The topic of this paper is the calculation of the thermal stability of a family house. The heat flux was calculated for the condition without thermal insulation and the condition with thermal insulation with a change in the parameters of thermal insulation thickness, external temperature and window size. The first part describes heat as a type of energy, as well as heat transfer conditions and basic expressions for calculating setpoints. The second part describes ETICS facade system with mineral wool as thermal insulator. Mineral wool was chosen as an insulator due to its suitable fireproof and insulating properties. Chapters 3 and 4 cover the budget part of this paper. The layers of the wall that participate in the heat transfer are listed first with a corresponding table of thickness and thermal conductivities. After that the calculation of the heat flow for the state without thermal insulation was performed, with a diagram of the heat losses for each face of facade. This is followed by the calculation of heat losses for the state with thermal insulation. The wall layers are enumerated in the same way and the calculation of heat flow was performed. Furthermore a comparison of the obtained values from both chapters was performed. In chapters 5, 6, and 7. the calculation of the heat flux was performed with a change in the parameters of thermal insulation thickness, external temperature and the size of glass walls.