- Email: [email protected]
Form Finding of PV Roof Top Using Parametric Study
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 169 (2016) 416 – 421
4th International Conference on Countermeasures to Urban Heat Island (UHI) 2016
Form Finding of PV Roof Top Using Parametric Study Religiana Hendartia*, Firza Utama Sjarifudina a
Department of Architecture, Faculty of Engineering, Bina Nusantara University, KH Syahdan No.9 Kemanggisan, Jakarta 11480, Indonesia
Abstract It is acknowledged that roof top made of PV cell could improve the surrounding environment when it is compared to conventional roof top that made of concrete. PV cell can converts solar radiation into electricity and as the consequence the remaining heat is lesser than that of the concrete roof. Based on this principal theory, this study focused on investigating the level of irradiance of a roof top made of PV modules. The construction process of the PV modules was conducted through simulation and parametric study in order to obtain not only an optimum irradiance level, but also to create an aesthetic form. In order to facilitate that objective, this study consists of 3 steps: (1) to determine the required parameter, (2) to construct all the required parameter into an algorithm and (3) to execute the constructed algorithm. The initial flat roof form was used as the basic form. The results show that the average shaded area of the final form is only 3%. © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
© 2016 The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of organizing the organizing committee of the 4th IC2UHI2016. Peer-review under responsibility of the committee of the 4th IC2UHI2016 Keywords: parametric study; algorithm and irradiance
1. Introduction Photovoltaic (PV) module when it is mounted over concrete roof could improve the surrounding environment thermal condition by reducing its convective heat flux. The reduction occurs since the PV modules can convert the energy of the sunlight into electricity [1]. A simulation study has also shown that PV module could reduce the convective heat flux when it is compared to concrete surface, as the results of its capability to produce electricity by converting the energy of the sunlight through its cells [2]. Depart from this evidences, a simulation study of creating roof top made of PV module was conducted on a campus building whereas its initial roof top was made of concrete.
* Corresponding author. Tel.: +62-21-5345830; fax: +62-21-5300244. E-mail address: [email protected]
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 4th IC2UHI2016
doi:10.1016/j.proeng.2016.10.051
417
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
The study not only considered on how to harvest an optimum sunlight but also to achieve a favorable form of roof top. Recent developments in contemporary design tools have initiated new approaches of form finding based on parametric development of multiple geometries with simultaneous consideration of various aspects. Baerlecken et.al research project demonstrated a form finding approach which was based on defined parameters that not only to fulfill aesthetic and functional aspects, but also to take into account a simultaneous structural properties and the resulting sun shading behavior [3]. Form finding method could also be used to develop design method that generates an initial form for a shading structure [4]. The structure form can be defined by programmatic demands for a desired shaded area, based on several parameters. The initial form generation stage employs a custom designed algorithm to generate preliminary envelope. The study used similar form finding method, but the main parameters used in this study are the sun path diagram model and incident light vector in order to generate form. To facilitate this gap, a study using parametric method was conducted. The simulation used Grasshopper™ (parametric editor for Rhinoceros™). Essentially, parametric method in order to find a form of an architectural building applies several parameters in the design process where all the parameters contribute to the final form of a building or an element of a building, such as roof top. 2. Methodology In principle, the methodology conducted in this study was simulation that used Grasshopper and Ecotect. The Grasshopper was used to find an optimum form in harvesting the sunlight, while Ecotect was used to analyze the level of the incident light. There were four steps conducted in this study : (1) to define the most influence parameter to obtain maximum electricity production, (2) to construct the parameter in algorithm, (3) to execute the algorithm in the Grasshopper to obtain the desired roof form, and (4) to investigate the amount of incident light of the final form using Ecotect. In executing the algorithm into a form, an initial form was used. The initial form was a flat roof top that face to the East. This flat roof was then extruded and was directed to the East. This orientation was chosen as the main entrance of the building is facing East and in order to accommodate the rising sun. 2.1. Obtaining the required parameter In order to build the algorithm for constructing the PV roof form, essentially the primary principle was to obtain irradiance level as high as possible to produce electricity. This study, therefor, used following equation [5]:
P
E uK u A
(1)
The Equation 1 shows that the electricity production depends on the incident of light or irradiance level (E, in Wm), the efficiency of the solar panel (Ș) and the area of the solar panel (Ac, in m2). The first parameter depends on how the PV module is mounted and the sun path of a particular area. While, the other two parameters are essentially determined by factory. This study, therefore, only selected the Irradiance level as the main parameter in the algorithm.
