Has anyone ever noticed how much it would improve cooling to insulate an attic? Have an old house with very little stuff up there and AC has trouble keeping up with 100 degree temp
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Has anyone ever noticed how much it would improve cooling to insulate an attic?
Several years back we replaced our shingle roof with metal and insulation below the metal. The improvement was significant for heating/cooling.
IP
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I mean I googled it but all the articles are by people who sell insulation…
We toured a model by Meritage here in Charlotte. They had cut away part of the second floor ceiling to showcase some sort of foam board up against the roof decking (the 4x8 sheets that shingles are fastened to).
Made a huge difference, it seems, because there was no huge pool of heat in the attic flooding into the house.
Our own house has some sort of roof decking with the foam board integral to it, plus foam board insulation on the outside walls. The attached garage is insulated. The attic is pretty warm on days like this (new record for this day in Charlotte of 101F), but our electric bills are trivial from my point of view.
It’s a 2550 square foot single story home. We have gas furnace, water heater and range… everything else is electric. We charge two Teslas at home and have a 9000 gallon/hour pump running 24/7 for a waterfall we have in the backyard, along with a nice amount of landscape lighting.
Electric bill for this June was $118. It’ll be somewhat higher for July and August perhaps.
I think the insulation helps keep our electric bill down. Can’t prove anything because it was built with decent insulation and there is no before/after.
Rob
Former RB and BL Home Fool, Supernova Portfolio Contributor & Maintenance Fool
He is no fool who gives what he cannot keep to gain what he cannot lose.
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Hi StockGoddess,
Our first house in TX was to have “light” insulation in the ceiling, 6 inches of blown fiberglass. I had them do 12.
A neighbor with a similar home ran over $400/month electric bill in the summer while our highest was $210, IIRC.
There are a lot of other variables that affect the bill, so I can’t say what the actual difference is.
However, when you put a 130 degree or higher “layer” on top of your house and there is little barrier to heat transmission between them, well, just think about it …
In our current house, the ceiling insulation was not put in because of rain/mud. The A/C ran 24x7 and would rarely shut down. It froze the chiller once. The lower level was a “refrigerator!” (Chilled beer anyone?)
Last Friday about 4AM, they started blowing the insulation in the house and the shop.
Now, there is much less difference between up and down stairs. When all the ducting gets properly closed, it will be better yet.
Now, the A/C turns off from time to time. Once the doors between the house and the garage are installed, it will even be better!
Then most important heat “windows”, in order, are:
- Windows.
- Doors.
- Ceilings.
- Walls.
The A/C is just one side. Heating in the winter is equally affected.
Increasing R/U values and reducing air infiltration help reduce energy use and increase comfort inside by reducing the hot/cold differences within rooms.
Does that help you?
Gene
All holdings and some statistics on my Fool profile page
http://my.fool.com/profile/gdett2/info.aspx
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You may want to check the local building codes as well as talk to your local fire department. They may have some ideas about what’s best in your area.
AC knows certain types of blown-in insulation can cause problems during fires
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Electric bill for this June was $118. That is a RIDICULOUSLY low electric bill for what you are running. Count yourself lucky!
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This home of ours, since ~1974, needed help, we still have no A/C, mainly because here in Southern Sonoma County, we normally pick up an evening coastal breeze, and the averages are 10° below Marin Co to the South or the County seat to the North…
But over the years I replaced all the single pane windows with nice double pane ones, we added a foot of blown fiberglass in over the meager amount the builder used, and we also insulated unde the floors…
So overall, it’s better, the last two roofing jobs we added ridge vents, to let the attic heat escape, We use a whole house fan I put in at least 20 years ago in the evenings… So in the years time, maybe only a week or two of rough heat times, yesterday, today was hitting triple digits, but overnight, not so bad…
Many times we discuss adding A/C, just haven’t pulled the trigger. Recent work upgraded all our ducting, and the Tree furnace is fairly new, so we just need to get on our guy’s list. Biggest concern has been where to locate the external unit so it doesn’t bug the neighbors… Up near their garage is likely the best… Close to the main breaker panel, too, so… We’re close…
Windows, ceiling insulation is the most effective as I recall, walls, limited to their depth… No air leaks… Ridge vents caught my eye years ago…
All the best!
Not only should you insulate to reduce cooling, it will help heating as well.
But besides insulating the attic you should try to “seal” up the house. This means sealing up dozens of small gaps, such as where pipes under the sinks enter the walls, gaps around electrical outlets behind the wall plate, etc. This is time consuming but not too costly – just some caulking or spray foam (great stuff). You can do a little bit at a time, unlike insulation which usually has to be done all at once to be economical.
Mike
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I mean I googled it but all the articles are by people who sell insulation…
Where to insulate in a home
https://www.energy.gov/energysaver/where-insulate-home
Read This Before You Insulate Your Attic
https://www.thisoldhouse.com/insulation/21018131/read-this-b…
Pros and Cons of Attic Insulation Types
https://www.familyhandyman.com/article/attic-insulation-type…
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I know that insulation will improve cooling but I don’t know how much. We installed an attic fan and found that helps a lot. When the attic temp hits a certain level, the fan kicks on and expels the hot air from the attic outside of the house.
