Look around you: idle assets are everywhere. From parked cars to empty buildings, vacant shops to derelict land, unused skills to leftover minutes on our mobile plans and, of course, storage warehouses jammed with stuff long forgotten by its owners. Idling capacity — the untapped value in under-utilised commercial, personal and urban assets such as these — is pervasive. It's in our homes, supply chains and cities. We usually don't notice it, or if we do, we believe it's normal.