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Research on Energy Efficiency Design Key Parameters of Envelope for Nearly Zero Energy Buildings in Cold Area
Available online at www.sciencedirect.com
ScienceDirect
Available online at www.sciencedirect.com Procedia Engineering 00 (2017) 000–000
ScienceDirect
www.elsevier.com/locate/procedia
Procedia Engineering 205 (2017) 686–693
10th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC2017, 1922 October 2017, Jinan, China
Research on Energy Efficiency Design Key Parameters of Envelope for Nearly Zero Energy Buildings in Cold Area Guohui Fenga,* ，Baoyue Doua，Xiaolong Xua，Dandan Chia，Yixin Suna and Peiyu Houa aa
School of Municipal and Environmental Engineering, Shenyang Jianzhu University, 9 Hunnan Road, Shenyang 110168, China
Abstract The insulation thickness of envelope, heat transfer coefficient of window and ratio window to wall are the main factors that affect the building energy consumption in cold area. The demonstration building model is established through DEST energy consumption simulation software. Multiple factors with single variable method is used to study the performance parameters of building envelope and establish the energy efficiency design key parameters of nearly zero energy buildings. According to the calculating result, the value of heat transfer coefficient for exterior wall is 0.096 W / (m2 • K). The value of heat transfer coefficient for outer window is 0.780 W / (m2 • K). The value of solar heat gain coefficient SHGC value is not less than 0.474. Based on these selections above envelops, the ratio window to wall is 0.15-0.25 in south facades. The energy consumption is increased linearly with the rise of ratio window to wall in other facades. © 2017 The Authors. Published by Elsevier Ltd. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Conditioning. Air Conditioning. Keywords: Cold area; Nearly zero energy buildings; Energy efficiency design; Performance parameters; DEST
1. Introduction According to the statistics of the BP World Energy Statistical Yearbook, China is the world's second largest economy at a cost of 23% of the world's primary energy, making it the world's largest energy consumer. Building energy consumption accounts for about 30% of total social energy consumption. According to the experience of developed countries, this proportion will gradually increase to about 40% [1]. Therefore, we must attach great importance to building energy consumption. European countries began to focus on building consumption since * *
Corresponding author. Tel.: 24690716; fax: 24690716. E-mail address: [email protected]
1877-7058 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Conditioning.
1877-7058 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Conditioning. 10.1016/j.proeng.2017.09.885
2
Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
687
1980s. After decades of development, gradually formed their own energy-saving building development concept. In recent years, nearly zero energy buildings in our country is gradually increased. With China's building energy efficiency technology gradually developed, China has also carried out research of nearly zero buildings and demonstration construction practice [2]. But the research of nearly zero building is still in its infancy, and the current reference design standards and practical projects are rarely. Therefore, this paper from the perspective of building energy consumption factors, through the computer simulation technology to calculate the main factors. According to the calculation, the energy efficiency design key parameters of nearly zero energy buildings are established. The result is meaningful. It provides quantitative data support for the development of nearly zero building, at the same time, it is of great practical value to guide the design of energy efficiency design in the cold area. 2. Methods The main method is the computer simulation technology. DEST is the building energy analysis software developed by Tsinghua University [3]. First, the demonstration building model is established with DEST software. Then multiple factors with single variable method is used to study the performance parameters of building envelope which influence the building energy consumption greatly. Finally, establish the energy efficiency design key parameters of nearly zero energy buildings. 2.1. Building overview The nearly zero demonstration building is in Shenyang Jianzhu University (see Figure 1). The demonstration building has two layers, the first layer is 3.3 meters high, and the second layers is 3.6 meters high, with a total construction area of 334.8m2. The first floor is a typical residential building, including a demonstration room, kitchen, bathroom, reception room, exhibition hall, control room and equipment room. The second floor includes open office area, conference room and bathroom. Make full use of solar energy, geothermal energy and phase change energy storage technology, greatly reducing the consumption of fossil fuels. The building uses a better external insulation structure of technical measures, heat transfer coefficient is 1.0 W / (m2 • K), the use of advanced doors and windows closed technology, airtight 8. The building body size is 0.47. The west ratio window to wall is 0.09, the south and north ratio window to wall is 0.12, the east ratio window to wall is 0.05.
Figure. 1. Building exterior
To simulate and study the energy consumption of the model building, we should first establish a physical model of building (see Figure 2), which can reflect the size, layout and structure of the building.
