On Aug 20, 6:49*pm, dicko wrote:
On Wed, 20 Aug 2008 08:54:03 -0700, mike wrote:
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

The heat loss into the attic through the newly insulated portion will
be less than what it was. Thus the temperature of the attic should
become lower. This new lower attic temperature will increase the heat
loss from the living space under the part of the attic that didnt get
more insulation. *

How much the attic temp will drop and how much extra loss from the
living space is unknown but I tend to agree with the energy audit guy.

-dickm- Hide quoted text -

- Show quoted text -


Most attics are well vented to the outside. Any difference in the
attic temp from half the attic having 6" of insulation and another 12"
is going to be negligible and not negate the value of adding
insulation to part of it.