2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES

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2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES 35 Years of Excellence ASHRAE www.ashrae.org. Used with permission from ASHRAE Journal at www.tlc-engineers.com.

HONORABLE MENTION INDUSTRIAL FACILITIES OR PROCESSES, EXISTING Cooling for Airline Passengers BY DOMINIC CACOLICI, P.E., MEMBER ASHRAE PHOTO CREDIT: CHRIS SLOAN BUILDING AT A GLANCE Tampa International Airport Location: Tampa, Fla.

Space Square Footage: 600 per bridge Substantial Completion/Occupancy: June 2015 Soaring summer temperatures can make flyers sweat as they wrestle their luggage down the long boarding bridge from the

1 2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES 35 Years of Excellence ASHRAE Used with permission from ASHRAE Journal at This article may not be copied nor distributed in either paper or digital form without ASHRAE s permission. For more information about ASHRAE, visit HONORABLE MENTION INDUSTRIAL FACILITIES OR PROCESSES, EXISTING Cooling for Airline Passengers BY DOMINIC CACOLICI, P.E., MEMBER ASHRAE PHOTO CREDIT: CHRIS SLOAN BUILDING AT A GLANCE Tampa International Airport Location: Tampa, Fla. Owner: Hillsborough County Aviation Authority Principal Use: Transportation Includes: HVAC to passenger boarding bridges Employees/Occupants: 19 million passengers annually on 44 bridges Conditioned Space Square Footage: 600 per bridge Substantial Completion/Occupancy: June 2015 Soaring summer temperatures can make flyers sweat as they wrestle their luggage down the long boarding bridge from the terminal onto the plane. To combat this misery, an airport in hot, humid Florida installed air conditioning on each boarding bridge. Boarding bridges connecting planes to the terminals are not typically conditioned, so during the summer temperatures frequently climb above 90 F (32 C). The Hillsborough County Aviation Authority, owner of Tampa International Airport (TPA), retrofitted 33 existing passenger boarding bridges (PBB) and added 11 new bridges with air conditioning. The bridges use a dedicated pre-conditioned air system, which can cool them by 45 F (25 C) in seven minutes. The new systems improve passenger thermal comfort and minimize cooling demand on the terminals. Dominic Cacolici, P.E., is a principal and senior mechanical engineer with TLC Engineering for Architecture in Tampa, Fla. 50

2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES Supply Ductwork to Bridge Duct Air Valve For PBB Cooling ABOVE Telescoping duct air valve provision for traditional passenger boarding bridge (PBB) cooling.

PHOTOS (PAGES 51 AND 52): TAMPA INTERNATIONAL AIRPORT The initial mock-up of the passenger boarding bridge air-conditioning system was completed at one gate and was evaluated for aesthetics,

Innovation A custom fabricated ductwork system was designed to fit the telescoping bridge.

