Walking the Talk at Work: A Seattle Firm Tries Green Tags
Miller|Hull Partnership Offsets CO2 Emissions

by Ron Rochon, AIA
Miller|Hull Partnership

Summary: Starting in August 2006, the Miller|Hull Partnership in Seattle entered into a three-year contract with the Bonneville Environmental Foundation to purchase Green Tags to support alternative energy initiatives that offset the carbon dioxide emissions produced by their business practices. Miller|Hull has long been a leader in sustainable design and is taking the lead on encouraging sustainable business practices.

According to the Bonneville Environmental Foundation, “Green Tags” represent the environmental attributes associated with electricity generation from new renewable technologies like wind and solar energy. By purchasing Green Tags based on one’s non-renewable energy use—chiefly coal or gas—a firm helps move us all to new wind, solar, and other renewable electricity sources. The Bonneville Environmental Foundation applies the net revenues realized by selling Green Tags to develop the next generation of renewable energy facilities. Miller|Hull focused its carbon reduction effort in three areas: office electricity use, automobile use, and air travel. The following is a description of how we calculated our impact in those areas.

Office Space
Miller|Hull leases a 15,000-square-foot office with electric heat. To estimate our yearly electrical consumption, we used the U.S. Environmental Protection Agency’s national average energy intensity for office space, which is 16.5 kWh per square foot annually. 15,000 x 16.5 = 247,500 kWh annually. Because each Green Tag equals the greenhouse gas reduction from generating 1,000 kWhs of electricity from a new renewable energy resource, or 1,400 pounds of greenhouse gas displaced, Miller|Hull will be able to offset 520 tons of CO2 emissions over the next three years.

Automobile Travel
Miller|Hull’s five cars average 23 miles per gallon, with each driven some 12,000 miles annually. Five cars x 12,000 = 60,000 miles annually x 23 mpg = 2,608.70 gallons of gasoline consumed. According to the U.S. Department of Energy (DOE) and Energy Information Administration (EIA), one gallon causes 19.564 pounds of CO2 emissions. 2,608.70 x 19.564 = 51,036.61 lbs of CO2 emissions annually. Eliminating this would result in a reduction of 76.5 tons of CO2 emissions over three years.

Air Travel
Some 200,000 air miles are traveled by Miller|Hull staff annually. According to EIA, traveling one air mile results in 1.36 pounds of CO2 emissions. Burning a gallon of jet fuel produces 21.095 pounds of CO2. Each passenger mile creates 0.63 lbs. of CO2 (21.095 pounds/gallon divided by 33.4 passenger mpg). Air travel also creates significant non-CO2 greenhouse gas emissions. These are expressed as CO2 equivalents, or CO2e. The Climate Neutral Network states that the appropriate approach is to double the 0.63 pounds of CO2, with a result of 1.26 pounds CO2e per passenger mile (CO2 + non-CO2 greenhouse gasses). An additional 8 percent is added to cover emissions associated with upstream refining of jet fuel. The result: 1.36 pounds of CO2e created for each passenger mile traveled (1.26 + 8% = 1.36). 200,000 miles x 1.36 lbs of CO2e = 272,000 lbs of CO2e annually. This results in 408 tons of CO2 emissions over three years.

In total, Miller|Hull anticipates that it will be able to offset 1,005 tons of greenhouse gas emissions over the next three years, and we are dedicated to renewing that commitment into the foreseeable future.