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Check with your electric company. Mine covered the expense of an energy audit. A couple of guys checked the whole house out, especially the attic. They fitted a frame into the open front door and ran a fan to test how well the house was sealed. They even used some foam-in-a-can to block a few holes. They finished by sending me a quote for upgrading the attic insulation extensively, with most of the cost paid by the electric company!
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Adding insulation to an attic floor assuming you have even a small amount (~ 6 inches) will not make an appreciable difference in Air-conditioning assuming you have adequate attic ventilation - i.e. ridge vents, soffit vents, etc. Hot air rises so the 140F/150F attic air will go out the top vent(s) and the 100F ambient air will replace it.
Adding insulation to an attic floor will make a large difference in heating.
If you are having Air conditioning issues, the first thing to do is call your HVAC person and get your system checked. Being just a little low on freon or slightly out of adjustment will cost you both efficiency (money) and the lowest possible temperature the system can deliver.
Most houses are designed to be able to hold a temperature in the mid 70s or maybe upper 70s in more southern climates for about 90% of the cooling season days. The rub is climate change is happening. This means there are more days above 90F vs the 1960s/70s and on those hottest days the temperature is higher.
Just last week one of the weather people at an Atlanta TV station said we had already experienced 3/4 the normal number of days above 90 over the last 100 years.
All this is to say, it is not out of the question the system you have may not be capable of cooling to say 75 in current weather. Depending on a lot of variables, the solution could be a simple as the next larger size or if ducting needs resizing a whole lot more. Hence my statement the first item is get your HVAC person involved.
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Check with your electric company. Mine covered the expense of an energy audit. A couple of guys checked the whole house out, especially the attic. They fitted a frame into the open front door and ran a fan to test how well the house was sealed. They even used some foam-in-a-can to block a few holes. They finished by sending me a quote for upgrading the attic insulation extensively, with most of the cost paid by the electric company!
Thanks for the tip. I had planned to do this a while back but then the pandemic… I just submitted a request with my power company.
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an attic fan to go with more attic insulation would do wonders…add enough solar panels to cover
your monthly electric bill and you will have it made in the shade…that’s what i did
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When we moved into our 1700 sq ft split level home, there was an awful downdraft through the fireplace. After much investigation, we determined that the attic fan that we had was oversized. It was drawing air from living areas into the attic as it was exhausting more air from the attic than the undersized gable vents could replace
So, we added baffles to the attic and fully opened up the soffits all the way around the house (adding the ventilated panels of course) and introduced a ridge vent. We also closed the gable vents and had a roofer remove the attic fan. Down draft no more 
We then added R-55 amount of blown in cellulose. This greatly improved our energy use (20-30% lower utility bills)
This is in NJ
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This is a 1956 brick home. I’m also replacing the original single pane wood windows with vinyl double hung and one of the wood doors with stainless steel. I’m hoping all together will improve it.
This is a 1956 brick home. I’m also replacing the original single pane wood windows with vinyl double hung and one of the wood doors with stainless steel. I’m hoping all together will improve it.
Windows usually help less than you might think. Reason is math. Windows are typically something like 20% of exterior wall area. The old single-pane window has an R value of about 1. The vinyl double panes have an R value of about 2. Your walls (if insulated) have an R value about 14. So, windows cost a lot for not much improvement. If your windows are failing, sure go ahead and replace them. But from an energy standpoint one of the last things you want to do.
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Hi syke6,
You are correct that going from single pane to double pane (with 1/2 inch air space) only doubles the R-value, there is one other important factor: Air Infiltration.
Many older windows are like sieves. A house we owned in the late 70’s/early 80’s was fairly new with double pane windows. We put film over the whole window and after about a week and a big wind storm, a number of the coverings were “blown” loose in one place or another.
I tested the windows on a day with 15-20 mph wind using a candle. On the lee side of the house, the smoke blew over to one bedroom window from about 4 feet away in a straight line with the door.
The next spring we replaced them and the physical comfort was quite noticeable.
We also had the grey film inside the windows which reduced the solar heat gain in the living room.
I am sure the technology has improved since 1979.
Gene
All holdings and some statistics on my Fool profile page
http://my.fool.com/profile/gdett2/info.aspx
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Windows usually help less than you might think. Reason is math. Windows are typically something like 20% of exterior wall area. The old single-pane window has an R value of about 1. The vinyl double panes have an R value of about 2. Your walls (if insulated) have an R value about 14.
The heat loss is in parallel and and the R values don’t just add. https://www.redcalc.com/parallel-path-r-value/ has a calculator. With 80% of the area at R-14 and 20% of the area at R-1 the whole house has an equivalent value of R-3.9. Changing the windows to R-2 puts the house at R-6.4, a 64% improvement.
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