Increasing Chilled Water Supply Temperature
It is become common practice to save energy by increasing chilled water supply temperature (CHWS) without considering AHU design requirements and indoor air quality.
CHWS temperature plays an important role in humidity control. At high temperatures, the ability of the AHU to dry the air is reduced which in turn will increase the humidity in the room. This of course can be avoided by pre-cooling of the outside air but to for pre-cooling to be effective it requires low CHWS temperature.
Therefore if you ever plan to save energy by increasing the CHWS temperature ((we call it Energy Avoidance!), remember to consider your AHU performance and measure the room condition before and after!
Chillers are already designed to counter building loads using vane controls (centrifugal chillers) or through the compression value (screw / scroll chillers). Increasing CHWS just because its raining outside is NOT GOOD ENGINEERING PRACTICE! If you building becomes very cold when it rains, it simply means your AHU controls are not working well enough!
Your building heat load is not temperature only - you have to look at enthalpy values to know if its gaining heat or losing it!