Variable Air Volume-Flow Systems - A Possible Way to Reduce Energy Use in the Swedish Dairy Industry

Growing concern about negative effects on the environment and increasing energy prices stress theimportance of energy efficiency. Support processes such as heating, ventilation and air-conditioning(HVAC) use large amounts of energy in the dairy industry. In this paper the energy aspects of the support processes at two large dairies, built at three different points in time, are analyzed and compared with energy use throughout the rest of the company. Significant differences in the use of energy and the resulting indoor climate were found. One way to reduce the impact of increasing energy used by HVAC is to use Variable Air Volume-flow (VAV) systems. The potential for using VAV systems in the dairy industry is studied using a whole-site simulation for one of the sites. The simulations predict a potential for reducing space heating by 60%, and the amount of electricity used to run fans and compressors for air-cooling systems by 21%. This remarkable potential for reducing heat use is due to the dynamics of the process during the heating season.The indoor climate and energy simulation was carried out using the commercial code IDA ICE. The model has been validated with extensive measurements over an entire year. The predicted indoor air temperatures are in good agreement with the measured values. The use of VAV systems is concluded to be an effective energy efficiency measure for reducing the energy used by HVAC systems in the dairy industry.