation of external wall would be added in the
energy efficiency scenario.
2.2 Modelling
According to the basic information, the standard building has been modelling in the software
Designbuilder, and the model can be shown as below.
In the figures, each zone represents a dwelling. On each floor, zone 1 and zone 2 has external walls on
three directions (zone 1 has external walls on the north, south, and east, while zone 2 has external walls
on the north, south, and west), and zone 3 to 8 has external walls on two directions (the north and south).
Besides, the block 1 is the ground floor and the block 6 is the top floor.
Figure 2-3 Building outlook
-22-
Figure 2-4 Building Block
Figure 2-5 Building Block – Top View
As mentioned before, the wall of the building is always 200mm concrete wall and then consider adding
external insulation in China, thus the wall of the standard building is assume as 200mm concrete wall
in the case, the details of the wall has been described as below.
-23-
Table 2-2 Basic information of the wall of the standard building
Table 2-3 Details of 200mm concrete wall
-24-
Figure 2-6 Structure of 200mm concrete
wall
Figure 2-7 Condensation analysis of
200mm concrete wall
Considering that most of the windows in China now are double glazed windows. In this case, the
windows are selected as double glazed as well. The proportion of the windows has been set as 25% of
walls. Details of the windows are shown in the next table,
-25-
Table 2-4 Details of the windows in the standard building
The lighting system is working following the schedule below.
Table 2-5 The Schedule of light system
-26-
Since the area of each dwelling is 105.48 m2, and the average number of persons per household in China
is 3.35 (National Health and Family Planning Commission, 2015), the density of occupancy should be
set as 0.03176 people/m2 in the Designbuilder. Considering people always go to work or school at
daytime, only stay at home to relax at home and only few time is used to clean the room or do some
other light work, the activity in the room is set as seated quiet. Due to almost every family is consisting
of man and women, some families have children, the metabolic factor is set to 0.9. The winter clothing
and summer clothing are set to 1.00 and 0.50 separately.
For the DHW, the range of 25-70 l/person*day has been given in the Standard for water saving design
in civil building (Ministry of housing and urban & rural development of the people's Republic of China,
2010). Besides, the research showed that the DHW in China is always 20-30 l/person*day nowadays
(Estate Business of Sina, 2016), what’s more, as mentioned before, the average residential area per
person in China is approximately 30 m2, the DHW water is around 1 l/ m2 *day.
The design parameter of indoor climate should be following the tables below which are concluded from
Design code of heating ventilation and air conditioning of civil buildings (Ministry of housing and urban
& rural development of the people's Republic of China and General Administration of quality
supervision, inspection, and Quarantine of the people's Republic of China, 2012).
Table 2-6 Design indoor temperature in Heating case
Region
Design indoor temperature (℃)
Severe cold region & Cold region
18~24
Hot-summer and cold-winter region
16~22
Table 2-7 Design parameters of indoor climate in cooling case
Parameters
Winter case
Summer case
Level of indoor
climate comfortable
Temperature
Relative humidity
Wind velocity
(℃)
(%)
(m/s)
I
22~24
30~60
≤0.2
II
18~21
≤60
≤0.2
I
24~26
40~70
II
27~28
≤0.25
In order to fit the regular above, the heating set point temperature and the cooling set point temperature
is set to 18℃ and 24 ℃ separately. The relative humidity is set to 50%. The minimum fresh air of
residential building should be 10 m3/h*person (Ministry of housing and urban & rural development of
the people's Republic of China and General Administration of quality supervision, inspection, and
Quarantine of the people's Republic of China, 2012), which can be fill into the software as 2.78
l/(s,person). Thus, the parameters are set as the table below.
-27-
Table 2-8 Parameters of standard building
-28-
2.3 Energy efficiency technologies
2.3.1 Introduction of energy efficiency technologies
To reduce the energy consumption, many technologies can be used. These technologies always can be
sorted into the following facts,
•
•
•
•
•
HVAC, Water Heating, & Appliance
Windows & Building Envelope
Lighting
Sensors & Controls
Building to Grid
Technical analysis has shown that heat pumps have the technical potential to save up to 50% of the
energy used by conventional HVAC technologies in residential buildings. New-generation windows and
building envelope technologies have a substantial technical potential to reduce energy consumption in
buildings (Office of Energy Efficiency & Renewable Energy, 2016). LED is not only sufficiently but
also more efficiency compare to Incandescent, and installing daylight channelling is become a new way
to improve the lighting system. Sensors and controls can keep the system working in an efficiency way,
working when it is needed and stop working if the indoor climate has reached to a good status.
2.3.2 Major research subjects
The most popular technologies that be vigorously promoted in China is adding external insulation. At
the same time, the HVAC system is needs to be improved so far. Considering the target building is the
residential buildings, which means not that much of sensors and controls are working in this range, and
the power efficiency lightings has already be pushed well in China, improving envelopes and optimizing
the HVAC system would be two important factors to be considered and be compared in the project.
2.4 Sample cities
2.4.1 Selection of sample cities
According to the geographical position and the economic situation, five sample cities have been decided
as below:
Table 2-9 Sample cities
Regions
Sample city
Severe cold
Changchun
Cold
Beijing
Hot-summer & cold-winter
Shanghai
Hot-summer & warm-winter
Guangzhou
Temperate
Kunming
And the sample cities can be found in the following map.
-29-
Figure 2-8 Sample Cities
2.4.2 Basic information of sample cities
2.4.2.1
Changchun
Changchun is the capital of Jilin province, which located in the central part of Northeast area of China.
The longitude and latitude of Changchun are North latitude 43 ° 05 ' ~ 45 ° 15' and longitude 124 ° 18 '
~ 127 ° 05', which is covered by North temperate on mid-latitudes of North hemisphere (News China,
2006).
