Article ID: 201904
Title:Field study on acceptable indoor temperature and wintry thermal improvement of makeshift shelters built after Nepal earthquake 2015
Authors:Rita Thapa*, Hom Bahadur Rijal, Masanori Shukuya, Hikaru Imagawa,
Graduate School of Environmental and Information Studies, Tokyo City University; *Corresponding author: thapareeta19@gmail.com
Keywords: Nepal, Earthquake, Temporary shelters, Season, Acceptable indoor temperature, Thermal insulation, Thermal improvement
Abstract:
Natural disasters and wars are the two main reasons that force populations to leave their homes; there emerges an urgent need to be provided the victims with temporary shelters. After massive earthquake in 2015, thousands of Nepalese who lost their home were doomed to live in temporary shelters, which can hardly provide sufficient thermal comfort. The indoor environments within these shelters are very much affected by local climate. In order to know the seasonal changes of acceptable temperature range experienced by people living in various of temporary shelters mostly self-built after the massive earthquake, a series of survey on thermal comfort was conducted in four main earthquake affected districts; i.e. Lalitpur, Kathmandu, Gorkha and Sindhupalchowk in three seasons i.e. autumn, winter and summer in 2015/16 with 1407 samples. Likewise, to evaluate the thermal characteristics of indoor thermal environment on the basis of materials used for the shelters; and to examine the possible improvement of the shelters, the continuous field measurement with interval of 10 minutes on indoor thermal environment in five shelters was conducted in one of the district hit by the earthquake, Lalitpur, in winter.
The mean indoor globe temperature varied between 12.1 and 18.5°C in winter and between 26.9 and 33.2°C in summer; thus, the seasonal difference is 21.1°C. The lowest value of mean comfort temperature among the four districts was 15.0°C and the highest was 28.6°C; that is, the seasonal difference is 13.6°C. Using the comfort temperature estimated, the range of indoor globe temperature, within which 80% of the respondents would accept, was found from 11°C to 30°C. The result obtained from acceptable range, which could be referred to in a development of thermally acceptable shelters to be prepared for a future disaster.
The mean indoor and outdoor air temperatures during the measured nighttime were found to be 10.3°C and 7.6°C in Lalitpur in winter, respectively, and the nocturnal indoor air temperature remained below the lowest acceptable temperature of 11°C in winter. This result assured that these shelters are not good for winter and must create various problems. We therefore analyzed the thermal characteristics of those shelters based on the measured results in order to seek a possible improvement. The total heat loss coefficient estimated per floor area in five shelters ranged from 11.3 to 15.2 W/(m2·K); due to low thermal insulation. We made a simple numerical analysis on the variation of indoor air temperature with the assumption of improved thermal characteristics and thereby found that it needs to be reduced about 2 to 7 W/(m2·K) to have the indoor air temperature higher than 11°C for 70% of the whole nocturnal hours. Such reduction of heat loss was found to be realized by adding affordable materials, e.g., cellular polyethylene foam and clothes for respective walls and roof. Thus, the knowledge obtained from this study should hopefully be applied to actual improvement of indoor thermal environment in existing shelters and also to a development for the preparation against future disaster.
Profile of the presenting author:
Rita Thapa is a PhD student of Tokyo City University, Graduate School of Environmental and Information Studies. Her research topic is “Study on Thermal Environment and Adaptive Thermal Comfort of Occupants in Temporary Shelters in Nepal after Massive Earthquake 2015”. She has completed her master’s degree in Sociology in Tribhuvan University of Nepal. In particular, to meet the research objectives; she measured the thermal environments and peoples’ comfort in temporary shelters built after massive earthquake 2015 in Nepal. She has written several conferences papers and presented them in national and international conferences i.e. Architectural Institute of Japan (AIJ) conference, NEAJ/NESAJ symposium, NAST conferences, RETRUD conference, Grand RENEWABLE ENERGY conference, as well as 17th and 18th conferences of the SCIENCE COUNCIL OF ASIA (SCA) in Philippines and Japan. She published one journal paper in Lowland Technology International_2016, Special issue on: Nepal Earthquake & Disaster. She published other two journal papers in the ELSEVIER publication, i.e. Building and Environment_2018 and Energy and Buildings_2019.
