The studies were conducted on four 216-apartment buildings, which account for a 10 / 0.4 kV substations. Built by spline interpolation in the MathCAD environment, the charts of the electrical load of homes by standard indicators and based on information measurement. Turning the obtained graphs into two stages, the parameters of the rated capacities of the oil transformers 400 and 250 kVA were chosen by their parameters, since the rated power by the standards turned out to be much higher than the actual one. The variant with the TM-250/10 transformer, will save (energy efficiency) by reducing electricity losses during operation about 492,2 tons conditional fuel, in case of electricity loss (economic efficiency), the option is cheaper by UAH 268,2 thousands, which will result in emission reductions (environmental efficiency) of about 163,6 tons.