Embodied energy and CO 2 emissions of building materials for residential buildings in Jakarta and Bandung, Indonesia

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1 Embodied energy and CO 2 emissions of building materials for residential buildings in Jakarta and Bandung, Indonesia Usep Surahman, Dr Osamu Higashi, Dr Tetsu Kubota, Dr [Indonesia University of Education] [Hiroshima University] [Hiroshima University] ABSTRACT The objective of this study is to evaluate the current building material stock and future demolition waste for urban houses using a material-flow analysis in Jakarta and Bandung. Their embodied energy and CO 2 emissions are also analyzed by using an input-output analysis method. The actual on-site building measurements were conducted in Jakarta (2012) and Bandung (2011), focusing on unplanned houses, to obtain building material inventory data. A total of 297 and 247 houses were investigated in Jakarta and Bandung, respectively. These houses were generally classified into the following three categories: simple (45%), medium (39%) and luxurious houses (16%). The results show that overall, the averaged material quantity per m 2 used for the houses is 2.14 ton/m 2 in Jakarta and 2.06 ton/m 2 in Bandung. Two scenarios with zero and maximum reuse/recycling rates were designed to predict future demolition waste and embodied energy/co 2 emissions of building materials in Jakarta. Closed- and open-loop material flows were applied. The maximum reuse/recycling rates not only decrease material waste ( ton/m 2 ) but also their embodied energy ( GJ) and CO 2 emissions ( ton CO 2 -eq). In contrast, the minimum reuse/recycling rates increase environmental burden, and the expansion of unplanned houses is anticipated to cause further urban sprawls and drastic land-use changes by INTRODUCTION One of the obstacles to analyze embodied energy and CO 2 emissions of building materials in developing countries such as in Indonesia is considered to be relatively poor data availability of life cycle building materials from material input to material output (waste) including construction and demolition waste (C&D). The majority of urban housing stocks in Indonesia are unplanned houses. These houses are not designed and constructed in a formal way. Therefore, there is a serious lack of building material inventory data which are required for the analysis of material flow and their embodied energy/co 2 emissions. This study analyzes flow of building materials and their embodied energy/co 2 emissions for urban houses in Indonesia, focusing on unplanned houses, through the material-flow analysis and the inputoutput (I-O) analysis methods. The actual on-site building measurements were conducted in Jakarta (2012) and Bandung (2011), to investigate building material inventory. The current status of material stock was evaluated. Further, life-cycle material flows, focusing on demolition waste and their embodied energy/co 2 emissions of urban houses are predicted in different scenarios with various reuse/recycling rates. Usep Surahman is a lecturer in the Faculty of Technology and Vocational Education, Indonesia University of Education, Bandung, Indonesia. Osamu Higashi and Tetsu Kubota are associate professors in the Graduate School for International Development and Cooperation, Hiroshima University, Hiroshima, Japan. 1

2 METHODOLOGY Case study cities and houses Jakarta and Bandung were selected as case study cities. Jakarta, the capital city, had a population of 9.99 million in 2012 (Jakarta, 2013) while that of Bandung had 2.45 million as of 2012 (Bandung, 2013). Both cities experience hot and humid tropical climates. However, the monthly average temperature in Bandung ( ºC) is not as high as Jakarta ( ºC) because of its relatively high altitude. On average, Bandung and Jakarta are located at 791 and 7 m above the sea level, respectively. In most of the major cities in Indonesia, unplanned houses called Kampungs account for the largest proportion of the existing housing stocks. These dwellings settled in unplanned and overcrowded urban villages without being provided with basic urban infrastructure and services properly. These unplanned houses accounted for about 74% of the total housing stocks in Jakarta as of 2012 (Jakarta, 2013) and about 89% in the case of Bandung (Bandung, 2013). Moreover, these unplanned houses can be further classified into three house categories based on its construction cost and lot size, namely simple, medium, and luxurious houses (Figure 1) having a lifespan of 20, 35, and 50 years, respectively (SNI, 1989). A total of 297 and 247 