Built in 1998...We have 50 windows...Anderson double-hung, double-pane plus 5 skylights.
Back in December when no one was in the house for 2 weeks and the therms (I have 5 of them in my house) were all set down to 55 degrees, I still got a $300 bill.
Maybe the utility company will assign a Customer Relationship Manager to my account. I might look into solar and more efficient Hot Water Heater (least efficient Rheem made). Plus I know my furnace is inefficient (low AFUE rating probably < 80%); but it's ~$22K to replace my upstairs and downstairs units.
Maybe baseboard heat....dunno...willling to try different stuff.