That is just the volume of material. According to http://www.nysm.nysed.gov/wtc/about/facts.html

200,000 tons of steel were used in the construction of the World Trade Center complex

425,000 cubic yards of concrete used in the construction of the World Trade Center complex

The amount of thermite or nanothermite, or nukes? required to drop these buildings would generate billions or more BTU of heat. Once compacted upon itself, it would insulate the heat within the core.

A little more than just an office fire