residential buildings were investigated in Jakarta and Bandung, respectively (see Table 1). As shown, the average household size is about 4-5 persons with a small variation between the three categories for both cities. The monthly average household income was also investigated by a multiple-choice question. As expected, the average income increases with house category from simple to luxurious houses. In general, the average income in Jakarta is slightly higher than that of Bandung. The total floor area also increases with house category in both of the cities. The major building materials used are found to be almost the same in both cities among the above three house categories, though slight differences can be seen in terms of materials for floor and roof. Current material stock in urban residential buildings The limitations of data for building, economy and environment in Indonesia make it difficult to clarify the current material stock in urban residential buildings, and to design and implement concrete policies to deal with the issues of C&D waste management. In this study, firstly, we attempt to evaluate a) the current building material stock in urban residential buildings in Jakarta and Bandung at the city level respectively, b) the future demolition waste in unplanned urban houses, and c) the future urban expansion due to demolition of unplanned houses in both of the cities, based on the survey results. The mathematical equations used to estimate the current material stock for urban houses are described as follows. In this analysis, it is assumed that 1) the number of housing stocks are equal with the number of households determined by number of populations and household size, 2) the income distribution in urban settlement areas of Jakarta and Bandung is the same as the status of whole Jakarta city assuming that low, middle and high income people live in simple, medium and luxurious houses, respectively. (1) ( ) (2) (a) (b) (c) Figure 1 Views of sample residential buildings. (a) Simple house; (b) Medium house; (c) Luxurious house 2

3 Table 1 Brief profile of sample houses in Jakarta and Bandung Jakarta Bandung Simple Medium Luxurious Simple Medium Luxurious Sample size (unplanned/planned) 125 (125/0) 115 (75/40) 57 (29/28) 120 (120/0) 99 (99/0) 28 (28/0) Household size (persons) Household income (%) < 100 (USD) > Total floor area (%) <50 (m 2 ) > Major building materials (%) Structure Concrete Foundation Stonene Concrete Floor Cement Ceramic Walls Clay brick Con-block Roof Clay roof Concrete roof Zinc roof Asbestos roof Source: Building material inventory surveys in Jakarta (2012) and Bandung (2011) (1) (3) (4) Where, TS: current total material stock of urban houses (kg), S i,j : stock of material i, included in the house type j (kg/house), subscript i: materials shown in Table 3, subscript j: house type (simple, medium and luxurious) shown in Figure 1, and H j : number of house type j, i : the density of material i (kg/m 3 ) shown in Table 3, PI i,j : volume of primary material i input for each type of house for production activities (m 3 ), MI i,j : maintenance volume of material i for each type of house (m 3 ), : share of population living in urban houses among the total population (Jakarta: 0.74; Bandung: 0.89), j: current income distribution (low income (living in simple houses): 0.75, medium income (living in medium houses): 0.20, high income (living in luxurious houses): 5) (Mizuho, 2010), TP: total population in 2012, : averaged household size for each type of houses, SA i,j : stock of material i per unit gross floor area in house type j (kg/m 2 ), F j : averaged gross floor area in house type j (m 2 ). The mathematical equations used to estimate demolition waste from unplanned houses until 2020 are described as follows. In this analysis, we only focus on the demolition waste, generated from the current material stock, estimated by Equation (1). It is assumed that 1) the predicted population of Jakarta and Bandung would be 11.6 and 2.9 million in 2020 (UN, 2011), 2) the share of each type of houses in unplanned residential buildings will be changed in proportion to the significant change in income level; 4% for high, 73% for medium and 23% for low income class (JETRO, 2011), 3) the medium and luxurious houses will not be demolished until 2020, based on the assumption of 2) and buildings life-spans (i.e. medium houses: 35 years, luxurious houses: 50 years), 4) zero reuse/recycling rates of each material. (5) (6) 3

