For some reason I was unable to post this entry. And then I lost internet service for a spell. Finally everything is back to normal, so at long last more than just a title!
Every so often when I’m at rock bottom, I get a snippet of news that brings me hope. One recent snippet came in the form of an ad in the local weekly for a week-long series of workshops on sustainability held at nearby Round Top Farm. By chance it was held on my week off and I planned to attend every evening. Unfortunately I caught a cold the first evening and so missed several of the workshops I wanted to attend. I did learn a lot from the few I made it to.
First on my agenda was Deep Energy Retrofit, which was offered by an energy auditor, Al Heath, who retrofitted an older, partially insulated 1,000 square foot ranch (which is now offered for sale). Al’s goal was to reduce energy use in that house by 75%. He exceeded his goal, spending about $22K (not including some $4500 in tax rebates) with an anticipated ROI of 7 years.
There are essentially three types of heat loss: conduction, convection and radiation. Conductive loss (where your “R” values fit in” accounts for 40-60% of a home’s heat loss. Convection (air movement) accounts for 30-40%, and radiant loss (mostly out windows) totals 2-5%. It makes sense, then, to attack conductive and convection loss first.
Your house can’t be too tight. It can, however, be under-ventilated. Most houses do not have lack of ventilation as a problem. Sealing up leaks is the first order of business; it is pointless to insulate if your house if full of leaks. The primary source of leaks can be closed up relatively easily:
- · The “sole plate” (where the foundation meets the wall) and “rim joint” (the top of the wall) combined lose 25% of your heat
- · Wall outlets, which can be plugged inexpensively with gadgets from your local hardware store), account for 20% of heat loss!
- · The duct system loses 14% of your heat
- · Windows lose 12% total, including radiant, convection and conduction
Once you have plugged up your leaks – and to find them all you are best off hiring an energy auditor – then you can turn to insulation. The general rule of thumb is to start with the attic, then the basement and finally the rest of the house.
Unfinished basements or crawl spaces should have a moisture barrier put on the ground and up the walls. Otherwise, your insulation will end up covered with mold and your wood may rot. Compare the square footage of the walls versus the floor. If you are insulating a porch or deck with a small footprint that was turned into a room, it *may* be less costly to insulate under the floor. Most of the time, however, the smaller square footage will be the walls unless they are very tall. An effective moisture barrier is something called EPDM rubber – rolled roofing paper.
Al was joined by an Insulator “Itchy” Charley Huntingdon of “Itchy Scratchy Insulation,” who described 3 types of insulation: fiberglass, dense pack cellulose, and foam. The high end is foam, but it is also very expensive. Foam comes in two types: open cell and closed cell. The auditor prefers open cell, which is less toxic. The insulator prefers closed cell, which has more toxic chemicals that need to “gas off” for a few days before the house is closed up, but which are less prone to water damage. The open cell type can absorb water and get moldy. At least here in Maine, the foam will need to be covered, usually with a special fire retardant paint that costs about half as much as the foam.
The best value insulation is dense packed cellulose, which will hopefully be produced locally in Maine in the not too distance future. It recycles used newspapers and is blown into walls (if they don’t already have fiberglass in them) using high pressure to pack it down tight. Installed in the attic, the cellulose will pack down over time. 16” equals R50; 24” equals R80. Fiberglass is the cheapest insulation and less effective than the other two, but still better than no insulation.
For 95% information (and 5% sales pitch) on energy retrofitting, visit coldclimatehome.com.
Next up: Interior Storm Windows
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