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An investigation on gas emissions from naturally ventilated dairy cattle buildings was carried out. The buildings had different floor types and manure handling systems. Ammonia emission rates were determined from measured concentration values and calculated values of air exchange rates. The gas emission duration patterns were presented and discussed using one-hour moving average values for total measurement period.

The results showed that the emission levels varied considerably during the measurement period. The variation of ammonia emission rates could be from 2 to 40 g/HPU per day in a building during a 24-hour period. The lowest emission rates during a 24-hour period tended to occur after midnight. The reason might be that the activity level of cows as well as the indoor air temperature and the floor temperature were lower. A few peak values during a 24-hour period might have been caused by the management schedules for feeding, floor scraping and milking, etc. The investigation indicated that the air exchange rates in the buildings affected emission rates significantly.

The results on the diurnal patterns indicate that in order to make a steady-state estimation of the gas emission from naturally ventilated cattle buildings, the measurement period should at least be longer than 24 hours.