Changchun is located in the North temperate continental monsoon climate zone. In the national
discriminate of wet and dry climate zone, Changchun is located in the transition zone from the humid
area to the sub-arid area (Changchun government, 2016). The annual average temperature of Changchun
is 4.8℃, the highest temperature is 39.5℃ and the lowest temperature is -39.8℃, the average temperature
of the hottest month (July) is 23.1℃, the average temperature of coldest month (January) is -15.1℃.
The average annual rainfall is 522 to 615mm. (China Meteological Administration, 2016).
The details weather information of Changchun shows in the table below (China Meteological
Administration, 2016). The data in the table is collected between the years of 1971 to 2000.
-30-
Table 2-10 Climate of Changchun
Month
Average
Lower
Temperature
(℃)
Average
Temperature
(℃)
Average
Higher
Temperature
(℃)
Extreme
Maximum
Temperature
(℃)
Jan
-19.9
-15.1
-9.8
4.6
-33
3.2
Feb
-15.9
-10.7
-5.0
14.5
-28.1
4.5
Mar
-7.6
-2.0
3.5
19.5
-27.4
12.3
Apr
1.9
7.8
14.1
28.3
-12.2
21.9
May
9.3
15.2
21.4
35.2
-3.1
49.9
Jun
15.4
20.6
26.1
35.7
4.5
99.7
Jul
19.0
23.1
27.6
34.5
11.1
161.1
Aug
17.3
21.6
26.4
34.3
6.3
121.6
Sep
10.1
15.4
21.3
30.6
-1.4
51.9
Oct
1.9
7.0
12.9
27.8
-13.4
28.9
Nov
-7.8
-3.4
1.7
20.7
-24.7
10.3
Dec
-16.1
-11.7
-6.6
11.7
-31.0
5.0
2.4.2.2
Extreme
Minimum Precipitation
Temperature
(mm)
(℃)
Beijing
Beijing is the capital of China, located in the east longitude115.7° ~ 117.4°, north latitude 39.4° ~ 41.6°,
the centre point of Beijing is located in the east longitude 116°25′29″ and north latitude 39°54′20″, the
area of Beijing is 16410.54 square kilometre (Beijing government, 2016).
The climate of Beijing is a semi humid and sub-arid monsoon climate of warm temperate zone. The
annual average temperature of the plain area is 11 ~ 13 ℃, the annual average temperature of mountain
area which is located lower than 800 meters above the sea is 9 ~ 11 ℃, while the cold mountain area is
3 ~ 5 ℃. The annual extreme maximum temperature is general between 35 to 40 ℃, and the annual
extreme minimum temperature is general between -20 to -14 ℃. For the temperature of the hottest month
(July), the average temperature of the plain area is around 26℃, and 21 ~ 25 ℃ in the mountain area of
lower than 800 meters above the sea. The average temperature of the coldest month (January) of the
plain area is -5 ~ -4℃, and -10 ~ -6℃ in the mountain area of lower than 800 meters above the sea.
(China Meteological Administration, 2016)
-31-
The details weather information of Beijing shows in the table below (Baidu Baike, 2016).
Table 2-11 Climate of Beijing
Month
Average
Lower
Temperature
(℃)
Average
Temperature
(℃)
Average
Higher
Temperature
(℃)
Precipitation
(mm)
Annual
Sunshine
Hours (h)
Average
Humidity
(%)
Jan
-7.5
-3.1
2.0
2.7
189.0
43
Feb
-4.5
0.2
5.7
4.4
192.1
42
Mar
1.3
6.7
12.3
9.9
228.2
42
Apr
8.8
14.8
20.7
24.7
244.5
44
May
14.8
20.8
26.7
37.3
267.9
50
Jun
19.6
24.9
30.5
71.9
238.2
59
Jul
22.5
26.7
31.4
160.1
202.7
71
Aug
21.5
25.5
30.3
138.2
209.3
73
Sep
15.8
20.7
26.2
48.5
215.3
66
Oct
8.6
13.7
19.4
22.8
211.5
59
Nov
0.3
4.9
10.2
9.5
182.0
53
Dec
-5.2
-1.1
3.8
2.0
175.2
47
Annual
8.0
12.9
18.3
532.0
2555.9
54
2.4.2.3
Shanghai
Shanghai is locating in the east longitude 120°52′~ 122°12′, north latitude 30°40′ ~ 31°53′. The city is
standing on the west bank of the Pacific Ocean, east of the Asian continent. It is the centre point of
China's north and south coast. It is the confluence of the Yangtze River and the Huangpu River to the
sea as well. (Shanghai Government, 2016)
Shanghai's climate is subtropical monsoon climate. The annual average temperature of Shanghai is
15.7℃, the highest temperature is 40.6℃ and the lowest temperature is -12.1℃, the average temperature
of hottest month (July) is 27.8℃, the average temperature of coldest month (January) is 3.5℃.
(Shanghai Meteorological Service, 2016)
-32-
The details weather information of Shanghai shows in the table below (China Meteorological
Administration, 2015). The data in the table is collected between the years of 1971 to 2000.
Table 2-12 Climate of Shanghai
Month
Average
Lower
Temperature
(℃)
Average
Higher
Temperature
(℃)
Precipitation
(mm)
Annual
Sunshine
Hours (h)
Average
Humidity
(%)
Jan
1.1
8.1
50.6
123.0
75
Feb
2.2
9.2
56.8
115.7
74
Mar
5.6
12.8
98.8
126.0
76
Apr
10.9
19.1
89.3
156.1
76
May
16.1
24.1
102.3
173.5
76
Jun
20.8
27.6
169.6
147.6
82
Jul
25.0
31.8
156.3
217.8
82
Aug
24.9
31.3
157.9
220.8
81
Sep
20.6
27.2
137.3
158.9
78
Oct
15.1
22.6
62.5
160.8
75
Nov
9.0
17.0
46.2
146.6
74
Dec
3.0
11.1
37.1
147.7
73
Annual
12.9
20.2
1164.5
1894.5
76.8
2.4.2.4
Guangzhou
Guangzhou is the capital of Guangdong province, which is locating near to the most south area of China
mainland.
