In this study, we focused on decarbonization strategies for detached houses and conducted an online citizens’ assembly targeting the residents of Kitakyushu City. By quantitatively assessing the participants’ changes in attitude through discussions, we aimed to clarify the process of consensus formation. Furthermore, we evaluated the relationship between these changes in attitude and psychological characteristics related to awareness concerning global warming. Initially, most participants favored integrating solar photovoltaic (PV) panels with electric vehicles (EVs) or batteries to maximize PV electricity use. The first discussion focused on the costs associated with GHG reduction measures, leading to a preference for cost-effective GHG emission reduction strategies. Information about the societal costs of GHG reduction subsidies for detached houses was shared before the second discussion, heightening the importance of cost considerations.

Nonetheless, the final scenario chosen was not just cost-focused; it also included the efficient utilization of PV electricity and battery use. While the attributes prioritized and scenarios chosen varied due to different levels of awareness of global warming, participants recognized the differences in others’ opinions during the discussions. They began to select scenarios that satisfied their criteria while also considering others’ living conditions and psychological tendencies.

There is a growing demand for local policies to combat climate change among zero-carbon declaring municipalities. Citizens’ Assembly, characterized by collecting diverse citizen opinions by randomly selecting participants providing them compensation, have gained attention as a method for involving residents in climate policy. The spread of online communication tools due to the COVID-19 pandemic has also allowed citizen assemblies to be held online as well as face-to-face.

This study focused on Kitakyushu City, using an online survey to analyze the relationships among the attributes, environmental awareness, climate change perceptions, and willingness to participate in online citizen assemblies. Results showed a general high level of awareness and urgency toward global warming. Especially respondents in their 60s and above exhibited higher environmental consciousness and proactive behavior than younger respondent groups, whereas those in their 50s and younger were more likely to lack information and question the impact of individual actions. Respondents were categorized into four groups based on their climate change awareness: G1 - Indifferent (46％), G2 - Proactive (26％), G3 - Skeptical (9％), and G4 - Passive (19％). Differences in climate action engagement were observed between these groups. However, there was no significant difference in willingness to join online citizens’ assembly, suggesting that compensated participation might encourage involvement from less interested groups.

More than 1,000 local governments have committed to achieving zero carbon cities by 2050 in Japan. Each region needs to draw up future scenarios and develop a strategic plan to realize combined value including decarbonization. Based on this recognition, we share the contents of our efforts for the “Development of Regional Planning System of Green Innovation for a Decarbonized Society and Establishment of Social Implementation Network through Regional Coalition Action”. Toward regional decarbonization, it will be necessary to diagnose the current state of the region, plan alternative future goals, and design the projects necessary to achieve them. We are building a “support system for regional decarbonization planning” based on a model that sets future goals related to regional energy, next-generation transportation, construction stock management, and others being studied by each working group of the project, using climate change impacts, regional socioeconomic characteristics, and national plans as input variables and integrally estimating and outputting socioeconomic and environmental effects for the development of regional scenarios and plans. We share our efforts and status, and discuss how research can support the realization of decarbonized regions.