Adding r-value to a 40 yr old cold storage freezer by adding 2 inches of spray foam and sealing cracks. Also applying for an incentive based on kWh saved per year. Calculations are getting extremely complex. Ran a test of shutting the freezer down and logging temperature every 10 seconds while it cooled off.

The calcualation for conductance is pretty straight forward but comes out to a much larger number (10x) than the actual total heat gain of (air mass)(enthalpy)(deltaT). What is going on here? Is concrete slab floor absorbing a bunch of this heat?

The plan was to do this shut-off-and-log temps test before and after insulating. But the incentive offerer is not confident we are going to get a reliable difference - nor am I. Comments? Help?