The geographical position of Guangdong is between east longitude 112°57′~ 114°3′ and north latitude
22°26′ ~ 23°56′. The city centre is located on the point of east longitude 113°15′53″ and north latitude
23°6′32″. (Guangzhou Government, 2016)
Guangzhou is located in the subtropical coastlines, the tropic of cancer crossing the city on the south
central part. The climate of Guangzhou belongs to a maritime monsoon climate of subtropical zone. The
annual average temperature is 20-22℃. Guangzhou is one of the cities, which has the smallest average
temperature difference in china. The hottest month of the year is July, with an average temperature of
28.7 ℃. The average temperature of the coldest month (January) is 9 ~16 ℃. The annual average relative
humidity is 77%, and the annual rainfall is about 1720 mm. (Guangzhou Government, 2016)
The details weather information of Guangzhou shows in the table below (China Meteological
Administration, 2016). The data in the table is collected between the years of 1971 to 2000.
-33-
Table 2-13 Guangzhou Climate
Month
Average
Lower
Temperature
(℃)
Average
Temperature
(℃)
Average
Higher
Temperature
(℃)
Extreme
Maximum
Temperature
(℃)
Jan
10.2
13.6
18.3
27.2
0.6
40.9
Feb
11.8
14.5
18.6
28.6
1.5
69.4
Mar
15.1
17.9
21.4
32.1
3.2
84.7
Apr
19.4
22.1
25.7
32.4
8.3
201.2
May
22.7
25.5
29.3
36.2
14.6
283.7
Jun
24.8
27.6
31.5
36.6
18.8
276.2
Jul
25.5
28.6
32.8
38.1
21.6
232.5
Aug
25.4
28.4
32.7
38.0
20.9
227.0
Sep
24.0
27.1
31.4
37.2
15.8
166.2
Oct
20.8
24.2
28.7
34.8
9.5
87.3
Nov
15.9
19.6
24.5
32.5
4.9
35.4
Dec
11.5
15.3
20.6
29.4
0.0
31.6
2.4.2.5
Extreme
Minimum Precipitation
Temperature
(mm)
(℃)
Kunming
Kunming is the capital of Yunnan province. The geographical position of Guangdong is between east
longitude 102°10′~ 103°40′ and north latitude 24°23′ ~ 26°22′. The centre point of the city is located on
the point of east longitude 102°42'31" and north latitude 25°02'11". (General Office of Kunming
Municipal People's Government, 2016)
The daily temperature difference is large while the annual temperature difference is small in Kunming.
The annual average temperature is around 15℃. The average temperature of hottest month (July) is
around 19 ℃, and around 8 ℃ at the coldest month (January). The extreme maximum temperature in
the history is 31.2 ℃ and -7.8 ℃ of the extreme minimum temperature in the history. (General Office of
Kunming Municipal People's Government, 2016)
-34-
The details weather information of Kunming shows in the table below (China Meteological
Administration, 2016). The data in the table is collected between the years of 1971 to 2000.
Table 2-14 Kunming Climate
Month
Average
Temperature
(℃)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
8.1
9.9
13.2
16.6
19
19.9
19.8
19.4
17.8
15.4
11.6
8.2
Average
Higher
Temperature
(℃)
15.3
17.2
20.7
23.8
24.4
24.1
23.9
24.1
22.7
20.4
17.4
15.1
Average
Lower
Temperature
(℃)
2.2
3.6
6.4
10
14.3
16.6
16.9
16.2
14.6
11.8
7.3
3.1
Extreme
Maximum
Temperature
(℃)
22.4
25.5
27
30.4
31.2
30.2
29.3
28.1
28.5
27.4
24.5
25.1
Extreme
Minimum
Temperature
(℃)
-5.4
-2.9
-5.2
1
5.5
9.9
11.6
9.9
6.2
2.4
-2.9
-7.8
Precipitation
(mm)
15.8
15.8
19.6
23.5
97.4
180.9
202.2
204
119.2
79.1
42.4
11.3
2.5 Base scenario
Following the most popular structure of external wall of existing Chinese buildings, the external wall of
base scenario has been set as 200mm concrete wall which adding with phenolic foam layer as insulation
layer.
Figure 2-9 Structure of existing external wall
-35-
The U-value of the external wall of existing buildings is 0.472, and the details of each layers has showed
in the table below.
Table 2-15 Calculated values of existing wall
The windows of base scenario are double glazed windows and the ratio of windows to walls is 25%.
In the severe cold (Changchun) and cold (Beijing) regions, radiator-heating systems are in use. Boilers
supply the domestic hot water, and the electricity from grid affords the power for the lighting systems.
In the hot-summer & cold-winter (Shanghai), hot-summer & warm winter (Guangzhou) and temperate
(Kunming) regions, VAV and air-cooled chillers are used in the air condition systems.
2.5.1 Changchun
The software Designbuilder has calculated the energy consumption of the modelled building in
Changchun.
In the base scenario, energy consumption of the building is 283 kWh/m2. Due to Changchun is much
colder than other cities in winter. The heating demand is much greater than other cities as well. Because
of the cold winter, the heating demand is significantly more than cooling demand. The heating demand
is almost 7.6 times of cooling demand.
The total energy consumption and energy consumption by categories have been calculated and showed
in tables separately.
-36-
Table 2-16 Total energy consumption of Changchun – base scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
1266240.95
282.59
Net Site Energy
1266240.95
282.59
Total Source Energy
4193746.02
935.94
Net Source Energy
4193746.02
935.94
Table 2-17 Energy consumption by categories of Changchun – base scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
986778.03
0.00
Cooling
0.00
141505.51
0.00
0.00
Interior Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
141505.51
1080641.33
1469.80
2.5.2 Beijing
The energy consumption of the building in Beijing base scenario has been showed below, the total site
energy of the building is 211 kWh/m2, which is much lower than Changchun because of the more
temperate climate.
