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Thickness of Building External Insulation in Chongqing Based on Intermittent Heating Supply
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) 2755–2761
10th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC2017, 1922 October 2017, Jinan, China
Thickness of Building External Insulation in Chongqing Based on Intermittent Heating Supply Yuchen Wang a,b,*, Mohamad Iskandar Joblic, Caidan Zheng a,b, Xiaokun Yang a,b, Ketong Li a,b Department of Building Environment and Energy Application Engineering, Chongqing Uni-versity, Chongqing 400045, China. National Centre for International Research of Low-carbon and Green Buildings, Ministry of Science & Technology, Chongqing University, Chongqing 400045, China. c School of the Built Environment, University of Reading, RG6 6AU, UK. a
b
Abstract It is a hot topic whether the choice of heating supply is necessary and what is the most suitable form of heating system for hot summer and cold winter regions. Apparently, the difference of climate and building envelope makes it a complex problem, which cannot rely on the northern heating measures directly. At the same time, the form of building envelope is closely related to energy consumption and indoor thermal environment. Thus, this paper looked at the importance of different thickness of building external insulation for residential building in Chongqing. This paper discussed the thickness of building external insulation in Chongqing based on the intermittent heating system, which used Dest to draw the conclusion. Economic and technical analyses were also carried out in order to find the balance point between the growth of cost and the amount of energy saving, due to the different form of building envelopes. © 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: building external insulation; Chongqing; thickness; residential building; Simulation; Dest
Nomenclature P I R
period of cost recovery, a total initial cost, CNY running cost, CNY
* Corresponding author. 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.2017.09.873
2756 2
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
1. Introduction The climate of Chongqing is known to be cold in winter and hot in summer. Nevertheless, the indoor thermal environment quality still needs to be improved. Regardless of huge energy consumption and human comfort in summer, the envelope in these areas cannot be the same as that in cold region. It is the form of building envelope that contributes a lot to the discomfort of human in these areas in winter. The average temperature in Chongqing is about 7.5°C, which is higher than the degree of -7.5°C in Bei Jing. Therefore, in order to improve the human comfort in winter, it’s a hot topic whether the choice of heating supply is necessary and what is the suitable form of heating system for these areas. From another perspective, taking human comfort and energy saving into consideration, we cannot only depend on heating measures, but also change the form of building envelope appropriately. Radiant floor heating system is popular because of the thermal comfort and energy saving. When it was applied to residential building in Chongqing, it showed that the room warmed up slowly and cooled down quickly when the heating system was turned off. The form of building external insulation con-tributes a lot to this phenomenon. So, this paper discusses the form of building external insulation in Chongqing based on intermittent heating system, which uses Dest to perform the simulation. The thickness of building external insulation is closely related to energy consumption and indoor thermal environment. If heat preservation and thermal insulating property of the building envelope perform well, the amount of heat loss in winter and heat gain in summer will be lowered significantly. The air-condition energy consumption accounts for almost 50% of the total consumption, among which, building envelope takes 20% to 50% [1]. On one hand, it has a big effect on energy saving. On the other hand, the thermal radiation of building envelope has a significant influence on human thermal comfort. We should reduce energy consumption based on the premise of human thermal comfort. 2. The Simulation Model The simulation model was established using Dest, which was based on a real residential building in Jiang Jin (Chongqing). This experiment platform was a residential building, with an area of 85 ㎡, in Chongqing. It was in north orientation, with 2 bedrooms and 1 living room. It used household gas fireplace as its air-condition system. Intermittent heating was carried out in this building. The single housing type and model are shown as Fig.1 & Fig.2.
Fig.1. House type
Fig.2. Model
The balcony was similar to an open space, which was constructed without windows and the opening area took more than 60% of the facade area. In this way, when modelling the building, the author ignored the balcony, which is shown in Fig.2. The whole building is in Fig.3.