2
2.2. The parametric method The step of the parametric method are as follows: (1) to create the solar position model using National Oceanic and Atmospheric Administration’s solar position calculator [6], and then, the code was ported into vb.net and was integrated into Grasshopper [7]; (2) to integrate the parametric model with the building project (Fig. 1(b)); (3) to determine the geometrical boundary in which the initial the roof form was used (Fig. 1(c)); (4) to simulate the incident light vector over the boundary condition and was followed by cutting the plane that perpendicular to the incident light (Fig. 1(d) and 1(e)).
418
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
a
b.
c
d
e Fig. 1. (a) the initial roof form that face to the East; (b) solar position model points and the building project; (c) the geometrical boundary; (d) incident light vector over the building; (e) cutting plane created that perpendicular to the incident light vector
3. Results and Discussion The resulted form is shown in Fig. 2. It can be analyzed that the surface is facing to two orientations, East and Northeast. It is essentially an expected form, as it is in line with the results from the Weather tool that the optimum orientation to harvest maximum sunlight is 77.5 degree (Fig. 3).
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
Fig. 2. The resulted surface form
Fig. 3. The optimum orientation for harvesting sunlight
Since the resulted roof form is still rough, a further step was taken for smoothing the form in Rhinoceros surface editor. Re-lofting technique was used to clean up rough edges. Initially, control point curves were created and projected onto the surface to acquire inner edges. Furthermore, the inner edges were simplified to minimize control point and to develop more seamless curve result, these curves were then used to create lofted surface and used as the final form. Fig. 4 shows the final form of the modified flat roof. 3.1. Irradiance level In order to calculate the potential electricity production, Ecotect was used to calculate the incident solar radiation. Table 1 shows the irradiance level and the average shaded area occurred on the final modified PV roof form.
419
420
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
Fig. 4. The final modified PV roof
Table 1. The resulted Irradiance level from Ecotect Month Roof A (Exposed area: 769.301 m2) Average Shade
Incident light (Wh/m2)
Jan
4%
126446
Feb
4%
109970
Mar
3%
141459
Apr
2%
136231
May
2%
138173
Jun
2%
130565
Jul
2%
142021
Aug
2%
150354
Sep
3%
151478
Oct
3%
145891
Nov
3%
124017
Dec
4%
119644
Total
1616250
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
It can be analyzed from the Table that between April and August the average shades are low, and as the consequence the Irradiance level is higher than the other months. These results are essentially the consequence from the orientation of the PV roof. 4. Conclusion A simulation study of constructing a PV roof form using parametric study has been conducted through several simulations. There two concluding remarks and are as follows: x The final modified roof top is essentially determined by the constructed algorithm and the local sun path. So that the main orientation of the modified roof form is 77.5 degree from North. x As the consequences from the first point, the average shade reaches its minimum between April and August. On the other hand, the irradiance level reaches its maximum as compared to the other months.
References [1] Jones, A.D. and Underwood, C.P., A thermal model for photovoltaic systems, Journal of Solar Energy (2001), vol. 70, pp. 349-359, [2] Hendarti, R., Wong, N.Y., Reindl, T., Yok, T.P., Chan, W.L., Integrated Photovoltaic and greenery for roof top as potential form for sustainable architecture element in the tropics, Proceeding of Kalam-UTM Conference: Bridging the old and new toward future sustainable Built Environment, Johor-Malaysia, 5-7th November 2012. [3] Baerlecken, M. Manegold, J. Reitz, A. Kuenstler., Integrative parametric Form-finding Process, New Frotiers: proceedings of the 15th CAADRIA International Conference, 2010, 303-312, Hong Kong. [4] Y.J. Grobman, R. Ron., Digital Form Finding: Generative use of simulation processes by architect in the early stages of the design process, Proceeding of the 29th eCAADe: City Modeling, 107-115, 2011. [5] Duffie, A.J. ;Beckman, W.A., Solar engineering of thermal processes, Wiley: Hoboken, New Jersey, 2006. [6] NOAA ESRL Solar position Calculator. Available: http://www.srrb.noaa.gov/highlights/sunrise/azel.html., retrieved at 8 December 2015. [7] Incident solar / Analemma, http://www.tedngai.net/?p=270 ., retrieved at 15 December 2015.
