研究者詳細 - 谷川　寛樹

物質ストックを考慮した資源生産性の要因分解の実証研究 ―住宅におけるケーススタディ―

山下奈穂, 郭静, 白川博章, 谷川寛樹

土木学会論文集Ｇ（環境） 77 巻 ( 6 ) 頁： II_23 - II_31 2021年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人土木学会

資源生産性は循環計画の大目標として掲げられている物質フロー指標であるが，本指標では物質フローを支える物質ストックの間接的な影響を評価できない点が課題であった．先行研究において，物質ストックを考慮した資源生産性の要因分解は行われているものの，物質ストックの価値はその用途や種類によって多様であることから，全ての物質ストックに一概に適用することは困難である．本研究では，提案型論文として日本の住宅を対象に要因分解式を試用し，住宅ストックの変化が資源生産性に及ぼす影響を明らかにした．分析の結果，2008年から2017年にかけてストックあたりのサービス発生効率の低下や空き家の増加による資源生産性への負の影響が明らかになった一方，住宅の長寿命化が資源生産性の向上に最も貢献していることが確認された．

DOI： 10.2208/jscejer.77.6_ii_23

Life cycle assessment of cleaner production measures in monosodium glutamate production: A case study in China 査読有り国際共著

Yang, D; Jia, XX; Dang, MY; Han, F; Shi, F; Tanikawa, H; Klemes, JJ

JOURNAL OF CLEANER PRODUCTION 270 巻頁： 122126 2020年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Cleaner Production

Monosodium glutamate (MSG) is one of the most commonly used seasonings in daily life and food industry. This study provides an initial Life Cycle Assessment (LCA) of maize-based MSG production in 2018 to determine the life cycle environmental impact of MSG production in China. The environmental performance of several cleaner production measures in the MSG industry were also analysed and evaluated using LCA. Results show that when producing 1 t maize-based MSG without any cleaner production measures, the global warming potential, aquatic ecotoxicity, aquatic acidification, and aquatic eutrophication are 6.26 t CO2eq, 848 t TEG watereq, 83.5 kg SO2eq, and 5.04 kg PO4 P-limeq. Energy consumption, direct emission in the MSG production process, and maize production are identified as the most significant contributors to the life cycle environmental impact in MSG production. Scenario analysis of different production measures, namely cogeneration, co-production and the hybrid scenario integrating the two listed measures, showed that the hybrid scenario, which represents the mainstream cleaner production technology level of the MSG industry of China, is the optimal option for environmental impact reduction of MSG production. In the hybrid scenario, the global warming potential, aquatic ecotoxicity, aquatic acidification, and the aquatic eutrophication decreased 13.90%, 7.19%, 64.29%, and 80.00% compared with the non-cleaner production scenario. Two major directions to further improve the environmental performance of the MSG production are improving energy use efficiency (and/or using cleaner energy) and modifying the production process to maximise material use efficiency.

DOI： 10.1016/j.jclepro.2020.122126

日本全国の利用度別物質ストックの定量化 -住宅におけるケーススタディ- 査読有り

谷川寛樹, 山本大陸, 山下奈穂, 白川博章

土木学会論文集 G（環境） 76 巻 ( 6 ) 頁： 9 - 16 2020年10月

衛星夜間光情報に基づく深層学習による建築物の延べ床面積推計に関する研究査読有り

齋藤隆成、平井千津子、芳賀智宏、松井孝典、白川博章、谷川寛樹

土木学会論文集 G（環境） 76 巻 ( 6 ) 頁： 1 - 7 2020年10月

A spatiotemporal urban metabolism model for the Canberra suburb of Braddon in Australia 査読有り国際共著

Schandl, H; Marcos-Martinez, R; Baynes, T; Yu, ZF; Miatto, A; Tanikawa, H

JOURNAL OF CLEANER PRODUCTION 265 巻頁： 121770 2020年8月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Cleaner Production

Decision makers, planners and actors in cities design policies, plan, invest money and build infrastructure, and consumers buy houses and use transport infrastructure without sound information about the environmental consequences of many of those decisions. Decisions, however, that have a lasting impact on sustainable development outcomes. In this study, we employ novel analytical techniques to align the spatial characteristics of the built urban environment with information for building materials and GHG embodiment to inform planning and investment decisions at the district, suburb and city scale. We represent a three-dimensional model of a suburb established from remotely sensed data and use algorithms to identify building types and align those with their typical material composition. We analyse the urban development of the modelled suburb in three historical time steps – 1955, 1981 and 2015 – and establish the consequence of urban planning decisions on material use and GHG embodiment. We test the new methodology for its applicability for a whole of city analysis and discuss the benefit for environmentally sustainable urban planning and design.