Guohui al. / Procedia Engineering 205 (2017) 686–693 Guohui FengFeng et al.et/ Procedia Engineering 00 (2017) 000–000
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Figure. 2. Building energy consumption calculation model Table 1. Basic parameters of room thermal disturbance of equipment and the environment
Room
Lounge
Person/m2
0.1
Light disturbance
Equip disturbance
W/ m2
W/ m2
3
2
Upper temperature limit
Lower temperature limit
Upper humidity limit
Lower humidity limit
℃
℃
%
%
25
20
60
50
Start-stop time 7:00-21:00
Reception
0.1
3
2
25
20
60
50
7:00-21:00
Toilet
0.1
3
0
28
18
60
30
7:00-21:00
Kitchen
2
3
2
28
18
60
30
7:00-21:00
Equip
0
3
2
28
17
60
30
－
Hall
0.2
3
2
27
18
60
50
7:00-21:00
Control
0
3
2
28
17
60
30
7:00-2100
Office
0.1
3
2
25
20
60
50
7:00-21:00
2.2. Set the calculation parameters The meteorological parameters are used in this simulation, based on the Chinese meteorological parameters of the Shenyang area weather data. Different rooms have different functions, and the staff density and lifestyle have a certain difference. Basic parameters of the thermal disturbance of room equipment and the environment are made (see Table 1). Take several rooms as an example, the room personnel schedules are as shown in Figure 3. The ventilation times are 0.5 times per hour. The light interference is 3W/m2, other heat interference take 2W/ m2. The temperature should maintain at 20-25℃ when people often stay in the place. The temperature can maintain the duty cycle at 15-28 ℃ for less or no people to stay [4]. Energy efficiency ratio of building refrigeration is 2.3, and the heating energy efficiency ratio is 1.9. The heating period is from November 15th to the next year in March 15th, and the air conditioning period is from June 1th to August 30th. To obtain the thermal parameters of the envelope structure with the initial model, the envelope structure is built through the standard building materials provided in the software. The enclosure structure parameters such as exterior wall, exterior window, roof and floor are set up.
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Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000 Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693
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Figure. 3. Room personnel schedules
3. Results 3.1. Analysis on the insulation thickness of wall According to relevant statistical data, the heat caused by building envelope heat loss ratio is as follows: the heat loss of the wall is about 60%-70%; the heat loss of the doors and windows is about 20%-30%; the heat loss of the roof is about 10% [5].
Figure. 4. Sketch of heat loss of building envelope
From Figure 4, we can see that the heat loss through the wall is dominant, followed by doors and windows. Strengthening the insulation of the wall structure is an important measure of building energy efficiency. There are several methods to improve the thermal performance of the wall, external insulation, internal insulation and self insulation. From the aspects of energy saving, economy and comfort, the external insulation system has a great advantage. The commonly used external insulation materials with polystyrene foam (EPS), extruded polystyrene foam (XPS), polyurethane foam and mineral wool etc. At present, the EPS insulation materials is the most mature technology and is widely used [6]. The EPS board and external insulation are used in the demonstration building. Concrete construction method: Table 2.
Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
690
5
Table 2. Structure and heat transfer coefficient Thermal conductivity
Insulation thickness
heat transfer coefficient
W/（m • K）
（mm）
W/（m2 • K）
Number
Construction method Polymer mortar
0.93
5
－
1
Graphite EPS board
0.033
100
0.228
2
125
0.194
3
150
0.169
2
4
175
0.15
5
200
0.135
6
225
0.122
7
250
0.112
8
275
0.103
9
300
0.096
10
325
0.089
11
350
0.084
Self - insulation wall
0.1
120
－
Silicon calcium board
0.24
10
－
Figure. 5. The relationship between building energy consumption and insulation thickness
From Figure 5, we can see that with the increase of the in the insulation thickness, the building heating energy consumption is gradually declined and the building cooling energy consumption is almost unchanged. It indicates that the insulation thickness has little effect on building cooling energy consumption. From the trend of building total energy consumption, the total energy consumption reduced significantly when the insulation thickness is from 100mm to 300mm. Further increase the thickness of the insulation layer, the total energy consumption is basically unchanged. So 300mm is the best insulation thickness, and the corresponding heat transfer coefficient is 0.096W / (m2 • K).
