Relation between energy use and indoor thermal environment in animal husbandry: a case study

Climate control is of the foremost importance in structures for intensive animal rearing because many animals (e.g. pigs and broilers) tolerate a small range of climate conditions (mainly air temperature and relative humidity) that may differ considerably from the outdoor environment. For this reason, the indoor climate in the majority of structures for animal husbandry is guaranteed by HVAC systems. On the one hand, the use of mechanical systems makes it possible to avoid production risks due to the unpredictability of the outdoor weather conditions and to maximize the feed efficiency, with positive effects on both the animal welfare and farm profit. On the other hand, the use of HVAC entails not negligible thermal and electrical energy consumptions. In literature, few data about the real thermo-hygrometric conditions and energy consumption of animal houses are present. In this work (in the framework of the EPAnHaus – Energy Performance certification of Animal Houses –project), the results obtained from a long-term monitoring campaign in two growing-finishing pig houses are presented. The performed measurements concerned environmental parameters and electrical power that were acquired during two production cycles (warm and cool seasons). For the environmental monitoring, both the buildings were equipped with temperature and relative humidity sensors embedded in portable data loggers (10 minutes logging time) that were placed in various spots inside the houses. Outdoor data were obtained through a weather station located near the test site. Concerning the energy monitoring, power transducers connected to portable data loggers (10 seconds logging time) were placed in the electric panel of each house to log the electrical energy consumptions due to ventilation, lighting and automatic feeding. The acquired data were used for carrying out analysis concerning the indoor thermal environment, its characterization in relation with the animal welfare, the electrical energy uses and the existing relations between all these aspects. The obtained data were used to evaluate the effectiveness of the HVAC system in guaranteeing the adequate indoor climate conditions (avoiding heat/cold stress conditions) and to identify electrical energy uses.