This is kind of a rough calc because I found close to no "extra information" about it.

The calc

Well, this calc is based on Sub-Zero's ice blast

The chars take around a second to be frozen. So, that's the time.

The heat capacity of a human being is 3500 J/kg.K

Let's say the temperature is room temperature. 23 Celsius.

The character being frozen is Jacque Briggs, let's say she is 50 kilograms.

Lowball: For someone to get frostbite, the temperature has to go down to -4 Celsius. 23+4 = 27.

The formula is: E=m*c*ΔT

So: E=50*3500*27

I get: 4,725,000 joules or, 1.129 kilograms of TNT.

Wall level

That is the energy required to freeze someone alive... but without taking into account the time, so the value must be far higher considering they freeze in one second. 

DontTalk's fixed version

Average human body temperature ≈ 37°C

Heat change = 37°C - (-4°C) = 41°C

E1 = 50kg * 3500 J/kg*K *41°C = 7175000J

Body of average female has 50% body water.

So 25kg = 25000g water.

Enthalpy of fusion of water = 333.55 J/g

E2 = 25000g * 333.55 J/g = 8338750 J

So total energy = 7175000J + 8338750J = 1.551375e7J

Wall level+

It should be noted that 50kg human female is a low end.

To do an average:

Average human weight = 62kg

On average 65% of the human body weight is water.

So water mass = 0.65*62kg.

So total energy = 62 * 3500 * 41 + 0.65*62*1000*333.55 = 2.2339065e7 J

Room level