Skip to main content Skip to main content
 

Air to Air Heat Recovery

William J. Howenstein, P.E., LEED® AP, CUH2A Architecture Engineering Planning

This presentation will provide an overview of the analysis performed to select the heat pipe air to air heat recovery system which serves the Georgia Tech Molecular Science and Engineering Building (MS&E). This presentation will also include an in depth look at the components and system operation of the heat pipe system installed at this facility. Photo's of the installation will be included.

MS&E is a 272,000 sq. ft. research facility which combines researchers from five major science and engineering departments at Georgia Tech. This facility has four 78,000 cubic ft./minute laboratory air handling units which are 100 percent outside air units. There were three types of air to air heat recovery systems investigated for this project. These included the rotary enthalpy wheel, the coil energy recovery loop (run-around loop) and the heat pipe. A Bin Data Analysis was performed to determine the annual estimated energy savings. System first cost, simple payback period, annual operating cost, and maintenance were also considered.

Laboratory facilities are know to be very high energy users, but unfortunately incorporating heat recovery systems into these types of facilities can be quite challenging. One major challenge is that separation between the supply and exhaust air handling systems is desirable in laboratory buildings to prevent entrainment of laboratory exhaust air into fresh air intakes. This quite often makes it difficult to use the rotary enthalpy wheel or heat pipe heat recovery systems since they require that the supply and exhaust air streams be in close proximity. This leaves the run-around loop heat recovery system, which unfortunately is the least efficient of the three and due to its low efficiency is generally only effective in colder climates.

The heat pipe heat recovery system used on this project is different from the more conventional heat pipe systems in that it has pumps that pump refrigerant through pipes which connect the heat recovery coils located in the supply and exhaust air streams. Although it is generally difficult to get a good payback on air to air heat recovery systems in mild climates such as Atlanta, Georgia, this system had a simple payback of approximately 7.2 years. Considering the amount of outside air (312,000 cfm) that is heated and cooled annually in this facility, Georgia Tech was very happy with the results.

Labs21 Connection:

Our approach to energy recovery on this project is unique in that this is the largest heat pipe heat recovery system ever installed in which refrigerant is pumped between heat recovery coils located in the supply and exhaust air streams. Heat pipe systems, although very efficient air-to-air heat recovery systems, have traditionally been designed with the supply and return air streams side by side. On this project, buy using refrigerant pumps, we were able to locate the supply air stream heat recovery coils in the penthouse mechanical room and the exhaust air stream heat recovery coils on the roof. Due to this fairly new design concept, we were able to incorporate heat recovery into the architecture of this project.

This presentation will reflect the principles of the Labs21 Approach to laboratory design by demonstrating that through innovation, a significant laboratory facility was designed and built with a very efficient air-to-air heat recovery system. (A 7.2 year payback period is very good for an air to air heat recovery system in a mild climate.)

This presentation will also reflect the principles of the Labs21 Approach to laboratory design in that sensors, controls and software have been put in place to track the performance of these systems so that the actual energy savings can be realized. Verification of the projected energy savings for these systems will probably lead to multiple future installations of this type of system on the Georgia Tech campus and lead to the incorporation of this type of heat recovery system on future CUH2A projects.

Biography:

William J. Howenstein has over 24 years experience in the mechanical engineering design field. His responsibilities have included: feasibility studies, establishment of project schedules and budgets, management of project budgets, project management, design of heating ventilating and air conditioning systems, preparation of specifications, code review, life cycle cost analysis, technical quality control reviews, cost estimating, and value engineering. His representative project experience includes laboratory experience in:

  • U.S. Centers for Disease Control and Prevention NCID/DVBID Replacement Laboratory, Fort Collins, CO.
  • U.S. Centers for Disease Control and Prevention Building 18 - Emerging Infectious Diseases Laboratory, Atlanta, GA.
  • Georgia Institute of Technology Molecular Science and Engineering Building (MSE), Atlanta, GA.
  • Georgia Institute of Technology Civil Engineering Laboratory, Atlanta, GA.
  • Bowdoin College, Brunswick, MI.
  • Kimberly Clark, Roswell, GA.

Back to the Agenda

EPA Home | OARM Home | DOE Home | FEMP Home


This page is no longer updated.
EPA gave I2SL permission to house this page as a historic record of the Labs21 Annual Conference.