Life Cycle Approach
The entire life cycle of a project should be taken into consideration to ensure environmental responsibility. A simplified Life Cycle Assessment, or LCA, has been performed to demonstrate the decision making process in Sustainable Product Design. The result was shocking than expected; whether the materials ware recycled or not, it does not make a big difference in terms of global warming. The most significant factors are the weight of the product and the travel distance.
Frame Design
The first two prototypes include common structure between the gurney and the wheelchair, which is composed of bent steel pipes welded together and wood parts that are cut into certain shapes. This structure is designed for different functions in the wheelchair and the gurney. In this design direction, the products include a small number of joints, and conversion can be easy. On the other hand, maintenance of wheelchairs may not be easy without sufficient facilities in developing countries.
Maintenance and Usage of Local Materials
LCA is a decision making tool, and does not provide any single answer. Instead, designers make a decision based on the LCA results along with considering other factors of Sustainable Product Design. Disaster areas need help from neighboring societies and it may not be easy to shorten the travel distance. We also need to consider usage and maintenance of wheelchairs on a sustainable basis; steel is heavier than aluminum, but easier to handle with minimum facilities.
Joinery Design
Another design direction is to include less common structure, and use a large number of parts in a simple shape, such as straight pipe and rectangular lumber. The third prototype was deigned based on this idea. In this design direction, gurney parts can be converted flexibly into wheelchair parts. Also, four wheelchairs can be produced from one gurney. leaving few surplus parts. Some types of joints that connect steel to steel or steel to wood have been explored.