The average temperature of a human body is 37 °C. Temperature of absolute zero is -273.15 °C
Temperature change= 37-(-273.15) = 310.15 °C
Average human weight = 62kg
Specific heat capacity of a human is anywhere from 3.47-3.6 kJ/kg or 3470-3600 J/kg. The average is 3535 J/kg
Specific Heat capacity= temperature change * mass * heat capacity in J/kg
Specific Heat capacity= (62 * 3535 * 311.15)= 6.79755755E7 Joules
On average 65% of the human body weight is water.
So, water mass = 0.65*62kg= 40.3 kg of water.
Enthalpy of fusion of water is 333.55 J/g or 333550 J/kg.
Enthalpy of Fusion, Q= m * L, where Q is the energy in joules, m is the mass in kg, and L is the specific latent heat.
Enthalpy of Fusion= 40.3 * 333550= 13,442,065 Joules
Temperature required to cause frostbite is -4 °C
Temperature change= -4 - (-273.15) = 269.15 °C
Specific heat capacity of ice = 2093 J/kg
Specific Heat capacity= (40.3 * 2093 * 269.15)= 2.2702237285E7 Joules
6.79755755E7 + 13,442,065 + 2.2702237285E7 = 1.04119877785E8 Joules (Small Building Level) or ~5x that of regular freezing