但in one corner of the project, construction workers are also doing something else: drilling hundreds of deep wells in a muddy pit that will eventually be covered by grass and trees.
The hidden wells will be the foundation of a large system that heats and cools the new buildings with an untraditional clean energy source: the constant temperature below the earth’s surface. Tunneling 550 feet into the ground — almost the height of the Space Needle in nearby Seattle — the wells will compose one of the largest “geoexchange” fields in the United States to harness the earth’s thermal energy. They will also be a big part of Microsoft’s ambitious goals to help the planet.
“We knew we wanted our new campus to be zero-carbon in its daily operations,” says Katie Ross, global sustainability lead for Microsoft real estate. “So we had to think outside the box on how to provide heating and cooling needs for these buildings. That’s really what drove us to geoexchange technology.”
称为热能中心，集中式和几乎完全碳系统不是初始计划的一部分campus modernization, which is redeveloping a fraction of Microsoft’s 520-acre headquarters over the next few years. The design had originally called for more typical individual utility units, powered by natural gas, for each new building.
“What I love about working in sustainability at Microsoft and on this project is that it’s like that improv comedy game ‘Yes, and,’” Ross says.
“When we decided to install a central system, it was ‘Yes, and we’re going to have it be electric.’ Then it was, ‘Yes, and we’re going to have geoexchange wells.’ And ‘Yes, and we’re going to put solar panels on the roof and we’re going make the center a feature that people can learn about on campus.’ That thinking really inspires me, because we’re always challenging ourselves to think differently and innovate.”
The process led to the current design for a 2.5-acre field of 875 geowells. More than 220 miles of piping will distribute 300,000 gallons of water as a heat-exchange medium across the wells and the new campus in a closed loop system. The three-story Thermal Energy Center will house enormous chillers, cooling towers, back-up generators, solar panels and 65-foot tanks that can store 280,000 gallons of the water as thermal energy. The entire system will run on renewable electricity except for the generators, which will use a negligible amount of energy and only during emergencies and scheduled maintenance.
“威廉希尔体育官网微软对2030年的碳负债具有非常强大的承诺，以及他们在日常行动中消除化石燃料使用的中央工厂的投资是这一校园项目最具创新性的品质之一，”环境设计Brian Meinrath说顾问atelier十, the sustainability consultant firm for the campus modernization project. “The plant has also been designed to be particularly water efficient.” He added that the large size of the geofield is unusual.
Geoexchange systems take advantage of the temperature difference between sub-ground soil, which remains constant year-round, and that of ambient air, which changes with the seasons. When air is colder than the ground in winter, pumps circulate fluid through looped pipes to transfer ground heat into buildings. When air is warmer than the ground in summer, the process reverses. Used for decades, geoexchange is more common in small projects like houses and on the U.S. East Coast, where extreme seasonal changes like scorching summers and sub-zero winters make the technology more cost-effective. But geoexchange is still much less common than traditional air conditioners and gas- and oil-fueled boilers and furnaces.
The work will play a key role in supporting Microsoft’s sustainability goals for carbon and water. In 2020, the company announced it will be碳负数为2030and by 2050 remove from the environment all the carbon it has emitted directly or by electrical consumption since its founding in 1975. It also announced it will bewater positive by 2030, which means it will replenish more water than it uses. The company said it will reduce water use intensity in its operations and replenish water back into basins that need it most.
When the newly redeveloped section of the campus opens, a grassy sports field and a dense canopy of trees will cover the geofield. But the nearby Thermal Energy Center — nicknamed a “machine in the woods”— will feature a see-through porch and façade so people can see and learn about the equipment.
“The building is not only a commitment to sustainability, but an opportunity to show employees and customers how we think about sustainability and how things work,” Ross says.
“我一直在建造我整个40多年的职业生涯，从来没有这样做过具有如此致力于温电能力等环境的项目，”建筑系统总监绿色说OAC., a construction and project management firm.
“To reduce energy and water use and eliminate carbon emissions in daily operations is a statement,” he says. “It’s the way of the future.”
Lead image: Architectural rendering of the Thermal Energy Center (image courtesy of NBBJ)
This story was published on March 16, 2021.