4 Where, TW: total demolition waste from unplanned residential buildings until 2020 (kg), W i,simple : demolition waste of material i from a simple house (kg) (equal with material stock of simple houses), simple: demolition ratio of simple houses by 2020, S i,simple : stock of material i, included in a simple house (kg), : income distribution of low income group in 2020 (0.23), WA i,simple : demolition waste i per unit gross floor area in a simple house (kg/m 2 ), F simple : average gross floor area of a simple house (m 2 ). The mathematical equations used to estimate the urban expansion caused by the demolition of unplanned simple houses and the transformation from these simple houses to larger medium houses by 2020 are described as follows. In this analysis, it is assumed that all the demolished simple houses will be reconstructed to be medium houses in the same cities. (7) ( ) (8) Where, FE: future urban expansion by 2020 (m 2 ), F medium : average gross floor area of a medium house (m 2 ). Flow of materials and their embodied energy/co 2 emissions for each type of houses Secondly, this paper analyzes the per-floor area flow of building materials and their embodied energy/co 2 emissions for each of the house categories by taking Jakarta for example. Embodied energy/co 2 emissions of building materials generally includes energy for productions in several phases, including material extraction, production, construction, maintenance, and demolition phases. However, construction and demolition phases were not considered in this paper due to the data unavailability. The design records such as building drawings are required for the analysis of embodied energy of building materials. These data were available for most of the planned houses and unplanned luxurious houses only. The other houses including most of the unplanned simple and medium houses were not constructed in the formal way (normally constructed by non-professional neighbors) and therefore the required design records could not be obtained. Thus, the actual on-site measurements by using laserdistance meters and tape measures were conducted for unplanned simple and medium houses in order to acquire the data. Since it was impossible to trace all the production processes for most of the building materials due to the data unavailability, this study adopted the I-O analysis-based method to calculate the embodied energy of materials and estimate their CO 2 emissions, which consistently followed the method described by Nansai et al. (2002). The latest Indonesian nationwide I-O table published in 2005 (Indonesia, 2005) consisting of 175 x 175 sectors was used for calculating the embodied energy/co 2 emissions, which was measured in the form of primary energy. The detailed procedures of the embodied energy/co 2 emissions were described in the previous paper (Surahman & Kubota, 2012). In this analysis, we assess the effects of policy of promoting reused and recycled material use through a scenario analysis. The first scenario (Scenario 1) assumes that both recycling and reuse rates are set to be zero (minimum) and the second scenario (Scenario 2) is designed under the assumption that both reuse and recycling rates for respective building materials are increased to the maximum values (see Table 2). The effects of the promotion of reused and recycled building materials use are evaluated through the comparison between two scenarios. The per-house material stock and demolition waste for respective house categories are estimated based on the following equations. ( ) (9) (10) 4

5 [ ( - - ) ( - - )] (11) Where, W i,j : demolition waste of material i from a house type j (kg/house), S i,j : stock of material i, included in a house type j (kg/house), RU i,j : reuse ratio of material i, applied to a house type j (as shown in Table 2), RC i,j : recycle ratio of material i, applied to a house type j (as shown in Table 2), TR i,j : treatment ratio of material i, applied to a house type j (assumed to be zero), WA i,j : demolition waste i per unit gross floor area of a house type j (kg/m 2 ), F j : average gross floor area of a house type j (m 2 ), (kg/house), : Stock of virgin material i in a house type j : reuse ratio of primary input (construction), : recycle ratio of primary input (construction), : reuse ratio of maintenance, : recycle ratio of maintenance. The potential reuse/recycling rates of building materials were studied from some references as shown in Table 2. RESULTS AND DISCUSSION Current building material stock This section discusses the current total material stock and future demolition waste in urban houses at the city level in Jakarta and Bandung. The current building material stocks in urban houses in two cities in 2012 were