1 Btu (british thermal unit) is the amount of heat required to raise the temperature of 1lb of water by 1degF, and roughly the amount of heat given off by a single match if allowed to burn down to the nub. Specific Heat is the Btu required to raise 1lb of a given substance by 1degF. The specific heat of air at sea level is .24; therefore, 1 Btu would raise the temperature of a lb of air (13 cubic ft) by a little over 4 degF. Calculating total Btu in a substance is not quite as straight forward a