If I could add to that, one of the points regarding building codes is that they are really safety codes. The energy efficiency standards are separate from that. One needs to think about how low one can go and what lighting values are acceptable, by reviewing the standards and establishing those on an area-by-area basis, and then identifying what energy consumption one would expect to have for both electrical and mechanical systems. Those are standards that are established quite independently of the building codes used for the guidelines for a building.
On March 5th, 2013. See this statement in context.