calculated utilizing Equations (1)-(4). Table 3 shows the composition of the current building material input, including those for maintenance, in the two cities. As shown, overall, the average material quantity per m 2 is 2.14 ton/m 2 in Jakarta and 2.06 ton/m 2 in Bandung. The average material quantity slightly varies among the different house categories in Jakarta and Bandung: 2.26 and 1.88; 2.06 and 2.23, and 2.05 and 2.26 ton/m 2 for simple, medium and luxurious houses, respectively. Overall, stone accounts for the largest percentage in Jakarta and Bandung (32% and 31%), followed by sand (31% and 30%), clay brick (19% and 19%), cement (8% and 8%), etc. The current total material stock in urban houses of Jakarta is measured at million ton, while that of Bandung was 77.2 million ton. The difference between the two cities is mainly due to the number of houses difference. Future demolition waste from unplanned residential buildings until 2020 If both reuse and recycling ratios are assumed to be zero, then the total demolition waste of unplanned houses (i.e. only simple houses) in Jakarta is found to be 41.5 million ton/m 2 until 2020 and all of them go to the landfills (Equations (5)-(7)). Meanwhile, the corresponding amount of waste in Bandung is predicted to be lower (12.6 million ton/m 2 ) due to less households of simple houses. This scenario will cause the waste to landfills would be very huge, thus results in the overload in the landfills. As a consequence, this scenario anticipates that both Jakarta and Bandung would be forced to construct new landfills to deal with the increased waste in the near future. Urban sprawl caused by the transformation from simple houses into medium houses Table 2 Potential reuse and recycling rates Materials Potential rate (%) Reuse Recycling Soil 100 a 0 a Stone 100 a 0 a Clay brick 10 a 90 a Concrete brick 0 a 0 a Cement 0 0 Sand 0 0 Steel 0 a 100 a Ceramic tile 0 a 0 a Clear glass 100 a 100 a Wood 50 a 50 a Gypsum 0 b 100 b Paint 0 0 Clay roof 100 a 100 a Concrete roof 100 a 0 a Asbestos roof 0 c 100 c Zinc roof 10 d 90 d a:(addis, 2006) b:(lund-nielsen, 2014) c:(cdra, 2014) d:(zinc sheet roofing, 2014) The future demolition of unplanned houses and the transformation of these houses to the larger medium houses by 2020 would cause the further urban expansions in both of the cities: at least, the additional area of 2 km 2 is required for the new constructions in Jakarta while the area of 5.7 km 2 is required in Bandung (Equation (8)). These expansions would accelerate urban sprawls. Scenario analysis: Policy effects of promoting reused/recycled materials use on reduction of building waste and embodied energy/co 2 emissions 5

6 Table 3 Current building material inventory (unit: kg/m 2 ) Materials Density Simple houses Medium houses Luxurious houses Whole sample (kg/m 3 )* Jakarta Bandung Jakarta Bandung Jakarta Bandung Jakarta Bandung 1. Stone 1, Clay brick Concrete brick 2, Cement 1, Sand 1, Steel 7, Ceramic tile 2, Clear glass 2, Wood Gypsum 1, Paint Clay roof 2, Concrete roof 2, Asbestos roof 2, Zinc roof 3, Total 2, , , , , , , ,063.6 *: (SNI, 1989) Scenario 1; zero reuse and recycling rates. The following section analyze the flow of building materials per-house for each of the house categories by taking Jakarta for example. As described before, we assess the effects of policy of promoting reused and recycled material use through scenario analysis. In this scenario (Scenario 1), the zero reuse/recycling rates are applied to all building materials used for a house. Figure 2 shows the results of flow analysis for average material input and output of urban houses in Jakarta utilizing zero reuse/recycling rates for whole sample as example. As shown, the total average material inputs including those for maintenance for whole sample ( B in the Figure 2) are derived from Table 3. A few materials are imported such as ceramics (37.5 kg/m 2 ) in the case of luxurious houses. There is no materials reused/recycled for other buildings/products ( E and F ) in this scenario. Thus, all materials go to the landfills ( G ). Equations (9)-(10) were used to calculate demolition waste for each of the house categories. The total average waste to landfills is larger than the average material input due to additional waste of soil derived from the surplus soil extracted in the construction phase ( C ), accounting for 2,931.1, 2,521.3, 2,371.5 and 2,665.1 kg/m 2 for simple, medium and luxurious houses as well as whole sample. Overall, mortar accounts for the largest material waste (23%), followed by soil (20%), stone foundation (17%), concrete (16%), clay brick (15%), etc. Scenario 2; maximum reuse and recycling rates. In this scenario (Scenario 2), we apply the maximum potential for reuse/recycling rates (see Table 2). Figure 3 shows the results of flow analysis of building material input and output for urban houses in Jakarta in Scenario 2 for whole sample. As shown, the total average material input including those for maintenance for respective houses in Jakarta are still the same as those in the Scenario 1 ( B in the Figure 3). However, some materials (589.9 kg/m 2 ) were reused for other buildings ( E ), including stone (77%), wood (11%), clay brick (7%), etc. Meanwhile, several materials (464.0 kg/m 2 ) are recycled ( F ), including clay bricks (79%), wood (13%), steel (6%), gypsum (1.5%) and zinc roof (0.5%). There is no material composted/burned ( I ). The rest of materials (soil, mortar, concrete, ceramic and asbestos) are assumed to be reclaimed to other products or infrastructure ( H ). The total waste used for reclamation accounts for 1,715.3, 1,596.3, 1,412.0 and 1,611.1 kg/m 2 for simple, medium and luxurious houses as well as whole sample. Overall, mortar accounts for the largest percentage (39%) followed by soil (32%), concrete (27%), and ceramic tile and asbestos (2%). These materials can not be reused/recycled for other building constructions due to difficulty of separation from mixed materials. Thus, it was found that closed-loop material flow is not enough to fully reclaim building materials and eliminatebuilding material waste to the landfills. Nevertheless, these materials can be reused/recycled by crushing them and used to reclaim for infrastructure such as road and building site. In this case, the total waste to the landfills would become zero. Figure 4 shows the average material waste of respective houses for both scenarios. As shown maximizing reuse/recycling rates would decrease the average material waste dramatically by 41%, 37% and 40% for simple, medium and luxurious houses, respectively. 6

7 Raw extraction Production Construction Operation Demolition (unit: kg/m 2 ) Raw extraction Production Construction Operation Demolition (unit: kg/m 2 ) A (2,144.3) F () B (2,144.3) E () C(520.8) E () F () D (63.4) H () G (2,665.1) A (1,090.3) F (464.05) B (2,144.3) E (589.95) C(520.8) E (589.95) F(464.05) D (63.4) G () H (1,611.1) Figure 2 Flow chart of average life cycle materials for whole sample (scenario 1) I () I () A= primary material input C=soil E=E =reused G=total landfill waste I=composting/burning B= total material input D=maintenance F=F =recycled H=reclamation for infrastructure/other products Figure 3 Flow chart of average life cycle materials for whole sample (scenario 2) Average Luxurious house Scenario 2 (maximum reuse/recy -40% - 27% cling rates) - 27% Scenario 1 (minimum Average material reuse/recy waste (ton/m²) - 27% -40% cling rates) - 27% Medium house - 37% - 28% - 28% Simple house -41% - 27% - 27% Mortar Soil Stone Clay brick Concrete Wood Concrete brickmortar Cement Sand Steel Ceramic tile Clear glass Gypsum Soil Paint Clay roof Concrete roof Asbestos roof Zinc roof Stone Figure 4 Average Clay material brick waste Figure 5 Embodied energy Figure 6 CO 2 emissions Concrete Wood Embodied energy Concrete and CO brick 2 emissions Cement Primary building Sand material inputs were obtained by utilizing Equation (11) for analyzing their Steel embodied energy/co Ceramic 2 tile emissions. The total embodied energy and CO 2 emissions were estimated by Clear glass combining initial, Gypsum maintenance and recycling embodied energy/co 2 emissions for respective houses Paint through previously Clay roof explained I-O analysis-based method. The potential energy saving through recycling Concrete roof was assumed about Asbestos 50% roof of embodied energy/co 2 emissions (Thornmark, 2002). Figures 5-6 show the total embodied Zinc energy/co roof 2 emissionsin the two scenarios (i.e. zero and maximum reuse/recycling rates). The results indicate that the reused/recycled materials reduce not only material waste but also diminish embodied energy/co 2 emissions. The maximum reuse/recycling ratesare expected to decrease embodied energy by 16.8 (27%), 58.1 (28%), (27%) and 58.6 (27%) GJ for simple, medium, luxurious and whole houses, respectively (Figure 5). Meanwhile, the reduction patterns of embodied CO 2 emissions are similar with those of embodied energy (Figure 6). The results of the above scenario analysis prove that the promotion of reuse/recycling are important to ensure the building material stocks and to reduce not only material waste but also their embodied energy/co 2 emissions. CONCLUSIONS Average material waste (ton/m²) Embodied energy (GJ) CO₂ emissions (ton CO₂-eq) This study analyzed flow of building materials and their embodied energy/co 2 emissions for urban houses in Indonesia, focusing especially on unplanned houses. The actual on-site building measurements were conducted in Jakarta (n=297) and Bandung (n=247) to investigate building material inventory. Overall, the average material quantity per m 2 was 2.14 ton/m 2 in Jakarta and 2.06 ton/m 2 in Bandung. 7

