I have 6" of rock wool in my attic. I'm in Portland, Oregon. About half of my 1400 square foot ranch is closed off and unheated. Much of the attic over the unheated space and part of the heated space is floored and covered with boxes of junk.
For about $200, I can double the insulation in the attic over the part that I actually live in. Sounds like a no-brainer.
BUT, I had an energy audit and they told me that If I didn't insulate ALL of the attic, including ripping out the flooring and moving all the boxes elsewhere, I'd get almost NO gain.
I'm haunted by he ghost of my thermodynamics professor saying that "that's crap!" When you insulate an area of ceiling, you get less heat loss through that area and the rest stays unchanged...but you don't lose anything. If I turn down the thermostat because the better-insulated rooms stay warmer, the rest of the house gets cooler and I should have a net gain even in the insulation-unimproved part of the house due to the lower temperature differential.
My objective is NOT to make the house warmer. It's to keep the part I live in at the same temperature using less gas.
So, do I trust an experienced energy expert or the ghost of a thermodynamics professor?
And I have the same question about insulating the floors in the inhabited part only. Thanks, mike