GIS-Based Urban Elements Study and Its Rooftop Greenery Potential in NUS Campus

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1 473 GIS-Based Urban Elements Study and Its Rooftop Greenery Potential in NUS Campus S. K. Jusuf, N. H. Wong National University of Singapore, Singapore ABSTRACT Microclimate condition in an environment is influenced by the local environment condition. Urban morphology, especially building, pavement and greenery are the main factors. The ambient temperature in a built area located nearby a large park can be reduced with the average of 1.3 o C as compared with no park built environment. In other studies also show that area of urban elements (building, greenery and pavement) determines the temperature of a built environment. In the other study, it is found that urban heat island exists in National University of Singapore (NUS). Therefore, in order to further investigate on the NUS microclimate, building, pavement and greenery areas were quantified by means of Geographical Information System (GIS). In terms of building area, different types of building roofs were also recorded to provide data for possibility of rooftop greenery application. From the GIS extracted data, it shows that 55.10% of NUS Kent Ridge Campus is covered with greenery where dense greenery area along the Kent Ridge Road gives the highest greenery contribution. To increase the greenery area in the other area, such as in the faculties and residences area, the potential of rooftop greenery application was quantified. It is found that most of the NUS buildings are using flat roof, metal pitch roof and tile roof. If these roofs are fully utilized, there will be an increase of greenery area about close to 180,000 m 2. Priority of rooftop greenery application can be made according to the largest area of flat roof and metal roof zones for the purpose of budgeting and future planning. Keywords: GIS, urban elements, rooftop greenery potential, NUS Campus. 1. INTRODUCTION This paper is one of the paper series presented in this PALENC 2007 Conference by the authors. Planting of vegetation is one of the methods to reduce the high ambient temperature in an environment. From some of the studies (Chen, 2006; Jauregui, E., 1990/91; Kawashima, 1990/ 1991; Steiling, 2003; Wong, 2006), it is clear that the size or area of urban elements (build- ing, greenery and pavement) determines the temperature of a built environment. The larger the size of greenery area, the lower is the ambient temperature. However, having a large greenery area for a small development area may be a constraint. For example, Singapore is a small country where land becomes a constraint for future development and on the other hand, the natural reserves should not be opened for building development. One of the solutions available now is the application of rooftop greenery. Switzerland has just passed a bylaw that new buildings must be designed to relocate the green space covered by the building s footprint to their roofs. This applies even for existing buildings including historical buildings where 20% of their rooftops must be green up (City Farmer, 2003). The case of Switzerland is worth to be considered by the Singapore authority. This is the main goal to maintain the environmental quality in a good balance. To achieve this goal, there is a problem faced by the planners, especially for a bigger estate area. It is the lack of quantitative data on the greenery condition of their estate in maintaining or improving the greenery condition. Thus, it is impossible to set a framework or plan to improve the estate s environmental quality. This research is to develop a framework for planners to evaluate and to improve the greenery condition in their estate. The main tool in this study is Geographical Information System (GIS). GIS is a technology that is used to view and analyze data from a geographic perspective and can be an organization s overall information system framework. GIS links location to information and layers to give a better understanding of how it all interrelates. 2. METHODOLOGY This study is the extension of Singapore Urban Heat Island study (Wong, 2004) and part of the micro-scale Urban Heat Island study in National University of Singapore (NUS) Kent Ridge Campus. a. Quantifying the current greenery area. In order to easily analyze the greenery condition, NUS Kent Ridge Campus was divided into 11 zones. Basically, the zoning division is based on the roads as the boundary of the each zone, as listed below: PALENC Vol 1.indd 473 3/9/2007 1:25:23 µµ

