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51 The majority of airports interviewed for this research project report that they do not systematically track the utilization rates of their gate electrification systems. Airports that received VALE grants for the purchase of gate electrification equipment do track its use for reporting emissions reductions. However, their focus is to determine the amount of emissions avoided; not on the percentage of time gate electrification equipment is actually used compared to what is possible. The VALE program requires that airports track equipment use to calculate estimated emissions savings from that equipmentâs deployment. For example, an airport that acquired electric PCA and/or ground power equipment with a VALE grant may record the use of this equipment through an hour meter. This information would then be correlated with the type of aircraft that used the equipment to determine the reduction in emissions from the use of gate electrification equipment compared to the use of a jet fuelâpowered APU. While this information is helpful, it does not necessarily provide the airport or airline with an understanding of the utilization rates of gate electrification equipment. Information gathered as part of the VALE program does not provide insight into the amount of time the equipment was used compared to the amount of time it could have been in use (see Section 5.1 for additional details). Other than tracking gate electrification equipment use for estimating emissions reductions for VALE grant compliance, airports have mainly focused on ensuring that the equipment is available for use by airlines (i.e., installed and maintained). Airports and airlines are now jointly striving to reduce the emissions footprint of APUs, as well as ensuring adequate aircraft cabin cooling and heating to address passenger needs. To facilitate these goals, and to receive the return on investment for system costs, there is a shared desire to increase utilization of gate electrification systems. Therefore, this report includes a basic example Utilization Tracking Methodology. The benefits of tracking utilization include: 1. Assists stakeholders to better understand their systemâs performance and utilization for benchmarking and compilation of data, 2. Enables stakeholders to identify conditions when equipment is not used and associated barriers to use to facilitate improvement, and 3. Enables stakeholders to verify that environmental objectives are achieved. The example methodology described in this chapter is designed to serve as a starting point for airports to estimate utilization rates of their gate electrification equipment. The accompanying Excel file can be used to calculate a basic utilization rate, or the airport can modify the spread- sheet to include additional information to suit their needs. The methodology is partially based on FAA VALE program reporting requirements, specifi- cally with regard to tracking equipment use. The methodology also incorporates some of the same assumptions included in the FAA VALE Program Technical Report, Version 7, with regard C H A P T E R 5 Utilization Tracking Methodology
52 Optimizing the Use of Electric Preconditioned Air (PCA) and Ground Power Systems at Airports to minimum APU use per turn and temperature ranges for PCA use. The intent in incorporating these elements is to maintain consistency with FAA guidance and to take advantage of informa- tion that some airports already have on hand. 5.1 Methodology Background The example Utilization Tracking Methodology is provided to assist owners and operators of electric PCA and ground power systems to calculate system utilization rates. The basic methodology developed for this ACRP project is designed to be simple and requires minimal technology and staff resources. It is also designed to be easily implemented by airport staff with little existing data. The methodology and accompanying Excel file will allow users to generate a reasonable estimate of electric PCA and ground power utilization at their facility. For the purposes of this methodology, utilization is defined as the percentage of time that available equipment is actually in use divided by the maximum amount of time it could be used. The maximum amount of time that equipment could be in use is calculated in the steps below and takes into account variables such as number of turns per gate, average time per turn, APU use, and temperature. Utilization average hours per day equipment is actually in use average total hours per day the equipment could be in use ( ) ( ) = The methodology allows users to calculate utilization rates for ground power systems and PCA systems separately, by individual gate, by terminal, or by a combined rate for the entire airport. The methodology includes averaging, and it incorporates an assumption with regard to the minimum amount of time that aircraft need to use the APU per gate turn (i.e., 7 minutes per turn, according to the FAA VALE Program