DOI： 10.1016/j.jclepro.2020.121770

Urban buildings material intensity in China from 1949 to 2015 招待有り査読有り国際共著

Yang, D; Guo, J; Sun, LW; Shi, F; Liu, JR; Tanikawa, H

RESOURCES CONSERVATION AND RECYCLING 159 巻頁： 104824 2020年8月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Resources, Conservation and Recycling

The building material intensity(MI) is one of the most common used and important indicators in buildings metabolism analysis including building material stock analysis, virgin materials extraction demand and construction & demolition (C&D) waste forecasting, as well as its recycling potential. However, in China developing with rapid urbanization and large-scale city construction, a complete building MI database is not documented well although some studies have intended to figure it out. The existing research mainly focused on the building MI for specific cities or construction material. In this study, we complied 813 buildings with different construction periods from 1949 to 2015, structures, functional applications, and their associated background information from 30 Chinese provinces by an extensive survey as the basic MI database for urban buildings. Based on this, material intensity of Chinese urban buildings for 10 kinds of construction materials and 14 categories of buildings is averaged, and its difference between categories was further described. The results indicate that the building MI exhibits specific trends related to the structural, function application, and building construction period. After comparing the MI database to the previous studies, the database established in this research is considered to have an improvement in terms of the building construction period, geographic distribution, application, structure and material categories. It is not only spanning all different combinations, but also acceptable and credible through comparison.

DOI： 10.1016/j.resconrec.2020.104824

CO2 emissions from the Chinese cement sector: Analysis from both the supply and demand sides 査読有り国際共著

Du, T; Wang, J; Wang, HM; Tian, X; Yue, Q; Tanikawa, H

JOURNAL OF INDUSTRIAL ECOLOGY 24 巻 ( 4 ) 頁： 923 - 934 2020年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Industrial Ecology

China is the largest producer and consumer of cement worldwide, and cement production entails the release of substantial carbon dioxide (CO2) emissions. As the cement sector is a crucial sector of the Chinese economy, understanding the role of supply- and demand-side factors may help accelerate efforts to mitigate CO2 emissions. However, few studies have analyzed the critical factors affecting CO2 emissions in the sector based on a combined supply- and demand-side perspective. In this study, we developed an integrated framework that included eleven indicators covering both the supply and demand sides. Results revealed that improving cement production technology cannot offset CO2 emissions from the growth in demand for cement. Improving technology on the supply side would considerably reduce CO2 emissions from Chinese cement production; nevertheless, the combination of rapid urbanization, GDP growth, and an ultra-high fixed capital formation ratio on the demand side increased CO2 emissions nearly 25-fold from 1990 to 2015. Notably, some demand-side factors also had an effect that reduced CO2 emissions. The in-use stock per unit of fixed capital formation and output per in-use stock reduced CO2 emissions by 332 million metric tons, which is comparable to the contribution of technological progress. Based on these results, we examine why these demand-side factors substantially influence CO2 emissions in the Chinese cement sector, and we provide recommendations for policy-makers on carbon-reduction measures in this CO2-intensive sector.

DOI： 10.1111/jiec.12986

Understanding and Managing Vacant Houses in Support of a Material Stock-Type Society-The Case of Kitakyushu, Japan 招待有り査読有り国際共著 Open Access

Wuyts, W; Sedlitzky, R; Morita, M; Tanikawa, H

SUSTAINABILITY 12 巻 ( 13 ) 頁： 5653 2020年7月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Sustainability (Switzerland)

From a sustainable material management perspective, vacant houses represent material stock and still have potential in the circular economy. This article addresses two aspects of understanding and managing vacant houses: the difficulty of understanding their spatial and temporal patterns and the management of the social costs behind the phenomenon of vacant houses. These aspects are approached by combining a 4D GIS analysis with expert interviews and additional qualitative tools to assess the spatial and temporal dimension of vacant houses. Furthermore, this manuscript presents a tool to estimate the obsolete dwelling material stock distribution within a city. The case of the city of Kitakyushu demonstrates the relationship that exists between the historical trajectories of housing norms and standards, such as comfort, cleanliness, safety, and convenience, and the dynamics of the built material stock and demography for three selected neighbourhoods. The results show that the more locked-in a district is in terms of "obsolete norms and codes", the more likely it is that the obsolete stock is dead, and consequently, urban mining should be considered. The article concludes that a revisiting of the norms and standards of convenience and other domains is one of the prerequisites of the transition toward a circular built environment and the prevention of obsolete stock accumulation.

