MINIMUM RIDGE OPENING WIDTHS FOR A NATURALLY VENTILATED SWINE BARN UNDER COLD WEATHER CONDITIONS

Traditional automatically controlled naturally ventilated (ACNV) barns for pigs in North America have had continuous ridge openings with wid ths ranging from 150 to 600 mm. This study evaluated the use of much s maller ridge opening widths of 6 and 20 mm (ridge opening to floor are a ratios of 1:2160 and 1:650 respectively). Equivalent intermittent sm all openings could be less costly to construct. Inside temperature and humidity distributions were monitored during cold weather. Test resul ts indicated that very satisfactory performance in terms of inside tem peratures and humidities near pig level (1.5 m height) were obtained u sing either the 6 or 20 mm wide ridge opening. However high relative h umidities near the ridge became a concern with the 6 mm opening.