In the paper the estimation of energy consumption of the automated ventilating systems and air conditionings (V and AC) under condition of their regulation "on deviation" is reviewed. The analysis of processes descending in V and AC and maintained room is given. The outcomes of numerical calculation of a non-steady thermal mode of a room with the computer program designed by authors are adduced. Calculations were organized on different combinations of radiant and convective components of variable heat ingress. The optimal control algorithm of V and AC from the point of view of minimal general energy consumption during the heating system is found. The presentation is illustrated by a graphic stuff and by a numerical example of technical and economical estimation of optimal control algorithm using.