Mechanical Systems Only in extremes of heat and humidity does the building require conventional air conditioning. When sensors determine that the outdoor climate is amenable, the mechanical system shuts down, motor-operated windows open, and signs tell employees they can open their windows to take advantage of the bay's cooling breezes. Photovoltaic panels produce a portion of the building's electricity, and solar hot-water heating reduces electricity demand. Approximately 30 percent of the building's energy load is provided through building-integrated or directly connected renewable energy sources. A closed-loop geothermal heat pump system relies on the constant temperature of the earth below the frost line.
Desiccant systems decrease humidity and greatly reduce energy demands on mechanical equipment.
Water systems One of the building's most prominent architectural features is its collection of massive cisterns that capture rainwater for everything but drinking, reducing by 90 percent the need to draw from wells and public water sources. Composting toilets are nonflushing units that recycle waste and greatly reduce the amount of water needed by an office building. The CBF staff has used composting toilets at various sites for 20 years, and they note that the quality of the compost is comparable to fine topsoil. The building was sited on the footprint of existing buildings so as not to increase existing impervious surface or site disturbance. Construction was not permitted to disturb untouched portions of the site.