The paper presents the exothermic reaction monitoring method used in solving the thermal conductivity problems as well as in the process of solidifying the concrete foundation. The finite element method was applied. The problem was solved in a three-dimensional model taking into consideration the thermal characteristics dependence during the process of concrete hardening. The unsteady temperature field of the foundation block was calculated taking into account the forced pipe cooling. The given methodology is implemented in software and used for performing the three-dimensional unsteady temperature calculations. The software "Temper-3D" having a compliance certificate was developed according to the mentioned methodology. The program was registered in the Computer Software Register.