A Low-Cost Wireless Sensor Network for Barn Climate and Emission Monitoring—Intermediate Results.

A barn's climate is vital for animal welfare and emissions control, including greenhouse gases like methane (CH₄) and carbon dioxide (CO 2 ) and environmental gases like ammonia (NH 3 ). The goal of this study was to investigate a developed low-cost online tool for monitoring barn climate and air pollutant emissions (OTICE) in naturally ventilated barns. OTICE employed a wireless sensor network with low-cost sensors for gases and climate variables, allowing scalable use across multiple barns. We evaluated the sensors for CO 2 , NH 3 , and CH₄ for accuracy, both in controlled lab conditions and in a dairy barn in Germany, where measurements were carried out continuously for a duration of 12 days. For the averaged concentration levels over the measurement period, the low-cost sensors agreed well with the reference system, with relative deviations lower than 7% for all three gases, with maximum peak deviations up to 32% for CO 2 , 67% for NH 3 , and 65% for CH 4 , with strong Spearman correlations for CO 2 and NH 3 ( ρ C O 2 = 0.8, ρ N H 3 = 0.68) and a rather weak correlation for CH₄ with ρ C H 4 = 0.24. Further calibration and stability investigations are required, especially for CH₄ sensing. However, the overall good results for NH 3 and especially CO 2 measurements indicate a huge potential of the low-cost system as a valuable tool for monitoring relative NH 3 emission levels and the measurement of air exchange rates in naturally ventilated barns. [ABSTRACT FROM AUTHOR]