Another initiative that is dealing with housing for displaced people is BetterShelter [8] that is cooperating with UNHCR and IKEA to design, prototype, test and implement better solutions for emergency sheltering.
In RMIT (Royal Melbourne Institute of Technology) there’s a group of experts called HARB (Humanitarian Architecture Research Bureau) [9] Their aim is to bring a multidisciplinary approach and gather different professionals (architects, engineers etc.) to work on sustainable solutions for emergency housing.
Global Shelter Cluster [10] is a coordination entity that in hand with IFRC and UNHCR assists in emergency housing responses. Each year they publish a case study overview [11] that describes the shelters developed across the world.
CLUSTEX
in Politecnico di Milano [12] is dealing with textiles structures with a particular focus for emergency sheltering. Several articles are published in recent years by member experts. The hub also carries out structural tests for textiles.
One of the first attempts to assess the internal thermal environment of the emergency shelter is the test by engineers from Cambridge University [13] in 2002 among whom was Peter Manfield that has done a significant effort in emergency sheltering research. The physical test was carried out with the external temperature of -20 Co. The internal comfort was registered through a set of sensors that were distributed across the surface and inner volume. Later on the physical model tests were calibrated into a simulation test and further the tent model was tested with the climatic data of Islamabad, London and Pristina. This was one of the first attempt of using the computer simulation for emergency shelter assessment. In their tests they revealed one of the dominant problems that occurs in emergency textile shelters. As below mentioned:
· The temperature shows a dramatic difference in height.
· Without a proper
insulation
it is unlikely to achieve an internal comfort by mere casual thermal gains.
· During peak activities inside the tent the humidity can get to its maximum
Several other attempts occurred in recent years. In 2013 engineers from University of Rome Tor Vergata, have tried to develop different solution for the emergency tents in order to improve the internal comfort [14]. Pursuing this, they assembled a tent and tested it’s performance during May 7-15. Then the received information of the physical test was used in highest details to calibrate a simulation model for the same period. And later on the calibrated model was tested with different solutions of design and materials in Torino (winter) and Palermo (summer). Their research shows that by adding high insulating material (aerogel pad) and a particular treatment of the floor a better internal environment can be achieved. This will dramatically decrease the energy demand for the tent.
A very interesting approach can be seen in the research and implementation project by
Clustex
/Politecnico di Milano researchers [15]. Together with S(P)
EEDKITS
[
7]
they have developed three different solutions with the use of textiles that were later given scores on various performances. The thermal comfort of the most promising solution was tested with the weather data of Ulaanbaatar (Mongolia), Tabriz (Iran), Damascus (Syria) and Dakar (Senegal). The winner concept was prototyped in ten units and tested by Senegal and Luxembourg Red Cross delegations.
Probably one of the most sustainable solutions in this field was proposed by researchers from Politecnico di Milano [16]. The concept was to collect the disposed skis that accumulate in significant quantities each year and are not a subject of recycling and to implement them as a construction element inside an emergency shelter. The designed ski yurt-like structure was enveloped by multilayer composite that was in a double PVC layer, both outside and inside, with thermo-reflective insulation system interposed in between. Later on the design was simulated for the thermal comfort analysis with the climate data of Palermo. The shelter was assembled in Italy then disassembled and sent to Guinea Bissau. In terms of internal comfort it was suitable for hot climates. The notable thing here was the chimney effect that due to the opening in the highest point could let the hot air out of the tent and thus not cause the height temperature variance as it usually happens with the vaulted tents without a skylight opening.
One of the few researches that showed a backward approach is the analysis by S. Obyn et al. [17] where instead of just doing the simulation for different climatic zones they actually did investigations on the real tents in different climatic zones (Brussels in Belgium, Sag Nioniogo in Burkina Faso and Bertrange in Luxembourg). They used the famous and omnipresent family tent from the UNHCR core relief items catalogue [5] to see how it actually performs. Afterwards, they made the corresponding computer simulations and the compare results were quite accurate. Also a good methodology for such kind of assessments is described.
