Studies on the Open Type Piggery

A case study of relation between resistance of total heat transmission of roof and heat transfer

Abstract

Of the open type piggery built in Kisarazu City, Chiba Pref., investigations carried out in summer and winter, authors studied the heat transfer on the roof where the resistance of total heat transmission differed.
1) Difference of the average temperature of piggery in summer and winter was about 20°C and that of the average relative humidity about 10%. The temperature and relative humidity inside piggery varied relating with those outside piggery.
2) The heat flow on the roof changed from heat gain to loss or from heat loss to gain at the time when the temperature varied so much. As resistance of total heat transmission of the roof become greater, both heat gain and loss tended to decrease.
3) During the daytime in summer, inside surface temperature of the west side roof of piggery was more affected than that of the east side roof by solar radiation.
4) As resistance of total heat transmission of roof increased as much as 1m²·h·°C/kcal, heat transfer by radiation from inside roof surface decreased significantly. Over 1m²·h·°C/kcal, heat transfer by radiation varied hardly.
5) As to the inside temperature below the roof, the temperature of small resistance of total heat transmission was considered to bo more affected than the roof of great resistance of total heat transmission dy heat from inside roof.
6) On the roof structure of piggery, authors have obtained the following views from our investigations.
(1) For the roof of piggery around Kisarazu city, it is recommended from the point of view of thermal environment to have threefold structure consisting of corrugated metal with 50mm air space, 20mm insulation and 3mm plywood.
(2) The above mentioned threefold structure with 10mm insulation instead of 20mm may be affected by solar radiation, especially in the west side of roof of piggery.
(3) Since the resistance of total heat transmission of the threefold structure described in (1) was 0.96, the roof corresponding with the value should be constructed for the future. Roof with slates, for example, is much used in the Kanto district. As 3mm slate has 0.0036 of resistance of total heat transmission, the roof need to have the threefold structure consisting of 3mm slate, 26.5mm insulation, and 3mm plywood in order to keep the thermal environment of inside roof surface effectively.