Table 2-18 Total energy consumption of Beijing – base scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
945379.54
210.99
Net Site Energy
945379.54
210.99
Total Source Energy
2684386.57
599.09
Net Source Energy
2684386.57
599.09
As a city located in the north area of China, the heating demand is larger than cooling demand, but not
so obviously as Changchun. The heating demand is around 2.2 times of cooling demand. The energy
consumption by categories has been showed below.
-37-
Table 2-19 Energy consumption by categories of Beijing – base scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water [m3]
Heating
0.00
0.00
529080.87
0.00
Cooling
0.00
278341.26
0.00
0.00
Interior Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
278341.26
622944.18
1469.80
2.5.3 Shanghai
The energy consumption of the building in Shanghai base scenario is 122kWh/m2.
Table 2-20 Total energy consumption of Shanghai – base scenario
Total Energy
[kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
545013.36
121.63
Net Site Energy
545013.36
121.63
Total Source Energy
1277662.52
285.14
Net Source Energy
1277662.52
285.14
The cooling and heating demand of Shanghai almost arrive a balance status, the energy consumption of
cooling and heating are nearly equal to each other. The details data can be found in the following table.
Table 2-21 Energy consumption by categories of Shanghai – base scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
144327.52
0.00
Cooling
0.00
262728.44
0.00
0.00
Interior Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
262728.44
238190.82
1469.80
2.5.4 Guangzhou
The energy consumption of the building in Guangzhou base scenario is 131kWh/m2.
-38-
Table 2-22 Total energy consumption of Guangzhou – base scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
589181.52
131.49
Net Site Energy
589181.52
131.49
Total Source Energy
1000958.12
223.39
Net Source Energy
1000958.12
223.39
Guangzhou is located in the south part of China, and the climate there is hot in summer and warm in
winter. Thus the cooling demand is much more than heating demand in Guangzhou. From the
calculation, the result shows that the cooling demand is around 3.9 times of heating demand. The data
of energy consumption by categories are showing below.
Table 2-23 Energy consumption by categories of Guangzhou – base scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
17911.03
0.00
Cooling
0.00
433313.09
0.00
0.00
Interior Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
433313.09
111774.33
1469.80
2.5.5 Kunming
Kunming is locating in the temperate region. The city has an alias named “spring city”. That is to say,
the weather of the city is always like in the spring. That’s why the energy consumption of the city is so
small, even only 46 kWh/m2.
Table 2-24 Total energy consumption of Kunming – base scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
204073.38
45.54
Net Site Energy
204073.38
45.54
Total Source
Energy
658516.65
146.97
Net Source Energy
658516.65
146.97
The energy consumption by categories of Kunming is shows below in the table.
-39-
Table 2-25 Energy consumption by categories of Kunming – base scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
42974.64
0.00
Cooling
0.00
23141.33
0.00
0.00
Interior Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
23141.33
136837.94
1469.80
2.6 Envelope improved scenario
Considering the U-value of the previous wall is 0.472, there still have a large space to improve the
property. A new structure of the wall could be introduced.
XPS extrude polystyrene is a kind of advanced thermal insulation material which can be used on the
building external wall. XPS was started to be a trail in China in recent years, and has not been promoted
(China wallmaterials network, 2016). That would be a significant promotion to use XPS as insulation
instead of traditional materials.
Figure 2-10 XPS extruded polystyrene
R – value is a measure of thermal resistance (Desjarlais, 2013). It is one of the most important parameters
to evaluate the thermal insulation performance of a material. The formula of R – value is
𝑅𝑅 =
∆𝑇𝑇
𝑄𝑄̇𝐴𝐴
In the formula, ∆𝑇𝑇 is the temperature difference and 𝑄𝑄̇𝐴𝐴 is the heat transfer per unit area per unit time.
A material with high R – value would welcome to become an insulation material, and the comprehensive
effect of other elements should be considered as well.
The typical physical properties of the XPS are shown in the table below (Kingspan Group, 2016).
-40-
Table 2-26 Typical physical properties of XPS
Property
Test Method
1/2"
Nominal
Thickness
3/4"
1"
Thermal Resistance, R-Value
(ºF-ft²-h/Btu)
ASTM C 518
(@ 75ºF Mean
Temperature)
3.0
4.0
5.0
Water Vapor Permeance
(perm)
ASTM E 96
(Procedure A)
0.8
0.8
0.8
Water Absorption
(Max % by Volume)
ASTM C 272
0.1
0.1
0.1
Fire Characteristics2
Flame Spread
Smoke Developed
ASTM E 84/UL 723
10
60-200
10
60-200
10
60-200
165
165
165
Max, Recommended Use
Temp. (°F)
An R-Value of 5.0 per inch of thickness makes it an excellent thermal insulator that increases the energy
efficiency of buildings (Kingspan Group, 2016). The feature of high R – value means that, to achieve
the same effect of thermal insulation, the thickness of insulation could be cut down than before. The
lightweight coating of the building will save more space.
While the performance of low water vapor permeance means the technologies of dehumidification
should be used well to prevent condensation on the wall.
The improved wall is consisting of 200mm concrete block, 200mm XPS extruded polystyrene layer,
53mm brickwork outer layer and 15mm plaster inner layer. The structure of the improved external wall
is shown in the figure below.
Figure 2-11 Improved external wall
-41-
And the thermal performance of the improved external wall has been shown in the table below. The U
– value of the improved external wall has optimized to 0.153.
Table 2-27 The performance of improved external wall
Besides, the triple glazed window is suggested to replace the double glazed windows. That will reduce
the energy consumption through the windows.
2.6.1 Changchun
After improving the external walls and windows, the energy consumption of Changchun decrease to
236kWh/m2. The data of energy consumption of Changchun in the enveloped scenario has shown below
in the tables.
