Thanks to its SunPower solar photovoltaic array and other green design choices, the Bullitt Center is the most energy-efficient office building in the U.S.
In the cloudy northwest corner of the United States, the Bullitt Center is changing the way people think about what solar power and sustainable building can accomplish. Called the “greenest commercial building in the world,” the project was created to influence the way people design, build and operate commercial real estate.
The 52,000-square-foot, multi-tenant office building, constructed in 2012, features a 242-kilowatt solar photovoltaic (PV) array to provide the structure’s annual energy needs. More impressively, the building is in Seattle, a city known for gray, rainy days and inconsistent sunshine.
Energy Use Intensity (EUI) is a common green building measurement used to describe the amount of energy a building uses annually relative to its square footage. While the projected energy budget of the Bullitt Center shaped all aspects of its design — with an expected EUI of 16 kBtu per square foot per year — in reality, the building is exceeding all projections. In 2014, the Bullitt Center produced 60 percent more electricity than it used, achieving an EUI of 9.4, which is a 90 percent reduction from the average office building in Seattle. Because tenant occupancy was still increasing during that time period (the building is now 100 percent leased), the owners expect the Bullitt Center will typically operate with an EUI of 12. This makes it the most energy-efficient office building in the United States by a wide margin, as the national median for office buildings is an EUI of 67.
The 14,000-square-foot PV array features 575 SunPower panels, which were the most efficient available at the time of purchase. While the solar panels are operating as expected, the building itself is performing beyond expectations. Because so many systems are optimized in the building — from a geothermal boost for the hydronic heating and cooling system to ultra-efficient windows with exterior automated blinds — tenant plug loads, which refers to the sum of energy used by anything plugged into an outlet, are a critical variable in energy performance. Luckily, occupants have embraced the project goals and have been able to work comfortably within the recommended energy budgets to help the project succeed.
With the Bullitt Center operating as a net-positive-energy office building in cloudy Seattle, some have wondered, “What’s up, Phoenix?” and are asking the same about virtually every other major city in the United States. Learn more about the Bullitt Center online.