Leppo/Ballast's ARE Building Systems Sample Problems and Practice Exams states that: "Electrical lighting generally demands half of the total energy consumed by an office building." (p.81, question #88)
MEEB states: "In commercial buildings, lighting consumes about 20% to 30% of electric energy" (p678, 12th edition)
First statement specifies "total energy" - Second statement specifies "electrical energy" ... but I think they mean the same thing.
Anyway - does someone have an authoritative answer on this?
This seems to agree with MEEB:
https://www9.nationalgridus.com/non_htm ... office.pdf