We recommended 28 ECM and O&M projects for the Rayburn House Office Building. The estimated cost to implement the recommended projects was $17.6 million with an associated savings of $2.4 million annually. 41% of the estimated construction cost, and 33% of the annual savings were attributed to the replacement of the pneumatic HVAC controls with Direct Digital Controls (DDC). This ECM included replacing the controls on 28 air handling units that contributed to a significant amount of cooling and reheating.

Rayburn is currently using three-way control valves on the air handling units and constant speed hot water pumps. A project was underway to replace the existing pumps and install new pumps with VFDs. We recommended replacing the existing, uninsulated three-way valves with two-way valves to repair leaks. This modification allowed the pumps to modulate system flow as the two-way valves closed, resulting in pumping savings and a payback of 1.2 years. Located at the most remote point in the system, one three-way valve would need to remain in place to prevent “starving” AHUs of water. One alternative to the two-way valve replacement included installing bypasses at the three-way valves. The closed bypass would allow the existing three-way valve to act as a two-way valve, and the proposed ECM savings would be augmented even further.