2 2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES Supply Ductwork to Bridge Duct Air Valve For PBB Cooling ABOVE Telescoping duct air valve provision for traditional passenger boarding bridge (PBB) cooling. LEFT New supply ductwork routing from airhandling unit to passenger boarding bridge. PHOTOS (PAGES 51 AND 52): TAMPA INTERNATIONAL AIRPORT The initial mock-up of the passenger boarding bridge air-conditioning system was completed at one gate and was evaluated for aesthetics, effectiveness, and financial feasibility prior to authorization to expand the design to 58 existing gates in four other terminals. Innovation A custom fabricated ductwork system was designed to fit the telescoping bridge. The ductwork, made of heavy gage, powder coated, continuously bent steel, has an airfoil-like design to provide stiffness, negating the need for bracing. A high performance linear diffuser was placed at the end of the first tunnel to distribute conditioned air 50 ft (15 m) down the bridge. The aesthetically pleasing ductwork has small linear diffusers and nozzles to condition the staging area, where air movement would have otherwise been limited. Computational fluid dynamics (CFD) was used (Figure 1) to determine performance characteristics needed to cool the 125 ft (38 m) long passenger boarding bridge from 120 F to 75 F (49 C to 24 C) in seven minutes, an aggressive cooling task for any HVAC equipment. By using 20 F ( 6.7 C) glycol from the existing pre-conditioned air central chiller plant, the 100% outdoor air unit positively pressurizes the bridge and achieves the design goals, which consider that the boarding bridges are uninsulated, constructed of heavy gage steel, and are located on a hot tarmac, surrounded by concrete, which creates a heat island effect. PHOTO 1 Passenger boarding bridge components. A) Temperature sensor; B) long throw diffuser; C) short throw diffusers. A B C The mock-up was tested and balanced to ensure operation matched both the CFD and the design documents. Readings were taken both while the cab door was open to the staged plane and without a plane to simulate pre-cooling the bridge before aircraft arrival. In both cases the system achieved a uniform temperature within the 3 F (1.7 C) bandwidth of the temperature sensor, located at the end of the first fixed portion of the bridge (Tunnel A). Maintaining building comfort levels from the gate to the aircraft could only be made possible by using 20 F ( 6.7 C) glycol to supply subfreezing air through compact ductwork. Indoor Air Quality and Thermal Comfort Using ASHRAE's Thermal Comfort Tool (which provides consistency with ASHRAE Standard ), the air distribution is proven to provide thermal comfort throughout the bridge. This was not achievable from the original pre-conditioned air (PCA) unit designs, which offered just a set of linear bar grilles at the cab, near the aircraft. Passengers in the bridge away from this outlet received no comfort, or airflow, unless positive pressure from the terminal provided it. Positively pressurizing the terminal enough to provide 30 fpm ( m/s) movement equates to 1,200 cfm (566 L/s) or 10 tons (35 kw) per gate, based on using 100% outdoor air, which leads to a significant cost and means continuously over-pressurizing the terminal enough to handle roughly 60% of the gates simultaneously boarding. ASHRAE Standard calls JUNE 2017 ashrae.org ASHRAE JOURNAL 51

2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES PHOTO 2 The AHU is suspended or ground mounted on the fixed bridge within 15 ft of the terminal building, protecting occupants from toxic fumes and odors.

120 F 88 F 55 F Low-Temperature Glycol Mixture to Unit Bridge Air-Handling Unit for roughly 300 cfm (142 L/s); therefore, TPA s system exceeds code standards.

3 2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES PHOTO 2 The AHU is suspended or ground mounted on the fixed bridge within 15 ft of the terminal building, protecting occupants from toxic fumes and odors. Supply Ductwork to Bridge FIGURE 1 CFD of temperature gradient within the passenger boarding bridge with AHU operating. 120 F 88 F 55 F Low-Temperature Glycol Mixture to Unit Bridge Air-Handling Unit for roughly 300 cfm (142 L/s); therefore, TPA s system exceeds code standards. Serving the bridge with an interior duct system fed from a dedicated PCA is not what is traditionally offered in the industry. The traditional bridge cooling method uses the same pre-conditioned air unit that serves the aircraft and diverts cooling from the aircraft to the bridge via an airflow damper located underneath the cab, at the end of the telescoping duct. This has two negative impacts; first, it is not cooling the aircraft and bridge simultaneously, and second, the constant speed fans use inlet dampers to reduce the airflow from the aircraft volume down to an acceptable airflow for the bridge grilles. This means a 30 hp to 50 hp (22 kw to 37 kw) motor is operating bridge cooling when it could be achieved with the equivalent of a 2 hp (1.5 kw) motor. At TPA, the dedicated low-temperature air-handling unit has been located within 15 ft (4.6 m) of the terminal Advertisement formerly in this space. 52

