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The University Health Network’s Lyndhurst Centre in Toronto is one of North America’s leading rehabilitation centres.  Constructed in 1974, the Centre was still using its original Cooling Plant, whose design included a single centrifugal chiller, oversized to accommodate a projected expansion that was never realized. The Chilled water pump was constant volume with three way valves on the Air Handling Units (AHUs). The Condenser water pump was constant volume, and the Cooling Tower had two constant speed fans.  The Cooling plant was not efficient and had very poor overall part load efficiency.

UHN’s Energy Manager, Mike Kurz, had a mandate to incorporate the most efficient available equipment to reduce energy usage.  He performed ‘before’ calculations for the original chiller operation, followed by ‘after’ calculations last summer (*See Mike’s blog).  The new chiller plant has achieved an 80+% reduction in energy consumption and an almost 50% reduction in demand to date, with the potential for even greater savings next year when the AHU cooling coil valves are converted from three-way valve to two-way valve operation, allowing chilled water pump modulation reduction by 60%.

UHN hired HH Angus and Associates to design and implement the project. The project scope was to replace the chiller, cooling tower, and convert the pumps to variable frequency drive (VFD) operation.   To provide pumping redundancy, the chilled water and condenser water pumps were replaced with duplex skid mounted VFD operated pump packages. Chilled, condenser, and domestic water meters, viewable from the building automation system, were provided to monitor energy consumption and to aid with verification for Hydro Incentives.

Cooling Tower 21

The original chiller operated at an efficiency of 0.96 kW/ton down to 1.27kW/ton (worse at part load). It was replaced with a variable speed magnetic bearing centrifugal compressor chiller.  The new chiller has three isolatable compressors, affording some redundancy and providing 9:1 turndown with efficiencies from 0.5kW/ton down to 0.2kW/ton at part load.  This provided the largest portion of the energy reduction.

HH Angus had previously completed with great success a cooling tower replacement with a Fiberglass Reinforced, plastic Pultrusion (FRP) tower at Barrie’s Royal Victoria Hospital.  This design came to the attention of UHN’s Energy team who, recognizing its benefits, decided to base the Lyndhurst Cooling Tower Tender performance on the same specification. The FRP tower has four direct drive fans, providing some redundancy, as it can operate at 75% capacity if a fan fails.  We were able to further reduce energy by modulating the fans, saving 80% compared to the original two fan-two stage cooling tower.

The project also included new DDC controls for the cooling plant, with an upgrade to the building automation system server and graphics monitor.  Working with Honeywell and UHN, HH Angus developed a custom Graphic Cooling Plant schematic that allowed the entire cooling plant and information most relevant to UHN’s Facilities Manager to be viewed on one screen.

The success of this project was due the contributions of the entire team.  Thanks go to Mike Kurz, UHN Energy Manager, Angelo Suntres, UHN Project Manager, and Andrew Peeters, Kelson Project Manager.

Mark Baniuk was HH Angus and Associates’ lead mechanical designer on the Lyndhurst project.

*Mike Kurz’s chiller blog: https://talkintrashwithuhn.com/2016/06/17/chiller-thriller-part-1/

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