Table 2-28 Total energy consumption of Changchun – Envelope improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
993015.10
235.78
Net Site Energy
993015.10
235.78
Total Source
Energy
3318361.81
787.90
Net Source Energy
3318361.81
787.90
-42-
Table 2-29 Energy consumption by categories of Changchun
– Envelope improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
765115.90
0.00
Cooling
0.00
98227.87
0.00
0.00
Interior
Lighting
41445.70
0.00
0.00
0.00
Water Systems
0.00
0.00
88225.63
1381.52
Total End Uses
41445.70
98227.87
853341.53
1381.52
2.6.2 Beijing
The energy consumption of Beijing achieves to 178kWh/m2 in the envelope improved scenario. The
details are shown in the tables below.
Table 2-30 Total energy consumption of Beijing – Envelope improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
751499.82
178.43
Net Site Energy
751499.82
178.43
Total Source
Energy
2206959.95
524.01
Net Source Energy
2206959.95
524.01
Table 2-31 Energy consumption by categories of Beijing
– Envelope improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
430262.95
0.00
Cooling
0.00
191565.55
0.00
0.00
Interior
Lighting
41445.70
0.00
0.00
0.00
Water Systems
0.00
0.00
88225.63
1381.52
Total End Uses
41445.70
191565.55
518488.58
1381.52
-43-
2.6.3 Shanghai
After improving the external walls and windows, the energy consumption of Shanghai decrease to
87kWh/m2. The data of energy consumption of Changchun in the enveloped scenario has shown below
in the tables.
Table 2-32 Total energy consumption of Shanghai – Envelope improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
367894.82
87.35
Net Site Energy
367894.82
87.35
Total Source
Energy
922972.84
219.15
Net Source Energy
922972.84
219.15
Table 2-33 Energy consumption by categories of Shanghai
– Envelope improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
86579.35
0.00
Cooling
0.00
151644.14
0.00
0.00
Interior
Lighting
41445.70
0.00
0.00
0.00
Water Systems
0.00
0.00
88225.63
1381.52
Total End Uses
41445.70
151644.14
174804.98
1381.52
2.6.4 Guangzhou
The energy consumption of Guangzhou achieves to 95kWh/m2 in the envelope improved scenario. The
details are shown in the tables below.
Table 2-34 Total energy consumption of Guangzhou – Envelope improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
398164.52
94.54
Net Site Energy
398164.52
94.54
Total Source
Energy
751022.11
178.32
Net Source Energy
751022.11
178.32
-44-
Table 2-35 Energy consumption by categories of Guangzhou
– Envelope improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
6856.12
0.00
Cooling
0.00
261637.07
0.00
0.00
Interior
Lighting
41445.70
0.00
0.00
0.00
Water Systems
0.00
0.00
88225.63
1381.52
Total End Uses
41445.70
261637.07
95081.75
1381.52
2.6.5 Kunming
The energy consumption of Kunming drop to 35kWh/m2 in the envelope improved scenario. The details
are shown below in the tables.
Table 2-36 Total energy consumption of Kunming – Envelope improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
147731.46
35.08
Net Site Energy
147731.46
35.08
Total Source
Energy
501333.62
119.04
Net Source Energy
501333.62
119.04
Table 2-37 Energy consumption by categories of Kunming
– Envelope improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
12597.81
0.00
Cooling
0.00
5462.32
0.00
0.00
Interior
Lighting
41445.70
0.00
0.00
0.00
Water Systems
0.00
0.00
88225.63
1381.52
Total End Uses
41445.70
5462.32
100823.44
1381.52
-45-
2.6.6 Payback time
In order to promote the development of the energy efficiency in China, the Chinese government has
adopted a series of compensating measurement to encourage the improvement of the residential building
envelope. In the building envelop improvement program, the government would afford 70% of the total
expenditure and the residents themselves only need to afford 30% (The ministry of finance of the
People's Republic of China, 2007).
In the case, there are 48 dwellings in the building and the area of each dwelling is 105.48m2. Besides,
the area of the wall can be calculated according to the length of each side of the building and the ratio
of windows to walls of the building, which is 2800m2. Each dwelling would afford 58.33m2
(2800m2/48dwellings) in the program.
The price of the labour and material XPS in China is shown in the table below. North and South area in
the table means north Yangzi River area and south Yangzi River area, which refer to Changchun and
Beijing in the north area and Shanghai, Guangzhou and Kunming in the south area separately.
Table 2-38 The cost of installing XPS insulation
Itemize
Price (Yuan/m2) - North Area
Price (Yuan/m2) - South Area
Labour
25 ~ 60
25 ~ 60
XPS
75 ~ 150
50 ~ 100
Total
100 ~ 210
75 ~ 160
According to the table, 150 Yuan/m2 and 120 Yuan/m2 in north and south area are reasonable. Thus, the
initial cost of improving the insulation of the external wall of the north area would be
150 Yuan⁄m2 × 58.33m2 /dwelling × 30% = 2625Yuan/dwelling
And the initial cost of the south area would be
120 Yuan⁄m2 × 58.33m2 /dwelling × 30% = 2100Yuan/dwelling
Due to the heat metering and charging method has not been implemented in China, in the north area, the
expense saving only comes from reduced cooling load and the expense saving of the south area comes
from the cooling and heating load together. The expense saving is embodied in the reduction of the
electricity bills of residential.
The electricity consumption per capita is 526kWh/year (National Bureau of Statistics of the People's
Republic of China, 2014), 3.35 residents per dwelling has been settled. Thus, the electricity consumption
per dwelling is around 1762 kWh/year (146.8 kWh/month).
The electricity prices (State Grid of China, 2016) of the five cities are shown in the tables below
separately.
