How many BTU per cubic meter does typical paper waste yield when burned in a modern domestic fireplace I am brewing on an idea where instead of cursing and throwing all our physical junk mail in the paper recycling bin, we process it into pellets to be burned in our fireplace as free fuel.

Before I start I would like to run the numbers but I am having a hard time finding the actual effect of burning said paper.

According to this page regular birch firewood will burn at 14 million BTU per cubic meter (20 per chord). What is the comparable amount for waste paper?
About 12 million BTU, or 3.5 MWh.

I searched for paper btu and got loads... of... hits.

Seems like 7000 BTU/lb is a decent starting point, or $1.6 \times 10^7\ \mathrm{J/kg}$. If we say a ream of letter-size paper weighs about 5 lb, then we can calculate that paper yields about $1.2 \times 10^{10}\ \mathrm{J/m^3}$ when burned — enough to heat the average US house for 15 weeks.