Correlations, variations, and modelling of indoor environment in a mechanically-ventilated pig building

Abstract

Indoor environment conditions in confined pig buildings are critical for pig health, welfare and reproductions. It is necessary to explore the correlations of indoor thermal environment and gas concentrations conditions and their characteristics in order to provide a basis for developing an optimal pig building environment control strategy. In this study, an innovative method integrating three correlation analyses was developed to make a comprehensive and quantitative description for the correlations and coupling abilities among multiple environment factors from different perspectives. A multiple regression model was developed for gas concentrations of NH3, CO2 and H2S, with second order polynomial expressions on temperatures of outdoor, pig living space (PLS) and pit, and the most correlated factors as input variables. The results showed that the PLS CO2 concentration and the outdoor temperature could be used as decisive factors for the established categories of GS and TH representing for gas concentration and thermal environment, respectively. It also found that the PLS air temperature varied greatly with the outdoor temperature, and the gas concentrations of NH3, CO2 and H2S were in the periodic and diel variation shapes of sine or cosine. The multiple regression model for the CO2 concentration achieved optimal performances determination coefficients R2 and root mean square error in the two rooms. Therefore, the model output of PLS CO2 concentration as well as the outdoor temperature could be used as a primary basis to improve the environmental control strategy, by means of reducing the types and number of sensors.