your heaters are actually more efficient than your furnace because they turn nearly 100% of the electricity into heat the problem is electricity, and as a said PG&E deemed that SF residents are not supposed to use very much because gas is abundant and temperatures don't vary that much (hot or cold side), I mean technically they'll say the baseline is based off some average of usage in the area but I have a hard time believing that since I don't think I've seen in change in 20 years