4 2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES building, achieving maximum separation from the aircraft exhaust. Depending on the gate configuration, the unit is either suspended from the bridge itself or grade-mounted. Locating the unit away from the aircraft exhaust is exceedingly important to protect occupants from toxic fumes and odors. The closest distance between the unit outdoor air intake and the aircraft engine exhaust is 81 ft (25 m), nearly tripling the separation distance per ASHRAE Standard s Table 5-1 for Class 4 exhaust. Similar to the PCA unit itself, the PBB AHU has a MERV 8 filter. The ductwork is routed externally to the side of the first fixed portion of the bridge, known as Tunnel A. Special structural considerations were made to penetrate the bridge, including turning vanes at the opening to allow for quick transition to the narrow interior ductwork. This has been proven to be an effective retrofit to the bridges, allowing for flexibility in locating the AHU amidst the congested ramp level, and uniformly routing exterior ductwork to the bridge. In all cases, the stops that prevent the bridge from retracting too far were moved forward 24 in. (610 mm) to allow the exterior ductwork to be mounted above the existing PCA unit and in front of the pivot rotunda (that connects to the terminal building). Energy Efficiency Ground service equipment (GSE) such as preconditioned air systems outside the building are not addressed under ASHRAE Standard GSE like the boarding bridge is not a building, so measuring the EUI would not be applicable. The best comparison is to measure against the alternative equipment types available on the market today. First would be a DX PCA unit, operating at 100% outdoor air, with an ambient temperature of 120 F (49 C), using 2.5 kw/ton (0.71 kw/kw). Second would be a central system using low-temperature glycol distribution to each PCA unit at the gate. The plant efficiency is typically between 1.2 kw/ton to 1.5 kw/ton (0.34 kw/kw to 0.43 kw/kw), including chillers piped in series counterflow, primary pumps, and secondary distribution Advertisement formerly in this space. JUNE 2017 ashrae.org ASHRAE JOURNAL 53

5 2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES pumps, to achieve the 60 F to 20 F (16 C to 6.7 C) leaving glycol temperatures. To conserve energy, the PBB AHU is connected to the existing pre-conditioned air central plant at each Airside Terminal Building, serving each PCA unit, so the piping was simply extended at the gate. No new PCA central plant capacity was required to implement this project. The recorded data for each PBB cooling AHU averaged a peak load of 150 tons (528 kw) for all gates combined. Since the PBB cooling load is roughly 12 tons (42 kw) vs. the 30 tons to 90 tons (106 kw to 317 kw) required for the PCA unit, the addition of PBB units to the glycol piping infrastructure accounted for 5% to 10% of the total connected load. To quantify the impact of the energy savings of connecting to the central system, two trend lines show the energy savings, first the actual operation of the PBB cooling using glycol, and the second line for its DX equivalent. The trending began after substantial completion of the terminal, Airside C (Figure 2), and represents the spring to summer months. As the months grow warmer, the savings improves because of the increase in cooling demand. kbtu kbtu FIGURE 2 Airside C glycol vs. DX cooling load (11 bridges). 3,500,000 3,000,000 2,500,000 2,000,000 1,500,000 1,000, ,000 The operation of the unit is controlled by the airline staff at the gate by pushing an illuminated button. The AHU controllers are programmed to automatically time out after 30 minutes. Further, the system is connected to the building automation system, so the operation may be monitored and overridden at any time. Environmental Impact The electrical energy savings achieved using a central system versus point-of-use equipment can be translated into a reduction in carbon emissions. Using the EPA s Greenhouse Gas Equivalencies Calculator, 1 we can convert reductions of kilowatt-hours into avoided units of carbon dioxide emissions* for power plants brought online to meet demand loads. Based on the sample data of 11 bridges operating for 9.5 months (March to Glycol DX Glycol cooling of 11 bridges on Airside C saved TPA $89,500 over the course of 9.5 months. 0 Mar Apr Apr May May Jun Jun Jul Jul Aug Aug Sep Sep Oct Oct Nov Nov Dec Dec Dec FIGURE 3 Energy Model. Annual glycol vs. DX cooling load (44 bridges). 2,500,000 2,250,000 2,000,000 1,750,000 1,500,000 1,250,000 1,000, , , ,000 0 Glycol DX Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec December) 24 hours per day, significant energy and cost savings are achieved (Figure 3). To predict the remainder of the year, the same information derived from the trending data was entered into an energy analysis program (Figure 4). The sum of 44 bridges yields an annual consumption of 7.8 Btu (8.2 million MJ, which is equal to 2.3 million kwh, eliminating 1633 metric tons of CO 2 emissions per year. For comparison, according to the EPA this would be removing 345 passenger vehicles per year from the roadways. 2 Cost Effectiveness Full implementation of the PBB cooling was split between two projects, the retrofit of Airsides A, C, E completing 34 of 44 bridges, and in Airside F where all the bridges were replaced with new ones, including new *Emission Factor: metric tons CO 2 /kwh (egrid, U.S. annual non-baseload CO 2 output emission rate, year 2012 data). 54

