Energy Consumption and Air Quality in Growing-Finishing Pig Houses for Three Climate Regions Using CIGR 2002 Heat Production Equations

Simulation of indoor climate, air quality and energy consumption for animal houses requires precise information on animal heat and moisture production at different housing conditions. In this article results are presented from an analysis of energy consumption for heating and ventilation of a dry and a wet growing-finishing pig house as well as on indoor climate and air quality in three climate regions in Finland, Denmark and Portugal. The analysis is based on the latest CIGR models of animal heat and moisture production on house level, not only taking the body weight, but also the feed intake into account. Four temperature set-point levels were analyzed. As representative of a house with no bedding, an indoor start temperature set-point of 22oC was used for 30 kg growing-finishing pigs. After 7 days the set-point was decreased linearly until reaching the lower temperature set-point of 18oC at an end weight of 100 kg. The effect on energy consumption for heating and ventilation of houses with bedding or covered pens was investigated using three lower temperature set-point levels with start set-points of 20, 18 and 16oC with the corresponding end set-points of 16, 14 and 12oC. In selecting set-point strategies for maximum relative humidity (RH), it is assumed according to CIGR recommendations, that higher RH is acceptable at lower temperatures. When normal air quality and low energy consumption is given first priority, the set-point sum of temperature (°C) and RH (%) is 90, e.g. for a 22-18°C temperature set-point level a RH set-point of 68-72 % is used. An alternative would be to use extra energy to achieve good air quality by selecting a setpoint sum of 85. The energy consumption for ventilation decreases nearly linearly with about 20 % when the start temperature for pigs of 30 kg decreases from 22 to 16oC. For fans with the energy efficiency 20 000 m3 per kWh, the energy consumption for ventilation is between 6.6 for Finland and 8.7 kWh per produced pig for Portugal for start set-point temperature of 22oC. Compared to Finland the energy consumption for ventilation is approximately 6 % higher in Denmark and 32 % higher in Portugal, due to higher outdoor temperatures and hence increased ventilation need. The energy consumption for heating under dry housing conditions is less than 1.5 kWh per produced pig in Denmark and Portugal at start temperatures up to 22oC, and less than 10 kWh per produced pig in Finland. The heat consumption under wet indoor housing conditions is higher and up to 8 kWh for Denmark and up to 23 kWh per produced pig for Finland at a start temperature of 22oC.