Temperature Distribution and Vertical Stratification near Side-Wall Inlets of Stacked Cage Broiler Houses in Winter

Inlet design assumes that supply air from side-wall inlets mixes with house air over several metres, but whether this holds in a densely caged multi-tier house, where cages and birds obstruct the jet, is untested. The bird-zone environment of a commercial stacked-cage house was measured with 24 in-cage sensors at three distances and two tiers over ten winter days. Three of four groups showed no resolvable cooling gradient at 1.5 m; only one north-side group cooled with distance, strengthening with ventilation (0.30 K per percent, R2 = 0.39), while another showed the opposite sign. Every fitted decay coefficient (αdh=0 to 0.004) lay below the free-jet design range (0.01–0.03), by five or more times over the window. Vertical stratification of 0.78 K dominated (side × tier p<0.001): the upper tier was up to 2.4 K warmer on the north side, while the south-side tiers differed by under 0.5 K. Shading nets lowered north-side inlet temperature by 0.80 K but warmed the south side. The practical consequence is that the thermal environment is organised by tier and side rather than by near-inlet distance, so monitoring, control and welfare-oriented assessment should target tiers and sides.