Premise[]
The old one is wrong, Ant asked me to fix it, here I am, doing the thing.
Calc[]
According to this, the (relatively) recent average of floorspace in a US house is 2687 ft^2, or 249.63 m^2.
We'll assume a two-story house, so roughly 28 feet, or 8.53 meters, tall.
Volume = 2129.34 m^3
Obviously subtract ~80% of that to account for hollowness. For all intents and purposes I'll be assuming stone-like materials, even though many modern buildings are made of steel or, in some cases, just wood. Incineration in this case would be the point at which the building itself melts.
Volume of Stone = 20% of 2129.34 m^3 = 425.87 m^3
Density of Concrete = 2400 kg/m^3
Mass of Building = 1022088 kg
Melting Point of Concrete = 1450 C
Typical Temperature = 16 C (obviously varies a lot but generally should be close to this value)
Specific Heat of Concrete = 880 J/(kg*K) (Note: I seem to have cited this from Assaltwaffle, but from a cursory Google search this lands within the typical range of Concrete specific heat so I suppose it's fine).
Specific Heat Energy = 1.2898e12 Joules, Multi-City Block level
Now to account for fusion. The heat of fusion for concrete, according to this, is 5700kJ/kg. So... simple math.
Heat of Fusion Energy = 5.826e12 Joules, Small Town level
Neat.
2023 Edit[]
After coming to check it out because I gagged at the notion of Skibidi Toilet using this shit, I noticed something.
Square footage of a house includes both stories. The land area of one floor, therefore, is about half of that, if we're dividing it into two stories (which is about standard here in the States).
New volume is (249.63 / 2) * 8.53 = 1064.672 m^3
Accounting for 80% hollowness, this becomes 212.934 m^3 of actual material.
Concrete is still fine. Most buildings are built from concrete.
Adjusted mass of theoretical "average" building is 511041.6 kg.
Energy from Specific Heat = (1450 - 16) * 880 * 511041.6 = 6.449e11 Joules
Energy from Fusion = 511041.6 * 5700000 = 2.913e12 Joules
Total Energy = 3.558e12 Joules, Multi-City Block level+
well that's just hilarious
Tallies[]
Total Energy of Totally Incinerating/Melting a Standard Building: 850.38 Tons of TNT, Multi-City Block level+