Research Paper Air exchanges and indoor carbon dioxide concentration in Australian pig buildings: Effect of housing and management factors T.M. Banhazi a,b, *, P. Stott c , D. Rutley c , V. Blanes-Vidal d , W. Pitchford c a National Centre for Engineering in Agriculture, Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, Qld 4350, Australia b Livestock Systems Alliance, University of Adelaide, Roseworthy Campus, SA 5371, Australia c School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy Campus, SA 5371, Australia d Faculty of Engineering, University of Southern Denmark, Niels Bohrs Alle ´ 1, 5230 Odense, Denmark article info Article history: Received 2 October 2010 Received in revised form 17 August 2011 Accepted 18 August 2011 Published online xxx There has been a growing interest in improving air quality within livestock buildings. However, the influence of housing and management factors on air exchange rates and indoor gas concentrations is not well understood. The aim of this study was to determine the effects of housing and management factors on the concentrations of carbon dioxide (CO 2 ) and air exchange rates in 160 representative Australian pig buildings. CO 2 concen- trations were measured, air changes per hour (ACH) were estimated using a CO 2 balance method, and structural and management parameters were recorded. The mean CO 2 concentration measured was 858 ppm and a mean air exchange rate of 22.8 ACH was estimated. The analysis showed that CO 2 concentrations were affected by the type of building, season, control of the wall and ridge vents, ceiling height, size of the wall vents and height of the ridge vents. Weaner buildings had the highest CO 2 concentrations while deep-bedding shelters had the lowest. Winter CO 2 concentrations were higher in all buildings compared to summer. Buildings with automated ridge ventilation control had the lowest CO 2 concentrations. The wall ventilation inlet height was negatively correlated with CO 2 concentration. Air exchange rates were primarily affected by the type of ventilation, inlet height, stocking density, and building width and height. In conclusion, the equable Australian climate has allowed the construction of cheaper pig buildings, which provide an adequate environment for pig production, although these buildings may not always provide an optimal environment for pig production. ª 2011 IAgrE. Published by Elsevier Ltd. All rights reserved. 1. Introduction Pig housing systems generate airborne pollutants comprising gases and airborne particles. Airborne pollutants emanating from pig buildings can adversely impact the amenity of neighbouring properties (Banhazi, Currie, Reed, Lee, & Aarnink, 2009). At levels commonly prevalent in commercial piggeries, poor air quality can adversely affect the health of * Corresponding author. National Centre for Engineering in Agriculture, Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, Qld 4350, Australia. Tel.: þ61 7 4631 1191; fax: þ61 7 4631 1870. E-mail address: Thomas.Banhazi@usq.edu.au (T.M. Banhazi). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/issn/15375110 biosystems engineering xxx (2011) 1 e8 Please cite this article in press as: Banhazi, T. M., et al., Air exchanges and indoor carbon dioxide concentration in Australian pig buildings: Effect of housing and management factors, Biosystems Engineering (2011), doi:10.1016/j.biosystemseng.2011.08.007 1537-5110/$ e see front matter ª 2011 IAgrE. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biosystemseng.2011.08.007