Details of a Researcher - Yoshiki YAMAGATA

Papers - Yoshiki YAMAGATA

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Mapping urban carbon emissions in relation to local climate zones: Case of the building sector in Bangkok Metropolitan Administration, Thailand

D Khamchiangta, Y Yamagata

Energy and Built Environment (Elsevier) 5 ( 3 ) 337 - 347 2024.06

Research paper (scientific journal)

This study focuses on carbon emissions of the building sector in relation to local climate zone (LCZ) classification, concentrating on two major parts. First, we estimated carbon emissions in the building sector, which were cal- culated for weekdays and weekends real-time daily energy consumption patterns. The estimations were divided into direct (from petroleum products consumption) and indirect emissions (from electricity consumption). Sec- ond, we examined urban carbon emissions mapping in relation to LCZ. Bangkok Metropolitan Administration (BMA) was used as the case study and 2016 as the base year for examination. The results illustrate that indirect emissions in Bangkok can be up to ten times higher than direct emissions. The analysis indicates that LCZ, such as compact high-rise, large low-rise, light industry, and warehouse zones had a relatively higher carbon emission intensity than others. Additionally, we identified that the compact high-rise zone has the highest indirect emission intensity, while the light industry and warehouse zone have the greatest direct emission intensity. These results provide insights into the dynamics of carbon emission characteristics in the building sector and the methodology purported here can be used to support low carbon city planning and policymaking in Bangkok.

Spatial exploration of rural capital contributing to quality of life and urban-to-rural migration decisions: a case study of Hokuto City, Japan

Y Takahashi, T Yoshida, S Shigeto, H Kubota, BA Johnson, Y Yamagata

Sustainability Science (Springer Japan) 19 489 - 506 2024.01

Globally, urbanization constitutes one of the major underlying drivers of global ecological degradation. Hence, deurbanization, i.e., demographic shift from urban to distant rural areas in a way that increases quality of life (QoL), can be one of the key pathways to address this global challenge. In this study, we investigated the contribution of nature and other types of rural capital to QoL and to people’s decision to migrate from urban to rural areas by studying residents in Hokuto City, a popular urban-to-rural migration destination in Japan. An integrated analysis of the 414 responses to a questionnaire survey and open and commercial geospatial datasets representing natural, built, human, cultural, and financial capital revealed the contributions of specific elements of rural capital to people’s QoL. These included natural capital (farmland, symbolic natural sites, mountain peak view, lower temperature, and tranquility), built capital (highways, railway stations, shops, and restaurants), and financial capital (employment). Many of these are related to the reasons that migrants, including return and one-way migrants, chose their present home location in Hokuto City, indicating their intention to increase QoL by migration. Particularly, one-way migrant homes were located predominantly on higher up mountain slopes with lower temperatures, higher forest cover, near natural parks, and symbolic natural sites, and yet with easier access to railway stations and employment. These results provide a valuable evidence base for rural spatial planning for increased QoL and attracting migrants that considers ecological–social feedbacks, and hence supports deurbanization.

Assessment of unutilized woody biomass energy and the cost and greenhouse gas emissions of woody biomass power plants in Hokkaido, Japan

Ryoga Ono, Yoichiro Fukuda, Masahiko Fujii, Yoshiki Yamagata

Cleaner Energy Systems (Elsevier) 6 100084 2023.12

Digital Transformation of Logistic and Maintenance for Water/City-Gas Supply Infrastructures

Masaaki Hashimoto, Yoshiki Yamagata, Yoshiaki Ohkami

2023 International Conference on Electrical, Computer and Energy Technologies (IEEE) 1 - 6 2023.11

This paper deals with application of cutting-edge information technology represented by Digital Transformation, DX, for maintaining critical infrastructures such as water and city-gas supply systems. Among many stakeholders related to such infrastructure, we have focused on system maintenance for the end-user by focusing on manufacturing, wholesale and retail, logistic, and on-site construction that formulate a very complex System of System. First, this paper describes a successful example of DX application to the water supply system. Second, the approach and means of this example were applied to an obsolete system of a city-gas supply system with successful results in relatively short period of time. In this DX application, there were several issues to overcome during the execution of reformation but finally the goal of this attempt has been attained by improving the process and increasing the profit. This has proven that appropriate application of the DX is useful and provides a powerful tool for improving business. Typical successful results are: 1) Service time has increased to 24 hours a day and 365 days a year. 2) Number of workforce has decreased from 37 to 27, and 3) Number of errors decreased to 1 to 4 out of 200 orders.

