The buildings in this list were not complete with only a solar array on their roofs. These structures were designed and built to incorporate nearly every technology of green building. Denis Hayes, President of the Bullitt Foundation, says, “Our chief innovation is that we brought all these ideas together in one place at the same time.” The meticulous design manages water, energy and light to make the buildings with the least environmental impact coupled with a positive impact on the people who use the space.
The greenest and most energy-efficient commercial building in the U.S. is the Bullitt Center in Seattle, Washington. The website proclaims:
The Bullitt Center was designed to show what’s possible today, changing the way people think about high performance green building.
The Bullitt Center contains 17 unique features working in harmony towards sustainability. These include;
- Radiant Heating
- Walk-able Neighborhood
- Solar Panels
- Computerized Systems
- Waterless Toilets
- Composting Toilets
- Grey-water Treatment
- Rainwater Catchment
- Regenerative Elevator
- Geothermal System
- “Irresistible Stairway”
- Heavy Timber Structure
- Constructed Wetlands
- Solar Array
- Exterior Blinds
- Bike-friendly Design
- Heat Recovery
Grouping these technologies into broader segments, the Bullitt Center uses smart technology to make heating, cooling, energy and water efficient while encouraging the tenants to live a more active, car-free life.
Heating and Cooling
Seeking to use the most energy-efficient method of heating and cooling, the center relies on radiant heating and cooling. The radiant system uses “cross-linked polyethylene” PEX under concrete flooring with a unique mix of water and glycol pumped through to rapidly heat and cool floor in winter and summer, respectively.
400 feet below the surface, the heating of the Bullitt Center begins with 26 geothermal wells. The geothermal heat sink system uses the surrounding constant ground temperature of 53 degrees Fahrenheit. The ground source heat pump also uses a water glycol mixture to rapidly dissipate heat or cold to the surrounding ground. During the heating process, the mixture reaches the mechanical room and is heated up to 90 degrees to pump through the building.
The heat sink field rests below the west side of the building. The site was chosen because the location contains a constant lens of ground water slowly draining into the Puget Sound, resulting in minimizing the heat pollution by dissipating the heat within 12 inches of the surface.
The impact on the tenants also drew consideration. The considerations center on promoting active lifestyles. The location of the site received careful thought with the determination it must be easily accessible by foot, bike or public transit. The center included on-site bike parking, showers and locker rooms to promote active transportation.
Achieving a building with an energy rating of net zero also drove the designers in building the Bullitt Center. Seattle does not boast the most friendly climate for solar energy. Yet designers were able to generate more energy than the center can use. A building determined to achieve status as a Living Building, requires the structure to produce as much energy as it uses through the year. To achieve this, the Bullitt Center uses a total of 575 solar panels for their solar array.
The amount of energy produced from the solar array during summer far exceeds the needs of a building. The excess power is sent into Seattle’s power grid. During the winter months, the building must draw power from the grid to meet the needs of operation. In order to achieve a “net zero energy” rating, the structure must produce more energy though out the year than it must draw during the entire year.
Another major consideration was on the collection, disposal and efficient use of water. The Bullitt Center is the first multi-story building to use composing toilet systems. A solution to getting human waste from the top floors down to the compost tanks arrives by the toilet emitting a foam-like substance. Since the compost system isn’t hooked up to methane producing the sewage system, the trap, or the ‘s’ section of pipe, isn’t required. Users however must be careful as a dropped wedding ring or cell phone will plummet straight to the composting tanks.
Once the cargo makes it down into the composting basement, it is held in a tank the size of a Fiat 500 and mixed with wood chips to ensure slow healthy decomposition into compost. The compost requires an adequate source of oxygen, which is sucked down the same toilet pipes the cargo arrives from. Another requirement is a precise mixture of liquids. Excess liquid is pumped into a holding tank and sent off site. The solid waste, after two years, makes its way off site to mix with saw dust and become fertilizer.
Finally the grey-water (water from sinks and showers) is piped into a maintained wetland where wetland plants absorb and process contaminates before the water returns to the water system.
Tying all these various technologies and processes together is an integrated Building Management System (BMS) which coordinates the heating and cooling, passive and mechanical ventilation and lighting systems. The main control room houses all monitoring equipment facilitating a person to monitor the efficiency of the building. The system is capable of opening the windows to promote ventilation, deploying the exterior blinds at the optimal angle for UV shielding. Finally, the system can enter a closed heating system, which shuts all windows and starts the geothermal heat sink all on its own.
Author: Kevin Vanderheiden
For more information about the Bullitt Center, please visit http://www.bullittcenter.org/building/building-features/active-design/.