This study evaluated whether the air and surfaces temperatures, humidity and NH3 concentrations inside a typical pig finishing unit of two parallel buildings were influenced by the prevalent winds and by the location inside the buildings. The farm had two North-oriented equal buildings (1 and 2) 10 m away. West front of building 1 was lashed by prevailing N-W cold and dry wind (“cierzo”). Each building had 2 corridors, west (W) and east €. Ventilation was natural, with inlets in both walls and outlets in the roof. Environmental traits were recorded fortnightly at 10:00 (March-July). There was a significant influence of the corridor, this effect being significant for the inner surface temperatures of the walls (P<0.05), the surface temperatures of slats (P<0.05) and for the air temperature (P<0.05). All of them were higher in the eastern corridor, the more protected from the incidence of the “cierzo”. There was also a significant effect of the corridor on NH3 concentrations, higher on corridor E (P<0.05), less aired than the W. These results highlight the significance of the prevalent winds from the Ebro Valley on the inside environmental parameters of pig North-oriented facilities.