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2757 3
Fig.3. The whole building
This paper conducted the simulation based on the whole building. The other building envelope parameters in Chongqing were as follows: Table 1. Building envelope parameters in Chongqing External wall Internal wall Roof Floor Window Door
Composition Plasterer(5mm)+EPS(30mm)+ Plasterer(20mm)+ Shale cavity brick(200mm)+ Plasterer(20mm) Plasterer(20mm) + Shale cavity brick(200mm)+ Plasterer(20mm) Crushed stone concrete(40mm)+ Plasterer(20mm)+ EPS(40mm)+ Plasterer(20mm)+ Reinforced concrete(120mm) Crushed stone concrete(30mm)+ Reinforced concrete(100mm) 6+9A+6 Wood based door
Taking practical situation into consideration, the operation schedule of the conditioning system was based on the masters’ working hours, where 8:00~12:00am and 14:00~18:00pm being excepted [2].The conditions operated during the rest time in the heating season. The operation schedule was as follows.
Fig.4 The operation schedule
In this simulation, the highest heating temperature was defined at 26℃, while the lowest temperature was at 16℃. These figures confirmed to standard requirements and practical situation. Thus, the author did not change the default value. Thermal disturbance caused by equipment, person and light were considered into this simulation.
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2758 4
3. Result Analysis 3.1. Load and energy consumption during the whole year In order to find out the effect on energy consumption and load over the whole year, this paper performed simulation based on 5 sets of thickness of building external insulation, which were known as 0mm, 30mm (The actual situation), 50mm, 80mm and 100mm. The wall structure is as mentioned above. Based on the result of the simulation, the differences caused by the thickness of building external insulation are significant. Air conditioning load over the whole year per unit area is as follows. It is obvious that thickness of building external insulation has a more remarkable impact on heating load than that on cooling load in summer.
(a) Air conditioning load over the whole year（0mm）
(b) Air conditioning load over the whole year（30mm）
(c) Air conditioning load over the whole year（50mm）
(d) Air conditioning load over the whole year（80mm）
Fig.5 Air conditioning load over the whole year.
This difference of heating and cooling load indicates the change of energy consumption. Then, this paper analyses the energy consumption with Dest. The result is shown in Fig.6. It should be pointed out that it is identified as split type air conditioner during summer.
Fig.6. Energy consumption over the whole year
It comes to a conclusion that, with the increase of thickness, the energy consumption over the whole year reduces, especially in winter. Therefore, it is a good choice to thicken building external insulation in order to reduce energy
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2759 5
consumption. From another perspective, building external insulation has a significant influence on energy saving in winter. 3.2. Economic and technical analysis • Growth of cost caused by thickness of building external insulation Given that this residential building uses EPS as its basis of building external insulation, this paper mainly discusses sets of thickness of EPS. It is cheaper than XPS and widely used in Chongqing in recent years. On one hand, the thickness makes the cost change. On the other hand, the cost of household gas fireplace is also different when different structure is used in the project. Then, this paper analysis the cost of building external insulation by construction evaluation. The cost of EPS is about ￥400 per unit volume [3]. The volume of external insulation is shown in the following table.2. Table.2. Vertical Envelope Orientation East South West North Total
Area(㎡) 412.27 449.28 412.27 351.37 1625.19
With the growth of thickness, the cost increases rapidly. However, the cost of household gas fireplace also changes when the load of the building is different. Additionally, it is also related to the form of building envelope. The results are shown in the table 3 and Fig 8 below. Table.3. Total cost (10� yuan) Thickness(mm) 0 30 50 80 100
Building envelope 0 1.95 3.25 5.20 6.50
Initial cost of equipment 4.37 1.97 1.37 0.92 0.75
Total 4.37 3.92 4.62 6.12 7.25
Fig.7. Total cost
Apparently, the lowest point of the total initial cost is around 20mm to 40mm. The initial cost of equipment declines with the increase of building envelope cost due to increased insulation thickness. The thicker the external insulation, the lower installed capacity is. It means that the energy consumption is lowered down, and the building is good at heat
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2760 6
insulation. On the contrary, the cost of building envelope goes up significantly. In this case, it is necessary to find a better choice of thickness. • Period of cost recovery Within the service life time of buildings, operating cost should also be considered into economic analysis. When this step has been done, we can draw a reasonable conclusion. According to the result of simulation, the running cost is shown as Fig.9. The running cost was calculate based on energy charge and depreciation cost. Period of cost recovery is calculated by using the following formula: ��
I �
(1)
Where P is the period of cost recovery (a), I is the total initial cost (CNY) and R is the running cost (CNY).