DOI： 10.3390/su12135363

Challenges towards carbon dioxide emissions peak under in-depth socioeconomic transition in China: Insights from Shanghai 査読有り国際共著

Liu, SW; Tian, X; Xiong, YL; Zhang, Y; Tanikawa, H

JOURNAL OF CLEANER PRODUCTION 247 巻頁： 119083 2020年2月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Cleaner Production

Chinese government committed to peak its CO2 emissions before 2030, while managing its in-depth socioeconomic transition to a slower but more balanced growth. Features of such a transition include rising high-tech manufacturing and services as well as fast-growing household consumption, which both have implications for China's CO2 emissions peak. In this study, we focus on analyzing the case of Shanghai, a leading city in China, for its experience of realizing CO2 emission stagnation during in-depth socioeconomic transition process. We find that emerging high-tech manufacturing and services in Shanghai, although to some extent having replaced carbon-intensive heavy industries, have generated additional CO2 emissions of respectively 364.7 Mt and 308.6 Mt, mainly through their supply chains during the 2007–2012 time period. We also find that soaring urban household consumption induced huge CO2 emissions, including 251.0 Mt embodied emissions in producing goods and services for urban residents, and additional CO2 emissions associated with massive investment in urban infrastructure and buildings from 2007 to 2012. The challenges we identified from Shanghai's real case provide useful insights for China to peak its CO2 emissions under its in-depth socioeconomic transition.

DOI： 10.1016/j.jclepro.2019.119083

Lost Material Stock in Buildings due to Sea Level Rise from Global Warming: The Case of Fiji Islands 査読有り国際共著 Open Access

Merschroth, S; Miatto, A; Weyand, S; Tanikawa, H; Schebek, L

SUSTAINABILITY 12 巻 ( 3 ) 2020年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Sustainability (Switzerland)

This study developed a methodology to estimate the amount of construction material in coastal buildings which are lost due to climate change-induced sea level rise. The Republic of Fiji was chosen as a case study; sea level rise is based on predictions by the Intergovernmental Panel on Climate Change for the years 2050 and 2100. This study combines the concept of a geographic information system based digital inundation analysis with the concept of a material stock analysis. The findings show that about 4.5% of all existing buildings on Fiji will be inundated by 2050 because of an expected global sea level rise of 0.22 m (scenario 1) and 6.2% by 2100 for a sea level rise of 0.63 m (scenario 2). The number of buildings inundated by 2050 is equivalent to 40% of the average number of new constructed buildings in Fiji Islands in a single year. Overall, the amount of materials present in buildings which will be inundated by 2050 is 900,000 metric tons (815,650 metric tons of concrete, 52,100 metric tons of timber, and 31,680 metric tons of steel). By 2100, this amount is expected to grow to 1,151,000 metric tons (1,130,160 metric tons of concrete, 69,760 metric tons of timber, and 51,320 metric tons of steel). The results shall contribute in enhancing urban planning, climate change adaptation strategies, and the estimation of future demolition flows in small island developing states.

DOI： 10.3390/su12030834

Open Access

南海トラフ巨大地震における災害廃棄物量の推計-既存研究との比較- 査読有り

野末浩佑, 矢澤大志, 奥岡佳次郎, 谷川寛樹, 橋本征二

廃棄物資源循環学会研究発表会講演集 31 巻 ( 0 ) 頁： 107 2020年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人廃棄物資源循環学会

南海トラフ巨大地震においては、東日本大震災以上の災害廃棄物が発生すると推計されている。東日本大震災の経験からも、災害廃棄物はできる限りリサイクルすることが肝要であるが、想定される津波によって、海水を吸収して塩分を多く含有する廃棄物も多く発生することになる。塩分を含有した災害廃棄物を処理・リサイクルするには、廃棄物に付着した塩分・泥土を除去する作業が必要になることから、津波が原因となって発生する廃棄物と地震動のみが原因となって発生する廃棄物を分けて推計しておくことも有益と考えられる。本研究では、南海トラフ巨大地震において津波の影響を受ける地域の1つである静岡県を対象に、地震動のみによる災害廃棄物、津波の影響を受けた災害廃棄物の発生量を分けて推計を行った。また、推計方法が少しずつ異なっている環境省及び中央防災会議の推計方法・推計結果の違いについても考察を行った。

