A middle-sized office building uses more energy than a smaller village on the countryside. Saving energy will make everyone happy: clients will decrease their costs, tenants will have cheaper office spaces, consumers will have cheaper products and our kids will have a greener future. The essence of the system developed by Re-Energy is to treat and harmonize the building as a single unit, meaning that in an unconventional way we not only optimize consumption on subunits. In addition, improvements in the efficiency of energy use can be achieved more significantly than in the market in a way that in addition to the well-known sources, we recycle the non-conventional sources of waste heat.