Utilization of a heat pump in pig breeding for energy saving and climate and ammonia control

The performance of three heating systems was analysed in closed-cycle pig farm (farrowing and weaning section). Three adjoining rooms were heated using one of the following systems: a reversible air to air heat pump (HP) for both heating and cooling; a standard liquid petroleum gas (LPG) boiler for heating coupled with mechanical ventilation for summer cooling; and natural ventilation with emergency convective heating. Their energy consumption and influence on production parameters were compared. Fifteen groups of sow and their litters were housed in succession in each room from the end of pregnancy through weaning (5 cycles). Temperature and humidity and production parameters (i.e. feed conversion index) were measured for each cycle and room. In the case of HP, the ammonia emissions produced in, and extracted from, the breeding room were also determined. The HP consistently maintained both temperature and humidity around optimal values (average 26.2 degreesC and 64.2% relative humidity) and allowed primary energy savings of 11% compared with the LPG heater. The piglets weaned in the HP room showed better growth performance. Finally, the air processed by the HP contained less than half the ammonia concentrations recorded in the naturally ventilated room. (C) 2000 Silsoe Research Institute.