Plate and Frame Heat Exchanger to Help with Winter Cooling Load
General Services Administration
Public Buildings Service National Capital Region
National Building Museum
“GSA helps National Building Museum target energy savings and emissions reductions – important GSA goals.”
In late 2004, the staff of the National Buildings Museum and GSA’s James Watson, Program Analyst, Metropolitan Service Center, identified a potential project to install a Plate and Frame Heat Exchanger (P&F HE) that would provide free cooling for the NBM’s winter cooling load of 160 tons. The use of the new heat exchanger would allow the existing 160 ton Dunham-Bush chiller to be shut off during the winter months of November through April and thereby contribute to energy savings and related emissions reductions, both important GSA goals.
The “free cooling” system benefits the government through not only the operating cost savings but also from reducing operating hours on the chiller and extending the useful life of the existing chiller.
GSA received an initial proposal in March 2005 from Washington Gas to provide a design-build project to construct a plate and frame heat exchanger for the National Buildings Museum. The project was prepared as an energy conservation proposal using the GSA Area Wide Public Utilities Contract no. GS-OOP-96-BSD-0029.
Washington Gas submitted a quote on December 15, 2005 in response to GSA’s Request for Quotation on November 17, 2005 of $95,097. At GSA’s request Washington Gas submitted a revised quote on January 23, 2006 of $91,455, a reduction of $3,642. The project was awarded to Washington Gas Energy Systems on February 22, 2006.
Based on the revised quote the P&F HE would have a simple payback of 3.23 years. This is derived from an estimated annual operating cost savings of $28,308 and an annual 329,165 kwh of electricity saved. This estimate assumes an electric cost of $0.086 per kwh. Several other assumptions are explained in the quantitative analysis section.
A project kick-off meeting was held March 21, 2006 and construction started April 24, 2006. Construction was completed by the end of June and a training session was held with GSA staff and the NBM O&M contractor’s staff on July 18, 2006.
The P&F HE will be operated with existing chilled water and existing condenser water pumps with capacities that match the chiller flow rates. The “free cooling” system is arranged for manual operation with the capability for future incorporation into the existing building energy management system to achieve automated operation.
Contact:
James R. Watson, Jr., Program Analyst
General Services Administration
Metropolitan Service Center (WPD)
james.watson@gsa.gov