Mapping urban carbon emissions in relation to local climate zones: Case of the building sector in Bangkok Metropolitan Administration, Thailand

Dararat Khamchiangta, Yoshiki Yamagata

Energy and Built Environment (Elsevier) 2022.11

WHAT ARE THE OPPORUNITIES AND LIMITATIONS OF NEW URBAN SYSTEMS DESIGN USING DIGITAL TWIN?

Yamagata Yoshiki ,Komiya Masahito ,Chang Soowon

2022.07

Joint Work, Lead author

COMMUNITY CARBON MANEGEMANT FRAMEWORK BY DESIGNING DIGITAL TWIN FESTIVAL USING GIS

Hideo Takahashi, Yamagata Yoshiki, Chang Soowon

2022.07

Joint Work, Corresponding author

Spatial-Temporal CO2 Mapping for Urban Carbon Management

Yoshida Takahiro, Murayama Akito, Yamagata, Yoshiki

2022.07

Joint Work, Last author

Smart cities and climate-resilient urban planning

Ayyoob Sharifi, Yoshiki Yamagata

Environment and Planning B: Urban Analytics and City Science (SAGE Publications) 49 ( 5 ) 1347 - 1353 2022.06

Assessment of Waterfront Office Redevelopment Plan on Optimal Building Arrangements with Rooftop Photovoltaics: A Case Study for Shinagawa, Tokyo

Younghun Choi , Takuro Kobashi , Yoshiki Yamagata and Akito Murayama

Energies (MDPI) 15 ( 3 ) 2022.01

Joint Work

Designing waterfront redevelopment generally focuses on attractiveness, leisure, and
beauty, resulting in various types of building and block shapes with limited considerations on
environmental aspects. However, increasing climate change impacts necessitate these buildings to be
sustainable, resilient, and zero CO2 emissions. By producing five scenarios (plus existing buildings)
with constant floor areas, we investigated how buildings and district forms with building integrated
photovoltaics (BIPV) affect energy consumption and production, self-sufficiency, CO2 emission, and
energy costs in the context of waterfront redevelopment in Tokyo. From estimated hourly electricity
demands of the buildings, techno-economic analyses were conducted for rooftop PV systems for 2018
and 2030 with declining costs of rooftop PV systems. We found that environmental building designs
with rooftop PV system are increasingly economical in Tokyo with CO2 emission reduction of 2–9%
that depends on rooftop sizes. Payback periods drop from 14 years in 2018 to 6 years in 2030. Toward
net-zero CO2 emissions by 2050, immediate actions are necessary to install rooftop PVs on existing
and new buildings with energy efficiency improvements by construction industry and building
owners. To facilitate such actions, national and local governments need to adopt appropriate policies.

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Rapid rise of decarbonization potentials of photovoltaics plus electric vehicles in residential houses over commercial districts

Takuro Kobashia, Younghun Choia, Yujiro Hiranob, Yoshiki Yamagataa, Kelvin Sayc

Applied Energy (Elsevier) 306 2022.01

Research paper (scientific journal), Joint Work

Rooftop photovoltaics (PVs) integrated with electric vehicles (EVs) has the potential to deeply decarbonize urban energy systems in a cost-effective way. The SolarEV City Concept suggested that the rooftop PV plus EV systems can supply up to 95% of electricity demand within cities in Japan. However, it was not clear which district in city could consume, generate, and store the PV electricity, as each district has different load patterns, building structures, and number of parked cars. In this study, we performed techno-economic analyses on rooftop PV systems integrated with stand-alone batteries or EVs in residential and commercial districts in Japan from 2020 to 2040. We found that rooftop PV systems in 2020 are already cost competitive relative to existing energy systems. However, “PV + EV” systems in residential houses rapidly increases its economic advantage over commercial districts due to greater rooftop space and higher number of available vehicles. Moreover, energy sharing significantly improved the decarbonization potential. By 2025, energy cost savings, payback periods, and internal rate of return (IRR) of residential “PV + EV” systems respectively reached 23%, 9 years, and 11%, and continued improving in subsequent years. CO2 emissions from electricity and gasoline consumption was reduced by 88%, and the system was capable to supplying 89% of electricity demand. The results indicate that residential “PV + EV” systems are a potential source for significant renewable energy generation and storage that can also produce increasingly dispatchable electricity. Policy makers, industries, and communities should prepare to establish these systems through regulatory reform and demonstration projects to scale-up after 2025.

