Project Brief

zColo, a Zayo Group company, runs colocation space at 600 S Federal Street in Chicago. Suite 142 on the first floor needed its computer room cooling replaced, and KeRi was the MEP engineer for Boon Energy, the owner's energy consultant, across the survey in 2015 and the design that followed.

The survey set the direction. The suite was running one nominal 15 ton air-cooled unit and two 20 ton glycol-cooled units with economizer coils. KeRi checked what the building's chilled water plant had left and found roughly 160 GPM of headroom against everything already committed to it, not enough to hang more chilled water units on. So the replacement went self-contained: three Liebert computer room units in the suite, each moving 14,600 CFM with 340 MBH of capacity, a 22 lb/hr humidifier, a condensate pump, integral smoke detection, and controls interfaced back to the existing panel.

The hard part was outside. Three 40 ton air-cooled condensing units had to go into a fenced yard with no room to stand them side by side, so KeRi stacked them three high on new structural steel. They sit beside the building's diesel engine generator, which meant selecting them at a 100 degree ambient and specifying a plexiglass wall to stop the generator's hot discharge air being pulled straight into the coils. A removable fence section keeps maintenance access, and the refrigerant piping runs from the yard through the laundry and tech rooms into the suite.

Inside, ductwork was run as high as the structure allowed to keep the ceiling clear above the cabinets, and diffuser positions were left to follow the owner's cold aisle containment barrier rather than being fixed in advance. Each unit got a motorized damper interlocked to close when that unit is off. As in Newark, the suite could not go down: the drawings require the contractor to field verify, prefabricate the new work, set the schedule with the owner, and fit MERV 8 filters to the units still running while construction went on around them.

MEP Engineering Scope

What We Engineered

Mechanical and electrical design for the suite cooling replacement:

• Survey of existing units and the building's remaining chilled water capacity
• Three Liebert CRAC units at 14,600 CFM and 340 MBH each
• Three 40 ton air-cooled condensers stacked on structural steel in a fenced yard
• Refrigerant piping routed from the yard back into the suite
• Ductwork and diffusers coordinated to the cold aisle containment
• Electrical demolition and new work, with no permitted shutdown of the suite

How the Work Ran

The Challenge

Suite 142 needed its cooling replaced while it stayed live, and neither of the easy routes was open. The building's chilled water plant had only about 160 GPM of spare capacity, so more chilled water units were not possible, and the fenced yard outside had no room to stand three new condensers side by side. What space there was sat next to the building's diesel generator, whose hot discharge air would be pulled straight into any coil placed there.

Our Solution

KeRi went self-contained, putting three Liebert computer room units in the suite on their own 40 ton air-cooled condensers rather than drawing on a chilled water plant with nothing left to give. The condensers were stacked three high on new structural steel to fit the yard, selected at a 100 degree ambient for the generator heat, and screened with a plexiglass wall to keep that discharge off the coils. Inside, ductwork was kept high and the diffusers were set to follow the owner's cold aisle containment, with the whole installation prefabricated and sequenced so the suite never came down.