# Another Thought of How Much Fire Wood

Aerospacedad, a follower of this blog, gives us a more scientific method of determining how much fire wood you may need. I don’t know if all this comes from his education at the University of Minnesota, the University of Tennessee Space Institute, or his work with Boeing and NASA on the International Space Station. Wherever it comes from it looks good to me. Here it is.

“Conversely, you could calculate by heat leak. Simplified equations assumes all walls (so you’d need to adjust it if there are a lot of windows or other heat leaks.) (Wall area x Temp difference)/Rvalue

Example: assume a 1500 sq. ft. house with 10 ft. walls. Heat leak thru walls, ceiling and floor. It’s a constant 28 deg. outside and you want to heat the house to 68. And your builder went cheap with R10 insulation. (1500 x 3 x (68-28))/10 = 10800 BTU/day.

To calculate a seasonal heat leak we go to a “degree day”. (1500 x 3 x (1))/10 x (24 hrs./day) = 10800 BTU/degree day. Your local weather service can tell you what your local area’s annual heating day is. In the Massanuttens it’s around 4000. 10800 x 4000 = 43.2 mil BTU

Assuming you are burning a mixture of Ash, Oak, Maple, and Birch you can get between 20 and 26 mil BTU/cord. So this would mean you would need a minimum of 2 cords. More needed if there are significant leaks, burn crappy wood, or want a warmer house.”

Like I said, “It looks good to me.”