2 474 2nd PALENC Conference and 28th AIVC Conference on Building Low Energy Cooling and 1. Zone 1 : University Cultural Centre (UCC) and Office of Estate & Development (OED) 2. Zone 2 : Sport & Recreation Centre (SRC) 3. Zone 3 : School of Design and Environment (SDE) and Faculty of Engineering 4. Zone 4 : University Hall (UH) and Yusof Ishak House (YIH) 5. Zone 5 : Faculty of Science 6. Zone 6 : Faculty of Art & Social Science (FASS) and Faculty of Law 7. Zone 7: King Edward VII (KE7), Institute of Materials Research and engineering (IMRE) and Singapore Synchrotron Light Source (SLSS) 8. Zone 8 : Eusoff Hall and Temasek Hall 9. Zone 9 : Kent ridge Hall (KRH) and Shears Hall (SH) 10. Zone 10: Institute for Infocomm Research (I2R) 11. Zone 11: Prince George s Park (PGP) In GIS, the NUS current site plan was extracted into three major aspects. They are greenery area, building area and pavement area. Shapefiles for these three areas were made in accordance with the data provided by Office Estate and Development (OED) NUS. The building area was calculated based on 2D plan area. Meanwhile, the 3D shapefiles for greenery and pavement areas were generated and calculated. b. Quantifying the potential of rooftop greenery In order to improve the area of greenery in different zones, application of rooftop greenery can be considered. Buildings in NUS are basically using 4 different roofing types and the sub types were made to find the potential of rooftop greenery application, listed as follows: 1. Flat roof, it was sub divided into: a. Flat roof b. Flat roof for cooling tower c. Flat roof for walkway d. Flat roof for staircase 2. Metal roof, it was sub divided into: a. Metal curve roof b. Metal pitched roof 3. Glass roof 4. Tile roof The sub division of the flat roof was made to reduce bias of the flat roof calculation. For example, flat roof which is used for cooling tower can not be used as rooftop greenery, thus it will not be counted as the potential for rooftop greenery and the other sub divisions were made for the ease of developing rooftop greenery strategy. These classifications were then assigned to the GIS shapefile of building roof types to calculate & analyze the potential of rooftop greenery. 3. RESULTS AND DISCUSSIONS a. Quantifying the current greenery condition Figure 1 shows the 11 greenery zoning in different colors. Roughly, it shows that some areas are densely populated with buildings, while the others are not. The calculated areas are listed in the Table 1 and shown in Figure 2. Zone 7 has the largest greenery area of 155, m 2 and followed by zone 4 of 111, m 2. However, this result may not represent the true condition since the zone divisions did not have the same area size. Thus, the ratio of building, pavement and greenery were calculated as listed in Table 1 and represented as percentage graph in Figure 3. Figure 1. Greenery zoning of NUS Kent Ridge Campus Table 1. Building pavement greenery area and ratio of current condition The ratio and proportion percentage are to give a clearer picture for the composition between the three elements building, pavement and greenery in each zone. It shows that zone 4 - UH and YIH has the largest greenery proportion followed by zone 7 KE7, IMRE & SSLS. For the building area proportion, zone 5 - Faculty of Science has the largest building proportion, followed by zone 9, KRH & SH. If the total proportion of building and pavement area are considered, zone 9 KRH & SH has the largest proportion, followed by zone 11 PGP. It is believed that large pavement and dense building arrangement will contribute to a higher ambient temperature. PALENC Vol 1.indd 474 3/9/2007 1:25:23 µµ

3 475 Table 2. Green rate calculation of current condition Figure 2. Building Pavement - Greenery Area b. Quantifying the potential of rooftop greenery The distribution of different roof applications can be seen in Figure 5. From Figure 6, it is clearly seen that in overall NUS buildings, the rooftop application is dominated by metal pitched roof 28.55%, flat roof 28.36%, and tile roof 27.03%. With the current technology, it is possible to have rooftop greenery on the metal roofing system. Thus, it will increase the potential of this application in NUS. Figure 3. Proportion of building pavement greenery area Green rate of each zone was also calculated to find the greenery contribution level to the overall NUS environment. Green rate is just simply the greenery area of each zone divided by the total NUS surface area, as seen in Figure 4 and Table 2. It is found that zone 7 - KE7, IMRE & SSLS has the highest greenery contribution of 10.75%, followed by zone 4 UH & YIH of 7.73%. The total greenery of current condition is 55.10% of total NUS surface area. Figure 5. Building roof types of NUS Kent Ridge Campus Figure 6. Percentage summary of rooftop application in different zones Figure 4. Green rate calculation of current condition There are two scenarios in this analysis. First scenario is to include flat roof, metal curve roof and metal pitched roof for the rooftop greenery application. The second scenario is to add flat roof walkway to the first scenario. The purpose to add flat roof walkway in the calculation is because it has a significant area, but it may not have a PALENC Vol 1.indd 475 3/9/2007 1:25:24 µµ

