What is district heating? One heating system for an entire city

Most buildings have their own boiler, furnace, or heat pump. District heating asks a very different question: why should every building make heat separately? Produce heat centrally, recover it from places already throwing it away, move it through insulated pipes, and an entire neighborhood—or city—can share one thermal system. The idea is old. What we can feed into those pipes is becoming much more interesting.