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Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
691
3.2. Influence of window performance parameters on Building Energy Consumption The energy consumption through the doors and exterior windows is very high, especially the exterior windows of buildings. The heat transfer coefficient of the external window is many times that of the outer wall heat transfer coefficient, and the heat dissipation through the external window is also very high[7]. Table 3. Window construction form and corresponding thermal performance parameters Number
Frame material
Window type
3 4 5 6
UPVC
SHGC
Gas
6/13
Air
1.368
0.575
Three-layer 3mm Low-E
13/13
Air
1.256
0.579
single-coated glass
6/13
Argon
1.135
0.575
13/13
Argon
1.058
0.579
13/13
Air
0.982
0.474
13/13
Argon
0.780
0.474
1 2
Heat transfer coefficient
Air layer mm
K=3.476W/ （m2•K） ~double coated glass
W / (m2 • K)
The outer window is the weak link of the thermal insulation of the envelope. In recent years, the domestic research show that the heat transfer loss caused by the hot and cold load accounted for about 1/3 of the total load [8]. So one of the key technologies to achieve building energy efficiency is improving the overall performance of the outer window. Hollow Low-E glass technology is outstanding and widely used nowadays because its glass heat transfer performance and radiation performance greatly improve the indoor light and heat environment, and greatly reduced the building energy consumption. In this paper, six typical energy-saving windows are selected. The main performance parameters are shown in Table 3. The relationship between the ratio window to wall and the building energy consumption of six typical energy-saving windows is simulated.
Figure. 6. The relationship between energy consumption and ratio window to wall in the south
Figure 6 reflects the relationship between energy consumption and ratio window to wall with different window types in the south. From the left figure, we can see that No.1-4 window, the building energy consumption is declined when the ratio window to wall in the south range from 0.05 to 0.15. Then with the rise of the ratio window to wall, the building energy consumption is increased. No. 5, 6 window, building energy consumption is declined when the ratio window to wall range from 0.05 to 0.20. Then with the rise of the ratio window to wall, the building energy
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Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
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consumption is increased. Compared with No.1-5 window, the energy consumption of No.6 (K=0.780 W/ (m2 • K), SHGC=0.474) is low. The building energy consumption is the lowest when ratio window to wall range from 0.15 to 0.25. The right figure reflects that the relationship between building heating consumption, cooling consumption, total consumption and the No.6 window south ratio window to wall. With the rise of ratio window to wall, the heating consumption is gradually declined, the cooling consumption is gradually increased, and the total consumption first reduced, then increased.
Figure. 7. The relationship between energy consumption and ratio window to wall
As is shown in Figure 7, the total energy consumption is a linear increase with the rise of ratio window to wall in the north, and 6 types window have the same trend. No.6 window has the lowest total energy consumption. With the rise in the east and west ratio window to wall, the building energy consumption is obviously increased, basically the linear law. So it is necessary to control the ratio window to wall in the east and west. In the case of different window and ratio window to wall, the building energy consumption of No.6 window is the lowest. 4. Discussion In this paper, a model of in cold area is established through the DEST energy simulation software, and the important parameters which affect the building energy consumption are simulated. According to the simulation, the heat transfer coefficient of the wall and the thermal performance parameters of the window are established. This research has a great value. It can provide quantitative data support for the development of nearly zero building design in the cold area. According to the simulation results, the building has the lowest heating and cooling energy when the insulation thickness of outer wall is 300mm, and the corresponding heat transfer coefficient is 0.096W / (m2 • K). For the outer window, because of its heat loss and solar radiation heat double attribute, so heat transfer coefficient and the different orientation ratio window to wall was simulated and analyzed. The energy consumption of the building is the lowest when the heat transfer coefficient of the outer window is 0.780 W / (m2 • K), and the solar heat coefficient is 0.474. Building energy consumption achieve the lowest value when the south ratio window to wall is from 0.05 to 0.15. Building energy consumption increases with the rise of ratio window to wall. It is necessary to reduce the ratio window to wall to meet the premise of lighting in the east, west, and north. Based on the above analysis results, the final calculation results of the key design parameters about the wall thermal performance, outer window thermal performance and ratio window to wall are summarized. The key parameters index of building envelope energy - saving design are shown in Table 4.