4 476 2nd PALENC Conference and 28th AIVC Conference on Building Low Energy Cooling and tremendous impact to the users or occupants as compared to the application for buildings. However, it is worth to be considered to improve the outdoor environment. In scenario 1, the significant increase of green rate can be found in zone 3 SDE & faculty of Engineering of 3.04% increase(see Table 4). It is because zone 3 has the largest flat roof and metal pitched roof area. The second highest increase is in zone 5 Faculty of Science of 2.27%. In total, by applying rooftop greenery, the in- crease of NUS green rate can be as high as 12.07%, thus increasing to 67.18% from 55.10%. The ratio of building, pavement and greenery is also increasing (see Table 5). In scenario 2, a further increase of green rate is occurring in zone 6 FASS and Law, because it has the largest flat roof walkway, increasing to 1.16% from 1.01% (see Table 6). Zone 5 Faculty of Science is increasing in green rate from 2.27% to 2.35%. Table 4. Green rate calculation of scenario 1 Table 5. Building pavement greenery area ratio of scenario 1 Table 6. Green rate calculation of scenario 2 PALENC Vol 1.indd 476 3/9/2007 1:25:24 µµ

5 477 Table 7. Building pavement greenery area ratio of scenario 2 By applying the rooftop greenery, the greenery area increases to 179,537.7 m 2. This is a very significant increase. From the strategic planning and budgeting point of view, this study provides a clear picture the area that should be given the priority. The priority of rooftop greenery application can be given to the largest area of flat roof and metal roof zones. It can be summarized in sequence as follows: 1. Zone 3 SDE and Faculty of Engineering 2. Zone 5 Faculty of Science 3. Zone 1 UCC & OED 4. Zone 6 FASS & Law 5. Zone 4 UH & YIH 6. Zone 2 SRC 7. Zone 7 - KE7, IMRE and SSLS 8. Zone 10 I2R 9. Zone 11 PGP 10. Zone 9 KRH and SH 11. Zone 8 Eusoff Hall and Temasek Hall 4. CONCLUSIONS In this study, the GIS and the green rate calculation show that 55.10% of the NUS Kent Ridge Campus area is covered with greenery. It is found that the dense greenery area along the Kent Ridge Road gives the highest greenery contribution. They are zone 7 - KE7, IMRE & SSLS (10.75%) and followed by zone 4 UH & YIH (7.73%). In the overall NUS buildings, the rooftop application is dominated by metal pitched roof 28.55%, flat roof 28.36%, and tile roof 27.03%. With the current technology, it is possible to have rooftop greenery on the metal roofing system. Thus, it will increase the potential of this application in NUS. By applying rooftop greenery, the greenery area increases up to 179,537.7 m 2. This is a very significant increase and worth to be considered. ACKNOWLEDGEMENT This research is supported by Department of Building, National University of Singapore. I would like to send my great appreciation to Office of Estate and Development, especially for Ms. Lina Goh and Mdm. Helen Yip in providing all of the supporting data. ABBREVIATIONS FASS : Faculty of Art & Social Science GIS : Geographical Information System IMRE : Institute of Materials Research and engineering I2R : Institute for Infocomm Research KE7 : King Edward VII KRH : Kent ridge Hall LT : Lecture Theater NUS : National University of Singapore OED : Office of Estate and Development PGP : Prince George s Park UCC : University Cultural Centre UH : University Hall SDE : School of Design and Environment SH : Shears Hall SLSS : Singapore Synchrotron Light Source SRC : Sport & Recreation Centre YIH : Yusof Ishak House REFERENCES Chen Yu and Wong Nyuk Hien. (2006). Thermal benefits of city parks. Energy and Buildings, 38, City Farmer. (2003). Urban Agriculture Notes. Rooftop Garden. Jauregui, E. (1990/91). Influence of a large urban park on temperature and convective precipitation in tropical city. Energy and Buildings, 15-16, Ong, B.L. (2003). Green plot ratio: an ecological measure for architecture and urban planning. Lansdcape and Urban Planning, 63, S. Kawashima. (1990/ 1991). Effect of vegetation on surface temperature in urban and suburban areas in winter, Energy and Buildings, 15 16, Streiling, S. and Matzarakis, A. (2003). Influence of single and small clusters of trees on the bioclimate of a city: a case study. Journal Arboriculture, 29 (6), Wong Nyuk Hien. (2004). Study of urban heat island in Singapore. Research report, National University of Singapore. Wong Nyuk Hien and Chen Yu. (2006). A comparison of two rooftop systems in tropical climates. 2 nd inta Conference Proceedings 2006, Jogjakarta, Indonesia. PALENC Vol 1.indd 477 3/9/2007 1:25:24 µµ