When it comes to creating energy efficiencies in a major commercial building, what can be more effective than free cooling? After over ten years of upgrades on Chicago’s historic Chase Tower’s ancillary systems, ESD began analysis of the building’s existing, original, 10,000-ton chiller plant. While free cooling through a waterside economizer seemed the right solution for the building initially, ESD’s detailed analysis of the building’s hourly energy model reports led to a more efficient solution for the tower.