When Seattle-based SMACNA contractor McKinstry recently got into hot water, the company was not in trouble. Rather, it was undertaking an innovative “green” project that saves enough energy annually to keep 365 Seattle homes warm or 80 million kilowatt hours of energy over the next 25 years.
“It’s a one-of-a-kind waste-heat recovery system,” said McKinstry’s Chief Market Officer Ash Awad.
The project started with formation of “Eco District,” a collaboration between McKinstry and Clise Properties, owner of the Westin Building Exchange. The Westin building is a 34-story, regional telecommunications hub in downtown Seattle that consumes 11 megawatts of electricity.
Eco District is a “micro-utility” designed to export up to 5 megawatts of waste heat from the Westin building to warm 4 million square feet of office space at the Amazon.com campus across the street.
“For the Amazon buildings, the Westin building is functionally equivalent to 36 miles of drilled and filled ground-coupled hydronic loop,” said McKinstry engineer Adam Myers. “So the mission-critical data center is a very powerful and reliable boiler. Meanwhile, to the Westin, the Amazon campus functionally equivalent to a very large cooling tower.”
A hydronic system removes excess heat from the Westin building. Heat moves through the data center as warm water though pipes. Amazon’s heat pumps transfer this thermal energy to Amazon’s heating systems, thereby cooling the data center. Whenever Amazon’s buildings need heat, a signal turns on two Eco District pumps.
The water is then pumped through a heat exchanger—as big as a refrigerator—that transfers the heat from the Westin building’s water to water that is pumped in from the Amazon campus. The newly-warmed water raises temperatures on the Amazon campus via a radiant floor system, while the newly-cooled water cools the Westin data center again. (When Amazon doesn’t need heat, Westin’s own cooling towers speed up again.)
McKinstry used welded stainless plate for the high pressure multiple circuit heat exchanger, welded black steel 10- and 8-inch pipe indoors, and PVC pipe underground between the buildings.
Because the mechanical room was very small and electrical systems in the basement were extensive, the contractor had to build a 3D model to determine the appropriate piping “spool piece” size to carry into the building, fit down the elevator shaft, and meet elevator load restrictions.
McKinstry then pre-fabricated the project in its Seattle shop and delivered the 10,000-pound heat exchanger in five pieces, accompanied by custom-made carts.
Besides the partnership with Clise, McKinstry had to work closely with several of Seattle’s city departments. The city allowed Amazon and Eco District to put heat-conveyance utilities in public rights of way below several streets.
Photos courtesy of McKinstry.