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Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
693
Table 4. Key parameter values of nearly zero building envelope energy-saving design in severe cold area Key factor
Design
Wall
K=0.096 W/（m2 • K）
Outer window Ratio window to wall
K=0.780 W/（m2 • K）
SHGC=0.474 South: 0.05-0.15
East, west, north: meet the lighting requirements to take the minimum
5. Conclusions In this paper, the key factors of nearly zero building envelope energy-saving design are simulated and quantified. The results as follows. • The main energy efficiency design parameters of the nearly zero building in the cold area, the heat transfer coefficient of the wall is 0.096W/ (m2 • K). • The heat transfer coefficient of the outer window is 0.780W/ (m2 • K), and the solar thermal coefficient is not less than 0.474. • The parameters of ratio window to wall is from 0.15 to 0.25 in the south. In other directions, with the rise of ratio window to wall the building energy consumption is almost linear growth. Take the lowest value of east, west, and north ratio window to wall to meet the requirements of building lighting. Acknowledgements This paper is supported by “12th Five Year” national science and technology support program (2014BAJ01B04-2). References [1] B.X.Qiu, Development of energy saving and green building without delay, China Economic Weekly, 9 (2005) 11. [2] H.L.Meng, B.S.Chen, Energy efficiency technology of building windows, Huazhong Architecture, 27(8) (2009) 160-163. [3] S.C.Zhang, X.Chen, W.Xu, The research and practice of Nearly Zero Building, Construction Science and Technology, 22 (2014) 27-29. [4] S.Y.Zhou, The envelope energy efficiency technology influence on office building energy consumption in different climate zone, Tianjin University, (2012). [5] J.F.Tu, H.Su, X.G.Li, Analysis of influence of enclosure structure on building energy consumption in cold area, Clean and Air Conditioning Technology, 1 (2014) 65-67. [6] W.D.Long, Building energy efficiency and building energy efficiency management, China Construction Industry Press, (2005). [7] S.B.H.Puleo, R.P.Leslie, Some Effects of the Sequential Experience of Windows on Human Response, Journal of the Illuminating Engineering Society, 20(1) (1991) 91-99. [8] Y.Q.Pan, Practical building energy consumption simulation manual, China Construction Industry Press, (2013).
ScienceDirect
Available online at www.sciencedirect.com Procedia Engineering 00 (2017) 000–000
ScienceDirect
www.elsevier.com/locate/procedia
Procedia Engineering 205 (2017) 686–693
10th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC2017, 1922 October 2017, Jinan, China
Research on Energy Efficiency Design Key Parameters of Envelope for Nearly Zero Energy Buildings in Cold Area Guohui Fenga,* ，Baoyue Doua，Xiaolong Xua，Dandan Chia，Yixin Suna and Peiyu Houa aa
School of Municipal and Environmental Engineering, Shenyang Jianzhu University, 9 Hunnan Road, Shenyang 110168, China
Abstract The insulation thickness of envelope, heat transfer coefficient of window and ratio window to wall are the main factors that affect the building energy consumption in cold area. The demonstration building model is established through DEST energy consumption simulation software. Multiple factors with single variable method is used to study the performance parameters of building envelope and establish the energy efficiency design key parameters of nearly zero energy buildings. According to the calculating result, the value of heat transfer coefficient for exterior wall is 0.096 W / (m2 • K). The value of heat transfer coefficient for outer window is 0.780 W / (m2 • K). The value of solar heat gain coefficient SHGC value is not less than 0.474. Based on these selections above envelops, the ratio window to wall is 0.15-0.25 in south facades. The energy consumption is increased linearly with the rise of ratio window to wall in other facades. © 2017 The Authors. Published by Elsevier Ltd. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Conditioning. Air Conditioning. Keywords: Cold area; Nearly zero energy buildings; Energy efficiency design; Performance parameters; DEST
1. Introduction According to the statistics of the BP World Energy Statistical Yearbook, China is the world's second largest economy at a cost of 23% of the world's primary energy, making it the world's largest energy consumer. Building energy consumption accounts for about 30% of total social energy consumption. According to the experience of developed countries, this proportion will gradually increase to about 40% [1]. Therefore, we must attach great importance to building energy consumption. European countries began to focus on building consumption since * *
Corresponding author. Tel.: 24690716; fax: 24690716. E-mail address: [email protected]
1877-7058 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Conditioning.
