Keep out the heat
Thermal insulation of shelters, both for winter and summer time, is a domain which is being investigated intensively by the humanitarian sector. In the S(P)EEDKITS project, Centexbel supports this research with lab tests of different textile materials, while the humanitarians have the possibility to perform real field testing. Juxtaposition of these two approaches will deliver really valuable and practical information for the future. The following article will briefly describe the on-going research of thermal insulation of shelters for summer times.
Whereas people living in (the northern countries of) Europe are longing for nice summer temperatures, people in disaster struck areas who are forced to live in tents for longer periods of time think otherwise. Unfortunately, the tents they are bound to live in are not always providing an agreeable environment: more than often, temperatures tend to rise above 55°C, which is really intolerable. The retainment of inner tent temperatures is a ‘hot topic’ among the humanitarian organisations. Within the S(P)EEDKITS project research is being executed to find a solution to this problem.
In some tent camps, shade nets are being distributed to the refugees. They can install the shade net over their shelter using locally available material (see picture, refugee camp in Burkina Faso) and provide shade to the shelter. Field studies have shown that the inner tent temperatures can be lowered with more than 10°C, so the effectiveness of shade nets is unquestionable. On the other hand, humanitarian organisations are unfamiliar with the material properties of shade nets, preventing them from selecting the best shade net material. Two existing solutions to lower the inner tent temperatures, i.e. shade nets and coated fabrics are explained below.
In cooperation with the Shelter Research Unit of the Red Cross and Red Crescent, Centexbel is examining and comparing an elaborated selection of different shade nets. Not only the physical parameters, such as tensile and tear strength, are being evaluated. A lot of emphasis is put on the thermal performance of the nets: which shade nets prevent temperature from rising in the most effective way? The aim is to provide guidelines to humanitarian organisations regarding which type of shade net to distribute in the future.
Often, in disaster areas, people provide shade to their shelter with locally available vegetal materials. These materials are also examined to verify if their thermal performances are equal to the ones of shade nets.
A different approach is to manufacture tents from heat reflective textile materials. These materials can be obtained by incorporating reflective pigments in a coating or by means of impregnation. Thanks to their special dimensions, these pigments are able to reflect the infrared sun light. This IR light is responsible for the heating of objects. Several of these pigments are being evaluated in a PVC coating, such as aluminium and mica based flakes. Measurements have shown that around 65% of the IR light can be reflected by adding these pigments to the coating. Making tents out of these materials can be an alternative to the use of shade nets.
The field trip of several partners to a refugee camp in Burkina Faso (Nov. 2013) was taken as an opportunity to investigate the influence of the colour of the tent material on the inner temperature. A series of cubes were cladded with different materials and exposed to the full sun for a period of 10 days. The inner temperature was recorded. Similar materials with different colours, or similar colours in different materials have been evaluated. The findings confirmed our gut feeling: independent of the material, the lighter the colour, the lower the inner temperature.
The research we have performed is just the onset of a more in-depth research that is needed to control the inner tent temperature. Although material research is important, material is not the only parameter; a well-considered tent design with ventilation options is also critical in the process. Cooperation between different research fields is crucial in order to obtain the best results.