The plate in brief

Warm water from the shower drain runs down a copper pipe wrapped in a coil of cold, clean water on its way to the heater. Heat crosses the copper. Water does not. The clean water arrives at the heater already prewarmed, and the drain water continues on to greywater treatment. The recovery works best when someone is showering, because the hot drain and the cold supply are flowing at the same time.

It is a small thing, but it shows the logic of the whole building: recovering heat and reusing water are two separate steps, and each resource gets used for everything it can do before it leaves.

Questions, corrections, or a site where this could be built? Write to me.