Green Your Heating -- Attic Insulation

November is here, and wintry weather has blown in with gusto. This week's tips cover ways to make the most of your home heating system.

Tip # 4: Insulate your attic

If you've managed to stop heat from escaping downstairs, you may still be letting it seep out through your roof. To make the most of energy saving efforts, consider checking insulation levels in your attic. According to the Alliance to Save Energy, households with less than 6 or 7 inches of insulation in the attic generally benefit from adding 6 to 10 additional inches. Energy Star recommends distributing insulation evenly, with no low spots out near the eaves.

--Mario Aguilar

Share your tips: Have you improved your home's insulation recently? What other changes have you made to keep heat from going to waste?

Comments

[Kaptain Klimate]

Thanks for the tip. It's starting to get a little brisk out there!

[Dean]

My house is in a spot that doesn't get enough sun to make solar panels worth the expense, but we still have a very warm attic from the sun we do get on a cool fall or warmer winter day in New England (we have about 12" of blown-in insulation in the attic) My question is: Has anyone devised a way to make use of that heat in the attic? There are days in the fall when my house is cold with the heat off, but it's quite warm in the attic.

[Beth, Grand Rapids MI]

Within the past couple years, I had 14 inches of Nu-Wool blown into my attic. I highly recommend using this green product.
http://www.nuwool.com/

[Carol]

My attic has blown in insulation with no vapor barrier, which was code at time of building. I want to add more insulation. Is it worth the aggravation of move the loose fill over to add a vapor barrier or should I just add batts without a vapor barrier on top?

[John E Meyn]

Don't forget your unheated basement which also draws off heat (via both convection and radiation) from the floor above. Use cans of foam ($6-ish) to fill in drain pipe holes (the older the house the larger the hole), hot and cold water pipe holes and electrical wiring (power, telephone, cable and TV) holes going through the floor. The same applies for corresponding basement holes from the outside as well as door (upstairs side as well)/bulkhead entrances. These entrances also likely require caulking and weather stripping installation.
Next on the complexity list is the effort to cover the basement ceiling nails from the floor above with duct tape prior to a vapor barrier installation (using commercial rolls of plastic sheeting). So far the entire above efforts are well within sweat equity capability at a fairly minor cost.
Finally, the basement ceiling insulation installation (say it fast!) which necessitates significant funding as well as more homework than this note can provide. John E. Meyn

[Andrew]

Carol,
If you're looking to add new insulation rolls over your old blown-in insulation, DO NOT use material with a vapor barrier as it will trap moisture between the two types of insulation and will make it less effective. Do this:

1) Fill in any low spots in the blown-in insulation between the beams to make it all uniform.
2) Add insulation rolls perpendicular to the beams, keeping the tight together.
3) If you want attic storage, use 2 by 4s to create an insulation "box", i.e. make a frame, fill with insulation, then cap the box with plywood. This nets you the insulation value and storage space.
4) If you need areas to walk, put down plywood, then put insulation foam boards down on top of it.

Got these steps from a new "This Old House" on Discovery's Green Channel. I've started doing some of these steps and I keep having to readjust my thermostat down since the insulation is now doing the job gallons of heating oil used to do.

[Harry Symonds]

One reason that your attic might be warm in the winter is because you do not have enough insulation to keep the house heat OUT of the attic. An excellent solution is to install radiant barrier to the rafters along with new insulation. Radiant barrier works much like a sunshield does in your car. In the summer time, it reflects the heat back before it warms up you insulation and your HVAC ducts. Conversely, Radiant barrier reflects the house heat back into the house in the winter. I saw a dramatic photo of a roof that was half done with the radiant barrier. The side with the radiant barrier still had snow on the roof. On the side without the radiant barrier, the snow was melted off the roof. The point being that the house heat had escaped through the ceiling insulation and warmed the roof WITHOUT the radiant barrier enough to melt the snow on the roof.

NOTE: for the same reasons that you would not want to add a vapor barrier directly on the insulation (mold) DO NOT install radiant barrier flat directly on top of the insulation. In order for radiant barrier to function correctly, there must be an air space between the roof and the foil barrier. The foil should be attached to the rafters so dust and dirt that naturally accumulates in the attic will tend to roll off the barrier. One more thing; if you are going to add radiant barrier AND insulation at the same time, do the radiant barrier FIRST. The reason is that in order to install the foil barrier, the installers must use knee boards in the ceiling to support their weight. If you have new insulation, the installer would have to put the knee boards on top of you new insulation compressing it in the process.

[Karen Sommers]

We were remodeling the whole house which made this practical, but this is applicable to an attic also. We contracted for Icynene foam insulation which was installed on the roof itself to a depth of 6" and it has better performance than any R value for fiberglass insulation. In an attic is is itself a vapor barrior and does not require venting. We had it installed in the walls (which had been stripped of drywall), and in the basement above the basement cement walls. The result is fabulous; we loose only a few degrees overnight when the heat is turned down below 60; and we also saved alot on air conditioning costs this summer. We live in Delaware.

[annmh]

After the attic insulation is in place, here are three tips for keeping out drafts at the living level.

1. I use the Frost King kit sold at Home Depot on the windows. Laying double sided tape on all frames and affixing clear plastic.
Seals drafts out for window lock area and window sills November through March.

2. I place nylon covered draft guards at each door entering house. Draft tube fits inside and outside door jam when in place. sold online at amerimark.com; reusable each season.

3. Check that your thermostat is operating properly. Steam heat radiators need to be bled, according to our plumber, about three times a season to heat most efficiently.

With these three tips in place, I have gone from setting the thermostat at 74 to 68 degrees farenheit during the coldest of NE winter storms.

[Karen]

My gas bill is $264/year; average for this area (Central Valley California) is $917/year. How?
1) Consider that the summertime bill is about $10/mo for basic service and hot water heater. So the heating bill is quite low.
2) I have 1000 sq ft 1954 home with old insulation, which I covered with space blanket ($2400 from Eagle Shield, one-time cost) that reflects back in radiated heat. (It also does a great job keeping heat out in the summer).
3) This spring I added blown-in "recycled newspaper" in the exterior walls ($1200 one time cost). So I expect next years cost to be even less.
4) Automatic set back thermostat sets at 56F when I leave for work, up to 68F at quiting time so it's warming up when I come home 15 minutes later, sets back to 60F at bed time, and up to 66F 15 min before the alarm goes off to get up. The house is even more comfortable than the numbers suggest, because the temperature declines slowly, and because the temperature is evenly distributed even to the outer walls - not just warm at the core where the thermostat is.
5) My electric mattress pad flash heats the bed when I crawl in and then is nearly off the rest of the night. A knit cap keeps my head warm and a furry puppy dog keeps my feet warm.
6) I've tackled radiant and conductive losses, I still have convective losses. My house still has air leaks - but I feel a need for the fresh air.

[Margie Campaigne]

Does anyone else have vaulted ceilings, and therefore no attic? That was my dilemma, and I finally found a solution - Hunter Cool-Vent Panels. After a complete tearoff, they install over your current roof and have several inches (your choice of thickness) of rigid foam attached to wood spacers above which is attached about 3/4" thick flakeboard. Your shingles or other material are attached on top of that. After installation of this system, I went from having icicles as big as my arm to icicles only in spots above windows, and only as big as my pinkie finger, if that. See - http://www.hpanels.com/pages/cool-vent_articles.html