Seems to me there are 3 sources of energy released when water freezes: Release of heat to lower from whatever temp you start with to 0°C, latent heat released in the transition to from water at 0 to ice at 0, and the expansion energy released as the water increases in volume during the phase change. I sort of no how to calculate the first two bits, but not sure how to quantify the expansion energy.
The expansion energy depends on the pressure in the medium that surrounds the ice. It's equal to p ΔV, where p is the pressure and ΔV the change in volume. In a vacuum it would be 0. for 1 kg of ice under atmospheric pressure, p is about 10^5 N/m^2 and ΔV is 10^-4 m^3, so the expansion energy is about 10J.
The expansion energy is already included in the latent heat which is usually tabulated as latent heat at constant pressure (and so is the specific heat)