In this masterclass, held at the 2022 National Design Festival of the Building Designers Association of Australia (BDAA), Paul explains how our selection of building materials can drive degradation or regeneration of the natural world and humanity it sustains. He covers concrete, steel, clay and timber products, highlighting their environmental impacts when specified and procured via business-as-usual and he introduces design thinking and a knowledge base to support more ecologically and socially sensitive selection of these core materials.