20% it is

The insulation salesman who sold me fiberglass mountain said it would cut about 20% off of my heating bill.

Well, we've had the insulation installed for a full billing cycle now (60 days for our utility company—way less work than every 30) and indeed, our power usage is down almost exactly 20% from last year.

* those of you who work for the same company I do may have thought the title of this post meant something else. It doesn't. At least, not necessarily.