DOI： 10.14912/jsmcwm.31.0_107

日本全国の利用度別物質ストックの定量化 ―住宅におけるケーススタディ―

谷川寛樹, 山本大陸, 山下奈穂, 白川博章

土木学会論文集Ｇ（環境） 76 巻 ( 6 ) 頁： II_9 - II_16 2020年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人土木学会

循環型社会の形成に向け，ストック型社会の重要性が高まっている．物質ストックはフローと表裏一体の存在であり，社会に価値を提供する一方，過剰な資源投入や将来廃棄量の増加にも影響する．社会に蓄積・滞留する物質ストックを適切に管理し，質の高い物質ストックを将来世代に残すには，利用度を考慮した物質ストックの把握が必要である．本研究では，使用年数モデル法を用いて日本全国の住宅ストック量を推計し，利用度区分に従い退蔵量・現役量を明らかにした．2018年の住宅ストック量は51.9億トンであり，構造種別では木造 22.4億トン，SRC造 3.9億トン，RC造 17.6億トン，S造 7.6億トンであった．また，住宅土地統計調査における空き家率によって空き家のストック量を推計した結果，退蔵量にあたる「その他の住宅」は3.0億トン存在し，住宅数の増加に伴い今後も増加することが予想された．

DOI： 10.2208/jscejer.76.6_ii_9

衛星夜間光情報に基づく深層学習による建築物の延床面積推計に関する研究

齋藤隆成, 平井千津子, 芳賀智宏, 松井孝典, 白川博章, 谷川寛樹

土木学会論文集Ｇ（環境） 76 巻 ( 6 ) 頁： II_1 - II_7 2020年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人土木学会

循環型社会の構築に向け，資源の蓄積・挙動を把握するための世界規模でのマテリアルストック・フロー分析が重要である．統計データの制約問題に対し，全球にて低コストで入手可能な衛星画像データの有効性が示唆される．近年，衛星画像解析の手法として，畳み込みニューラルネットワーク（CNN）が注目されている．本研究では，CNNを用いて夜間画像から建物延床面積を推計するモデル開発を行うことを目的とした先行的研究を行った．日本の三大都市圏（東京都市圏，大阪都市圏，名古屋都市圏）を対象範囲として，学習地域と推計地域を交代させ，延床面積を推計した．さらに，推計精度を検証した．大阪学習-名古屋推計では，名古屋都市圏全域の建物延床面積は450 million m2と判明した．

DOI： 10.2208/jscejer.76.6_ii_1

Extending or ending the life of residential buildings in Japan: A social circular economy approach to the problem of short-lived constructions 査読有り国際共著

Wuyts, W; Miatto, A; Sedlitzky, R; Tanikawa, H

JOURNAL OF CLEANER PRODUCTION 231 巻頁： 660 - 670 2019年9月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Cleaner Production

The construction of residential buildings requires the extraction and production of large amounts of materials, with obvious consequences on the natural environment. Buildings are capital-intensive, requiring considerable physical, economic, and societal investments. In order to amortize their environmental impact, buildings should be used for a period of time that maximises their utility. However, the average lifespan of a residential building in Japan is of only 25 years, a time that has been shortening since the World War II. Numerous Japanese houses are used for less than a generation before being demolished or abandoned, posing a risk for public health, decorum, and safety. This study presents a holistic view of the pressing societal and environmental concerns related to short-lived buildings, which can be used to identify sustainable strategies for the realization of a circular built environment in Japan. This study used a qualitative approach (i.e., media content analysis, field visits to local communities and citizens, expert interviews, and statistical validation) to identify the factors and path dependencies that have led to a low average building lifespan during the second half of the 20th century; moreover, the study investigated the stakeholders in favour of these short lifespans, their own motivations, and the rationale behind recent countermeasures initiated at the local to governmental levels. Numerous stakeholders were motivated by the economic costs or alternative post-materialist values, attitudes and aspirations, emotional attachment, or by a combination of these factors. Their decisions resulted from reflections and personal experiences of societal issues related to short-lived constructions in Japan. The article concludes that all residential buildings should be serving society and presents a framework for the identification of delayed, justified, or premature obsolescence. This framework can be used to decide whether the life of a residential building should be extended or ended.

