STUDY OF RESOURCE SUSTAINABILITY ASSESSMENT FOR BUILDING - PART 2. AN ASSESSMENT CASE STUDY FOR A MODEL BUILDING -

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1 STUDY OF RESOURCE SUSTAINABILITY ASSESSMENT FOR BUILDING - PART 2. AN ASSESSMENT CASE STUDY FOR A MODEL BUILDING - Masahiro KATO M.Eng. 1 Masaaki SATO M.Eng. 2 Yoshinobu ARAI Dr.Eng. 3 Toshiharu IKAGA Dr.Eng. 4 Toshiya CHIKADA Dr.Eng. 5 Takashi MAMIYA Dr.Eng. 6 1 Kajima Technical Research Institute, Tobitakyu, Chofu-city, Tokyo , Japan m-katoh@kajima.com 2 AE Division, Kajima Corporation, Akasaka, Minato-ku, Tokyo , Japan masaaki@kajima.com 3 Kajima Technical Research Institute, Tobitakyu, Chofu-city, Tokyo , Japan arai-yoshinobu@kajima.com 4 Nikken Sekkei Ltd., Iidabashi, Chiyoda-ku, Tokyo , Japan ikaga@nikken.co.jp 5 Comprehensive Housing R&D Institute, Sekisui House, Ltd., Kabutodai, Kizu-cho, Sourakugun, Kyoto, Japan chikada@gz.sekisuihouse.co.jp 6 Kajima Technical Research Institute, Tobitakyu, Chofu-city, Tokyo , Japan mamiya@kajima.com Keywords: Life cycle assessment, Material input, Waste, Life cycle resource, Life cycle waste Summary This report presents the results of an analysis in which the resource recycling level of a model building was evaluated using the AIJ-LCA tool in combination with LCR and LCW indices (AIJ-LCA/LCW tool). A 25-story high-rise multi residential building with a total floor area of about 25,600 m2, located in the central area of Tokyo, was selected for the analysis. In the analysis, two models based on the 25-story building were used for comparison: one is a conventional building model, and the other is a resource recycling type building model which assumed the use of various methodologies. The analysis using the AIJ-LCA/LCW tool revealed that, compared to conventional buildings, resource recycling type buildings can greatly reduce the LCR and LCW indices. Factors that contribute to reduction of the LCR and LCW indices were also analyzed. As a result, it was found that use of recycled materials and extension of their service life are important for reducing virgin resource volume (LCR index) and that the promotion of recycle of waste materials and extension of their service life are important for reducing waste generation (LCW index). These findings prove that the AIJ-LCA/LCW tool can effectively determine the LCR and LCW indices. It is important in future projects to utilize the results obtained by this tool so that highly recycling oriented buildings are designed and constructed. 1. Introduction The previous report (Part 1) demonstrated that the AIJ-LCA/LCW tool is capable of general-purpose assessments of the LCR and LCW. The authors have used this tool to assess residential buildings with reinforced concrete structures. This report describes the characteristics of the buildings and the problems encountered using LCR and LCW. This study was performed as part of the sustainable housing technology development project under the supervision and financing of the Ministry of Economy, Trade and Industry from FY 2000 to FY Outline of building used for the assessment 2.1 Basic information The building used for the assessment is a 25-story high-rise residential building located in central Tokyo. The building has a total floor area of about 25,600 m 2 and contains 240 residential units, each with a floor area of about 87 m 2. As the reference design a benchmark design upon which to base the assessment a conventional building constructed using a commonly used HiRC method was selected. As the alternative design, a resource recycling type building incorporating resource recycling technologies was selected

2 2.2 Technologies used in resource recycling type buildings The alternative design adopts a superstructure construction method that eliminates columns and beams as well as allows the separation of the skeleton from the infill (as shown in Fig. 1). This construction method permits greater freedom to change the layout plan. It also makes it possible to carry out renovations, thereby allowing good use of the building for a long time. Piles, building foundation, frames Construction Use of recycled materials Fig. 1 Model of resource recycling type high-rise residential building Table 1 Principal conditions for the reference and alternative designs Reference design - Alternative design Separation of skeleton from infill by the adoption of superstructure construction method Slag cement Aggregate recycled from coal ash (for building frames) Crystallized aggregate (for piles and building foundation) Reuse Reuse of surplus soil (recycled at other construction sites) 10 (reused at the construction site) Reuse of piles 8 Same as at left (when the building is demolished) Reuse of interior finishing materials 3 Waste recycling Concrete 98% (recycled crushed stone) Same as at left Iron scrap 98% (electric furnace steel) Same as at left Sludge 5 (liquefied soil stabilization) Aluminum (sashes) 85% Same as at left Gypsum board 5 (8 in new construction) Waste wood 61% (fuel chips) 10 (raw material chips and fuel chips) Waste glass and ceramics 5 (recycled by manufacturers) Waste plastics 1 (thermal recycling) 5 (thermal recycling) Service life and repair ratio Building as a whole 50 years 100 years Piles, building foundation, frames 50 years 100 years Exterior finishing materials 50 years Same as at left Interior finishing materials Interior finishing materials 18 years Same as at left Base materials for interior finishes 18 years 50 years Repair ratio 1% per year Same as at left - Slag cement and recycled aggregate are used in the concrete in the piles, building foundation and frames.

