Received this e-mail from Woodstock Stove a couple of weeks ago. Uninsulated basements are tough to heat!
How to reduce home heat loss
(plus save money, reduce energy consumption, and shrink your carbon footprint at the same time)
When it comes to heating, there are really only 3 ways to reduce energy usage -
decrease demand,
reduce heat loss, and
increase appliance efficiency.
This eNewsletter addresses one strategy for reducing heat loss (more coming in future eNewsletters).
Recently I visited a neighbor who was heating with wood, and trying to reduce his wood consumption. He had installed a stove in an un-insulated basement (concrete walls with a small number of casement windows). He was burning NINE cords of wood per year to heat the basement and the house above it.
Even I was surprised when I calculated the heat loss in his un-insulated basement. My calculations are below. (You can use the formulas to calculate your own heat loss.)
Simple formula for calculating heat loss
The basic formula for heat loss in BTUs/hr = (Area)x(Temperature Differential)/R-Factor of wall (see box below for explanation)
In my neighbors 20x30x8 ft basement, the area is 800 Sq. Ft. (the sum of two 30 ft walls and two 20 ft walls is 100 linear feet x 8 feet in height or 800 sq. ft.) The temperature differential is the difference between inside and outside temperature. The R-Value of an 8 inch concrete wall is 1.11. A good table of R-values is available at
http://www.coloradoenergy.org/procorner/
stuff/r-values.htm. Another site with good general information about insulation is the Department of Energy website:
http://www.ornl.gov/sci-roofs+walls/
insulation/ins_16.html.
This site includes important information about preventing moisture accumulation as well as r-value recommendations for different areas of the home.
At 70 degrees inside and 10 degrees outside, my neighbors heat loss in BTUs/hr is 43,243 BTU/hr (800 x 60)/1.11 = 43,243).
To get the heat loss in a full day, just multiply by 24 (in this case 1,037,832 BTUs)
To calculate the heat loss per degree day, change the Temp differential to 1 and multiply by 24 (in this case 800 x 1/1.11 x 24 = 17,297 BTUs lost per day, per degree temperature drop.
To calculate the drop over a heating season, multiply by the number of degree days in your area. In our area, there are about 7,000 degree days, so the loss in an un-insulated basement over a full heating season was 121,079,000 BTUs. To find the average number of degree days in your area, click here and visit NOAA:
http://lwf.ncdc.noaa.gov/oa/documentlibrary/hcs/hcs.html (Youll have to scroll down and open their pdf archives, which include the last 15 years of data on a year-to-year basis. Be sure to select heating degree days and not cooling degree days.)
Is this possible, you ask?
Yes! The loss of heat in a 20 x 30 un-insulated basement in Northern New England is equal to approximately 5 cords of wood at 22,500,000 BTU/cord. By insulating the basement with 2 Polystyreme beadboard, this heat loss gets reduced to 15,125,000 BTUs (a little more than 1/2 cord). Insulating the basement with 3.5 inch fiberglass bats (R-11) will reduce heat loss to less than1/2 cord.
I sound like an insulation salesman, but I'm not. These are real numbers. Weve always been concerned about heat loss in un-insulated basements, but when we sat down and did the math we were stunned. This exercise was so mind-boggling that we posted an article in our Web Library which you can read
Tom Morrissey
Woodstock Soapstone Company
66 Airpark Road
West Lebanon, NH 03784