1877-7058 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Conditioning. 10.1016/j.proeng.2017.09.885
2
Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
687
1980s. After decades of development, gradually formed their own energy-saving building development concept. In recent years, nearly zero energy buildings in our country is gradually increased. With China's building energy efficiency technology gradually developed, China has also carried out research of nearly zero buildings and demonstration construction practice [2]. But the research of nearly zero building is still in its infancy, and the current reference design standards and practical projects are rarely. Therefore, this paper from the perspective of building energy consumption factors, through the computer simulation technology to calculate the main factors. According to the calculation, the energy efficiency design key parameters of nearly zero energy buildings are established. The result is meaningful. It provides quantitative data support for the development of nearly zero building, at the same time, it is of great practical value to guide the design of energy efficiency design in the cold area. 2. Methods The main method is the computer simulation technology. DEST is the building energy analysis software developed by Tsinghua University [3]. First, the demonstration building model is established with DEST software. Then multiple factors with single variable method is used to study the performance parameters of building envelope which influence the building energy consumption greatly. Finally, establish the energy efficiency design key parameters of nearly zero energy buildings. 2.1. Building overview The nearly zero demonstration building is in Shenyang Jianzhu University (see Figure 1). The demonstration building has two layers, the first layer is 3.3 meters high, and the second layers is 3.6 meters high, with a total construction area of 334.8m2. The first floor is a typical residential building, including a demonstration room, kitchen, bathroom, reception room, exhibition hall, control room and equipment room. The second floor includes open office area, conference room and bathroom. Make full use of solar energy, geothermal energy and phase change energy storage technology, greatly reducing the consumption of fossil fuels. The building uses a better external insulation structure of technical measures, heat transfer coefficient is 1.0 W / (m2 • K), the use of advanced doors and windows closed technology, airtight 8. The building body size is 0.47. The west ratio window to wall is 0.09, the south and north ratio window to wall is 0.12, the east ratio window to wall is 0.05.
Figure. 1. Building exterior
To simulate and study the energy consumption of the model building, we should first establish a physical model of building (see Figure 2), which can reflect the size, layout and structure of the building.
Guohui al. / Procedia Engineering 205 (2017) 686–693 Guohui FengFeng et al.et/ Procedia Engineering 00 (2017) 000–000
688
3
Figure. 2. Building energy consumption calculation model Table 1. Basic parameters of room thermal disturbance of equipment and the environment
Room
Lounge
Person/m2
0.1
Light disturbance
Equip disturbance
W/ m2
W/ m2
3
2
Upper temperature limit
Lower temperature limit
Upper humidity limit
Lower humidity limit
℃
℃
%
%
25
20
60
50
Start-stop time 7:00-21:00
Reception
0.1
3
2
25
20
60
50
7:00-21:00
Toilet
0.1
3
0
28
18
60
30
7:00-21:00
Kitchen
2
3
2
28
18
60
30
7:00-21:00
Equip
0
3
2
28
17
60
30
－
Hall
0.2
3
2
27
18
60
50
7:00-21:00
Control
0
3
2
28
17
60
30
7:00-2100
Office
0.1
3
2
25
20
60
50
7:00-21:00
2.2. Set the calculation parameters The meteorological parameters are used in this simulation, based on the Chinese meteorological parameters of the Shenyang area weather data. Different rooms have different functions, and the staff density and lifestyle have a certain difference. Basic parameters of the thermal disturbance of room equipment and the environment are made (see Table 1). Take several rooms as an example, the room personnel schedules are as shown in Figure 3. The ventilation times are 0.5 times per hour. The light interference is 3W/m2, other heat interference take 2W/ m2. The temperature should maintain at 20-25℃ when people often stay in the place. The temperature can maintain the duty cycle at 15-28 ℃ for less or no people to stay [4]. Energy efficiency ratio of building refrigeration is 2.3, and the heating energy efficiency ratio is 1.9. The heating period is from November 15th to the next year in March 15th, and the air conditioning period is from June 1th to August 30th. To obtain the thermal parameters of the envelope structure with the initial model, the envelope structure is built through the standard building materials provided in the software. The enclosure structure parameters such as exterior wall, exterior window, roof and floor are set up.
