According to the equations of the balances of heat and moisture, the experimental and the analytical data, the mathematical model is created to ground the temperature regime and to calculate the parameters of the ventilation system of the uninsulated cow shed and that with the insulated roof. The suggested countable difference of the value between the internal and external temperatures is 3 degrees C, the greatest permitted meaning is 6 degrees C, and it does not depend on the other parameters of the building in the damp climate zone (in winter, the average dampness of the air is 85%), when the heat transmission coefficient of the external barriers of the cow sheds is k = 3.0 W/(m(2) K). When the roof is insulated (k(r) = 0.3 W/(m(2) K)), the countable value of the temperature differences rises up to 7-11 degrees C. (C) 2000 Elsevier Science S.A. All rights reserved.