Reduce electric bill by installing radiant barrier in attic?

[Nords]

Some folks like the turbines, but I'm not a big fan due to their appearance and that fact that I've experienced more water infiltration from them than with typical "turtle vents (or "hat vents"). Just my opinion.

Another alternative, especially in Texas, is solar-powered exhaust fans. We've been through hurricane-force rains with them and had no intrusion problems.

 

[cute fuzzy bunny]

I couldnt get mine to turn enough air to make it worthwhile. I even added a second panel.

On medium warm days it was sufficient. On july/august days it just delayed the onset of flamethrowing heat in the attic by an hour or so.

 

[ls99]

I couldnt get mine to turn enough air to make it worthwhile. I even added a second panel.

On medium warm days it was sufficient. On july/august days it just delayed the onset of flamethrowing heat in the attic by an hour or so.

Yep, no substitute for large area venting from the eaves to rooftop. Most solar fans are about as effective as peeing on a volcano. Even in the northeast in August.

 

[lets-retire]

Yeah, soffit vents only wont do you any good. Nowhere for the air to go. It might have had some eyebrow vents or gable vents at one time but a prior homeowner might have removed them or covered them up when doing a roof or siding job.

I figured a previous owner did away with the ridge vent when a new roof was put on. I couldn't find anyplace else that looked as if it had a vent, except the ridge where the roof boards didn't meet.

 

[eridanus]

Yep, no substitute for large area venting from the eaves to rooftop. Most solar fans are about as effective as peeing on a volcano. Even in the northeast in August.

I've installed thermometers in the attic. One of these days, I'll go up there and disconnect the solar gable fan and see what the temperature does, if anything.

I'm also looking forward to watching what effect the soon-to-be-added ridge vent has.

 

[ls99]

I've installed thermometers in the attic. One of these days, I'll go up there and disconnect the solar gable fan and see what the temperature does, if anything.

I'm also looking forward to watching what effect the soon-to-be-added ridge vent has.

Yes, definitely interested in results. No substitute for real world numbers.

 

[cute fuzzy bunny]

I figured a previous owner did away with the ridge vent when a new roof was put on. I couldn't find anyplace else that looked as if it had a vent, except the ridge where the roof boards didn't meet.

If it was about a 1.75-2" space then yeah, you probably had a ridge vent and the roofer was an idiot. Theres usually a little space between the sheeting at the ridge even when you dont have a ridge vent.

But you had to have had something or the house wouldnt have passed code.

Besides ventilation, that may have created some condensation/moisture issues in the attic.

Thats the one thing I was more or less pleased with as far as the solar gable fan was concerned...at least i was getting some powered ventilation on any sunny day, helpful for moisture removal.

 

[hankster]

The home we're living in now has a "whole house fan" mounted in the ceiling in the central hallway area. We've had temps in the 90s recently and have been able to keep the house quite comfortable by starting the fan and opening the basement windows and basement stairway door. The negative pressure developed by the fan pulls outside air into the cool basement and up the stairway. It flows through the main living areas and is finally blown through the fan and into the attic where it exhausts out the gable and roof vents. It seems to be the next best thing to air conditioning and definitely moves a lot of air through the attic too.

 

[Rambler]

With only one panel, our solar fan didn't help a lot. When I added the second panel, it seems that it performed much better...didn't actually measure the temp though. This is in the lower attic that is maybe 600sq ft of ceiling max (only the master bed and master bath). I'm satisfied with it.

When I get around to it, I'm adding more cellulose in the upper attic, and maybe a solar fan or two as well. While it is always warmer upstairs, it seems DD's room is not just warm, it is hot, so I'm thinking there is a thin patch of insulation over her room.

We have a whole house fan as well, but can't use it in the middle of the day or we just bring in the hot air. Rather, we turn it on at night and early morning, cool the house down to about 68F, and it stays under 78 until 4-5pm on most days unless we have 105F++ outside.

R

 

[soupcxan]

Update: Over the last month I've made the following improvements.

Install 2000 sq. ft. radiant barrier: $260
Install 8 larger soffit vents: $16 (added 2 sq. ft. of net free vent area)
Replace 4 recessed light fixtures with airtight cans: $24
Tweak A/C thermostat programming: free
Leave attic stairs open to allow more air circulation: free
Add 40 bags of blown-in cellulose insulation to attic: $320

These were done throughout July so it's hard to say what the relative impact of each was, however an initial glance at the electric meter indicates that usage in July was flat compared to June, although July was a few degrees hotter, so there would appear to be some savings there. The insulation wasn't added until the end of July, so I'll have to wait until the end of August to see if that helped any. We blew the cellulose in over about 10 inches of rockwool, but this should take the R-value close to the recommended R-49 for Dallas.

