“Negawatts:” A win-win for the Bullitt Center and Seattle
Under The Bullitt Foundation’s innovative arrangement with Seattle City Light (SCL) the Foundation compares the energy use of the Bullitt Center (the world’s largest commercial Living Building) with the energy use of a new office building, built to code with similar tenants. SCL pays The Bullitt Foundation each month for the metered, saved kilowatt-hours or as Amory Lovins, co-founder of the Rocky Mountain Institute, coined them “negawatts.”
As you can see from the graphic above, as the summer temperatures rose, other office buildings turned on their air conditioning and paid for it. The Bullitt Center was kept comfortable with automatic external shading, natural ventilation and night flushing, and radiant floors (used only on the hottest days). According Denis Hayes, President of the Bullitt Foundation, “We ‘sailed’ it, taking full advantage of the environmental conditions instead of fighting them.”
Instead of contributing to peak energy demands on SCL, the Center’s energy use was low and steady. Additionally, the long and sunny summer days allowed the 242kW rooftop solar array to produce at a very high rate, contributing a surplus of energy to help SCL meet its peak summer demands.
So far the arrangement is a win-win. The Bullitt Foundation earns money off of clean energy while simultaneously saving Seattle City Light, and its consumers, money by contributing to available energy and keeping SCL from having to purchase peak natural gas generation.