Zero is the crossover point between a building that consumes a resource and one that produces the resource. Conceptually, it is envisioned as the point where the energy needs of the building has no impact.
First, on the definition front—the word “zero” is really “net zero.” The sums of the flows in and out are equal and opposite. This does not imply zero flows.
If a building owner has the goal of creating a building that has a net zero, the design team first must define what that means, as it is open to interpretation. What do you mean by energy—is it source energy, site energy, energy cost, or emissions as a result of using energy? At least four ZEB definitions, which are incor- rectly assumed to be interchangeable, are in use today