## 1 Introduction  
For large public facilities used by many people, energy saving is an important element. Spaces with high ceilings and large areas, such as airports, focus on saving air conditioning energy by minimizing heat loss [1]. The efficient control of HVAC systems is essential, especially in cold or hot areas [2, 3]. On the other hand, in facilities that require visibility and safety, the efficiency of lighting energy tends to be important, including office buildings and railway stations. In offices, lighting energy accounts for about 60% of the total energy consumption, and in the case of railway stations, where many users' movement lines overlap, lighting energy is in more demanded [4]. Among the energy consumed in railway station spaces, building energy represents the largest share, accounting for 81% of the total energy consumption [5, 6]. In the breakdown of items included in building energy electricity accounts for 99.4% of the total [7]. Therefore, the management of power consumption is critical for the operation of railway stations [8]. Significant infrastructure damage was created by the Great East Japan Earthquake in 2011, and the damage to the nuclear power plant caused a major disruption in Japan's power supply [9; 10]. Therefore, it was necessary to begin forced power saving nationwide, and the Japanese government issued a power use restriction decree to reduce power consumption in public facilities by 15% [11; 12]. This significantly affected railway stations, which are representative public facilities used by numerous people, and users experienced many inconveniences. In the breakdown of items that make up the power consumption of railway stations, 44% is lighting energy, 16% is air conditioning equipment, 14% is mobile equipment, such as elevators and escalators and others comprise the remaining 17% [13; 14]. It is almost impossible to reduce the operation of indoor air conditioning facilities and mobile facilities at railway stations and maintain the safety and comfort of the users [15; 16]. For this reason, power savings through lighting energy which consumes the most power, was adopted as a reasonable way to reduce power consumption by 15%. However, because of the sudden power-saving operation due to the earthquake, a smooth transition could not be achieved, and a simple method, the 'using partial light' method was adopted. Therefore, it was argued that blind spots occurred in various places inside the railway station, the overall interior became dark, and accidents became a concern [17]. The darkening of the environment in the platform through which the train passes can lead to hazardous accidents [18; 19]. In particular, if platform screen doors are not installed, there is a risk of falling [20; 21]. Therefore, replacing lighting fixtures as a long-term and efficient power-saving method has been suggested as an alternative, and the introduction of next-generation lighting (LED, organic light-emitting diode, etc.) with low costs and high efficiency is gradually increasing [22]. Additionally, following the 2012 Japan Regeneration Strategy, next-generation lighting for all public facilities in Japan within 10 years was set as the goal [23]. The spatial structure of railway stations is more complex than that of other public facilities [24]. The structures are generally classified as 'platform', 'concourse', or'stair-case', and because the characteristics of the spaces are different, the required lighting performances are also different [25; 26]. Therefore, the application of different standards is required for the lighting plan of the railway station and the power-saving method. If the using partial light method is adopted for all spaces, there is a concern that comfort and safety may deteriorate [27; 28]. In this study, a large-scale survey was conducted to understand railway stations' environmental conditions after the power use restriction decree following the 2011 Great East Japan Earthquake, in Japan.