Life Cycle Energy and CO2 Emissions in Unplanned ...

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Nov 9, 2012 - Life Cycle Energy and CO2 Emissions in Unplanned Residential ... operational energy of simple, medium and luxurious houses varied widely ...
PLEA2012 - 28th Conference, Opportunities, Limits & Needs Towards an environmentally responsible architecture Lima, Perú 7-9 November 2012

Life Cycle Energy and CO2 Emissions in Unplanned Residential Buildings of Indonesia A case study in Bandung USEP SURAHMAN1, TETSU KUBOTA1 1

Graduate School for International Development and Cooperation, Hiroshima University, Hiroshima, Japan

ABSTRACT: The goal of this study is to propose a simplified LCA model for residential buildings in Indonesia, which can be used under relatively poor data availability conditions. A survey was conducted in Bandung in 2011, in order to obtain both material inventory data and household energy consumption profiles for constructing the above model. This paper analyzes life cycle energy and CO2 emissions employing an input-output analysis-based method within unplanned houses (n=250), which are classified into three categories, namely simple, medium and luxurious houses. The results showed that the average embodied energy of simple, medium and luxurious houses was 36.3 GJ, 130.0 GJ and 367.7 GJ respectively. The cement consumed the largest energy and emitted the most CO 2 emissions among all materials. The annual average operational energy of simple, medium and luxurious houses varied widely at 11.6 GJ/year, 17.4 GJ/year and 32.1 GJ/year respectively. The energy of cooking accounted for the largest percentage of operational energy. The profiles of CO2 emissions were similar with those of energy. The factors affecting embodied, operational and life cycle energy were also studied. Keywords: life cycle assessment, energy consumption, CO2 emissions, input-output analysis, Indonesia.

INTRODUCTION One of the obstacles to conducting life cycle assessment (LCA) in developing countries is considered to be relatively poor data availability of building, environment and economy. The goal of this study is to propose a simplified LCA model for residential buildings in Indonesia, which can be used under relatively poor data availability conditions. A survey was conducted in Bandung city in September to October 2011, in order to assemble the necessary data for constructing the above model. This paper analyzes life cycle energy and CO 2 emissions at household level employing an input-output (I-O) analysis-based method within unplanned houses in the city. The factors affecting embodied, operational, and life cycle energy are also discussed further. METHODOLOGY Case study houses Bandung city was selected as a representative city of rapidly developing cities. The city is located on 791 m above the sea level having humid and relatively cool climate. In most of the major cities in Indonesia, unplanned houses account for the largest proportion of the existing housing stocks, which is about 89% in case of Bandung [1]. Hence, this study focuses on these unplanned houses. These houses are classified into three categories based on construction costs and lot area (Fig.

1), namely simple houses, medium houses and luxurious houses, having a life span of 20, 35 and 50 years respectively [2]. A total of 250 unplanned houses were investigated in the survey (Table 1). As shown, the averaged total floor area of simple houses was 57 m2, while that of medium houses was 127 m2. Luxurious houses had larger area of 300 m2. The major building materials used were found to be almost the same among the above three categories, though a slight difference can be seen in terms of materials for floor and roof. A brief profile of respondents is shown in Table 2. The average household size of the sample was 4.7 persons in simple houses, 4.9 persons in medium houses and 5.5 persons in luxurious houses. The average monthly household income was also investigated by a multiple-choice question. As shown, the households in luxurious houses have higher monthly incomes than the others as expected. Life cycle assessment (LCA) LCA generally involves six phases, namely design, material production, construction, operation, maintenance and demolition phases. However, design, construction and demolition phases are not considered in this paper. This is because most of the housing stocks in Bandung are not designed in formal way but constructed and demolished by manual labor. Thus the energy

PLEA2012 - 28th Conference, Opportunities, Limits & Needs Towards an environmentally responsible architecture Lima, Perú 7-9 November 2012

(b)

(a)

(c)