Technical Report, Version 7). It does not require the user to determine actual APU use, as that would likely require the installation of more sophisticated technology and/or the acquisition of data from airlines that are not readily available. For these reasons, the utilization rates obtained with the application of this methodology should be regarded as reasonable estimates and not precise rates. The estimates can be used to track an airportâs system utilization over time for that individual airport. Given the range of variablesâweather, climate, percentage of gates equipped with PCA and ground power, air- line activities and policies, maintenance practices, and so onâthat can affect PCA and ground power utilization from location to location, one airportâs estimated utilization rates should not be compared to other airportsâ rates. The example methodology requires that users have information on the run timeâor hours of useâfor both PCA and ground power equipment. This information can be obtained from hourâor run-timeâmeters installed on individual pieces of equipment. (These are not elec- trical meters, which record kilowatt hours of electricity use.) In many cases, PCA and ground power equipment already have these devices installed; if not, the equipment can be retrofitted relatively easily at a low cost. If hour meters are not installed on equipment at every gate, this approach may still be used to track utilization. If hour meters are only available on some pieces of equipment, the airport operator will simply calculate the estimated utilization rate for those pieces of equipment that have hour meters. Pieces of equipment that do not have meters can be retrofitted should the airport operator wish to obtain a more precise estimate of overall utilization. The accuracy of
Utilization Tracking Methodology 53 the estimates obtained through the use of this methodology will increase as the percentage of gates monitored also increases. If the gate electrification equipment with hour meters is the same type or model as equip- ment without meters, and if the equipment is similar in age, it may be reasonable to scale up the estimated utilization rates across the entire airport. However, simply extrapolating the utiliza- tion rates obtained from a few gates to the whole airport may not be a reasonable approach if the nonmetered equipment is different, older, requires more maintenance, or is otherwise out of service for a longer time. Likewise, the Excel file can be modified if the airport has additional data that they would like to include. For example, a column can be added to provide space for the user to enter information about the specific type or model of PCA and ground power equipment at each gate. Section 5.1.1 contains instructions on how to unprotect the worksheets for modification. 5.1.1 Worksheet Formulas and Protection The accompanying Excel file has a number of formulas built into the file to simplify the cal- culations and data entry process. Each worksheet, or tab, is protected, and cells with formulas are locked to prevent accidental edits or deletion of the formulas. However, for users who wish to add rows to record data for additional gates or terminals, change default settings in cells with formulas, or copy or delete whole worksheets, the file may be unlocked. To do so, follow the steps below: â¢ Click on the âReviewâ tab at the top of each worksheet. â¢ Click âUnprotect Sheet.â â¢ When prompted, enter passcode 1234 to unlock the worksheet. To lock an unprotected worksheet, the user should follow the same steps, but select âProtect Sheetâ as the second step. Users can input the same passcode to lock the worksheet or enter a new passcode of their choosing. Before the user enters any data into the highlighted columns, cells that are programmed with a formula may appear to have the following text â#DIV/0!â. This is not an error message; those cells will repopulate once data have been entered by the user into other fields. The Excel file tab labeled âExample Sheetâ is not protected. Users are encouraged to explore this worksheet and change data, add columns or rows, or delete unwanted columns or rows to familiarize themselves with the worksheet and how the outputs change when different data are entered. 5.1.2 Worksheet Labels Worksheets labeled âPeriod 1â through âPeriod 4â only contain space for 400 Hz ground power use. The final worksheet on the spreadsheet, labeled âPeriod 1 (incld. 28VDC)â includes a column for 28 VDC (volts direct current) ground power use, as well as for those airports wishing to track both. The references to specific columns in the following steps refer to worksheets labeled âExample,â âPeriod 1,â âPeriod 2,â âPeriod 3,â and âPeriod 4.â The worksheet labeled âPeriod 1 (incld 28VDC)â has two extra columns in the ground power section to account for 28 VDC utilization. Therefore, column letters on that worksheet do not exactly match those in the other worksheets, as described in the following instructions.
