One major goal of the Commons is for the students to manage the building toward net zero energy use.  Living Building is an upper school elective course in which students look at data about energy use in the Commons and work with community members to be more energy efficient.  This past Thursday, the new crew of Living Building members were learning how to use the commons website.  During our lesson, we learned that on Wednesday September 16th, the net energy use in the Commons was -23 kWh.  This means that we generated 23 more kilowatts of energy in the solar panels than the energy we consumed in the building.  We were doing better than net zero!  The graph below is a graph of power, which represents energy per time.  Notice net power, the black line, is below zero for almost the whole school day!

Another interesting point of data to note during this warm September is the range of temperature in the solar chimneys. The solar chimneys are located on both ends of the south-facing greenhouse windows. They have photovoltaic glass which captures the solar energy from the sun. In addition to capturing the energy, the panels also serve to direct the heat from the sun to the air within the chimneys. This raises the temperature significantly so that we can then vent the heated air to the various rooms in the Commons to passively control the temperature without having to engage the HVAC system. Choosing how and where to release the heated air (directly into a room to raise the temperature, or vented out the top of the chimney, thereby drawing other hot air out of a warm room via the vent, to cool a room) is an ongoing experiment! Take a look at the graph below to see how warm the air gets on a full-sun day—150 degrees!