Fig.8. Period of cost recovery
When the thickness is about 20mm to 50mm, the period of cost recovery is shorter than other range of thickness. This result is similar to the total initial cost mentioned above. 4. Conclusion In conclusion, when the economic and technical analyses have been performed, the conclusions are as follows: • The reasonable range of thickness is around 30mm in Chongqing when household gas fire-place is used in residential building. This project just uses an appropriate thickness of building external insulation. • The energy consumption decreases when the thickness of building external insulation in-creases. When the value of thickness is less than 50mm, the energy saving result is apparent. • When the thickness reaches more than 50mm, the period of cost recovery becomes longer. Additionally, the incremental cost, which takes equipment cost and building envelope into consideration, is lower when the thickness is around 20mm to 40mm. • This paper did not consider the thickness from various orientation [4]. It is also a meaningful perspective in real project. Also, this paper did not discuss other system forms. Acknowledgements The authors would like to thank International Science & Technology Cooperation Program of China. This work was supported by the key Technologies for Terminal Distributed Heating Systems in Yangtze River Basin, No.2014DFA62970.
Yuchen Wang / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et alet/al. Procedia Engineering 00 (2017) 000–000
27617
References [1] W. Fan, Economic technique analysis about energy conservation of building envelope in hot summer and cold winter zone, Master’s degree, ZheJiang University, China Zhejiang, 2008. [2] C T. Xu, The impact on the indoor thermal environment and building energy consumption based on the study of external envelope in residential building, Master’s degree, Chongqing University, China Chongqing, 2008. [3] H.H. Wang, W.W. Wu, The optimization analysis of the insulation thickness of the exterior wall in residential building, Journal of ChongQing University. 08 (2008) 937-941. [4] B.G. Ma, M. Li. The study on energy saving 65% of building envelope in hot summer and cold winter zone in residential building, Wall material innovation and building energy saving. 11 (2008) 46-48+4.
ScienceDirect
Available online at www.sciencedirect.com Procedia Engineering 00 (2017) 000–000
ScienceDirect
www.elsevier.com/locate/procedia
Procedia Engineering 205 (2017) 2755–2761
10th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC2017, 1922 October 2017, Jinan, China
Thickness of Building External Insulation in Chongqing Based on Intermittent Heating Supply Yuchen Wang a,b,*, Mohamad Iskandar Joblic, Caidan Zheng a,b, Xiaokun Yang a,b, Ketong Li a,b Department of Building Environment and Energy Application Engineering, Chongqing Uni-versity, Chongqing 400045, China. National Centre for International Research of Low-carbon and Green Buildings, Ministry of Science & Technology, Chongqing University, Chongqing 400045, China. c School of the Built Environment, University of Reading, RG6 6AU, UK. a
b
Abstract It is a hot topic whether the choice of heating supply is necessary and what is the most suitable form of heating system for hot summer and cold winter regions. Apparently, the difference of climate and building envelope makes it a complex problem, which cannot rely on the northern heating measures directly. At the same time, the form of building envelope is closely related to energy consumption and indoor thermal environment. Thus, this paper looked at the importance of different thickness of building external insulation for residential building in Chongqing. This paper discussed the thickness of building external insulation in Chongqing based on the intermittent heating system, which used Dest to draw the conclusion. Economic and technical analyses were also carried out in order to find the balance point between the growth of cost and the amount of energy saving, due to the different form of building envelopes. © 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: building external insulation; Chongqing; thickness; residential building; Simulation; Dest
Nomenclature P I R
period of cost recovery, a total initial cost, CNY running cost, CNY
* Corresponding author. 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.2017.09.873
2756 2
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