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Diverse values of urban-to-rural migration: A case study of Hokuto City, Japan

YasuoTakahashi, Hiroyuki Kubota, Sawako Shigeto, TakahiroYoshida, Yoshiki Yamagata

Journal of Rural Studies (Elsevier) 87 292 - 299 2021.10

Research paper (scientific journal), Joint Work, Accepted, ISSN 0743-0167

The global population is concentrating unprecedentedly into urban areas, raising concerns on global sustainability and human well-being. There also exists a niche trend of migration from urban to rural areas particularly in countries with post-industrial economies. This paper investigated values of migration expressed by the migrants arrived in Hokuto City, a Japanese rural municipality experiencing pervasive population decline but is also a popular destination for migrants from urban areas. Statistical analyses of 868 responses to a Hokuto City's migrant survey between April 2017 and January 2019 identified their common values of migration, i.e., nature, housing and food. In addition to these common values, households with different demographic characteristics had different priorities: employment for singles in ages between 16 and 29; favorable environment for raising children for married couples in their 30s and 40s; not specific or ‘lifestyle’ for migrants in 50s; and staying with or near family for retirees over 60 years. Knowledge of heterogeneity in migrants and of their values, as described herein, will enable targeted policies and public services concerning migration. Widespread acceptance of teleworking after experiencing the COVID-19 pandemic might offer people of working age, particularly in their 20s and younger, a wider range of options of places to work and live, and thus is likely to influence future urban-rural population flow. A more detailed analysis of the region's natural attributes which are central to the values of migration to rural areas, such as Hokuto City, will be useful to inform regional land use planning that is salient to the values of migrants.

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The Need for Urban Form Data in Spatial Modeling of Urban Carbon Emissions in China: A Critical Review

Cai, Meng, Yuan Shi, Chao Ren, Takahiro Yoshida, Yoshiki Yamagata, Chao Ding, and Nan Zhou

Journal of Cleaner Production (Elsevier) 2021.08

Joint Work

Cities produce over 70% of global carbon emissions and are thus crucial in driving climate change. Urban carbon emissions may continue to increase especially in those less-developed countries and regions which are still under rapid urban development. Policymakers need to find ways to effectively control and reduce carbon emissions. Thus, spatial modeling methods to map and predict urban carbon emissions have been developed to meet these needs. This paper examines the progress of the spatial modeling of carbon emissions and the relationship between urban form and carbon emissions in China by reviewing more than 100 peer-reviewed journal articles in the Scopus database. The latest prediction methods and techniques are described in the paper. Their advantages and limitations are then discussed. Urban forms have a significant influence on carbon emissions and have been applied in spatial modeling studies in other countries. However, this review has identified the lack of urban form data and high-resolution inventories from existing studies in China. Future developments in the spatial modeling in China should therefore have a fine spatial resolution and incorporate open and high-quality urban form data, including urban morphology and land use/land cover.

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Machine learning model for predicting out-of-hospitalcardiac arrests using meteorological and chronological data

Takahiro Nakashima , Soshiro Ogata , Teruo Noguchi , Yoshio Tahara , Daisuke Onozuka , Satoshi Kato , Yoshiki Yamagata , Sunao Kojima , Taku Iwami , Tetsuya Sakamoto , Ken Nagao , Hiroshi Nonogi , Satoshi Yasuda , Koji Iihara , Robert Neumar , Kunihiro Nishimura

2021.05

Joint Work

Objectives: To evaluate a predictive model for robust estimation of daily out-of-hospital cardiac arrest (OHCA) incidence using a suite of machine learning (ML) approaches and high-resolution meteorological and chronological data.

Methods: In this population-based study, we combined an OHCA nationwide registry and high-resolution meteorological and chronological datasets from Japan. We developed a model to predict daily OHCA incidence with a training dataset for 2005-2013 using the eXtreme Gradient Boosting algorithm. A dataset for 2014-2015 was used to test the predictive model. The main outcome was the accuracy of the predictive model for the number of daily OHCA events, based on mean absolute error (MAE) and mean absolute percentage error (MAPE). In general, a model with MAPE less than 10% is considered highly accurate.