3 Surplus soil is reused at the construction site. In addition, interior finishing materials are made reusable by separating the skeleton from the infill. Regarding the recycling of waste, the building is designed so that waste can be easily separated according to type when the building is demolished. Assuming further development of waste recycling technologies, the waste recycling ratios should increase in the future. The recycling ratios for construction materials and waste were established by examining the results of a survey of actual recycling conditions conducted by the Ministry of Land, Infrastructure and Transport, as well as data obtained from construction material suppliers. To extend the service life of the building, the building was constructed of highly durable concrete and designed to facilitate renovations in response to shifting lifestyles. In addition, highly durable base materials were used in the interior in order to extend the service life of the building. The principal conditions for the reference and alternative designs are listed in Table Results of assessments of the LCR and LCW indices Figure 2 shows the LCR and LCW indices by building element for the reference and alternative designs. Each index is expressed as a total value per total floor area (kg/m 2 ) during the life span of the building. There are many instances where the value of the service life of a building (kg/m 2 -year) is used to compare two cases. In this section, however, the total values over the life span of the building were used to compare the detailed analyses of the LCR and LCW indices. Surplus soil and sludge Piles and building foundation Building frames Exterior finishes Interior finishes Building equipment Reference design Total material input Primary material input Waste generation Total material input Waste for treatment Alternative Primary material design input Total material input Primary Waste material generation input [kg/m2] Waste generation Waste for treatment Waste for treatment [kg/m 2 ] Fig. 2 LCR and LCW indices (by building element) 3.1 Total material input In the case of the reference design building, the building frames require the most material, followed by the piles and building foundation, interior finishing materials, and building equipment, in decreasing order of total material input. In the case of the alternative design building, the amounts of material used for the piles and building foundation, the building frames, and the building equipment are smaller than those in the reference design. The primary reason for this is that the aggregate recycled from coal ash (recycled aggregate) is light in weight. In addition, because the alternative design assumes a building service life twice that of the reference design, repairs and renovations of the exterior finishes, interior finishes, and building equipment require more materials under the alternative design than under the reference design. 3.2 Primary material input The primary material input is calculated by deducting the sum of the quantities of reused and recycled materials from the total material input.

4 In the case of the reference design building, the quantity of the primary material input into the building elements is reduced by the quantity of the recycled materials. The quantity of the primary material input for building equipment is the same as the total material input for building equipment because building equipment is not commonly recycled. In the case of the alternative design, the primary material input is reduced in comparison with the total material input because recycled concrete is used for the piles, building foundation, and frames. 3.3 Total waste generation Input materials end up as waste. Surplus soil and sludge generated during the construction stage also end up as waste. The amount of waste is reduced by the quantity of waste that is recycled. Generally speaking, the surplus soil and sludge generated during construction comprise a large proportion of the LCW. In the case of the reference design, this surplus soil and sludge account for 23% of the total waste generated. Building frames form the largest proportion of generated waste. However, piles and building foundations make up a small proportion of the generated waste because, even in the case of the reference design, 8 of the piles are expected to be recycled when the building is demolished. In the case of the alternative design, surplus soil is not counted as waste because the soil is reused at the construction site. In addition, the alternative design generates less waste than the reference design because some of the exterior and interior finishing materials can be recycled. 3.4 Waste for treatment The amount of waste for treatment is calculated by deducting the quantity of recycled materials from the total quantity of waste. The Construction Material Recycling Act has improved the recycling of waste generated from building frames (concrete and steel reinforcement waste). For this reason, the proportion of waste generated from building frames to the waste for treatment is very small in both the reference and alternative designs. Because surplus soil is expected to be used at other construction sites, the reference design does not generate waste for treatment. On the other hand, sludge is counted as waste because, instead of being recycled, it is disposed of at a landfill site. Interior finishing materials make up a large proportion of the waste for treatment because it has a low recycling ratio. The alternative design assumes that 5 of the sludge is recycled and that the interior finishing materials are recycled. Accordingly, considerably less waste needs to be treated under the alternative design as than under the reference design, indicating that these approaches are important. 4. Detailed analysis of the LCW 4.1 Analysis of waste generation by waste item The waste is classified by waste item, and the form in which the input materials are turned into waste is analyzed. Figure 3 lists the waste items. Non-industrial waste Industrial waste (stabilized type) Debris Waste glass and ceramics Waste plastics Waste metals Industrial waste (controlled type) Sludge Waste glass and ceramics Waste plastics [kg/m 2 Waste wood ] Waste textiles Fig. 3 Total waste generation (by waste item) The characteristics of the waste generated under the reference design are as follows. a. Debris makes up the largest proportion more than half of the waste generated. Much of the debris is concrete waste generated from building frames. Next in volume is the surplus soil generated during construction work, followed by waste metals.

