The industrial sites are well known as large energy consumers. That is why the optimization of energy consumption represents for the industrial owners one of the best opportunities to cut the costs of their products. Our study is conducted for a new factory near Bucharest producing bread, pasta and cookies. Our first goal was to dynamically simulate the energy consumption for heating and cooling factory zones. The second goal was to minimize the costs of the HVAC system, by minimizing the HVAC equipment capacities.