4
Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000 Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693
689
Figure. 3. Room personnel schedules
3. Results 3.1. Analysis on the insulation thickness of wall According to relevant statistical data, the heat caused by building envelope heat loss ratio is as follows: the heat loss of the wall is about 60%-70%; the heat loss of the doors and windows is about 20%-30%; the heat loss of the roof is about 10% [5].
Figure. 4. Sketch of heat loss of building envelope
From Figure 4, we can see that the heat loss through the wall is dominant, followed by doors and windows. Strengthening the insulation of the wall structure is an important measure of building energy efficiency. There are several methods to improve the thermal performance of the wall, external insulation, internal insulation and self insulation. From the aspects of energy saving, economy and comfort, the external insulation system has a great advantage. The commonly used external insulation materials with polystyrene foam (EPS), extruded polystyrene foam (XPS), polyurethane foam and mineral wool etc. At present, the EPS insulation materials is the most mature technology and is widely used [6]. The EPS board and external insulation are used in the demonstration building. Concrete construction method: Table 2.
Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
690
5
Table 2. Structure and heat transfer coefficient Thermal conductivity
Insulation thickness
heat transfer coefficient
W/（m • K）
（mm）
W/（m2 • K）
Number
Construction method Polymer mortar
0.93
5
－
1
Graphite EPS board
0.033
100
0.228
2
125
0.194
3
150
0.169
2
4
175
0.15
5
200
0.135
6
225
0.122
7
250
0.112
8
275
0.103
9
300
0.096
10
325
0.089
11
350
0.084
Self - insulation wall
0.1
120
－
Silicon calcium board
0.24
10
－
Figure. 5. The relationship between building energy consumption and insulation thickness
From Figure 5, we can see that with the increase of the in the insulation thickness, the building heating energy consumption is gradually declined and the building cooling energy consumption is almost unchanged. It indicates that the insulation thickness has little effect on building cooling energy consumption. From the trend of building total energy consumption, the total energy consumption reduced significantly when the insulation thickness is from 100mm to 300mm. Further increase the thickness of the insulation layer, the total energy consumption is basically unchanged. So 300mm is the best insulation thickness, and the corresponding heat transfer coefficient is 0.096W / (m2 • K).
6
Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
691
3.2. Influence of window performance parameters on Building Energy Consumption The energy consumption through the doors and exterior windows is very high, especially the exterior windows of buildings. The heat transfer coefficient of the external window is many times that of the outer wall heat transfer coefficient, and the heat dissipation through the external window is also very high[7]. Table 3. Window construction form and corresponding thermal performance parameters Number
Frame material
Window type
3 4 5 6
UPVC
SHGC
Gas
6/13
Air
1.368
0.575
Three-layer 3mm Low-E
13/13
Air
1.256
0.579
single-coated glass
6/13
Argon
1.135
0.575
13/13
Argon
1.058
0.579
13/13
Air
0.982
0.474
13/13
Argon
0.780
0.474
1 2
Heat transfer coefficient
Air layer mm
K=3.476W/ （m2•K） ~double coated glass
W / (m2 • K)
The outer window is the weak link of the thermal insulation of the envelope. In recent years, the domestic research show that the heat transfer loss caused by the hot and cold load accounted for about 1/3 of the total load [8]. So one of the key technologies to achieve building energy efficiency is improving the overall performance of the outer window. Hollow Low-E glass technology is outstanding and widely used nowadays because its glass heat transfer performance and radiation performance greatly improve the indoor light and heat environment, and greatly reduced the building energy consumption. In this paper, six typical energy-saving windows are selected. The main performance parameters are shown in Table 3. The relationship between the ratio window to wall and the building energy consumption of six typical energy-saving windows is simulated.
Figure. 6. The relationship between energy consumption and ratio window to wall in the south
Figure 6 reflects the relationship between energy consumption and ratio window to wall with different window types in the south. From the left figure, we can see that No.1-4 window, the building energy consumption is declined when the ratio window to wall in the south range from 0.05 to 0.15. Then with the rise of the ratio window to wall, the building energy consumption is increased. No. 5, 6 window, building energy consumption is declined when the ratio window to wall range from 0.05 to 0.20. Then with the rise of the ratio window to wall, the building energy
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Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
7
consumption is increased. Compared with No.1-5 window, the energy consumption of No.6 (K=0.780 W/ (m2 • K), SHGC=0.474) is low. The building energy consumption is the lowest when ratio window to wall range from 0.15 to 0.25. The right figure reflects that the relationship between building heating consumption, cooling consumption, total consumption and the No.6 window south ratio window to wall. With the rise of ratio window to wall, the heating consumption is gradually declined, the cooling consumption is gradually increased, and the total consumption first reduced, then increased.
