ASSESSMENT OF VISUAL ENVIRONMENT NECESSARY FOR BUSINESS CONTINUITY IN EMERGENCIES (PART 1) ： A STUDY OF VISUAL ENVIRONMENT ASSESSMENT USING HEAD MOUNTED DISPLAY VIRTUAL REALITY SYSTEM

Abstract

Natural disasters that had recently happened in Japan, including Great East Japan Earthquake in 2011, destroyed social infrastructure especially electricity systems for more than several months. During this period, electric supply tremendously decreases and caused many problems to emergency response, lifeline infrastructure management, life supporting related activities in hospitals and refugee accommodations and also government administrative business. In order to sustain these basic activities, we need minimal lighting systems to facilitate workers in offices maintaining these activities. However, most of lighting research on emergency, Boyce et al., Akizuki among others, concentrate on emergency escape lighting system. Mochizuki et al. studied the impacts of shortage of electricity on office lighting environment during Great East Japan Earthquake aftermath. To our knowledge, there are no studies analyzing the minimum lighting system required in offices during emergency period. Appropriate assessment of visual environment for business in disaster effected areas is required. Thus, the purpose of this paper is to develop a virtual reality simulation system (VRS) which can provide real focal-ambient lighting environment for workers in the office and to find the minimum lighting environment required to continue working for more than 10 days during emergencies. 2400 observations from 20 participants (9 students and 11 office workers, 9 female and 11 male) assessing 30 VR scenes on 4 business continuing periods (1 day, 3 days, 10 days, over 10 days) were obtained in the experiment. We found the following results from the experiment: 1. VRS can provide focal-ambient lighting environment for experiment participants more realistically than other devices. It has high 96.7% accuracy representation percentage of real environment luminance-chromaticity values of VR scenes and provides 360 degrees experience of real visual environment at 3 degrees of freedom to participants. 2. Minimum lighting on working surfaces can be as small as 75 lux for more than 10 days office work in emergency. 3. Ambient lighting is strongly required to keep comfortable room brightness and focal ambient lighting system for the workers. At working surface illuminance of 75 lux, 100% of participants can continue to work for more than 10 days with ambient light and only 85% of participants can continue to work for 10 days without ambient light. 4. There may exist some possibilities that student participants of experiments may not have strong tolerance against less lighting than office workers. Office workers can work for 10 days with 15 lux on working surface while students require twice this illuminance of 30 lux. i.e. we need to study more about the effects of participants’ attributes on experiment results. 5. 360 degrees Brightness Estimation Image can be used to assess how much ambient and focal brightness is required in the given visual environment. 6. Ambient visual environment is confirmed to be strongly correlated with how much light is available in desk surroundings, walls, and ceilings and not with horizontal surfaces such as floor discussed in the literature.