DOI： 10.1016/j.jclepro.2019.05.258

Transferability of Material Composition Indicators for Residential Buildings: A Conceptual Approach Based on a German-Japanese Comparison 査読有り

Schiller, G; Miatto, A; Gruhler, K; Ortlepp, R; Deilmann, C; Tanikawa, H

JOURNAL OF INDUSTRIAL ECOLOGY 23 巻 ( 4 ) 頁： 796 - 807 2019年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Industrial Ecology

Most anthropogenic material stocks and flows are associated with the building sector. Several recent studies have developed material composition indicators (MCIs) suitable for calculating material stocks and flows of the building sector using bottom-up approaches, which hold great potential to provide information to support resource efficiency policies. A major limitation is the lack of country-specific MCIs. This study aims to introduce a concept for a better transferability of MCI across different contexts by proposing requirements for defining MCIs and to discuss options and limits of the transferability. We take existing MCIs for residential buildings in Germany and Japan as case studies and make them comparable by applying harmonization methods. Based on that, similarities and differences are systematically identified and discussed, considering their socioeconomic, cultural, technical, and environmental factors. Our results indicate significant limitations to the transferability of MCIs for detached houses, while bigger apartment complexes show greater homogeneity despite the very different environments in which they are constructed. This indicates that while it is possible to assume foreign MCIs as plausible for large constructions, local coefficients need to be estimated for smaller single-family homes.

DOI： 10.1111/jiec.12817

Spatially explicit material stock analysis of buildings in Eastern China metropoles 査読有り国際共著

Guo, J; Miatto, A; Shi, F; Tanikawa, H

RESOURCES CONSERVATION AND RECYCLING 146 巻頁： 45 - 54 2019年7月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Resources, Conservation and Recycling

China is experiencing a period of rapid urbanization and fervent construction activities, which are responsible for the accumulation of large amount of material stocks (MS). Fundamental in every society, buildings not only shape material flows before and during construction, but also during maintenance and demolition, inducing the extraction of resources and the production of construction waste. It is thus imperative to understand the amount, composition, and location of current building MS as a first step to design appropriate management strategies for an environmentally sustainable society. This research uses the latest GIS dataset of buildings in 14 representative Eastern China metropoles to quantify the current status of building MS by employing a bottom-up method. The selection of the study areas relies on the law of the primate city, which permits to quickly target the most important urban areas of a region. We review and discuss existing material intensity (MI) coefficients for Chinese buildings, and produce a new set of MIs manipulating those available in the literature. We then calculate the total MS, MS density, and per capita MS for each city. Results find that in 14 cities 7.9 Gt of building materials are currently stored in a total area of 3790 km2, resulting on an average density of 2.1 Mt/km2. The per capita building MS results being 283 t/cap, and this value correlates with a growth of the per capita GDP. We conclude the research with a hotspot analysis of the spatial distribution of the MS, identifying the MS clusters.

DOI： 10.1016/j.resconrec.2019.03.031

Estimating the Material Stock of Roads: The Vietnamese Case Study 査読有り国際共著

Nguyen, TC; Fishman, T; Miatto, A; Tanikawa, H

JOURNAL OF INDUSTRIAL ECOLOGY 23 巻 ( 3 ) 頁： 663 - 673 2019年6月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Industrial Ecology

This study is a pioneering effort to quantify the materials stocked in the road network of a developing country, Vietnam, and analyze its relationships to the country's recent economic development. National road networks function as capital and infrastructure investments that are necessary catalysts for countries’ development, while requiring the extraction of vast amounts of construction materials for expansion and maintenance causing environmental impacts. However, there has so far been little research on the subject, especially in developing countries. We compile material stock and flow accounts for Vietnam's roads from 2003 to 2013 on the national and provincial levels, finding that approximately 40% of the domestic consumption of construction materials is for expanding and maintaining the road network, and the materials stocked in the road network doubled from 1,321 million metric tons in 2003 to 2,660 million metric tons in 2012. Material stock growth rates closely resembled those of gross domestic product (GDP) in this period, suggesting a codependency of physical infrastructure development and economic development. On the provincial level, our results show local disparities in the stock and its capacity to support the transportation of passengers and freight, especially considering the surging growth of vehicles in urban centers. By showcasing the challenges of conducting a material flow and stock analysis in a developing country, this study not only sheds light on Vietnam's transportation material stock and its policy implications, but also serves as a case study for further work in similar countries.

DOI： 10.1111/jiec.12773