So City Hall would actually save less money (12k vs 13k/14k) than the two regular homes I tried in San Francisco. If the numbers are correct, we're looking at $650-700 a year in savings. Not bad, but not that great either, especially considering heating alone in both buildings I looked at ran $150-300 / month (including summer which is hardly warmer at night in SF). Can solar panels be installed at such a price on a regular home? I doubt there's any incentive for City Hall here.

EDIT: I also doubt the calculations are correct considering that city hall's roof is many times larger than the two homes I looked at, yet saves less money.