I recently finished my attic this Fall/Winter and enjoyed wonderful
room temperatures since, however, as the temp starts to rise this
spring, the attic is unbelievably hot. 70Degrees outside usually means
85 degrees in the attic. I am scared to think what 90degrees outside
will mean for the attic. I have researched portable air conditioners
and have determined that they will be inadequate for the attic (about
450sq ft.). The windows are too narrow for standard window units. Has
anyone used attic fans to cool a finished attic? Also, does anyone
have any other suggestions for this problem.

Thanks,

Tom

"TomD" wrote in message
ups.com...
I recently finished my attic this Fall/Winter and enjoyed wonderful
room temperatures since, however, as the temp starts to rise this
spring, the attic is unbelievably hot. 70Degrees outside usually means
85 degrees in the attic. I am scared to think what 90degrees outside
will mean for the attic. I have researched portable air conditioners
and have determined that they will be inadequate for the attic (about
450sq ft.). The windows are too narrow for standard window units. Has
anyone used attic fans to cool a finished attic? Also, does anyone
have any other suggestions for this problem.

Thanks,

Tom



How much are you willing to spend per month on electricity to cool your
attic?

Well, being that we have our computer and TV in the attic and it will
be used quite a bit, I will be willing to try anything. I don't want
to see huge electric bills, but I would be willing to run an AC all day
during summer days.

Tom

Well, being that we have our computer and TV in the attic and it will
be used quite a bit, I will be willing to try anything. I don't want
to see huge electric bills, but I would be willing to run an AC all day
during summer days.

Tom

"TomD" wrote in message
oups.com...
Well, being that we have our computer and TV in the attic and it will
be used quite a bit, I will be willing to try anything. I don't want
to see huge electric bills, but I would be willing to run an AC all day
during summer days.

Tom


The problem is that it sounds like your attic space is underinsulated based
on the 15F solar gain on a temperate 70F day. The size AC you need will far
exceed the rule of thumb sizes based on an average insulated room of a
particular size. You may need to double or triple the capacity of the AC
normally needed to adequately cool that space.

A typically sized AC has no problem overcoming the heat brought in by hot
air but a sun heated space needs a lot more power.

I suggest you look at better insulation and increasing the ventilation. Did
you just insulate up to the roof deck and slap wallboard over it or did you
put in a baffle to ensure proper air circulation between the insulation and
roof deck (if not, you may be replacing your roof sooner than necessary).
What R value do you think you have overhead. If you can loose a little
headroom, some foam panels and another layer of wallboard will help a bit.
I've seen other thinner insulation that resembles foil coated bubble wrap
but don't know how effective it is.

I don't think any portable A/C is going to meet your needs, look into a
split system (but not central air) like are popular in apartments, motels
and overseas.

Have you analyzed the increase in your heating bill from this winter to last
year, the cooling effect will be worse because it all comes from electric
not gas.

"TomD" wrote in message
oups.com...
Well, being that we have our computer and TV in the attic and it will
be used quite a bit, I will be willing to try anything. I don't want
to see huge electric bills, but I would be willing to run an AC all day
during summer days.

Tom



I asked because I used to live in a cape-style home whose upstairs was
really a finished attic. We faced the same problem: There wasn't a room air
conditioner large enough to make it comfortable unless we ripped out a
window and made it much larger. We didn't. This is simple physics. Heat
rises, and the attic is where it collects. If you want to use it in hot
weather, you're fighting the sun. Good luck.

Thanks,

The house was built in the 1860's and the attic was partially fimished
when I bought it. The ceiling and knee walls for the area that I
finished was finished with plaster. I didn't add any insulation for
the roof (just floor). I will be very difficult for me to insulate
this portion of the roof as it will require tearing out walls and the
ceiling.

I was hoping that instaling an attic fan would draw out the extreme
temperatures and get it closer to the outside temperature. This would
make it livable in the evenings when the temp. drops. I'n not sure if
an attic fan will accomplish this.

