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The North Point Office Complex - Case Study
North Point Towers in Cleveland, Ohio, is home to a cadre of professional tenants including insurance companies, healthcare staff, government agencies and Jones-Day Law, the world’s largest law firm. North Point Towers consists of two buildings, five stories each, connected by an atrium; tenant amenities include fitness facilities, a cafeteria and underground parking.
In 2006, North Point Towers realized the need to upgrade its heating, ventilating and air conditioning (HVAC) system—mostly replacing 22 air-conditioning units that varied in size between 10,000 and 20,000 cfm. Much of the HVAC equipment had been installed more than 20 years prior and was now operating with poor efficiency and even less reliability. When he tried to service or replace the equipment, the North Point Towers facilities manager was told his parts were obsolete or discontinued, and that we would have to purchase and entirely new system. He finally decided to do so, but with a completely different provider; he chose a Trend system, installed by The K Company.
The facilities manager’s biggest challenge was making a decision on a final design. He had three options: Replacing the air-conditioning units according to the system’s original design; installing individual, distributed chillers to mechanical rooms and adding matched variable air volume (VAV) air handling units (AHUs); or providing a central plant chilled water system that used the original condenser water piping with matched VAV AHUs and variable speed pumping. A further challenge was to get the service providers to bid exactly what needed to be bid, once the final design was chosen.
The current design of North Point Towers included one mechanical room on each floor of the West Tower and two mechanical rooms on each floor in the North Tower. Each mechanical room essentially acted as a standalone air-conditioning plant. The new system would need to centralize all the cooling functions.
Technicians also had to transport large, unwieldy equipment amid high-end office furnishings. Offices in North Point Towers feature expensive, custom-made décor pieces that could not be moved or damaged in any way.
Finally, the facilities manager also required installation to occur without any interruption to tenants or day-to-day operations. That meant equipment taken offline for replacement had to be in place, tested and running when the next business day started.
North Point Towers chose the option of creating a central plant chilled water system controlled by a Trend IQ3 solution. Trend’s 963 Supervisor software serves as the front end and IQ3xcite controllers monitor centrifugal chillers, chilled water coils and XX. IQView touchscreen displays provide at-a-glance views of setpoints, a single piece of equipment or the entire facility.
The existing HVAC water distribution inside North Point Towers was a condenser water loop with self-contained, water-cooled AHUs and cooling towers with piping to cool the mechanical rooms. The K Company created the central plant chilled water system by first installing three 350-ton centrifugal chillers in the basement of the North Tower.
All the mechanical room compressors were eliminated, and then technicians replaced all the old AHUs with new 16–20,000-cfm models that featured chilled water coils.
With this new design, North Point Towers is able to use water-side economizer free cooling to pump water directly to the coils. Pumped water that previously cooled the compressed is now used as chilled water for cooling. This leaves a single point in each mechanical room that the facilities manager can use to send water into the heat exchanger. He can then use outside temperatures during the winter to create chilled water and cool the building for free. Rather than running the chillers, North point Towers instead uses outside temperature through the heat exchanger to cool, saving significant energy and costs.
The K Company installed variable frequency drives (VFDs) on the existing building and tower pumps as well as the new AHUs. This allows the Trend controllers to speed up or slow down the VFD motors only when needed to maintain a setpoint, further minimizing the system’s energy use.
To ensure none of the expensive office décor was damaged, the K Company created a sterile hallway between service elevators and the mechanical rooms. Temporary flooring was installed and areas taped off to avoid interaction between the high-end furnishings and the large pieces of equipment that technicians needed to convey through the corridors. At the end of each work session, they cleaned up the areas to ensure to no inconvenience or discomfort to the tenants’ next work day.
Because there could be no downtime during installation of the new Trend system, The K Company coordinated with the North Point Towers facilities staff to conduct the work in the evenings and during weekends. For each mechanical room renovation, the crew would enter after business hours on a Friday evening and clear out the room, bringing equipment out through the service elevators. Each new AHU was shipped to the North Point Towers garage—broken up into sections—and then brought upstairs and reassembled in the mechanical room. Technicians connected and tested each AHU throughout the night, and ensure it was up and running by Saturday morning. Coordination between the North Point Towers facilities manager and the service provider was key to success. The K Company held weekly meetings with the owner and tenants to make certain schedules and expectations were on track.
The Trend system inside North Point Towers offers centralized control of the entire facility. Most importantly, it provides an economic and scalable solution for the future; the building owner has already planned an East Tower, which will add about 600,000 square feet to be controlled by the Trend system.
Although creating a centralized plant was the most expensive option, the North Point Towers facilities manager also realized it was his easiest and most efficient option. The new design enabled him to configure the existing cooling tower and heat exchanger to provide free cooling during the winter, which drastically reduce the buildings’ energy costs across the board. An analysis of the overall KW-per-ton inside the central plant has already showed a significant reduction in energy use over a packaged equipment system.
The new system has also considerably reduced the ambient noise inside the towers, increasing tenant comfort and providing an even more professional environment.