EA - Pre-Conditioned Air

Innovation Preconditioned Air (PCA) Systems: Preconditioned Air (PCA) systems provide for cooling of the aircraft cabin while parked at the gate, and can offer PBB cooling. Alternatives for providing PCA include mobile ground based units, Central Plant systems (with or without thermal storage), and Point of Use (POU) Systems. Central plant systems typically are the most efficient over the facility life cycle, and providing thermal storage can significantly reduce chiller size and energy consumption, although they have a higher capital cost and greater interior space requirements. Central plant systems distribute a glycol water solution to air handling units mounted directly on each PBB. POU systems utilize self-contained direct expansion (DX) refrigeration package units that also mount directly to the PBB. POU systems typically have the lowest initial capital costs, but highest long term operation and maintenance costs. Mobile PCA units are typically only used at remote parking positions, or on a temporary basis in the event of an equipment failure at gate.

The Central PCA design provides an opportunity to significantly lower energy use and operating costs. Since PCA is considered “process equipment” and not part of the comfort cooling HVAC for the building, it is exempt from the Energy Compliance defined in the Florida Energy Code and ASHRAE 90.1-2010. We highly recommend that the base building design team consider submitting exceptional calculations for the energy savings between a Central PCA system and a Point-of-Use (POU) system under the LEED V4, Energy and Atmosphere or Innovation credits. This should be explored because the PCA will be coupled with the CEP, and if it is not pursued as an Energy Conservation Measure (ECM), it would otherwise dilute the total building energy savings. The expected energy use is half of the POU annually, which will comprise a healthy portion of the total building energy consumption. This system arrangement has (2) key ECM’s; 1. Using 42⁰F CHWS for 1st stage of cooling. This lowers the EWT into the PCA chillers from 60⁰F to 44⁰F. 2. Using 56⁰F CWR for the PCA Chiller Condenser Water Source. System Descriptions for Exceptional Calculations; 1.4.2 - ASHRAE 90.1 Section 6: HVAC (Air-Side) Include units for all relevant inputs Model Input Parameter / Energy Efficiency Measure Baseline Case Proposed Case Primary HVAC Type1 PC Air Unit PC Air Unit Unitary Cooling Capacity Ranges3 25-90 Tons 25-90 Tons Unitary Cooling Efficiency4 2.5 KW/Ton 0.75 KW/Ton Unitary Heating Capacity Ranges5 same as proposed TBD Fan System Operation VFD VFD Outdoor Air Design Min Ventilation7 100% OA 100% OA HVAC Air-side Economizer Cycle Y Y Economizer High-Limit Shutoff 40 DEG F 40 DEG F 3 | P a g e 1.4.3 - ASHRAE 90.1 Appendix G: HVAC (Water-side) Include units for all relevant inputs Model Input Parameter / Energy Efficiency Measure Baseline Case Proposed Case The Project Has District Heating (Y/N) N N The Project Has District Cooling (Y/N) N Y District Cooling Plant Efficiency - CHILLER KW/TON + PUMPS KW/TON + COOLING TOWER KW/TON ESTIMATED = 0.9 KW/TON District Cooling Plant PCA Capacity - 600 TONS PCA Plant - Number of Chillers - 3 PCA Chiller Part-Load Controls1 - VFD PCA Chiller Capacity (Per Chiller) - 300 TONS PCA Chiller Efficiency2 - 0.58 KW/TON PCA Glycol Water Loop Supply Temperature - 20 DEG F PCA Glycol Water (CHW) Loop Delta-T - 40 DEG F PCA GS Loop Temp Reset Parameters TBD. EXAMPLE: OAT<40 DEG F, GST = 28 DEG F. PCA Glycol Loop Configuration3 VARIABLE PRIMARY Number of Primary CHW Pumps 3 Primary CHW Pump Power 75 HP Primary CHW Pump Flow 324 GPM Primary CHW Pump Speed Control VFD Condenser Water Leaving Temperature 66 DEG F Condenser Water (CW) Loop Delta-T 10 CW Loop Temp Reset Parameters - Number of CW Pumps 3 CW Pump Power 25 HP CW Pump Flow 922 CW Pump Speed Control CV PEAK DESIGN DAY LOAD PROFILE