People commonly (by default) compare electric bills on $$ rather than on kW*hr, so an increase in rate would reduce the savings-as-compared. Different baseline

People commonly (by default) compare electric bills on $$ rather than on kW*hr, so an increase in rate would reduce the savings-as-compared. Different baseline electricity use and thermostat preferences could play a significant role as well. (Previous owners may have gone for a lower daytime setting and a deeper setback because of the inefficiency. A new owner with a more efficient system may quite reasonably choose to bias towards greater comfort than the prior owner did.)