8 The average material quantity slightly varied among the different house categories in Jakarta/Bandung: 2.26/1.88, 2.06/2.23 and 2.05/2.26 ton/m 2 for simple, medium and luxurious houses, respectively. On average, the stone accounted for the largest percentage for all houses (32%/31%), followed by sand (31%/30%), clay brick (19%/19%), cement (8%/8%), etc. If both reuse and recycling rates are assumed to be zero, then the total demolition waste of unplanned simple houses in Jakarta was found to be 41.5 million ton/m 2 until 2020 and the corresponding waste in Bandung is predicted to be lower (12.6 million ton/m 2 ). All of them go to the landfills. Moreover, the transformation of these simple houses to the larger medium houses by 2020 would cause further urban expansion in both of the cities: at least, the additional area of 2 km 2 is required for the new construction in Jakarta, while the area of 5.7 km 2 is required in Bandung. A scenario analysis was conducted for Jakarta to assess the effects of policy of promoting reused and recycled material use. The two scenarios with the zero and maximum reuse/recycling rates were compared in the analysis. The results showed that maximizing reuse/recycling rates would decrease the average material waste dramatically by 37% to 41%. The promotion of reuse/recycling were proved to reduce embodied energy/co 2 emissions of building materials effectively (27% to 28%). The lack of policies for promoting 3Rs (reduce, reuse and recycling) specifically target C&D waste (Indonesia, 2008) at the national level is considered one of the crucial problems in Indonesia. The increase in larger landed houses would directly result in the rapid horizontal expansions of the cities, thus accelerates urban sprawls. Provision of mid-to-high-rise apartments to the growing middle class in the cities would be one of the effective housing policies for already crowded Indonesian cities. ACKNOWLEDGMENTS This research was supported by a JSPS Grant-in-Aid for Young Scientist (B) (No ). We also would like to thank Mr. Yohei Ito, Mr. Ari Wijaya, M.SI of Universitas Persada Indonesia, Dr. Hanson E. Kusuma of Institut Teknologi Bandung and the students who kindly supported our survey. REFERENCES Addis, B. (2006). Building with Reclaimed Components and Materials. A Design Handbook for Reuse and Recycling. Earthscan publishing, London, UK. Bandung. (2013). Bandung in Figures. Agency for the Centre of Statistic of West Java, Bandung. Construction and Demolition Recycling Association (CDRA). (2014). Asbestos in asphalt shingle. CDRA. Accessed 5 March Indonesia. (2005). Input-Output Table of Indonesia. Statistic Centre of Indonesia, Jakarta. Indonesia. (2008). Reuse and Recycling of Hazardous and Toxic Waste. The Act of the Republic of Indonesia Number 2 year Ministry of Environment, Jakarta. Jakarta. (2013). Jakarta in Figures. Statistical Centre of Jakarta, Jakarta. UN World Urbanization Prospect. United Nation, New York. JETRO. (2011). Market Investmen Attraction Indonesia. Japan External Trade Organization, Japan. Lund-Nielsen. (2014). Gypsum recycling. Gypsum Recycling International. Accessed 5 March Mizuho Research Institute. (2010). Expanding middle class as centre for the biggest consuming market in ASEAN (in Japanese). Journal of Mizuho Research Institute, Nansai, K., Moriguchi, Y., Tohno, S. (2002). Embodied Energy and Emission Intensity Data for Japan Using Input-Output Table (3EID)-Inventory Data for LCA-. National Institute for Environmental Studies, Japan. SNI. (1989). Imposition Planning Procedures for Houses and Buildings (in Bahasa Indonesia). SNI , Indonesia. Surahman, U. & Kubota, T. (2012). Development of simplified LCA model for residential buildings in Indonesia. A pilot survey in Bandung. AIJ Journal of Technology and Design, 18 (40), Zinc sheet roofing. (2014). Life cycle assessment (LCA) of zinc sheet roofing, Zinc for life fact sheet. vailable in Accessed 10 March 2014 Thornmark, C.(2002). A low energy building in a life cycle-its embodied energy, energy need operation and recycling potential. Building and Environment, 37,