Testing of Daylighting and Heat Load Parameters in Different Design Types of Dairy Cow Housing

The aim of the work was to test the level of daylight conditions and the heat load of animals in the summer season in two identically oriented dairy barns with different construction and material solutions. Measurements were carried out in the same farm and at the same time. A classic massive building – reconstructed barn (RB) for 158 dairy cows with a volume of 34.3 m 3 per animal supplemented in summer by motor ventilation (522.15 m 3 per animal, total 82,500 m 3 ·h −1 ) had an indoor daylight factor DF below the limit DF avg, int = 0.21% (against the recommended DF = 1% for housing dairy cows). In the external feeding alley, which was screened by a shelter and an adjacent building, lighting conditions were compliant with DF avg, ext = 4.02%. However, the level of heat load as measured by indices was above the limit ( THI avg, int = 84.65) despite the motor ventilation used; in the outdoor feeder THI avg, ext = 81.63, against the recommended stress-free level THI = 72. Similarly, according to the ETIC assessment, the results were deficient ETI Cavg, int = 26.16 and in the outdoor feed ETI Cavg, ext = 25.24 against the recommended level of ETIC = 20. The second building, a new barn (NB) for 444 dairy cows was a new large-cubicle indoor structure with 82.53 m 3 per animal, with a translucent roof (37.87% of the total 4,927.6 m 2 was of translucent polycarbonate triple-pipe roofing). This amount of translucent elements together with large window openings of a total area of 879.6 m 2 was also reflected in the values of the daylight factor DF avg, int = 7.59%. The level of heat load was not significantly lower compared to a massive RB with motor ventilation over a double row of bunks (fans with a total capacity of 82,500 m 3 ·h −1 ). In NB, no animal cooling features were activated, but technically and spatially they were easily solvable (whether economical ventilation systems with laminar flow, precisely controlled sprinkling of animals, or another combination of evaporative and flow solutions). These efficient types of cooling would be almost impossible to deploy in RB or only with a special renovation of the building, which would be comprehensively costly.