1. Introduction The climate of Chongqing is known to be cold in winter and hot in summer. Nevertheless, the indoor thermal environment quality still needs to be improved. Regardless of huge energy consumption and human comfort in summer, the envelope in these areas cannot be the same as that in cold region. It is the form of building envelope that contributes a lot to the discomfort of human in these areas in winter. The average temperature in Chongqing is about 7.5°C, which is higher than the degree of -7.5°C in Bei Jing. Therefore, in order to improve the human comfort in winter, it’s a hot topic whether the choice of heating supply is necessary and what is the suitable form of heating system for these areas. From another perspective, taking human comfort and energy saving into consideration, we cannot only depend on heating measures, but also change the form of building envelope appropriately. Radiant floor heating system is popular because of the thermal comfort and energy saving. When it was applied to residential building in Chongqing, it showed that the room warmed up slowly and cooled down quickly when the heating system was turned off. The form of building external insulation con-tributes a lot to this phenomenon. So, this paper discusses the form of building external insulation in Chongqing based on intermittent heating system, which uses Dest to perform the simulation. The thickness of building external insulation is closely related to energy consumption and indoor thermal environment. If heat preservation and thermal insulating property of the building envelope perform well, the amount of heat loss in winter and heat gain in summer will be lowered significantly. The air-condition energy consumption accounts for almost 50% of the total consumption, among which, building envelope takes 20% to 50% [1]. On one hand, it has a big effect on energy saving. On the other hand, the thermal radiation of building envelope has a significant influence on human thermal comfort. We should reduce energy consumption based on the premise of human thermal comfort. 2. The Simulation Model The simulation model was established using Dest, which was based on a real residential building in Jiang Jin (Chongqing). This experiment platform was a residential building, with an area of 85 ㎡, in Chongqing. It was in north orientation, with 2 bedrooms and 1 living room. It used household gas fireplace as its air-condition system. Intermittent heating was carried out in this building. The single housing type and model are shown as Fig.1 & Fig.2.
Fig.1. House type
Fig.2. Model
The balcony was similar to an open space, which was constructed without windows and the opening area took more than 60% of the facade area. In this way, when modelling the building, the author ignored the balcony, which is shown in Fig.2. The whole building is in Fig.3.
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2757 3
Fig.3. The whole building
This paper conducted the simulation based on the whole building. The other building envelope parameters in Chongqing were as follows: Table 1. Building envelope parameters in Chongqing External wall Internal wall Roof Floor Window Door
Composition Plasterer(5mm)+EPS(30mm)+ Plasterer(20mm)+ Shale cavity brick(200mm)+ Plasterer(20mm) Plasterer(20mm) + Shale cavity brick(200mm)+ Plasterer(20mm) Crushed stone concrete(40mm)+ Plasterer(20mm)+ EPS(40mm)+ Plasterer(20mm)+ Reinforced concrete(120mm) Crushed stone concrete(30mm)+ Reinforced concrete(100mm) 6+9A+6 Wood based door
Taking practical situation into consideration, the operation schedule of the conditioning system was based on the masters’ working hours, where 8:00~12:00am and 14:00~18:00pm being excepted [2].The conditions operated during the rest time in the heating season. The operation schedule was as follows.
Fig.4 The operation schedule
In this simulation, the highest heating temperature was defined at 26℃, while the lowest temperature was at 16℃. These figures confirmed to standard requirements and practical situation. Thus, the author did not change the default value. Thermal disturbance caused by equipment, person and light were considered into this simulation.
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2758 4
3. Result Analysis 3.1. Load and energy consumption during the whole year In order to find out the effect on energy consumption and load over the whole year, this paper performed simulation based on 5 sets of thickness of building external insulation, which were known as 0mm, 30mm (The actual situation), 50mm, 80mm and 100mm. The wall structure is as mentioned above. Based on the result of the simulation, the differences caused by the thickness of building external insulation are significant. Air conditioning load over the whole year per unit area is as follows. It is obvious that thickness of building external insulation has a more remarkable impact on heating load than that on cooling load in summer.
(a) Air conditioning load over the whole year（0mm）
(b) Air conditioning load over the whole year（30mm）
(c) Air conditioning load over the whole year（50mm）
(d) Air conditioning load over the whole year（80mm）
Fig.5 Air conditioning load over the whole year.
This difference of heating and cooling load indicates the change of energy consumption. Then, this paper analyses the energy consumption with Dest. The result is shown in Fig.6. It should be pointed out that it is identified as split type air conditioner during summer.
