OPTIMIZATION OF EXTERIOR WALL AND ROOF INSULATION THICKNESS OF A GROWING-FINISHING PIGGERY BUILDING

摘要

Increasing the insulation thickness of a piggery building reduces the heating requirements by lowering the thermal losses but may also cause an undesirable increase of the inside temperature, thus increasing cooling requirements, during periods of elevated ambient temperature. This process, combined with animal heat loads, alters the inside temperature and relative humidity (RH) values, resulting in potential animal heat-stress throughout the year. Therefore, an optimum insulation thickness exists at which the annual hours outside the production space (PS, the optimal temperature and RH zone) are minimum. A detailed transient simulation model of a conventional piggery building with no heating or cooling systems was used for calculation of the free-floating inside temperature and RH values. Hourly climatic data from the regions of Heraklion and Kastoria in southern and northern Greece, respectively, the sensible and latent heat losses from pigs, the heat flow through the building elements, and the ventilation heat losses were taken into account. The optimum insulation thickness of the exterior walls and roof was found to be between 4.25 and 5.55 cm for Heraklion and between 14.25 and 18.20 cm for Kastoria. The corresponding percentage of hours outside the PS was between 35.4% and 99.5% for Heraklion and between 13.6% and 76.7% for Kastoria. The annual hours outside the PS at Heraklion were 6094 (69.6% of the 8760 yearly total hours), which was 43.7% greater than the 3434 hours at Kastoria (39.2% of the 8760 yearly total hours). In northern Greece, use of the optimum insulation thickness at conventional piggeries with no heating or cooling systems could result in fewer hours outside the PS compared to southern Greece.