Figure. 7. The relationship between energy consumption and ratio window to wall
As is shown in Figure 7, the total energy consumption is a linear increase with the rise of ratio window to wall in the north, and 6 types window have the same trend. No.6 window has the lowest total energy consumption. With the rise in the east and west ratio window to wall, the building energy consumption is obviously increased, basically the linear law. So it is necessary to control the ratio window to wall in the east and west. In the case of different window and ratio window to wall, the building energy consumption of No.6 window is the lowest. 4. Discussion In this paper, a model of in cold area is established through the DEST energy simulation software, and the important parameters which affect the building energy consumption are simulated. According to the simulation, the heat transfer coefficient of the wall and the thermal performance parameters of the window are established. This research has a great value. It can provide quantitative data support for the development of nearly zero building design in the cold area. According to the simulation results, the building has the lowest heating and cooling energy when the insulation thickness of outer wall is 300mm, and the corresponding heat transfer coefficient is 0.096W / (m2 • K). For the outer window, because of its heat loss and solar radiation heat double attribute, so heat transfer coefficient and the different orientation ratio window to wall was simulated and analyzed. The energy consumption of the building is the lowest when the heat transfer coefficient of the outer window is 0.780 W / (m2 • K), and the solar heat coefficient is 0.474. Building energy consumption achieve the lowest value when the south ratio window to wall is from 0.05 to 0.15. Building energy consumption increases with the rise of ratio window to wall. It is necessary to reduce the ratio window to wall to meet the premise of lighting in the east, west, and north. Based on the above analysis results, the final calculation results of the key design parameters about the wall thermal performance, outer window thermal performance and ratio window to wall are summarized. The key parameters index of building envelope energy - saving design are shown in Table 4.
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Guohui Feng et al. / Procedia Engineering 205 (2017) 686–693 Guohui Feng et al. / Procedia Engineering 00 (2017) 000–000
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Table 4. Key parameter values of nearly zero building envelope energy-saving design in severe cold area Key factor
Design
Wall
K=0.096 W/（m2 • K）
Outer window Ratio window to wall
K=0.780 W/（m2 • K）
SHGC=0.474 South: 0.05-0.15
East, west, north: meet the lighting requirements to take the minimum
5. Conclusions In this paper, the key factors of nearly zero building envelope energy-saving design are simulated and quantified. The results as follows. • The main energy efficiency design parameters of the nearly zero building in the cold area, the heat transfer coefficient of the wall is 0.096W/ (m2 • K). • The heat transfer coefficient of the outer window is 0.780W/ (m2 • K), and the solar thermal coefficient is not less than 0.474. • The parameters of ratio window to wall is from 0.15 to 0.25 in the south. In other directions, with the rise of ratio window to wall the building energy consumption is almost linear growth. Take the lowest value of east, west, and north ratio window to wall to meet the requirements of building lighting. Acknowledgements This paper is supported by “12th Five Year” national science and technology support program (2014BAJ01B04-2). References [1] B.X.Qiu, Development of energy saving and green building without delay, China Economic Weekly, 9 (2005) 11. [2] H.L.Meng, B.S.Chen, Energy efficiency technology of building windows, Huazhong Architecture, 27(8) (2009) 160-163. [3] S.C.Zhang, X.Chen, W.Xu, The research and practice of Nearly Zero Building, Construction Science and Technology, 22 (2014) 27-29. [4] S.Y.Zhou, The envelope energy efficiency technology influence on office building energy consumption in different climate zone, Tianjin University, (2012). [5] J.F.Tu, H.Su, X.G.Li, Analysis of influence of enclosure structure on building energy consumption in cold area, Clean and Air Conditioning Technology, 1 (2014) 65-67. [6] W.D.Long, Building energy efficiency and building energy efficiency management, China Construction Industry Press, (2005). [7] S.B.H.Puleo, R.P.Leslie, Some Effects of the Sequential Experience of Windows on Human Response, Journal of the Illuminating Engineering Society, 20(1) (1991) 91-99. [8] Y.Q.Pan, Practical building energy consumption simulation manual, China Construction Industry Press, (2013).