Eco Station on East Jemez Road. Photo by James RobinsonIn July, I was reappointed to the Los Alamos County Environmental Sustainability Board by the County Council. Although this board is mainly known for the Plastic Bag Ban and the recent Wildlife Ordinance discussion, this board, and Los Alamos County Environmental Services, has done a lot of work to make Los Alamos more sustainable, and save our citizens money. It is a wonderful opportunity to work with your fellow citizens to answer the questions brought before us, and explore new ideas for the county to save money and energy.
However, one of greatest benefits to serve on a county board and commission is the information presented from areas all over Los Alamos. This last Thursday, the Environmental Sustainability Board received a wonderful presentation from Anthony Strain, Los Alamos County Projects Manager, about the Eco Station’s Night Sky Radiant Cooling (NSRC) technology.
Anyone who has been to the Eco Center (each resident receives 12 free trips annually) will notice that there are five black panels on the south side of the building. What you might not know is that there are also solar panels on the roof of the Eco Center, and together, these panels form an award-winning system from Solar Logic that helps the Eco Center HVAC system maintain a comfortable temperature.
Mr. Strain explained that in the winter, the primary-loop piping configuration of this system allows solar heat to be delivered directly to the concrete radiant heated floors, bypassing the domestic hot water tank. It can also deliver heat to the water tank while bypassing the floors or it can do both heating jobs simultaneously. In this type of standard plumbing configuration, the heat delivery is controlled simply by turning hydronic circulator pumps on or off.
The heating decisions are made by the Solar Logic Integrated Controller (SLIC) based on the temperatures available and the priority settings for the heating jobs that are calling for heat. Two stage room thermostats are used to establish priority in the different space heating zones.
When you compare the heat-energy delivered, to the pump-energy consumed, you can calculate an equivalent Coefficient of Performance (COP), which is an interesting way to compare the efficiency of the solar heating system. In this case, on a typical day in December, if the solar pumping system runs for 5 hours per day, and delivers 167,000 BTUs/Day, the COP can be estimated at just over 47.
In other words, for every unit of energy it takes to run the circulators for solar heat, 47 units of useful heat energy are delivered to the building. This is a very high-performing “heat pump” indeed. The NSRC panels on this building are flush-mounted on a nearly-flat roof. There are 12 flat-plate panels connected together as one bank, for a total of 576 square feet of surface area. These are unglazed, copper finned-tube panels.
The horizontal tilt allows the panels to have a clear view of the night sky, so that heat may radiate from the surface of these metal plates to the cold night sky in a direct and unobstructed straight line. On a clear night in the summer, the metal plates will lose heat rapidly by radiation to the cold sky so that the surface temperature of the panels will drop below the surrounding air temperature. These panels are used as a source of cooling for the hydronic fluid in the building. During summer evenings, the cool hydronic fluid is pumped through the concrete floors, which pre-cools them in advance of the next day.
This system was put into service in 2012 after the original system was damaged in a severe hail storm. Since then, the system has operated almost error free. The system can also be monitored and updated remotely through web based software. The public is always welcome to tour the system, if you are interested please call Los Alamos County Environmental Services, 505.662.8163.
This is just one of the many benefits of serving on a local board, and I encourage everyone to consider applying for a LAC Board and Commission.