Ideally materials and products should be non-toxic, non-polluting, sustainable, and renewable, produced with low energy and low environmental and social costs, are easily biodegradeable, reused and recycled. That said, weighing the relative merits and disadvantages of materials has become a complex science. A reclassification of all building materials to take into account concerns for health and ecology is long overdue.

Assuming that a product complies with the technical requirements and government standards it should also meet as many as possible of the following criteria:

•     Renewable and abundant
•     Production has a low impact on the environment
•     Non-polluting, emitting no harmful vapours, particles, or toxins into the environment, either in manufacture or in use.
•     Energy efficient, using low energy in production, transport, and use and generally coming from local regions.
•     Good energy conservers with high insulation values that retain heat in winter and keep the building cool in summer.
•     Durable, long lived, and easy to maintain and repair.
•     Equitable and produced via socially fair means.
•     Low waste and capable of being reused and recycled, thereby saving the vast amounts of energy spent processing raw materials.
•     Radioactive safe and electromagnetic safe.