Minimal labor and management resources had to be invested in the operation of the heat recovery system. If considering that the capital and running cost of the waste system is not included and that the first purpose of the waste management system is for manure treatment and odour control, the heat recovery system is cost effective by the money saved on energy costs. The pay-back period of the heat pump is around 3 to 4 years. As the operating cost of aeration treatment are superior to the heat recovery by the heat pump, improving the aerator efficiency would be more appropriate than improving the heat recovery system. The behavior of such system under very cold weather would need to be verified as the micro-organisms activity would be lower at low temperature and could probably not maintain temperature high enough to achieve a good treatment.