From our limited analysis, the use of one central cooling coil was determined to be the best cooling coil option. Determination of the proper size for the central cooling coil was influenced by several parameters. A cooling coil must be designed such that the face velocity does not exceed approximately 550 feet per minute with a maximum fin density of 11 fins per inch to avoid moisture carry over into the supply air. Also, the coil size was kept as small as possible to minimize first cost. A Greenheck coil sizing calculator was used to size different iterations of coils. The final design choice had a face area of 83.3 ft2 with a face velocity of 500 fpm and an overall size of 8’ x 10’. Design details as well as sample hand calculations are shown in Appendix H. The coil has a built in drain pan and can be drained into an existing floor drain in the adjacent room. The proposed locations for the central coil, chiller and chilled water piping are shown in Appendix D. To regulate zone temperatures using the central coil, a return and supply fan VFD and variable speed motors are recommended as well as automatic zone control dampers. This retrofit equipment will not only provide an energy efficient means of regulating the mechanical cooling but will improve energy efficiency of the mechanical system year-round. As energy saving measures, the VFD with motors and the zone dampers qualify for ETO incentives. ETO requires that measures be assessed individually for qualification of incentives. The payback analysis of these measures (see Table 10) showed a payback of 11.3 years for the VFD and 3.1 years for the zone dampers. With a payback of over 10 years, the VFD would not qualify for an incentive. ETO might consider these items as one system since they are interdependent which would allow both to qualify. Phase 4: Complete DDC Conversion This phase is an upgrade from Phase 2. Rather than having a hybrid control system using EPT, all the pneumatic controls and actuators will be replaced with a complete digital package. This full conversion will improve system control and reduce maintenance costs associated with a
From our limited analysis, the use of one central cooling coil was determined to be the best cooling coil option. Determination of the proper size for the central cooling coil was influenced by several parameters. A cooling coil must be designed such that the face velocity does not exceed approximately 550 feet per minute with a maximum fin density of 11 fins per inch to avoid moisture carry over into the supply air. Also, the coil size was kept as small as possible to minimize first cost. A Greenheck coil sizing calculator was used to size different iterations of coils. The final design choice had a face area of 83.3 ft2 with a face velocity of 500 fpm and an overall size of 8’ x 10’. Design details as well as sample hand calculations are shown in Appendix H. The coil has a built in drain pan and can be drained into an existing floor drain in the adjacent room. The proposed locations for the central coil, chiller and chilled water piping are shown in Appendix D. To regulate zone temperatures using the central coil, a return and supply fan VFD and variable speed motors are recommended as well as automatic zone control dampers. This retrofit equipment will not only provide an energy efficient means of regulating the mechanical cooling but will improve energy efficiency of the mechanical system year-round. As energy saving measures, the VFD with motors and the zone dampers qualify for ETO incentives. ETO requires that measures be assessed individually for qualification of incentives. The payback analysis of these measures (see Table 10) showed a payback of 11.3 years for the VFD and 3.1 years for the zone dampers. With a payback of over 10 years, the VFD would not qualify for an incentive. ETO might consider these items as one system since they are interdependent which would allow both to qualify. Phase 4: Complete DDC Conversion This phase is an upgrade from Phase 2. Rather than having a hybrid control system using EPT, all the pneumatic controls and actuators will be replaced with a complete digital package. This full conversion will improve system control and reduce maintenance costs associated with a
MTANGEL_FINALREPORT.docx