June 27, 2017
In a recent study of the longterm effects of tent habitation as a result of disaster relief, some surprising facts have been ascertained regarding the general comfortability of tent fabric in extreme and long term conditions.
This study, entitled: Effect of retro-reflective materials on temperature environment in tents, and presented by doctoral candidates Lili Zhanga, Xi Menga,⁎, Fei Liua, Long Xub, and Enshen Long, has determined several key factors in long term performance of tent fabrics in regards to the effect on the human condition. Some excerpts from the study are as follows:
"Tents are widely used as temporary shelters, temporary houses after a disaster and temporary offices for construction projects due to their easy transport, rapid construction, low cost and so on. In the Wenchuan earthquake (2008) and the Lushan earthquake (2013), tents played a significant role as temporary shelters. Only in the Wenchuan earthquake, more than 1.5 million tents are used as relief supplies. Before the completion of permanent buildings, victims had to live in these tents for a long time. However, due to the poor thermal performance of tents, indoor temperature environment were very poor, and thereby victims were tormented mentally and physically.
According to the experimental data [1–3], during the day in summer, indoor air temperature can b up to above 40 °C in the open tents and 52 °C in the closed tent. Especially under the high solar radiation intensity, indoor temperature environment will be worsened further. And this poor thermal environment has a negative influence on occupant's health, so it is a very urgent task to improve the indoor temperature environment in tents. As per the indoor health status of residents in disaster relief tents after the Wenchuan earthquake. Their thermal environment improvement in tents, some studies have been done. "
Wang et al. analyzed indoor thermal environment and the results showed that the high temperature and high humid environment in tents can lead to the anorexia, high morbidity, and mental fatigue. In this study, the influence of retro-reflective materials is researched on outdoor and indoor thermal conditions by a comparative experiment under the summer climate conditions of Chengdu, resulting in following conclusions:
"(1) Due to the low thermal inertia and poor thermal insulation, there is no obvious time lag between indoor and outdoor air.
(2) Owing to integrating with retro-reflective materials, the peak values of indoor air temperature and inner surface radiation temperature are reduced by 7.7 °C and 9.2 °C, while their average values are lowered by 4.8 °C and 4.9 °C. It shows that retroreflective materials have an significant influence on indoor temperature environment improvement in tents.
(3) The retro-reflective materials can reduce outer surface temperatures of tents significantly and the reduction value of the peak temperature can be more than 15 °C, which shows outdoor temperature environment has been improved obviously.
(4) Through a comparison of the walls in different orientations, on which retro-reflective materials are covered, the top, east and north walls were found to be better choices, while the north wall is the worst one to cover retro-reflectivity materials."
Though this study doesn't prove any definitive conclusions regarding the best practice when applying reflectivity to tent fabric, it does give a foundation for study that could lead to the benefit of tent users, manufacturers, and enthusiasts. It also offers insight into the physical dynamics of the need for reflectivity in tent fabrics and a directional layout to consider in regards to the environment.