5 b. Waste metals consist mainly of structural steel and steel reinforcements from building frames, but also include interior finishing materials and plumbing fixtures. c. Large quantities of controlled industrial waste are generated from gypsum boards as well as from waste glass and ceramics. Stable industrial waste is generated from plumbing fixtures as well as ALC panels and partitions. d. Plywood flooring materials, base materials for interior finishes, and cabinets make up a large proportion of the wood waste. e. Relatively small quantities of plastic waste are generated from the wallpaper and cloth used for interior finishes or from adhesives and thermal insulation materials. f. Waste textiles are generated from synthetic fibers contained in building equipment. The characteristics of waste generation under the alternative design were compared with those of waste generated under reference design. a. In the reference design, some of the wall bases used not gypsum board but a material with a longer service life. The waste generated from this material is categorized as waste glass and ceramics (stable type). Accordingly, the proportion of stable waste increases while that of controlled type waste decreases. b. Because the alternative design assumes a building service life twice that of the reference design, repairs and renovations during the life span of the alternative design building generate more waste metals and plastics that require treatment. c. The alternative design generates less waste than the reference design because surplus soil is reused at the construction site. d. Overall, the waste generated under the alternative design is less than that generated under the reference design even though the alternative design building has a service life twice that of the reference design building. 4.2 Analysis of items of waste to be recycled or treated Figure 4 lists the items of waste to be recycled. Figure 5 lists the items of waste to be treated. The alternative design generates approximately half the waste for treatment generated by the reference design during the life span of the building. This is accomplished by recycling sludge, increasing the recycling ratio for waste wood, and recycling waste glass, ceramics, and gypsum board, which make up a large proportion of the generated waste [kg/m 2 ] Surplus soil Sludge Waste wood Debris Waste metals Waste glass and ceramics Waste plastics Fig. 4 Waste items to be recycled [kg/m 2 ] Sludge Waste wood Debris Waste metals Waste glass and ceramics Waste plastics Fig. 5 Waste items for treatment

6 5. Effects of technologies for resource recycling type buildings 5.1 Conditions of calculations The technologies for the resource recycling type buildings described in Section 2 were applied individually to calculate the LCR and LCW indices. A comparison was made to the reference design in order to determine which technology is more effective at recycling resources. In the comparison, the period of assessment was equal to the service life of the building, and the quantity of waste recycled per floor area during the service life of the building was compared. Comparisons were made for the following seven cases. Table 2 Conditions of calculations Case 1) Adoption of a superstructure construction method Case 2) Use of concrete that utilized recycled materials Case 3) Promotion of waste recycling by making it easy to separate waste when the building is demolished Case 4) Reuse of interior finishing materials and extension of replacement cycle time Case 5) Reuse of surplus soil generated at the same construction site by construction work Case 6) Extension of the service life of the building Case 7) Total of Cases 1 to 6 (same as alternative design) 5.2 Total material input Figure 6 shows the calculated total material input by building element. In Case 2, the total material input is reduced by 4% because the weights of the piles, building foundation, and frames are decreased by the use of lightweight recycled aggregate. In Case 4, the total material input is reduced by 5% because the total material input into interior finishes is decreased by the extension of the replacement cycle time for the wall bases. In Case 6, the total material input is reduced by 4 during the life span of the building because the service life of the building is extended from 50 years to 100 years, and the material that is input into the piles, building foundation, and frames, which is done only during construction, is reduced by half during the service life of the building. In Case 7 (alternative design), the total material input is reduced by 45%, indicating that the material input can be effectively reduced by extending the service life of the building and the replacement cycle time for the interior finishing materials. Case1 Case2 Case3 Case4 Case5 Case % 5% -4% -5% Piles and building foundation Building frames Exterior finishes Interior finishes Building equipment [kg/m 2 /yr] Fig. 6 Effects of technologies for reducing total material input 5.3 Primary material input Figure 7 shows the calculated primary material input by building element. In Case 2, the primary material input is reduced by 36% because the primary material input into the piles, building foundation, and frames is reduced by the use of recycled aggregate. In Case 6, the primary material input is reduced by 4 during the life span of the building, as is the case with the above-mentioned material input, because the service life of the building is extended from 50 years to 100 years.