Economics: if I used 12000 kwh/year before the improvements, and can reduce usage by 10%, that's a savings of $180/year at $0.15/kwh for roughly 3.3 year payback period. If usage decreases 15%, payback occurs in 2.2 years. Either way, I'll pick up some more savings since my winter heating bill (gas) will also decrease. I figured these improvments were a fairly low-risk investment because I was able to DIY. If you hired someone to do them all, the total cost could approach $2000, at which point payback is less certain.

 

[cute fuzzy bunny]

Tell me about replacing the recessed lights. I have a bunch of them and they're open on top to the attic, and from what I read they'll catch fire if you cover them with insulation or block the vents. The only thing I saw involved building a sheetrock box about 2' per side and a foot or two tall to put over the top of the can in the attic.

I guess you could use an enclosed can and specify CFL lights only for that fixture, but everything I read about covering or insulating the recessed cans screamed about fire dangers.

I was actually going to remove them, and either put in a regular light fixture or fill the holes with sheetrock and insulate it, then relocate the wire to the center of the room and install a ceiling fan.

But if theres some easy way to replace the cans with closed, insulate-able ones, I'm interested.

 

[cute fuzzy bunny]

As an aside on our energy saving maneuvers, we replaced our old aluminum double pane windows with insulated low e vinyl ones, added r4 of foam insulation under the new stucco, and replaced last years 9seer a/c with a 15 seer.

Our july electric bill this year with all those improvements and similar weather was 25% lower.

Only thing I'd like to do is some attic insulation, but i've been holding off as having a dozen recessed fixtures full of vent holes that I'm not supposed to put insulation within a foot of sort of makes stacking more insulation up there pointless.

 

[lets-retire]

CFB--Lowe's and Home Depot have cans made to allow insulation to cover them. I put them in my last house I did renovations to.

 

[Leonidas]

Only thing I'd like to do is some attic insulation, but i've been holding off as having a dozen recessed fixtures full of vent holes that I'm not supposed to put insulation within a foot of sort of makes stacking more insulation up there pointless.

Three ways to deal with that.

1. Get a roll of chicken wire and make an exclusion zone around the cans to keep insulation from touching.

2. Buy fixtures that are designed to be in contact with insulation. "IC"

3. Buy fixtures that are designed to be in contact with insulation and which don't leak air. "ICAT"

I'm cheap and the attic was hot, so I used some chicken wire I had laying around in the garage from a school project.

 

[ls99]

CFB FWIW, in our kitchen are 8 recessed cans, non-insulation contact type. I did not want to go thrugh the hassle of changing them, but wanted to eliminate airflow to attic.

At Lowe's found bathroom light covers for recessed fixtures. These have glass in the frame and gasket around the rim. Pop out the old director insert, put in place rim with glass and gasket.
Ergo, no more airflow to attic. Also replaced incandescent with CFL.

Even DW likes it!

 

[unclemick]

Three ways to deal with that.

1. Get a roll of chicken wire and make an exclusion zone around the cans to keep insulation from touching.

2. Buy fixtures that are designed to be in contact with insulation. "IC"

3. Buy fixtures that are designed to be in contact with insulation and which don't leak air. "ICAT"

I'm cheap and the attic was hot, so I used some chicken wire I had laying around in the garage from a school project.

I used to walk 300 ft or so up the drive to HWY 90 and shut off the electricity outside the meter at the first power pole.

Electricity like sanity is overrated. You really don't need electricity in the Louisiana swamp.

Alas - those were the days - first I upgraded the whole house fan from 1/4 to 1/2 hp, got rid of penetrating light fixtures - 4 and 8 foot flourescent lights(for times when I turned on the juice).

Then later a window A/C - downhill ever since.

heh heh heh - now in my old age(65) I watch on PBS (like last night) a guy from Iowa built a log cabin in Alaska and live their 35 yrs. In A/C on cable yet - oh how fall I've fallen from frugal. Heck I don't even know what kind of insulation is in my attic!

 

[soupcxan]

Tell me about replacing the recessed lights.

I replaced mine with 6-inch Commercial Electric insulation-rated (IC), airtight, new construction cans from Home Depot. The benefit of replacing the fixtures (as opposed to just putting chicken wire or a drywall box around them) is that you can actually bury them in insulation (which I did). Getting cans that are rated "airtight" will also help prevent the flow of heat/cold from the unconditioned attic to the living space. I have read that if you leave even a small uninsulated gap around the fixture (from chicken wire or whatnot), you will greatly reduce the efficency of the total attic insulation. So you're better off getting IC fixtures and burying them. The pack I bought contained both the fixtures and the baffle/trim, which I think also needs to be IC-rated. There is no requirement to use a CFL in these fixtures - they're made to take up to a 75W incandenscent bulb which is what I'm using. Since you have access to the attic, you can buy the cheaper "new construction" fixtures (versus the "remodel" fixtures).

