The three key words in the title deserve scrutiny. ‘Innovation’ can mean something that is completely new, but more often innovations are drawn from practice in other fields. Innovations can be imposed from above, developed from practitioners or even happen incrementally. They are very often creative responses to other pressures, necessity being the mother of invention in this field as much as any other. Innovations can be reflected in day-to-day practice or they can be embodied in whole new units. Stale, out-of-date practice can happen in new units, and vice versa. It is too easy to see new buildings alone as innovations.