Fig.6. Energy consumption over the whole year
It comes to a conclusion that, with the increase of thickness, the energy consumption over the whole year reduces, especially in winter. Therefore, it is a good choice to thicken building external insulation in order to reduce energy
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2759 5
consumption. From another perspective, building external insulation has a significant influence on energy saving in winter. 3.2. Economic and technical analysis • Growth of cost caused by thickness of building external insulation Given that this residential building uses EPS as its basis of building external insulation, this paper mainly discusses sets of thickness of EPS. It is cheaper than XPS and widely used in Chongqing in recent years. On one hand, the thickness makes the cost change. On the other hand, the cost of household gas fireplace is also different when different structure is used in the project. Then, this paper analysis the cost of building external insulation by construction evaluation. The cost of EPS is about ￥400 per unit volume [3]. The volume of external insulation is shown in the following table.2. Table.2. Vertical Envelope Orientation East South West North Total
Area(㎡) 412.27 449.28 412.27 351.37 1625.19
With the growth of thickness, the cost increases rapidly. However, the cost of household gas fireplace also changes when the load of the building is different. Additionally, it is also related to the form of building envelope. The results are shown in the table 3 and Fig 8 below. Table.3. Total cost (10� yuan) Thickness(mm) 0 30 50 80 100
Building envelope 0 1.95 3.25 5.20 6.50
Initial cost of equipment 4.37 1.97 1.37 0.92 0.75
Total 4.37 3.92 4.62 6.12 7.25
Fig.7. Total cost
Apparently, the lowest point of the total initial cost is around 20mm to 40mm. The initial cost of equipment declines with the increase of building envelope cost due to increased insulation thickness. The thicker the external insulation, the lower installed capacity is. It means that the energy consumption is lowered down, and the building is good at heat
Yuchen Wang et al. / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et al / Procedia Engineering 00 (2017) 000–000
2760 6
insulation. On the contrary, the cost of building envelope goes up significantly. In this case, it is necessary to find a better choice of thickness. • Period of cost recovery Within the service life time of buildings, operating cost should also be considered into economic analysis. When this step has been done, we can draw a reasonable conclusion. According to the result of simulation, the running cost is shown as Fig.9. The running cost was calculate based on energy charge and depreciation cost. Period of cost recovery is calculated by using the following formula: ��
I �
(1)
Where P is the period of cost recovery (a), I is the total initial cost (CNY) and R is the running cost (CNY).
Fig.8. Period of cost recovery
When the thickness is about 20mm to 50mm, the period of cost recovery is shorter than other range of thickness. This result is similar to the total initial cost mentioned above. 4. Conclusion In conclusion, when the economic and technical analyses have been performed, the conclusions are as follows: • The reasonable range of thickness is around 30mm in Chongqing when household gas fire-place is used in residential building. This project just uses an appropriate thickness of building external insulation. • The energy consumption decreases when the thickness of building external insulation in-creases. When the value of thickness is less than 50mm, the energy saving result is apparent. • When the thickness reaches more than 50mm, the period of cost recovery becomes longer. Additionally, the incremental cost, which takes equipment cost and building envelope into consideration, is lower when the thickness is around 20mm to 40mm. • This paper did not consider the thickness from various orientation [4]. It is also a meaningful perspective in real project. Also, this paper did not discuss other system forms. Acknowledgements The authors would like to thank International Science & Technology Cooperation Program of China. This work was supported by the key Technologies for Terminal Distributed Heating Systems in Yangtze River Basin, No.2014DFA62970.
Yuchen Wang / Procedia Engineering 205 (2017) 2755–2761 Yuchen Wang et alet/al. Procedia Engineering 00 (2017) 000–000
27617
References [1] W. Fan, Economic technique analysis about energy conservation of building envelope in hot summer and cold winter zone, Master’s degree, ZheJiang University, China Zhejiang, 2008. [2] C T. Xu, The impact on the indoor thermal environment and building energy consumption based on the study of external envelope in residential building, Master’s degree, Chongqing University, China Chongqing, 2008. [3] H.H. Wang, W.W. Wu, The optimization analysis of the insulation thickness of the exterior wall in residential building, Journal of ChongQing University. 08 (2008) 937-941. [4] B.G. Ma, M. Li. The study on energy saving 65% of building envelope in hot summer and cold winter zone in residential building, Wall material innovation and building energy saving. 11 (2008) 46-48+4.