-46-
Table 2-39 The price of residential electricity in Changchun
Class
Annual electricity consumption (kWh/year)
Price (Yuan/ kWh)
1st
≤2040
0.525
2nd
2040 ~ 3120
0.575
3rd
≥3120
0.825
Table 2-40 The price of residential electricity in Beijing
Class
Annual electricity consumption
(kWh/month)
Price (Yuan/ kWh)
1st
≤240
0.488
2nd
240 ~ 400
0.538
3rd
≥400
0.788
Table 2-41 The price of residential electricity in Shanghai
Class
Annual electricity consumption (kWh/year)
Price (Yuan/ kWh)
1st
≤3120
0.617
2nd
3120 ~ 4800
0.667
3rd
≥4800
0.917
Table 2-42 The price of residential electricity in Guangzhou
Class
Annual electricity consumption
(kWh/month)
Price (Yuan/ kWh)
1st
≤260
0.61
2nd
260 ~ 400
0.66
3rd
≥400
0.91
Table 2-43 The price of residential electricity in Kunming
Class
Annual electricity consumption
(kWh/month)
Price (Yuan/ kWh)
1st
≤170
0.45
-47-
2nd
170 ~ 260
0.50
3rd
≥260
0.80
Thus, the payback time of each dwelling in different areas is shown below.
Table 2-44 The payback time of each dwelling
City
Initial cost (Yuan)
Payback time (year)
Changchun
2625
2.93
Beijing
2625
2.96
Shanghai
2100
0.92
Guangzhou
2100
0.91
Kunming
2100
4.02
The payback time of Changchun and Beijing both are around 3 years, Shanghai and Guangzhou need
around only 1 year to achieve cost recovery, the longest payback time of these cities is Kunming, which
is 4 years. Objectively, the payback time of envelope improvement project is not a long period, which
means the measure is a reasonable method.
2.7 HVAC system improved scenario
2.7.1 Changchun
The heating system would be improved in Changchun to decrease the energy consumption. In the subject,
considering the modeling building is a new building which would locate in different areas of China, the
radiator heating system in the precious design would be instead by heated floor in new buildings.
The heating cable spread all over the room floor, which can give a more evenly heating than radiator,
thereby the room would have a better indoor climate. Besides, the usage of heated floor would reduce
the temperature requirement of heat resource. Lower temperature resource could save a large amount of
energy instead of higher temperature resource when radiators had been used.
The energy consumption of Changchun after HVAC systems been improved is showing in the tables
below.
Table 2-45 Total energy consumption of Changchun – HVAC improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
1198706.12
267.52
Net Site Energy
1198706.12
267.52
Total Source Energy
4059136.74
905.90
Net Source Energy
4059136.74
905.90
-48-
Table 2-46 Energy consumption by categories of Changchun – HVAC improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
962023.04
0.00
Cooling
0.00
98725.67
0.00
0.00
Interior
Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
98725.67
1055886.34
1469.80
2.7.2 Beijing
The heating system in the previous design, same as in Changchun, is heat radiator, and heated floor
would be the substitution in order to reduce the energy consumption as well.
The improved energy consumption of Beijing has been shown in the tables below.
Table 2-47 Total energy consumption of Beijing – HVAC improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
847530.77
189.15
Net Site Energy
847530.77
189.15
Total Source
Energy
2547265.46
568.49
Net Source Energy
2547265.46
568.49
Table 2-48 Energy consumption by categories of Beijing – HVAC improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
515855.76
0.00
Cooling
0.00
193717.60
0.00
0.00
Interior
Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
-49-
Total End Uses
44094.10
193717.60
609719.07
1469.80
2.7.3 Shanghai
In China, there have no district heating system in the area south of the Yangtze River. No matter cooling
or heating is realized by air conditioning. To improve the energy efficiency of the air conditioning, heat
recovery is urgently needed. In that case, the method to improve the air conditioning in the area south
of Yangtze River is to add heat recovery in the system.
The energy consumption after improved in Shanghai is shown below in the tables.
Table 2-49 Total energy consumption of Shanghai – HVAC improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
441508.53
98.53
Net Site Energy
441508.53
98.53
Total Source
Energy
1162052.72
259.34
Net Source Energy
1162052.72
259.34
Table 2-50 Energy consumption by categories of Shanghai – HVAC improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
141847.45
0.00
Cooling
0.00
161703.67
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
161703.67
235710.75
1469.80
2.7.4 Guangzhou
When the heat recovery is added, the energy consumption of Guangzhou has changed, and details of the
data are shown below in the tables.
Table 2-51 Total energy consumption of Guangzhou – HVAC improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
440166.57
98.23
Net Site Energy
440166.57
98.23
-50-
Total Source
Energy
842687.07
188.07
Net Source Energy
842687.07
188.07
Table 2-52 Energy consumption by categories of Guangzhou – HVAC improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
17535.32
0.00
Cooling
0.00
284673.85
0.00
0.00
Interior
Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
Total End Uses
44094.10
284673.85
111398.62
1469.80
2.7.5 Kunming
Adding heat recovery is the method to improve the HVAC system efficiency in Kunming as well. The
energy consumption of Kunming after improve has shown in the two tables below.
Table 2-53 Total energy consumption of Kunming – HVAC improved scenario
Total Energy [kWh]
Energy Per Total Building Area [kWh/m2]
Total Site Energy
183647.11
40.99
Net Site Energy
183647.11
40.99
Total Source
Energy
634814.46
141.68
Net Source Energy
634814.46
141.68
Table 2-54 Energy consumption by categories of Kunming – HVAC improved scenario
Electricity
[kWh]
Cooling [kWh]
Heating [kWh]
Water
[m3]
Heating
0.00
0.00
42138.38
0.00
Cooling
0.00
3551.32
0.00
0.00
Interior
Lighting
44094.10
0.00
0.00
0.00
Water Systems
0.00
0.00
93863.30
1469.80
-51-
Total End Uses
44094.10
3551.32
136001.69
1469.80
3 Result
Two directions would compare the result of the case. The first one is comparing the energy efficiency
of the same technologies in different climate zones, and another one is comparing the effects of different
technologies in the same climate zone. The combination effects of the two directions would give the
final result and suggestion.
3.1 Comparison of the same technologies in different cities
3.1.1 Envelope improved scenario
Since the new envelope had been used onto the model, the energy consumption has been reduced more
or less in different cities.
