Building materials provide the greatest benefit when they can be sourced locally and sustainably. There is no single set of benchmarks for sustainable materials, but they are often produced within 500 miles, sturdy to avoid constant replacement, and typically follow the three R’s of reuse, reduce and recycle. They should also be produced with the least amount of energy possible (e.g. no plastics) and should not be toxic. Sustainable materials veer primarily towards naturally occurring materials that can be replenished frequently and safely.