In addition, we have recently come across a couple of articles that deal with winter operation. The first two, from SPX Cooling Technologies, provide discussion of how to operate cooling towers in freezing temperatures and the impact of icing on cooling towers. The third is a detailed white paper from Baltimore Air Coil (BAC) which goes into detail about how free cooling can help conserve energy for towers in cool climates. Both SPX and BAC have excellent technical resources that you should be aware of.