For the sustainability assessment of the shelters, three categories
were defined. The environmental impact category accounted
for the effects on the natural environment of the production and
transport of construction materials and the construction of shelters.
Cost was associated with the purchase and transport of construction
materials and the erection of shelters. Finally, technical performance
was related to the risk zones in which the communities
live as well as the mechanical performance of the shelters during
the occurrence of a natural hazard event, such as earthquakes,
winds, and/or flooding. The aim of this methodology is to compare
the sustainability performance of the shelters. To achieve this goal,
it was necessary to develop a functional unit for each category.
These functional units allow the comparisons across not only
shelters but also categories, which increases the consistency of the
results. The two main factors we identified for the development of
functional units: life span and area covered. The life span of the
shelters accounts for the fact that some of these structures are
temporary, intended to be relocated or dismantled, and thus might
require less material. This is very important because if the life span
is not considered, then the best-performing shelters are those that
are the lightest and least durable, which is not always the best
solution for a post-disaster reconstruction project. The expected
shelter's lifespans used on the calculations were taken from the
reports of the International federation of red cross societies [2,3].
These reports present estimated lifespans for the studied sheltersbased on their application on the field. The second factor (covered
area) represents a series of technical and social issues. It is clear that
a larger covered area provides more useful space for future inhabitants
of these shelters, which results in a better sense of privacy,
cultural adaptation and health. For the environmental impact
category, the functional unit was defined as the ratio between the
shelters' environmental impact and its covered area and life span.
The functional unit for the cost category was defined as the ratio
between the projects' cost per shelter, its covered area and its life
span in months. For the technical category, the functional unit was
defined as the ratio between the risk zone in which the shelter was
located and the shelter's mechanical performance in the case of a
natural event. The methodologies used to assess each category's
environmental impact, cost and technical performance are
described in the following sections.