This study presents the results of three measurement campaigns (4th, 5th, and 9th July 2024) conducted at a biogas plant to assess odour emissions using both instrumental and sensory methods. Odour concentrations, intensity, hedonic tone, and detection frequency were analysed alongside gas concentrations of hydrogen sulphide (H2S), ammonia (NH3), and total volatile organic compounds (tVOCs). The highest emissions were consistently recorded at the waste sorting area, with peak odour values exceeding 1300 ou/m3 and elevated gas concentrations (up to 0.7 ppm H2S, 4 ppm NH3, and 15 ppm tVOCs). Moderate levels were observed in composting and digestate handling zones, while background and administrative areas exhibited negligible values. Results from electronic noses and gas sensors showed strong agreement with sensory panel evaluations, confirming the dominant role of raw waste handling in odour nuisance. The use of the Odour Air Quality Index (OAQI) enabled an integrated interpretation of multidimensional data. Across all campaigns, it consistently classified the sorting hall as very poor, placed the composting and digestate zones in the moderate band, and clearly captured day-to-day variability driven by wind conditions. These findings underscore the value of combining real-time instrumental monitoring with trained panel assessments to guide odour mitigation strategies in biowaste treatment facilities.