Increasing suction pressure and energy efficiency

Hi,

Increasing suction pressure is a common recommendation in energy efficiency guidelines published by various bodies.

I am looking for a good simple explanation on how this is typically done in practice. Specifically I am interested in the case of industrial refrigeration plants (either packaged R134a or R22 chillers or large ammonia plants) that chill glycol into a tank (glycol temp can be -8 to +4 deg C), which is then reticulated for process cooling.

I understand the basics of refrigeration but I currently know very little about the practicalities of refrigeration plant control systems.

Thanks in advance for your help.