| Resumo: |
Several dairy farms still have old multi-span barns which are encountering several problems in summer and they are: low ventilation rates, non-uniformed air distribution, heat stress and high indoor concentrations of harmful gases. A solution has been suggested, in this study, which is refurbishing the roofs of old multi-span dairy barns by modifying the roof design, increasing the cowshed height and the roof slope angle. In order to implement this new roof design, rigorous experimental measurements and theoretical calculations were carried out to evaluate the indoor environment before and after refurbishment which was determined by measuring and estimating the following parameters: air exchange rate, indoor temperature, gaseous concentrations (NH3, CH4, N2O, CO2, CO and H2S) and difference between indoor and outdoor temperatures. The results of the field measurements showed that the air exchange rates were 9.6 h-1 and 53.7 h-1 before and after refurbishment, respectively. The measured temperature differences (outdoor to indoor) were 1.1oC and 7.2oC before and after refurbishment, respectively. The indoor gaseous concentrations were 5.6, 19.9, 0.89, 1487, 8.95 and 0.52 mg m-3 before retrofitting; and were 2.8, 13.6, 0.59, 998, 3.3, 0.17 mg m-3 after retrofitting for NH3, CH4, N2O, CO2, CO and H2S, respectively.
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