7 In Case 7 (alternative design), the primary material input is reduced by 59%, indicating that the use of recycled materials for building frames has the same effect as extending the service life on reducing the primary material input. Case1 Case2 Case3 Case4 Case5 Case6-36% -4-59% 3% -3% Piles and building foundation Building frames Exterior finishes Interior finishes Building equipment [kg/m 2 /yr] Fig. 7 Effects of technologies on reducing primary material input 5.4 Total waste generation Figure 8 shows the calculated waste generated by building element. In Case 5, the generated waste is reduced by 15% because the surplus soil is reused at the construction site. In Case 6, the generated waste is reduced by 41% during the life span of the building because the service life of the building is doubled, while the quantities of surplus soil and sludge (generated only during construction), piles, building foundation, and frames (generated only when the building is demolished) are all halved. In Case 7 (alternative design), the generated waste is reduced by 55%, indicating that extending the service life and reusing surplus soil and interior finishing materials have large effects on the amount of waste that is generated. Case1 Case2 Case3 Case4 Case5 Case6-41% -55% -15% 7% -4% -5% Surplus soil and sludge Piles and building foundation Building frames Exterior finishes Interior finishes Building equipment [kg/m 2 /yr] Fig. 8 Effects of technologies on reducing total waste generation 5.5 Waste for treatment Figure 9 shows the amount of waste for treatment calculated by building element. In Case 3, the waste for treatment, including sludge and exterior and interior finishing materials, is reduced considerably by recycling. In Case 4, the waste for treatment that is generated from interior finishing materials is reduced considerably by 21%. In Case 6, the waste for treatment is reduced by 25% during the life span of the building because such waste, generated only when the building is under construction and demolished, is decreased by half,

8 although the waste for treatment that is generated during renovations is increased by 48% due to the extended service life of the building. In Case 7) (the alternative design), the waste for treatment is reduced by 75%. The most effective means of reduction is to increase the waste recycling ratio. Because interior finishing materials make up a large proportion of the waste for treatment, reusing interior finishing materials and extending the replacement cycle time have the same effect as extending the service life on reducing the amount of waste for treatment. Case1 Case2 Case3 Case4 Case5 Case6-75% -48% -21% -25% -7% Surplus soil and sludge Piles and building foundation Building frames Exterior finishes Interior finishes Building equipment [kg/m 2 /yr] Fig. 9 Effects of technologies on reducing the amount of waste for treatment 6. Conclusion A comparative assessment was made of conventional and resources recycling type residential buildings using the AIJ-LCA/LCW tool. The results of the assessment reveal that the LCR and LCW indices are substantially reduced in a resource recycling type residential building. In addition, a detailed analysis of the LCW was carried out, and the characteristics of waste generation and waste for treatment were clarified. Furthermore, the technologies used to reduce the LCR and LCW indices were analyzed. The following conclusions were reached. a. Extending the service life of the building has an overall effect. b. Reducing the number of times the interior finishing materials are replaced by extending the replacement cycle time is effective at reducing the total material input. c. Use of recycled materials has the same effect as extending the service life on reducing the primary material input. d. Reusing the surplus soil and increasing the recycling ratios of the waste are the most important factors in reducing the amounts of waste and waste for treatment, respectively. This assessment shows that the AIJ-LCA/LCW is an important tool for constructing resource recycling type buildings. References Sato M., Arai Y., Ikaga T., Chikada T., Mamiya T. and Kato M., 2004, Study of Resource Sustainability Assessment for Building, In Proceeding of Annual Conference of AIJ, pp