Measurement Campaign on Ammonia Emissions from Traditional Naturally Ventilated Dairy Barns

On behalf of Flanders Environmental Department, a measuring campaign is performed to determine the ammonia emission factor for a traditional dairy barn. Emission measurements are being performed on four barns spread throughout Flanders, housing 95 to 160 animals.

A newly developed emission measuring method is used which is based on wind speed measurements for the determination of ventilation rates. The barns are equipped with about 20 ultrasonic anemometers (UA) collecting data at a sampling frequency of 1 minute. The velocity and wind direction measured by these UA’s, in combination with the dimensions of the barn openings (roughly Height:3 m x Length:40 m) are used to determine the air flow rate through the barn openings. In order to determine emissions, the ammonia concentrations are measured at 6 locations using sampling lines. Two sampling lines are located outside the barns (at both NE and SW side of the barn) and used to measure concentrations in the incoming air. Inside the barn, two sampling lines are located at the ridge (one directly at the ridge, the other 3 meters below the ridge) and two at the upper part of the ventilation openings (thus one at NE and one at SW side). This set-up enables concentration measurements of ammonia (and methane) where the air is leaving the barn. A multisampler is used to switch between the six channels and feed the central analyser (Picarro or Axetris) with the gas sampled at these locations. This enables the calculation of hourly emission values.

The end of the measuring campaign is foreseen in September 2024. Preliminary results will be shown, differences between barns will be discussed.