421
ScienceDirect Procedia Engineering 169 (2016) 416 – 421
4th International Conference on Countermeasures to Urban Heat Island (UHI) 2016
Form Finding of PV Roof Top Using Parametric Study Religiana Hendartia*, Firza Utama Sjarifudina a
Department of Architecture, Faculty of Engineering, Bina Nusantara University, KH Syahdan No.9 Kemanggisan, Jakarta 11480, Indonesia
Abstract It is acknowledged that roof top made of PV cell could improve the surrounding environment when it is compared to conventional roof top that made of concrete. PV cell can converts solar radiation into electricity and as the consequence the remaining heat is lesser than that of the concrete roof. Based on this principal theory, this study focused on investigating the level of irradiance of a roof top made of PV modules. The construction process of the PV modules was conducted through simulation and parametric study in order to obtain not only an optimum irradiance level, but also to create an aesthetic form. In order to facilitate that objective, this study consists of 3 steps: (1) to determine the required parameter, (2) to construct all the required parameter into an algorithm and (3) to execute the constructed algorithm. The initial flat roof form was used as the basic form. The results show that the average shaded area of the final form is only 3%. © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
© 2016 The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of organizing the organizing committee of the 4th IC2UHI2016. Peer-review under responsibility of the committee of the 4th IC2UHI2016 Keywords: parametric study; algorithm and irradiance
1. Introduction Photovoltaic (PV) module when it is mounted over concrete roof could improve the surrounding environment thermal condition by reducing its convective heat flux. The reduction occurs since the PV modules can convert the energy of the sunlight into electricity [1]. A simulation study has also shown that PV module could reduce the convective heat flux when it is compared to concrete surface, as the results of its capability to produce electricity by converting the energy of the sunlight through its cells [2]. Depart from this evidences, a simulation study of creating roof top made of PV module was conducted on a campus building whereas its initial roof top was made of concrete.
* Corresponding author. Tel.: +62-21-5345830; fax: +62-21-5300244. E-mail address: [email protected]
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 4th IC2UHI2016
doi:10.1016/j.proeng.2016.10.051
417
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
The study not only considered on how to harvest an optimum sunlight but also to achieve a favorable form of roof top. Recent developments in contemporary design tools have initiated new approaches of form finding based on parametric development of multiple geometries with simultaneous consideration of various aspects. Baerlecken et.al research project demonstrated a form finding approach which was based on defined parameters that not only to fulfill aesthetic and functional aspects, but also to take into account a simultaneous structural properties and the resulting sun shading behavior [3]. Form finding method could also be used to develop design method that generates an initial form for a shading structure [4]. The structure form can be defined by programmatic demands for a desired shaded area, based on several parameters. The initial form generation stage employs a custom designed algorithm to generate preliminary envelope. The study used similar form finding method, but the main parameters used in this study are the sun path diagram model and incident light vector in order to generate form. To facilitate this gap, a study using parametric method was conducted. The simulation used Grasshopper™ (parametric editor for Rhinoceros™). Essentially, parametric method in order to find a form of an architectural building applies several parameters in the design process where all the parameters contribute to the final form of a building or an element of a building, such as roof top. 2. Methodology In principle, the methodology conducted in this study was simulation that used Grasshopper and Ecotect. The Grasshopper was used to find an optimum form in harvesting the sunlight, while Ecotect was used to analyze the level of the incident light. There were four steps conducted in this study : (1) to define the most influence parameter to obtain maximum electricity production, (2) to construct the parameter in algorithm, (3) to execute the algorithm in the Grasshopper to obtain the desired roof form, and (4) to investigate the amount of incident light of the final form using Ecotect. In executing the algorithm into a form, an initial form was used. The initial form was a flat roof top that face to the East. This flat roof was then extruded and was directed to the East. This orientation was chosen as the main entrance of the building is facing East and in order to accommodate the rising sun. 2.1. Obtaining the required parameter In order to build the algorithm for constructing the PV roof form, essentially the primary principle was to obtain irradiance level as high as possible to produce electricity. This study, therefor, used following equation [5]:
P
E uK u A
(1)
The Equation 1 shows that the electricity production depends on the incident of light or irradiance level (E, in Wm), the efficiency of the solar panel (Ș) and the area of the solar panel (Ac, in m2). The first parameter depends on how the PV module is mounted and the sun path of a particular area. While, the other two parameters are essentially determined by factory. This study, therefore, only selected the Irradiance level as the main parameter in the algorithm.
