**2. Case community**

**1. Introduction**

100 Sustainable Air Conditioning Systems

[4, 5]. However, CO2

energy-efficient measures and CO<sup>2</sup>

incorporate various regional efforts.

Protocol, reduction of CO2

As global warming becomes more serious, development of a low-carbon society has become an urgent task [1–3]. In particular, reduction of the energy used to cool and heat buildings, which is a large portion of energy usage during summer and winter, is an important issue

As shown by recent examples, such as locally implemented plans to counteract global warming, formulation of new regional energy conservation visions, and proposals for environmental model/future cities, there are many opportunities for local governments to employ

cooling and heating is strongly influenced by local factors such as climate, land use, and

structural and structural measures is high [9], and there are proposals for such measures that

In Japan, energy usage has changed greatly since the 2011 Great East Japan Earthquake [10–12]. Before the earthquake, during the period between the United Nations Framework Convention on Climate Change and the first commitment period prescribed by the Kyoto

term global warming countermeasures. Since the earthquake, there have been many global warming countermeasures and energy policies such as government-imposed power-saving measures to mitigate power peak loading, various programs associated with nuclear power

There are three reasons that the Great East Japan Earthquake caused changes to energy-related matters. First, the vulnerability of Japan's large-scale energy supply network was exposed. The supply network for power and gas was disrupted during the earthquake, and the energy supply was discontinued over wide areas, even in areas that suffered only minor earthquake damage. In some cases, people survived the earthquake and tsunami but ultimately died due to the absence of power, which resulted in a lack of heating and a shortage of dry clothes. This situation led to a focus on renewable energy as an emergency power source during disasters. Through the introduction of a distributed power supply and construction of an autonomous energy network, energy supply and demand are becoming more efficient at the local scale [13]. Second, the earthquake-related accident at the Fukushima Daiichi Nuclear Power Plant increased the public's awareness of energy supply issues [14–16]. To mitigate peak power loading as the nuclear power plant ceased to function, rolling blackouts and legally binding power usage restrictions were implemented. Additionally, radioactive contamination led to a large-scale evacuation order for residents. During post-disaster reconstruction, many citizens cooperated with energy-saving measures during periods of peak energy demand in summer.

generation, a renewable energy feed-in tariff, and liberalization of power retailers.

As a result, a large number of citizens became aware of energy supply issues.

Third, the Great East Japan Earthquake intensified the problems of depopulation, declining birthrate and the aging population in Japan. For municipalities in disaster-affected areas, these issues are pressing. Population decline along with decentralization of residential areas

increasing. Thus, practical measures are needed to reduce CO<sup>2</sup>

building-related aspects [7, 8]. The potential for energy and CO<sup>2</sup>

emission due to heating and cooling-related energy consumption is still

emissions.

reductions from both non-

emission reduction plans [6]. Energy consumption for

emissions was an important policy issue for mid-term to long-