In the available
sources
only few research attempts were encountered that dealt with
acoustics
of tensile membrane structures and none of them
were
about the emergency cases.
However
the
below presented
research cases have some common parameters and help to understand the general principles and approaches for acoustical assessment in this kind of structures.
ETFE is one of the ubiquitous materials in tensile membrane structures. Although it is not so commonly used in emergency because of the price the analysis [18] done by Japanese researchers on reducing the rain noise on ETFE membranes gives clues on understanding the problem and proposes solutions that may be applied for other materials as well such as PVC membranes. The researchers designed several theoretical solutions (adding double air chamber, gel sheet, non-woven fabric) to the raindrop drumming problem and then applied laboratory tests to determine their effect on noise reduction. Despite some discrepancies the tests showed that by adding some damping materials the inner acoustical comfort may be fostered.
In 2014 researchers from University of Catania published an article [19] in The 21st International Congress on Sound and Vibration. Here the goal was to investigate a case of a study room covered by a textile structure in order to improve its acoustical characteristics. The problem here is that as usually it happens the tensile membrane structures may have high ceilings due to the structural properties. These high ceiling create dead volumes that extend the wave traveling to the unoccupied distant spaces that will afterwards in laggard reflection cause inconveniences. The room was examined with sensors and later with the corresponding simulation was carried out to optimize the solutions. The researchers made clear that for better outcome of the design in acoustical terms the corresponding simulations and optimizations should be carried out.
One of the very few research attempts done to deal with the acoustics inside the textile tent structures is the Analysis of the Acoustic Conditions in a Tent Structures [20] by Slovakian researchers (2015).They pinpoint out one of the main differences of acoustical behavior of textiles structure which is that in these structures usually you have more reflection of high frequency waves as opposed to the higher reflection of low frequency waves which exists in conventional
quasi flat
structures. The research is about a case study of a big tent dedicated for cultural activities and thus is only partially corresponding to the problems of this research. The tent performance was measured in situ and later simulated for comparison. As a result of the analysis it was shown that curtains can be inside the tent to improve acoustical characteristics but nevertheless for better sound propagation in big tents some audio equipment may be required for cultural events. Although this doesn’t relate to the given topic much but from the analysis it’s beneficial to know that simulation techniques may be applied to
tent like
structures to determine acoustical environment for the emergency tents as well.
By analyzing the above given researches and investigations we can say that the studies of textile emergency shelters’ internal environment are very recent and progressively are entering into the realm of computer simulation and weather
data driven
analysis. As we see in the examples of thermal assessment the computer models can be very well calibrated with the real shelters and give enough accurate results. However the post-implementation data of comfort for such tents are limited and long-term evaluation of these objects are required to see whether the initial design anticipations do really match with the actual performance or not. On the other hand in recent years more and more tools are becoming available for researchers for comfort simulation. These tools continuously improve the accuracy and ease of use, thus giving an opportunity to the design developers not only to assess their concepts in terms of structural stability but also for internal comfort for practically any climatic zone. The weather data is increasingly accumulating in platforms such as ASHRAE and can serve for better decision making in the concept stage. As it is mentioned [17] it is better to solve these problems earlier rather than trying to solve it with the huge supply of wood and fuel.
Evidently, the aspect of acoustical comfort
as opposed to the thermal comfort
was a matter of lesser concern so the knowledge and solutions here are much scarcer. Though the lack of acoustical comfort may not cause severe detriment to the occupants it
may be
a reason
of
a very poor life quality.
As we saw [3] the number of people that require sheltering is continuously increasing. The impact of this is truly global and requires immediate action. The solutions must become better and more sustainable.
Specifically, by far we can’t see any research that tries to deal with the problems of thermal and acoustical comfort simultaneously. Developing an enclosure concept that takes into consideration both aspects may be beneficial.
On the other hand, until now the design processes were mainly human creativity driven and few optimization techniques may have been applied. By using nowadays available computation power we can evaluate hundreds of solutions in a row and determine the best possible properties in given constraints.
The research will aim to develop a solution of an emergency membrane shelter that will be optimized both in terms of thermal and acoustical comfort with
high
degree of localization.