The heating bill was slightly higher since we used the attic quite a
bit, but not out of control. I anticipate the greatest energy need, as
you mentioned, being for cooling the attic.

BTW, right now I am using window fans and they do help lower the
temperature.

you might be abl;e to insulate the roof using foam, or blown in
insulation without removing the plaster, just some small holes that can
be filled.

a thru the wall AC unit will work fine.

what color is the roof? if its dark when you re roof consider light
clored shingles it will help a lot....

On 20 Apr 2006 16:53:40 -0700, "TomD" wrote:

I recently finished my attic this Fall/Winter and enjoyed wonderful
room temperatures since, however, as the temp starts to rise this
spring, the attic is unbelievably hot. 70Degrees outside usually means
85 degrees in the attic. I am scared to think what 90degrees outside
will mean for the attic. I have researched portable air conditioners
and have determined that they will be inadequate for the attic (about
450sq ft.). The windows are too narrow for standard window units. Has
anyone used attic fans to cool a finished attic? Also, does anyone
have any other suggestions for this problem.


Use a split-system AC that doesn't use up the window. That
way you can exhaust the hot air for a while in the early
evening before turning on the AC.

If you're willing to spend a great deal of money,
then the next time you get your roof re-shingled,
do a complete tear-off, add 4" urethane foam, and
then put on a layer of self-ventilated nailable
decking.

And use white shingles.

If you're not willing to spend that much money,
then you need to make more holes somewhere so that
you can pump more air through the attic space.

X-No-Archive

TomD wrote:
Thanks,

The house was built in the 1860's and the attic was partially fimished
when I bought it. The ceiling and knee walls for the area that I
finished was finished with plaster. I didn't add any insulation for
the roof (just floor). I will be very difficult for me to insulate
this portion of the roof as it will require tearing out walls and the
ceiling.

I was hoping that instaling an attic fan would draw out the extreme
temperatures and get it closer to the outside temperature. This would
make it livable in the evenings when the temp. drops. I'n not sure if
an attic fan will accomplish this.

The heating bill was slightly higher since we used the attic quite a
bit, but not out of control. I anticipate the greatest energy need, as
you mentioned, being for cooling the attic.

BTW, right now I am using window fans and they do help lower the
temperature.

My home had a 200 sq ft screened-in porch that the previous owner
turned into a "room". I'm in Texas where it gets to over 100 in the
summer months and beyond.

When I bought the house it was March, all of the windows were open and
the house was nice and cool. When May came along and the temps started
hitting 90, I noticed the "room" that was built, was a LOT warmer than
the rest of the house, even when the AC was running, the rm would not
get cool.

My house is block and the "room" is standard frame with 3, 4'x4' single
pane windows and a pair 6' single pane french doors. And, it also
located on the SW side of the house.

So I figured it would be warmer than the rest of the house, but not
FIFTEEN degrees warmer in the summer! So I'm trying to figure out why
this rm is so hot. I went into the attic to see what kind of insulation
was in the "rooms" ceiling. Basically had to crawl to get to that
section of the house (something the inspector didn't do btw) and I
found that the idiot (pervious owner who "built" the "room") didn't put
ANY insulation in the ceiling.

There was plenty of space between the roof and ceiling, goes from about
3' down to 10" and it has soffits, so there was NO reason not to put in
insulation.

So I put in 8" of fiberglass insulation and a turbine on the roof. The
"room" is still warmer than the rest of the house by about 5 degrees
but that's because of all of the glass. My next step is to remove 2 of
the windows and possibly put in a single door.

Sorry for rambling. My point is, somehow, someway, you need to get
insulation in that ceiling. And possibly a vent in the roof. I used a
12" turbine because it draws more heat out as it starts to spin . Free
power.

One poster suggested drilling holes and blowing in insulation. That
might work depending on how much space you have between the ceiling and
the roof and whether or not the ceiling is vaulted.

I wish you luck.