Figure 1: Case study houses; (a) simple house; (b) medium house; (c) luxurious house. Table 1: Size and major materials of case study houses House category

Sample size

Simple houses Medium houses Luxurious houses

120 100 30

Total

250

Average floor/lot area (m2)

Structure

Foundation

Building materials Floor

Walls

Roof

57/49 127/122 300/480

Concrete Concrete Concrete

Stone Stone and concrete Stone and concrete

Cement Ceramic tile Ceramic and granite tile

Clay brick Clay brick Clay brick

Clay tile Clay tile Concrete tile

Table 3: Data sources and collection methods in LCA phases

Table 2. Profile of respondents House category

Major ethnic group

Simple houses Medium houses

Sundanese (90%) Sundanese (77%)

Luxurious houses

Sundanese (53%)

Average household size (person(s)) 4.7 4.9 5.5

Average monthly income (USD) 222 - 333 444 - 555 556 - 1111

consumption and materials used during the above phases are considered negligible. Data sources and collection methods used in respective phases of the present survey are shown in Table 3. The design records such as building drawing are required for the analysis of embodied energy. These data can normally be obtained from the local authorities, developers, consultants, contractors or architects [3-5]. Nevertheless, these data were only available for a few medium houses and most of the luxurious houses in Bandung. On the other hand, most of the simple and medium houses are constructed not in the formal way in practice and therefore the inventory record cannot be obtained. Thus, for simple and medium houses, the actual on-site building measurements were conducted instead in order to acquire the data (Fig. 2a). The detailed household energy consumption data are necessary for the analysis of operation phase. Few previous investigations on the household energy consumption were carried out in Indonesia [3, 4] by interviewing the house owners and measuring the energy on-site. Since the energy consumption data record is not available in Bandung, the detailed interview was conducted to obtain the data (Fig. 2b). These data collections were time consuming and costly. Therefore, simplified projection methods are strongly needed to acquire the necessary data for LCA. This study uses I-O analysis-based method to calculate embodied energy and estimate its CO2 emissions. This is because this method is considered the most appropriate and effective under relatively poor data availability conditions such as in Indonesia compared

Phase

Source

Collection methods

Material production

Material inventory

Design record

Operation

Household energy consumption Material inventory repaired

Usage of appliances Utility bills -

 House owner interview  On-site building measurement  House owner interview  On-site measurement  House owner interview

Refurbishment

(a)

Data

(b)

Figure 2: On-site measurement; (a) Building material survey; (b) Household energy consumption survey

with two other LCA methods, namely process-based and hybrid-based methods [6]. The latest Indonesian nationwide I-O table published in 2005 [7] consisting of 175 x 175 sectors was used for calculating the embodied energy and CO2 emissions. The detailed procedure of the embodied energy and household energy consumption calculation are described in the previous paper [8]. RESULTS AND DISCUSSION Embodied energy Fig. 3 shows the volume of each material used in respective houses, including reused materials. As shown, the sand accounts for the largest proportion in all the houses (36-47%), followed by the clay brick (20-24%), the stone (16-24%) and the cement (3-6%), etc. The steel accounts for about 0.5 to 1%. Reused materials account

PLEA2012 - 28th Conference, Opportunities, Limits & Needs Towards an environmentally responsible architecture Lima, Perú 7-9 November 2012

150.00 150

Volume (m3)33 (m )) Volume(m Volume

125 125.00

Reused Re-used Reused Initial (luxurious house) New Initial (medium house) Initial (simple house)

100.00 100

75 75.00 50 50.00 25 25.00

Clear glass

Clear glass

Paint

Paint

Clay tile

Clay tile

Steel

Steel

Gypsum

Gypsum

Ceramic tile

Ceramic tile

(brick & tile)

Concrete Concrete

Wood

Wood

Cement

Cement

Stone

Stone

brick Clay Clay brick

Sand

Sand

0.000

Figure 3: Proportion of building material volume of each house

for a small amount (