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

On Aug 20, 11:54*am, 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


Did you ask the energy audit alleged experts for the physics behind
what they are saying? I agree with your assessment. If the attic
is about uniformly insulated now and you only add insulation to half,
you will save about half as much energy as you would if you did the
whole attic. I'd like to hear the explanation for how it could make
almost no difference unless you did the whole thing.

I also agree with the thermodynamics professor.

On Aug 20, 11:54*am, 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

I would ignore anything that guy said.

On Aug 20, 10:54*am, 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

6" rock wool is about R 22.5. R 50-60 is possibly optimal. Is your
code so low as to be R 23? You will save alot insulating where you
heat. What is your heat zone, for only 200 you can double it, for 400
you can tripple it. If you do rockwool it will settle alot so go alot
higher.

ransley wrote:
On Aug 20, 10:54 am, 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

6" rock wool is about R 22.5. R 50-60 is possibly optimal. Is your
code so low as to be R 23? You will save alot insulating where you
heat. What is your heat zone, for only 200 you can double it, for 400
you can tripple it. If you do rockwool it will settle alot so go alot
higher.
Well, that's another issue.
Blowing it in would be nice, but I've got all that stuff up there
that's not protected from lots of insulation dust. I was just gonna
get the r-19 batting with the home depot rebate, roll 'em out and be
done with it. Turns out that the way they have it priced, 2xR19 is
cheaper than R38 and should be a lot easier to handle. Still need to
look to see if I can buy it wholesale in small quantities.

I spend $550/year on heat. I've gotta be a little careful with the ROI.

Blattus Slafaly wrote:
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\

And if you sell the house and somebody else wants to use the whole thing?

That's not MY problem. I'll be dead...

wrote:
On Aug 20, 11:54 am, 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


Did you ask the energy audit alleged experts for the physics behind
what they are saying? I agree with your assessment. If the attic
is about uniformly insulated now and you only add insulation to half,
you will save about half as much energy as you would if you did the
whole attic. I'd like to hear the explanation for how it could make
almost no difference unless you did the whole thing.

I never did get an actual answer to the question.
I think there is some validity to the argument for floors.
If you put less heat thru the floor, the underside gets colder
increasing losses in the uninsulated area.
I still think insulating part of the floor is a good idea.

mike wrote:
....
I never did get an actual answer to the question.
I think there is some validity to the argument for floors.
If you put less heat thru the floor, the underside gets colder
increasing losses in the uninsulated area.
I still think insulating part of the floor is a good idea.

There's no real difference in the floor and the ceiling -- they're both
conduction problems from a warmer to a cooler region.

The underside of the flooring itself won't get cooler, it'll be slightly
warmer if anything as the resistance on it's cool side goes up that'll
raise the outside temperature slightly. Eventually when to the cool
side of the insulation the outside temperature or basement or attic will
be essentially unchanged.

--

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

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.

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


Insulating over the livable area is where you want to add more
insulation. After adding more insulation your house will stay the
same temperature as before, but your A/C or furnace will work less.
Don't forget to caulk and seal areas around bath fans, air returns, or
pipes before insulating. Also, you may need to fasten "chimneys" to
the underside of the roof for proper ventilation.

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.

I'd insulate the whole attic, at least what can be reached within
reason perhaps with the help of a 11-16 year old kid for the tight
spots (and wear breathing protection!)

I've added insulation to three different houses and every time it has
made a huge difference. Rock wool sucks compared to the combination
of the existing rock wool plus modern fiberglass insulation. It is
like putting a big comforter over the whole house.