FIELD: heating. SUBSTANCE: heat is taken off from hot water of the regional water supply system and transferred to working fluid of heating branches 6,7 for building heating, production of hot tap water and heating of ventilation air supplied to building A. Heating branches 6,7 of building interior heating and ventilation heating are connected in series in such a way that heating fluid flowing in circulation pipe-line 5 heats (after passage through heat exchanger 4) first building heating branch 6, and then supplied ventilation air branch 7. EFFECT: enhanced efficiency. 10 cl, 5 dwg
