Cowshed roof insulation and ventilation

Abstract

There is a strong trend towards outdoor stall (uninsulated) solutions. While in a winter a warm stall the focusis on temperature balancing, the outdoor climate stall, which cannot be run without high air exchange even in the winter, mainly requires the interactions of the different ventilation mechanisms to be understood. In winter, one must avoid the animals being exposed to draft or the occurrence of construction damage due to the formation of condensation water. Using the rules of thermophysics, aerodynamics, mathematics and the results of our previous research, it was analysed how the constructional and technological factors of the building influence the parameters of rational insulating rate and ventilation. It was composed the formula for calculating the outside building surface optimum heat transfer coefficient. This formula integrally evaluates the heat balancer of the building, incondensable water vapour condition, constructional and technological patameters. Using the composed formula was established that after increasing the amount of animal total heat flow to the ground area unit from 90 to 150 W/m² it would be rational to reduce the outside building surface heat transfer coefficient from 5.0 to 2.3 W/(m².K). The last-mentioned mean satisfies the wall heat transfer coefficient - 3.6 W(m².K), and roof - 1.9 W/(m².K). After reducing the heat transfer coefficient, the indoor air temperature during the cold period increases about 7° C. It was composed the formula for calculating the parameters of cowshed ventilation system, according to outdoor air temperature. According to calculations, when the outdoor air temperature is dropping from 20°C to -20°C, it would be rational to reduce 85% the went area.