2
2.2. The parametric method The step of the parametric method are as follows: (1) to create the solar position model using National Oceanic and Atmospheric Administration’s solar position calculator [6], and then, the code was ported into vb.net and was integrated into Grasshopper [7]; (2) to integrate the parametric model with the building project (Fig. 1(b)); (3) to determine the geometrical boundary in which the initial the roof form was used (Fig. 1(c)); (4) to simulate the incident light vector over the boundary condition and was followed by cutting the plane that perpendicular to the incident light (Fig. 1(d) and 1(e)).
418
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
a
b.
c
d
e Fig. 1. (a) the initial roof form that face to the East; (b) solar position model points and the building project; (c) the geometrical boundary; (d) incident light vector over the building; (e) cutting plane created that perpendicular to the incident light vector
3. Results and Discussion The resulted form is shown in Fig. 2. It can be analyzed that the surface is facing to two orientations, East and Northeast. It is essentially an expected form, as it is in line with the results from the Weather tool that the optimum orientation to harvest maximum sunlight is 77.5 degree (Fig. 3).
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
Fig. 2. The resulted surface form
Fig. 3. The optimum orientation for harvesting sunlight
Since the resulted roof form is still rough, a further step was taken for smoothing the form in Rhinoceros surface editor. Re-lofting technique was used to clean up rough edges. Initially, control point curves were created and projected onto the surface to acquire inner edges. Furthermore, the inner edges were simplified to minimize control point and to develop more seamless curve result, these curves were then used to create lofted surface and used as the final form. Fig. 4 shows the final form of the modified flat roof. 3.1. Irradiance level In order to calculate the potential electricity production, Ecotect was used to calculate the incident solar radiation. Table 1 shows the irradiance level and the average shaded area occurred on the final modified PV roof form.
419
420
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
Fig. 4. The final modified PV roof
Table 1. The resulted Irradiance level from Ecotect Month Roof A (Exposed area: 769.301 m2) Average Shade
Incident light (Wh/m2)
Jan
4%
126446
Feb
4%
109970
Mar
3%
141459
Apr
2%
136231
May
2%
138173
Jun
2%
130565
Jul
2%
142021
Aug
2%
150354
Sep
3%
151478
Oct
3%
145891
Nov
3%
124017
Dec
4%
119644
Total
1616250
Religiana Hendarti and Firza Utama Sjarifudin / Procedia Engineering 169 (2016) 416 – 421
It can be analyzed from the Table that between April and August the average shades are low, and as the consequence the Irradiance level is higher than the other months. These results are essentially the consequence from the orientation of the PV roof. 4. Conclusion A simulation study of constructing a PV roof form using parametric study has been conducted through several simulations. There two concluding remarks and are as follows: x The final modified roof top is essentially determined by the constructed algorithm and the local sun path. So that the main orientation of the modified roof form is 77.5 degree from North. x As the consequences from the first point, the average shade reaches its minimum between April and August. On the other hand, the irradiance level reaches its maximum as compared to the other months.
References [1] Jones, A.D. and Underwood, C.P., A thermal model for photovoltaic systems, Journal of Solar Energy (2001), vol. 70, pp. 349-359, [2] Hendarti, R., Wong, N.Y., Reindl, T., Yok, T.P., Chan, W.L., Integrated Photovoltaic and greenery for roof top as potential form for sustainable architecture element in the tropics, Proceeding of Kalam-UTM Conference: Bridging the old and new toward future sustainable Built Environment, Johor-Malaysia, 5-7th November 2012. [3] Baerlecken, M. Manegold, J. Reitz, A. Kuenstler., Integrative parametric Form-finding Process, New Frotiers: proceedings of the 15th CAADRIA International Conference, 2010, 303-312, Hong Kong. [4] Y.J. Grobman, R. Ron., Digital Form Finding: Generative use of simulation processes by architect in the early stages of the design process, Proceeding of the 29th eCAADe: City Modeling, 107-115, 2011. [5] Duffie, A.J. ;Beckman, W.A., Solar engineering of thermal processes, Wiley: Hoboken, New Jersey, 2006. [6] NOAA ESRL Solar position Calculator. Available: http://www.srrb.noaa.gov/highlights/sunrise/azel.html., retrieved at 8 December 2015. [7] Incident solar / Analemma, http://www.tedngai.net/?p=270 ., retrieved at 15 December 2015.
421