The EcoCenter is an example of an “off-the-grid” building—the first one in San Francisco as a matter of fact. This means that the building is not connected to the electrical power grid maintained by our local energy utility; all of the equipment, electrical outlets, lights, appliances etc., are powered by renewable energy harnessed onsite. The EcoCenter is, in essence, an energy independent structure—we’ve NEVER received an electric bill! And as you can see from the figures at the top of this webpage, we produce on average more energy than we consume—on average about 2 kilowatt-hours (kWh) more each day.
The way this is achieved is through the capture and storage of energy from the sun. Solar photovoltaic panels are installed on the roof of the EcoCenter. When they are exposed to sunlight, an electrical current is generated and flows into a battery storage bank, consisting of 16 lead-acid batteries. Electricity then flows into the building where it is converted from DC to AC current and is consumed as needed. Since the sun doesn’t shine 24 hours a day and the skies aren’t always clear, having a method to store the electricity produced is a must given that we are “off-the-grid”.
Harvesting and storing electrical energy are not the only sustainable features of the energy systems at the EcoCenter. The design and orientation of the building structure along with materials choices are passive solar strategies that have been employed to reduce the need to consume energy. Our south facing “wall of windows” (called a Trombe wall) and the thermal mass properties of the concrete floor help keep the building cool when it’s warm out and warm when it’s cold. Other sustainable design features include daylighting. As the name implies, this is the use of windows and skylights to bring natural light into a building thus reducing the need for artificial light. In fact, we almost NEVER turn on the lights during the day. The lighting fixtures in place all use highly energy efficient LEDs (light emitting diodes). Even the appliances are energy efficient. Other structural features of the EcoCenter that are part of the energy system are its exterior walls and rooftop. They are made of Structural Insulated Panels, known as SIPs. Along with the living roof, the SIPS serve to insulate the building interior.
Another solar energy strategy in place but not yet complete is a radiant floor heating system. One day soon we will install solar thermal panels on the rooftop to use the sun’s energy to heat the building and the water we use.
As you can see, there is quite a lot going on regarding the EcoCenter’s energy systems. If this general introduction has piqued your interest, please use the subpages listed below (to be developed) and the hyperlinks (more to be added) in the text to learn more about the specific components, the science and logic behind them, and renewable energy in general.