Replacing the fixtures didn't take any particular skill, just time and patience. Our house's wiring is modern so it was easy to untwist the wires and pop them into the new fixtures' quick-connect fittings. One concern, if you have older wiring, is that it may not be rated to be covered in insulation (there is some wiring specification that the light fixture instruction referred to). The only difficult parts of the job were:

1) working in the attic heat
2) maneuvering through the existing insulation
3) getting access to the fixtures that were installed close to the exterior walls, because the slope of the attic limited overhead clearance to wrestle the existing cans out.

The link below is very similar to what I bought, although the interweb concensus is that Halo is a better brand than Commercial Electric (don't know why, my CE's are fine so far). If you have a lot of fixtures to replace, I've heard you can get a better deal at a commercial supply store rather than Home Depot/Lowe's.

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100096552&N=10000003+90016+501111

 

[Leonidas]

Electricity like sanity is overrated. You really don't need electricity in the Louisiana swamp.

I got to say that if I lived in the swamp without AC during August I wouldn't have to worry about an excess of sanity either! You're a manly man for being able to do it.

Then later a window A/C - downhill ever since.

Don't negate the importance of a refrigerator and ice. One must have cold beverages to maintain sanity.

The benefit of replacing the fixtures (as opposed to just putting chicken wire or a drywall box around them) is that you can actually bury them in insulation (which I did).

I'm cheap and balked at the price, but mostly I was reluctant to spend any more time in the attic in July than I had to. July worked because I had my [-]slaves[/-] sons home from school and they were helping. I was a tad skeered of inciting a mutiny if I prolonged their time on the job during the heat to stop and do electrical work. I think I'll revisit this issue in February.

 

[HFWR]

I think I'll revisit this issue in February.

I noted the temp in my attic yesterday afternoon: 140F!

Jeez, Louise...

 

[eridanus]

I noted the temp in my attic yesterday afternoon: 140F!

Jeez, Louise...

During the day, my attic temp is about 25-30 degrees warmer than the outside temp. It cools off pretty quickly at night, leading me to believe that I have enough passive air flow (2 turtle vents, 5 gable vents, and vented soffits). I also think there's some serious leakage from the house due to sheetrock repairs I've been doing. Cooled air goes into the walls and into the attic. I'm going to finish most of those repairs this weekend (I hope).

 

[boutros]

One thing that I did that no one has mentioned was glue batt insulation to the attic access panel so that when we close the attic access it forms a better seal against leaking air. You could even improve upon that by using weather stripping around the edges .

 

[cute fuzzy bunny]

Good info. I've never installed or changed a recessed light before. I didnt know they had insulation friendly versions and oddly enough, the stuff I read up on didnt mention replacing the non insulation friendly versions with different ones.

I do have one of the sealed ones over the tub in the master. I'll have to snoop around home depot and see if I can buy covers for the rest of them.

 

[hogwild]

Here are two options that a syndicated radio home improvement show suggests for recessed lights:

1. If they are the non-IC type, simply purchase a $1 or $2 dollar styrafoam minnow buckect and put a bead of calk around the rim and place over the fixture.

2. Replace the bulb with one of those new flourescent type that look like the regular spot light type but enclose a flourescent bulb.

I guess a third option would be do both.

 

[soupcxan]

Maybe I'm just being impatient, but I expected to see a huge reduction in my A/C usage the day after I installed the extra cellulose insulation. No such luck. I guess the benefits from increasing attic insulation from R-35 to R-49 are more subtle.

The suggestions to jury-rig non-IC rated light fixtures with inverted buckets or styrofoam coolers makes me nervious. If a fire were to start smoldering in your attic, you'd probably not realize it until it was too late. The using chicken wire or roof flashing to keep the insulation away sounds like a safer approach, but then you're still going to have air leaks through the light fixture and some uninsulated drywall (which is like, what, R-0.5?).

 

[Patrick]

Here are two options that a syndicated radio home improvement show suggests for recessed lights:

1. If they are the non-IC type, simply purchase a $1 or $2 dollar styrafoam minnow buckect and put a bead of calk around the rim and place over the fixture.

2. Replace the bulb with one of those new flourescent type that look like the regular spot light type but enclose a flourescent bulb.

I guess a third option would be do both.

If you do 1 you better do 2. I'm surprised any reputable home improvement show would suggest this. The reason the cans are vented is to allow heat to escape. By gluing a bucket over it, you will be trapping that heat against a flammable (styrofoam) material. Not too bright (so to speak). By changing to a CFL, you might reduce the heat production enough to prevent your styrofoam bucket from catching on fire. Good luck.