Landmark Square is a 7-building office complex located in Stamford CT which totals over 1 million square feet. The 7 buildings each have separate HVAC systems and utility meters both electric and gas. Part of Dynamic’s responsibility for this property owner was to evaluate operating cost and make recommendations to lower those costs. Three of these buildings had unusually high gas consumption. Since these buildings were served by closed-loop heat pump systems, high gas consumption jumped out.
The systems included water-source heat pumps, boilers, fluid coolers and a piping system connecting all the components together. After performing heat loss calculations, it became apparent that the heat pumps were sized correctly meaning there was a good heat balance in the systems. So, why was the gas consumption so high? What could account for such heat loss?
Dynamic’s attention turned to the cooling towers on the buildings with high gas consumption. They were closed-loop fluid coolers. The water circulated through the heat pumps and boilers also passed through these coolers with no heat exchangers. Examining the fluid cooler manufacturers published data it became apparent that the heat loss, even with damper control, was almost equal to the heat required to keep the system loop temperature at design temperature.
Dynamic redesigned the heat rejection system using new cooling towers and heat exchangers to keep heat loss to a minimum. There were several challenges to this project. Three buildings that were nearly 100% occupied, systems that could not be shut down for extended periods of time and a site that included underground parking garage that could not support the weight of crane large enough for the rig the new equipment.
The only viable solution was a helicopter rig. Dynamic had performed numerous helicopter rigs but the difference this time was the weight. The project required the use of the largest non-military helicopter in the country. Erickson Skycrane uses a custom designed helicopter capable of lifting 25,000 lbs. The weight of the new cooling towers was not the problem but estimating the weight of the old coolers was difficult. Accounting for the cooler and the decades of sediment and scale in the tubes we estimated the weight at 21,000 lbs each. The project was a go. After considerable planning and pre-fabrication of piping, we chose the 4-day Thanksgiving weekend.
Days of planning with the City of Stamford, Stamford Fire and Rescue, the FAA, Dynamic was cleared to commence. Dynamic had to apply tape across storefront glass for two blocks around the staging site. The rotor wash from the helicopter with two 4,800 horsepower engines was considerable. The old equipment was removed and the new equipment was put into place by 2pm Thanksgiving Day. Then, working around the clock, the buildings were back on line late Sunday evening.
Dynamic is proud of this accomplishment and proud of the men and women that made it happen.