Results: Among the 1 299 784 OHCA cases, 661 052 OHCA cases of cardiac origin (525 374 cases in the training dataset on which fourfold cross-validation was performed and 135 678 cases in the testing dataset) were included in the analysis. Compared with the ML models using meteorological or chronological variables alone, the ML model with combined meteorological and chronological variables had the highest predictive accuracy in the training (MAE 1.314 and MAPE 7.007%) and testing datasets (MAE 1.547 and MAPE 7.788%). Sunday, Monday, holiday, winter, low ambient temperature and large interday or intraday temperature difference were more strongly associated with OHCA incidence than other the meteorological and chronological variables.

Conclusions: A ML predictive model using comprehensive daily meteorological and chronological data allows for highly precise estimates of OHCA incidence.

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Carbon analytics for net-zero emissions sustainable cities

Anu Ramaswami, Kangkang Tong, Josep G. Canadell, Robert B. Jackson, Eleanor (Kellie) Stokes, Shobhakar Dhakal, Mario Finch, Peraphan Jittrapirom, Neelam Singh, Yoshiki Yamagata, Eli Yewdall, Leehi Yona & Karen C. Seto

Nature sustainability (Springer) 4 ( 6 ) 460 - 463 2021.05

Joint Work

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Estimating Building Electricity Performance Gaps with Internet of Things Data Using Bayesian Multilevel Additive Modeling

Chang S, Castro-Lacouture D, Yamagata Y

Journal of Construction Engineering and Management (Journal of Construction Engineering and Management) 146 ( 12 ) 2020.12

Joint Work, ISSN 07339364

Energy models should be simplified to handle data limitations and should predict reliable energy use. Currently, it remains challenging to ensure an appropriate level of detail for simplifying building energy models and to avoid performance gaps when predicting electricity consumption. In this respect, this research proposes to identify an appropriate level of simplifying a building energy model, predict electricity demands and performance gaps using the simplified energy model, and expand the model usability through the operational stage. Building electricity demands predicted through EnergyPlus (version 8.7.0) simulation are compared with actual electricity data collected through Internet of Things (IoT) sensors. Consideration of performance gaps increases the predictability of electricity consumption of a simplified energy model. Also, the Bayesian multilevel additive model updates the performance gaps along with the collection of new IoT data. The findings of this study contribute to forecasting electricity demands with a simplified energy model by predicting performance gaps that can be applied to predicting the electricity needs of similar buildings in the design stage and controlling operational electricity use in the operational stage by comparing sensor measurement with reference data provided by the energy model.

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Spatiotemporal analysis of deforestation in the Chapare region of Bolivia using LANDSAT images

Bagan H, Millington A, Takeuchi W, Yamagata Y

Land Degradation and Development (Land Degradation and Development) 31 ( 18 ) 3024 - 3039 2020.12

Research paper (scientific journal), Joint Work, ISSN 10853278

The purpose of this study is to quantify (a) spatiotemporal deforestation patterns, and (b) the relationships between changes in the main land-cover types in the Chapare region of Bolivia. We applied subspace classification methods to LANDSAT data from 1986, 1999, and 2018 and used grid cells at scales of 150, 300, 600, and 900 m to measure deforestation trajectories. The 150 m grids provided better detail to determine deforestation trajectories than coarser-scale grid cells. Differences in grid-cell scale did not influence the statistical trends in land-cover changes significantly. Changes in forest area were negatively correlated with changes in cropland (r = −.44), grassland (r = −.34), swamp grassland (r = −.38), and regrowth (r = −.32) areas. Correlations between forest losses in cropland, grassland, and regrowth change analyses were weaker between 1999 and 2018 compared to 1986 to 1999. Forest cover declined from 6,635 km (1986) to 3,800 km (2018), and the deforestation rate increased from an annual average of 1.36% between 1986 and 1999 to 2.0% between 1999 and 2018. The key proximate drivers of forest clearance rates and patterns were increasing population, agricultural expansion, and road building. While coca is an economically important crop in Chapare, its direct and indirect effects on deforestation could not be determined unambiguously. It is probable that the expansion of agriculture will lead to further deforestation and forest fragmentation and, along with decreases in forest cover, further changes will take place between non-forest categories. 2 2

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Decision support for retrofitting building envelopes using multi-objective optimization under uncertainties

Chang S., Castro-Lacouture D., Yamagata Y.