In Changchun, 47kWh/m2 has been saved. The energy consumption reduction of Beijing, Shanghai, and
Guangzhou are all around 35kWh/m2 (they saved 33kWh/m2, 34kWh/m2, and 37kWh/m2 energy
separately). The energy saving of the hottest city Guangzhou is the most one except for Changchun.
Only 10kWh/m2 has been saved in Kunming. The data has been managed in the table below.
Table 3-1 Energy saving in the Envelope improved scenario
Base Scenario Energy Consumption
(kWh/m2)
Energy saving by Envelope Improving
(kWh/m2)
Changchun
282.59
46.81
Beijing
210.99
32.56
Shanghai
121.63
34.28
Guangzhou
131.49
36.95
Kunming
45.54
10.46
The comparison data of different cities on the envelope-improved scenario is shown in the bar chart
below.
-52-
Comparison of different cities - Envelope improved
scenario
300.00
250.00
200.00
150.00
Base Scenario(kWh/m2)
100.00
Envelope Improved
Scenario(kWh/m2)
50.00
0.00
Figure 3-1 Comparison of different cities – Envelope improved scenario
More energy has been saved in the cold or hot region. While in the temperate area, the energy saved is
not so much as other district. That is to say the more extreme the weather is, the greater the impact of
the thermal insulation.
3.1.2 HVAC system improved scenario
In the HVAC system improved scenario, Guangzhou has been influenced most significantly. 33kWh/m2
has been saved in Guangzhou. Shanghai is standing on the second position, 23kWh/m2 has been saved
in Shanghai since the HVAC system is improved. Then, Beijing and Changchun are following, the
energy saving by improving HVAC system in Beijing and Changchun are 22kWh/m2 and 15kWh/m2
separately. Kunming is still the city which energy saving is the least, only 5kWh/m2 has been saved by
improving HVAC system. The data has been managed in the table below.
Table 3-2 Energy saving in the HVAC improved scenario
Energy Consumption
Base Scenario
Energy saving by HVAC system improving
(kWh/m2)
(kWh/m2)
Changchun
282.59
15.07
Beijing
210.99
21.84
Shanghai
121.63
23.10
Guangzhou
131.49
33.26
Kunming
45.54
4.55
The comparison chart of HVAC improved scenario is attached below.
-53-
Comparison of different cities - HVAC improved
scenario
300.00
250.00
200.00
150.00
Base Scenario(kWh/m2)
100.00
HVAC Improved
Scenario(kWh/m2)
50.00
0.00
Figure 3-2 Comparison of different cities – HVAC improved scenario
By analyzing of the data, Kunming, the only city which located in the temperate region, is impact the
least by the HVAC system. For the other cities, the warmer the city is, the greater the impact of the
HVAC system.
3.2 Comparison of two technologies in the same city
Because of the climate, the two different methods would influence the energy efficiency in different
cities. As we can see from the chart below, both of the methods improving envelop and HVAC system
can achieve the goal of energy efficiency, the difference is the extent of them.
-54-
Energy Consuption in different cities
300.00
250.00
200.00
Base Scenario(kWh/m2)
150.00
100.00
Envelope Improved
Scenario(kWh/m2)
50.00
HVAC Improved
Scenario(kWh/m2)
0.00
Figure 3-3 Energy Consumption in different cities
Obviously, in Changchun, the envelope improving method is much higher efficiency than HVAC
improving. It saves more than 30kWh/m2 than HVAC improving method. In Beijing and Shanghai,
envelope-improving method is higher efficiency than HVAC improving method as well. While the
amount is not that much as Changchun, around 10 kWh/m2 more energy is saved by envelope improving
than HVAC system improving in Beijing and Shanghai separately. At the same time, the amount
difference of the two methods in Guangzhou and Kunming is not that obvious, envelope improving
method is saving only around 5kWh/m2 more than HVAC system improving method in these two cities
separately. (The table below shows the energy saving difference by two methods, the energy saving
difference is calculated by the energy saving of envelope-improved scenario minus the energy saving of
HVAC system improved scenario)
Table 3-3 Energy saving difference by two methods
Energy saving by Envelope
Improving （kWh/m2）
Energy saving by HVAC system
improving （kWh/m2）
Energy saving
Difference（kWh/m2）
Changchun
46.81
15.07
31.74
Beijing
32.56
21.84
10.72
Shanghai
34.28
23.10
11.18
Guangzhou
36.95
33.26
3.69
Kunming
10.46
4.55
5.91
In order to further comparison, the percentages of energy saved by two scenarios have been compared
in the chart below.
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The percentage of energy saved by two scenario
30.00
25.00
20.00
15.00
Envelope Improve
Scenario(%)
10.00
HVAC Improve
Scenario(%)
5.00
0.00
Figure 3-4 The percentage of energy saved by two scenario
From the chart, the percentage of energy saving has shown intuitively. Envelope improved methods
saves 16.6% of total energy consumption in Changchun, however, only 5.3% of total energy
consumption in Changchun has been saved by HVAC improved method. In Beijing, energy saving by
envelope improving and HVAC improving methods are 15.4% and 10.4% separately. Energy saving by
envelope improving and HVAC improving in Shanghai are around 28% and 19% separately. That is to
say, envelope improvement is still has a higher extent of saving energy than improving HVAC system.
The percentage of envelope improvement and HVAC improvement is pretty near, they are 28.1% and
25.3% separately in Guangzhou. In Kunming, the percentage of energy saving by envelope improvement
is more than two times of HVAC improvement, 23% of total energy has been saved by improving the
envelope of the building, while around 10% of total can be saved by improving the HVAC system in
Kunming.
3.3 Comprehensive comparison
In terms of the comparison above, the suggestions can be given.
In Changchun, which represents the cities located in the severe cold region, because of the significant
effective, improving the building envelope would be the most recommended technology to achieving
the energy efficiency in residential buildings.