6 2017 ASHRAE TECHNOLOGY AWARD CASE STUDIES PCA and PBB cooling. Tampa Airport is fortunate to have central pre-conditioned air chiller plants at each Airside Terminal Building, making the connection to the existing system very cost-effective. An alternative view is to consider the cost for point-of-use DX units, which would cost the project more for electrical infrastructure, including a 15 year unit replacement, and maintenance (Table 1). Operation & Maintenance Having local operator control and being connected to the building controls has allowed for ease of use, while also providing the authority feedback on use and service calls. The unit is designed for exterior use, with 18-gauge double wall aluminum panels limiting deflection to L/240 at 10 in. of w.g. (2.5 kpa) and less than 2% leakage rate. Hinged doors with cam lock handles make for easy access to the VFD driven 2 hp (1.5 kw) Class II fan, filter rack, and cooling coil for cleaning. The unit is braced for hurricane force winds, making it as strong and resilient as the best ground service equipment. Advertisement formerly in this space. TABLE 1 Life-cycle cost analysis summary. LOCATION (NUMBER OF BRIDGES) DIRECT EXPANSION POINT-OF-USE 15-YEAR LIFE-CYCLE (COST) CENTRAL SYSTEM 30-YEAR LIFE-CYCLE (COST) Airside A (12) $104,858 $41,943 Airside C (11) $96,120 $38,448 Airside E (11) $96,120 $38,448 Airside F (14) $122,335 $48,934 DIFFERENCE DIRECT EXPANSION POINT-OF-USE SYSTEM VS. CENTRAL SYSTEM TOTAL ANNUAL OPERATING COST $419,433 $167,773 ($246,417) TOTAL CONSTRUCTION COSTS $3,076,638 $2,416,638 ($660,000) LIFE-CYCLE COST SAVINGS 30 YEARS $14,793,959 Notes: Airside A, C, E numbers account for 34 of the 44 bridges installed for this project. Airside F costs are a separate project, bid by the same contractor; therefore, costs are duplicated from main project. DX point-of-use cost based on initial pricing exercises. Conclusion The Hillsborough County Aviation Authority certainly understands Florida s humid climate is a constant challenge for maintaining indoor comfort, especially with the constant movement of passengers in and out of the terminals. Tampa International Airport continues to implement boarding bridge cooling across the entire airport at each gate, providing continuous passenger comfort from aircraft to terminal. The implementation of cooling has been emphatically received by the airlines at TPA, who provide both domestic and international service with the end result of enhancing the passenger experience. Acknowledgments Thank you to the TPA leadership, Joseph Lopano, CEO; Paul Ridgeway, director of maintenance; Nick D Jimas, maintenance manager, and Doyle Wiggins, HVAC maintenance superintendent, for their innovation and support during the design and construction processes. References 1. EPA Greenhouse Gases Equivalencies Calculator Calculations and References EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: Chap. 3, Tables 3-12, 3-13, EPA 430-R U.S. Environmental Protection Agency. 56

Holistic Design Approach For Energy Efficiency ASHRAE TECHNOLOGY AWARD CASE STUDIES

Holistic Design Approach For Energy Efficiency ASHRAE TECHNOLOGY AWARD CASE STUDIES ASHRAE TECHNOLOGY AWARD CASE STUDIES This article was published in ASHRAE Journal, June 2018. Copyright 2018 ASHRAE. Posted at www.ashrae.org. This article may not be copied and/or distributed electronically