Research Paper Temperature distribution in a finisher pig building with hybrid ventilation Khem R. Gautam a,* , Li Rong a , Guoqiang Zhang a , Bjarne S. Bjerg b a Department of Engineering, Aarhus University, Inge Lehmanns Gade 10, DK-8000, Aarhus C, Denmark b Department of Veterinary and Animal Sciences, Copenhagen University, Denmark article info Article history: Received 16 December 2019 Received in revised form 7 September 2020 Accepted 13 September 2020 Keywords: Hybrid ventilation Automatically controlled windows Temperature distribution Diurnal variation Spatial variation Animal housing The differences between temperatures in the animal occupied zone (AOZ) and tempera- tures measured by control system sensors are rarely explored. This experimental study quantifies the dry-bulb air temperature [hereinafter temperature] distribution inside a finisher pig building that combines natural ventilation through automatically controlled openings with a mechanical ventilation system. Year-long temperature data from 28 sensors located at 3 different heights in the building was analysed to help understand the temperature distributions and indicate the temperatures below or above an assumed optimal temperature range, defined as between 14  C and 24  C. Relatively large variations in the spatial temperature distribution were found, and they were higher in the vertical direction than in the longitudinal direction. The temperatures measured in the AOZ at 0.25 m height, were on average, 7  C warmer than that at 1.5 m height. The AOZ temper- ature correlated better with temperatures measured at 0.7 m or 1.5 m height in the same pen than with temperatures measured in the AOZ at other pens. The analyses show that a proportionaleintegral based control system effectively counteracts the effects of outdoor wind conditions, and the control system is capable of maintaining the defined optimal temperature at the measurement height. However, the optimum temperatures at the measurement heights above AOZ do not correspond to the measured temperatures in the AOZ. © 2020 IAgrE. Published by Elsevier Ltd. All rights reserved. 1. Introduction A major challenge in modern pig production facilities is to combine good animal welfare, high animal productivity, and low environmental impact with affordable capital costs at profitable operating costs (Santonja et al., 2017). A crucial precondition for obtaining good animal welfare and high animal productivity in a pig production facility is the ability to control the climate conditions around the animals within specified limits. A review by Hansen and Bjerg (2018) on finisher pigs indicates that the highest growth rate is obtained at dry-bulb air temperature [hereinafter temperature] of 15  C. The growth rate is reduced by 10% if the air temperature is increased to 24  C. This review indicated that the highest feed * Corresponding author. E-mail addresses: krg@eng.au.dk (K.R. Gautam), Li.Rong@eng.au.dk (L. Rong), guoqiang.zhang@eng.au.dk (G. Zhang), bsb@sund.ku.dk (B.S. Bjerg). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/issn/15375110 biosystems engineering 200 (2020) 123 e137 https://doi.org/10.1016/j.biosystemseng.2020.09.006 1537-5110/© 2020 IAgrE. Published by Elsevier Ltd. All rights reserved.