In Beijing (cold region) and Shanghai (hot-summer and cold-winter region), improving the building
envelope would be recommended as well. Though the effective is not that obvious better than HVAC
improving as Changchun, the improvement of envelope still is the better efficiency method.
In the hot-summer and warm-winter region, which is represented by Guangzhou, the most suggestion
method is improving the HVAC system. Although the data shows that envelop improvement brings a
better efficiency result, to improve the HVAC system by adding a heat recovery system would be much
cheaper than adding insulations on the whole building. Since the effective of energy efficiency by the
two methods have no great difference, to improve the HVAC system would be a good method not only
energy efficiency but also economical.
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In the temperate region represented by Kunming, which method to be chosen can be decided in depends.
The climate of the region determines that the energy consumption of the building is very small. Two
methods both can reduce the energy consumption but not that obviously because of the small cardinality.
So the house owners can decide which method to choose according to their own requirement. If they
would like to have a better indoor climate, improving the envelope of the building would be suggested,
while if they would like to choose an economical program, to improve the HVAC system would be
recommended.
4 Discussion
As mentioned before, there are lots of technologies to achieve the goal of energy efficiency of the
residential building. For example, to improve the HVAC system of the building can decrease the energy
consumption of the heating, cooling and ventilating, adding the insulation on the external wall and
improving the windows can cut down the energy consumption of the buildings’ envelope. Besides,
installing solar PV can reduce the energy using in heating the domestic water, changing the external
incandescent lamp to LED lamp can reduce the power consumption. What’s more, the usage of heat
pumps and sensors and controls can decrease the energy consumption as well.
Due to some technologies are great for public buildings and industrial buildings but not that practically
for residential buildings, not all of these technologies were discussed in the case. Besides, even the
technologies such as improving the lamps or installing solar PVs are pragmatically for residential
buildings, considering these technologies have already been wildly and effectively used in China, they
were not be discussed in the case as well. While the fact is that even these technologies are wildly used,
still are several building not adopted these measures, so if the measures can be discussed in those
buildings, which did not use these technologies, the result would be better consummate.
Five representative cities are chosen from five different climate zones, the whole program is discussing
by separate the China mainland into five climate zone according to the Code for design of civil buildings
(China Architecture Design & Research Group(CAG), 2005). However, the fact is that there are many
cities locating on the boundary of two, even three climate zones. The weather characteristic of these
“boundary cities” is intervenient between those of close climate zone. This will lead a much more
complex method to decide which is better for the building in the city to achieve energy efficiency. That
is to say, when we consider which way can be used to decrease energy consumption in these “boundary
cities”, the decision should be made in depends.
For those regions which almost have not difference when two technologies were used separately, the
decision can be made by considering the combination effective of the economic situation, the indoor
climate requirements of the householder and the implementation of the difficulty etc. in the region.
For those cities which have a better economic situation, if the householders have a high requirement of
the indoor climate, the two methods can be used together of their buildings. The combination effective
would be much better than use any of them by itself.
5 Conclusion
By comparing the simulation of the base, envelope improved and HVAC improved scenarios of the
residential buildings in five climate zones, the suggestions would be a difference in depends. In the
severe cold region, cold region, and hot-summer and cold-winter region, improve the envelope would
recommend obtaining a better indoor climate. In the hot-summer and warm-winter region, improve the
HVAC system is a better choice since lower investment and the same effect of the indoor climate. In the
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temperate region, two methods have the similar effective. The choice would be decided by the owners
of the houses according to their requirements and their economical status.
The definition of the “optimal” method in the title is the most reasonable method to achieve in a short
period of time by using less money, which means the method can play a role in the energy efficiency of
Chinese residential buildings not only efficiently but also economically and quickly.
Obviously, there are many further improvements can be used when we ease of economy and time
limitation. These further improvement methods can be introduced into the case after the first step has
been achieved.
The first further improvement is to improve the control system in order to adjust indoor district heating
system. In China, most of the residential buildings have no control systems to adjust the indoor
temperature by individual users. A few residential buildings have the control systems to adjust the indoor
temperature for the users, while due to the Chinese heating company haven’t implemented the household
heat metering and charging method, the users would rather open their windows to decrease indoor
temperature and get fresh air at the same time instead of turning off or turn down the control valve of
the heating system. This problem contributes to a significantly waste of heating energy. Thereby, to add
the control system on the heating system and adopt the household heat metering and charging method
could be promoted in China.
The second further improvement is to build the district heating system in China south area. For reasons
of climate characteristic and mostly considering the operation cost, there has no district heating system
in the south Yangzi River area of China. However, the true situation is that the indoor temperature always
pretty low even lower than 10 ℃ in the winter in this area. Due to getting a warmer indoor climate,
residents always use individual heating devices like electric heaters or room air conditioners. Theses
devices actually cannot afford a comfortable indoor climate but waste the electricity severely. Thus, the
government should build the district heating system in this area. Although the heating period would be
pretty short and there have no possible to recovery the operation cost. In order to get energy efficiency
social and protect the energy in the world, the government has an obligation to build the system and
afford the investment.
The third one is promoting the district cooling system in China. There has no district cooling system in
China now. Most of the Chinese residential building is using the room air conditioner to get a cooler
temperature in summer. District cooling system will bring a better cooling situation of residential
buildings and would be a better way to manage as well. Due to it is a large project to build a new system,
the government should arrange the project and invest for the project at a full stretch.
At the same time, the technology of using the waste heat should be introduced to China. For example,
the technology of using the heat from biomass is a good choice, although the project would be a large
challenge because of the imperfect technology and waste recovery system. The government has
obligation to improve the whole waste recovery system and promoting the waste heat utilization. Besides,
the heat resource from the wastewater can be recovery and used to preheat the heating system.
Besides, the furniture which can be fold in is a new trend of achieve saving energy, and this can be
suggest in the new buildings. By using this kind of furniture, the total area of dwellings can be reduced
a lot. The following impact is the reduction of the energy consumption.
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