Journal of Building Engineering (Journal of Building Engineering) 32 2020.11

In the last decade, retrofitting strategies have been reviewed to improve energy efficiency and reduce the environmental impact of existing buildings. One retrofitting strategy consists of innovating building envelopes with the adoption of high-performance materials or systems. Despite the potential performance enhancement, opportunities for new envelopes have been constrained because various envelope options are difficult to be evaluated synthetically. Also, the decisions should consider the optimization of multiple objectives as well as uncertainties. In this respect, this paper aims to support the decision of selecting building envelopes to meet multiple objectives under uncertainties while considering possible envelope options. A multi-objective optimization model is developed considering the existing built form, uncertainties in performance predictions, and incorporating newly developed façade systems. The optimal selection includes emerging materials and technologies that are provided with building envelope renovation options to satisfy indoor thermal comfort, energy balance, environmental emissions, and economic aspects. The decision-support framework is also devised to add any envelope options. This adaptable framework enables decision makers to accommodate new system materials and proactively evaluate their feasibility. The optimization model and framework proposed in this research will contribute to providing a roadmap for transforming existing buildings into smart and sustainable built systems.

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MIROC-INTEG-LAND version 1: A global biogeochemical land surface model with human water management, crop growth, and land-use change

Yokohata T, Kinoshita T, Sakurai G, Pokhrel Y, Ito A, Okada M, Satoh Y, Kato E, Nitta T, Fujimori S, Felfelani F, Masaki Y, Iizumi T, Nishimori M, Hanasaki N, Takahashi K, Yamagata Y, Emori S

Geoscientific Model Development (Geoscientific Model Development) 13 ( 10 ) 4713 - 4747 2020.10

Research paper (scientific journal), Joint Work, ISSN 1991959X

Future changes in the climate system could have significant impacts on the natural environment and human activities, which in turn affect changes in the climate system. In the interaction between natural and human systems under climate change conditions, land use is one of the elements that play an essential role. On the one hand, future climate change will affect the availability of water and food, which may impact land-use change. On the other hand, human-induced land-use change can affect the climate system through biogeophysical and biogeochemical effects. To investigate these interrelationships, we developed MIROC-INTEG-LAND (MIROC INTEGrated LAND surface model version 1), an integrated model that combines the land surface component of global climate model MIROC (Model for Interdisciplinary Research on Climate) with water resources, crop production, land ecosystem, and land-use models. The most significant feature of MIROC-INTEG-LAND is that the land surface model that describes the processes of the energy and water balance, human water management, and crop growth incorporates a land use decision-making model based on economic activities. In MIROC-INTEG-LAND, spatially detailed information regarding water resources and crop yields is reflected in the prediction of future land-use change, which cannot be considered in the conventional integrated assessment models. In this paper, we introduce the details and interconnections of the submodels of MIROC-INTEG-LAND, compare historical simulations with observations, and identify various interactions between the submodels. By evaluating the historical simulation, we have confirmed that the model reproduces the observed states well. The future simulations indicate that changes in climate have significant impacts on crop yields, land use, and irrigation water demand. The newly developed MIROC-INTEG-LAND could be combined with atmospheric and ocean models to develop an integrated earth system model to simulate the interactions among coupled natural-human earth system components.

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On the potential of “Photovoltaics + Electric vehicles” for deep decarbonization of Kyoto's power systems: Techno-economic-social considerations

Kobashi T., Yoshida T., Yamagata Y., Naito K., Pfenninger S., Say K., Takeda Y., Ahl A., Yarime M., Hara K.

Applied Energy (Applied Energy) 275 2020.10

ISSN 03062619

To minimize the impacts of climate change, it is increasingly clear that global CO emissions should be eliminated by 2050 and that leading low-carbon cities should reach net zero emissions by 2040. However, the precise pathways by which they can reach such ambitious goals have yet to be identified. As costs of photovoltaics (PV), batteries, and electric vehicles (EVs) are likely to keep falling, they can jointly play a key role for deep decarbonization. Here, we conduct a techno-economic analysis of a city-scale energy system with roof-top PV, batteries, and EVs for Kyoto City, Japan. We find that aggressive EV adoption and the use of EVs for electricity storage could help roof-top PV penetration in the city with substantially lower costs than just deploying PV and batteries alone or allowing EV to charge only. CO emissions from vehicle and electricity usage in the city could be reduced by 60–74% if the entire current car fleet is replaced by EVs while also reducing energy costs by 22–37% by 2030. The largest challenge of a city-wide “PV + EV” system (named as “Solar-EV city”) is its implementation. We explore how it could be realized in Kyoto through peer-to-peer (P2P) power trading/blockchain technology initially on a community scale as smart microgrids, then gradually expanding/converging into a city-wide. For the transition to decentralized power systems, citizen's decision-making process is one of the keys to overcome social, institutional, and regulatory barriers. 2 2

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