Designing and constructing buildings to high standards is an obvious big step toward achieving energy efficiency. But there’s a new report [PDF] out that shows the important role that analyzing and monitoring systems can play in saving energy and money.
It’s all a matter of reigning in what the experts call “operational stray” – those instances when a building’s energy systems deviate from their optimal performance.
The study that delivered these insights was undertaken by the Natural Resources Defense Council’s Center for Market Innovation at what are described as “three large, multitenant office buildings” in Washington, D.C., owned by the Tower Companies.
The initiatives undertaken – without new construction, disruption to the operating buildings, or a lot of capital investment – cut electricity use in the three buildings by 13.2 percent. One of the three buildings went from using 1,965,135 kilowatt-hours of electricity in 2011 to using 1,516,274 kWh in 2012, a savings worth $58,352.
What sort of “stray” was identified to make these savings? One example given was a case of two chillers in one of the buildings cycling on and off for short periods, the result of faulty variable-air-volume controls. This problem showed up as an “unusual pattern” in an analysis of the building, and was quickly remedied.
Another example: Regularly checking to be sure that buildings were honoring “deadband” settings. As the report explained:
This means the heating, ventilation, and air-conditioning (HVAC) would cool the building to, say, 72 degrees, then remain off until the temperature rose to 76 degrees. A larger deadband allows the HVAC system to remain off while the building is in the “comfort zone,” resulting in energy savings and reduced wear and tear on equipment.
Another large component to the program was engaging a service that would monitor system settings and provide alarms – direct messages to building engineers – if system conditions weren’t within the desired parameters.
These services cost money to set up, about $21,233 per building, and would entail recurring costs of about the same amount every year. But that was more than offset by the savings, with a net payoff of $74,000 bewteen the three buildings. And as the NRDC’s Philip Henderson blogged:
These amounts probably understate the actual savings. The implemented measures will likely save energy beyond the study period we measured. And Tower expects reduced maintenance expenses – that is, preventing a chiller from turning-on at night when it should stay off will lengthen the life of this expensive equipment, and running fans at lower speeds will reduce wear and tear on the machinery.