One of the main difficulties of designing truly sustainable solutions is the complexity of scope and domain that need to be taken into account. Projects often focus on one or at most a few subject areas, such as energy, waste, or materials. It is rare for a project to be developed that aims to be sustainable in a truly integrated sense.

The ELSIA system helps map the larger set of relationships between the project at hand and the ways in which it will influence the world around it. This system can be used for management and policy issues as well as design problems. It is essentially a tool for "systems thinking" that functions by systematically allowing the user to map relationships between objects. It can be used for indicator selection, effect mapping and many other stages of systems analysis.

ELSIA takes its name from the five main categories seen in the SiD stack diagram to the right. The categories are:

• Energy & Materials (Matter)
• Life (Species & Ecosystems)
• Society (Economy & Culture)
• Individual (Health & Happiness)
• Actions (Utility & Purpose)

The categories of ELSIA are functionally nested within each other. All materials are made from energy, and all ecosystems are made of materials. The economy is a subset of culture, just as each individual is always a part of society, and so on.

Using the SiD stack and the ELSIA relationship system one can prevent developing systems that improve specific domains, but externalize issues to other key areas.

The ELSIA relationship system and SiD Stack are part of the Symbiosis in Development sustainability methodology.