54 Optimizing the Use of Electric Preconditioned Air (PCA) and Ground Power Systems at Airports 5.2 Methodology Instructions The following sections provide step-by-step instructions for calculating the PCA and ground power utilization rates. The steps describe which information the user should enter into the accompanying Excel file. Columns highlighted in yellow in the worksheets are the fields that require the user to enter data. Columns L and R provide space for the user to enter the amount of time that equipment is out of service at each gate. These fields are optional and are, therefore, not highlighted yellow. Step 1. Determine the reporting period(s). It is recommended that users identify a simple reporting period of a week or a month. This will enable the user to quickly become familiar with how to collect data, how to use the meth- odology, and how to analyze the results. Once familiarized, the user can develop more defined reporting periods for answering specific comparative analysis questions (e.g., if the user wants to compare utilization rates of gate electrification equipment in summer versus winter). A reporting period is the length of time over which data are collected and averaged. In general, a week is a reasonable time frame over which to collect data, as this reporting period should capture both peak and off-peak travel times, business travel (weekdays), and leisure travel (weekends). A week of data collection is also relatively more manageable from a staff resources perspective than a longer reporting period. The user should decide if shorter or longer report- ing periods would be more useful, depending on the userâs needs and the comparative analysis questions that the user is attempting to answer. Since one of the more frequent challenges to PCA utilization reported by airports and pilots occurs when ambient temperatures exceed the PCA system design standards (e.g., ambient tem- peratures are either too hot or too cold for the PCA to effectively condition aircraft cabins), it may be important for users to select multiple reporting periods to examine utilization rates during different seasons (see Section 3.5 for a discussion on climatic factors affecting utiliza- tion). Another factor to consider when selecting a reporting period may include whether the airport experiences distinct high and low seasons for passenger traffic. If so, an airport may wish to examine utilization at multiple periods when passenger traffic and number of operations differ significantly. The accompanying Excel file contains worksheets for four reporting periods by default: Period 1, Period 2, Period 3, and Period 4. Users should determine whether fewer or more reporting periods are most appropriate to meet their needs. If the user does not need all the worksheets, extra worksheets can be left blank. If more worksheets are needed, they can be copied to create additional reporting periods. Step 2. Select terminals and gates to be included. Ideally, all electric GPUs and PCA units are equipped with hour meters and can be included in the analysis. If this is not feasible, the user should select a variety of gates to be monitored. The selection may include gates with differing equipment types, age, and models, as well as airline use and gate configuration. For example, if different types of PCA and ground power equipment are installed (or equipment varies in age), the user should select gates representing each of the various types to ensure a comprehensive review. Likewise, if some terminals have exclusive use gates for one or more airlines and other terminals are mixed use, the user should include both types of gates. This methodology is designed to provide the user with a basic understanding of utilization rates at the airport. In general, the more gates and equipment that are monitored, the more accurate the estimates of utilization. However, once the user has completed simple analysis,
Utilization Tracking Methodology 55 the data can be used to perform other comparative analyses to identify the root causes of dif- fering utilization rates across airlines and equipment in a given reporting period. For example, if utilization rates show significant differences at gates with identical equipment but are served by different airlines, the airport operator could further investigate the effect of different airline practices and policies on utilization. Terminals and gates to be monitored should be entered into Columns A and B of the accom- panying Excel file, respectively. Each of the worksheets in the Excel file is built with space for 10 gates at three terminals. Users can leave rows blank if monitoring less than 10 gates per terminal or less than three terminals. Users can also add more rows if more than 10 gates are to be monitored per terminal or if more than three terminals will be monitored. If the user is monitoring more than 10 gates in a given terminal, follow this process to add rows: â¢ Click on the âReviewâ tab at the top of each worksheet, and then click âUnprotect Sheet.â When prompted, enter 0276 to unlock the worksheet. â¢ Select Cell A13 on sheet âPeriod 1â and right-click the mouse. Select âInsert.â Then select âEntire Row.â â¢ Once the new row(s) has been added, highlight the entire Row 14 and right-click the mouse. Select âCopy.â â¢ Select the blank row above, right-click the mouse, and select âPaste.â Repeat as necessary until the desired number of rows has been added. Step 3. Determine average number of daily operations for each gate. For each gate included in the monitoring process (listed in Column B of the Excel file), determine the average number of daily operations (or turns) (i.e., aircraft serving that gate during the reporting period). For example, if the reporting period is one week, the number of operations per gate per day should be recorded and then averaged over the week. This number should be entered into Column C for each gate. Many airports already collect gate block time, which can be used, or these data can be obtained from airline schedules. This methodology does not require the user to determine the number of operations by type of aircraft (i.e., narrow body, wide body, jumbo jet, or regional jet) or by specific APU models, as one might do when developing emissions inventories. Although this information is impor- tant for understanding the environmental benefits of gate electrification equipment, the intent of this methodology is to be a starting point for determining utilization rates. While utilization rates at some airports may be influenced by aircraft type, collecting these data is not crucial to this particular exercise. Step 4. Determine average amount of time aircraft are at gates. The next step is to determine the average amount of time aircraft remain at each gate per turn (i.e., departure time minus arrival time). If possible, the user should determine actual turn times to increase accuracy. If this information is not available, the default time per turn used in the FAA Aviation Environmental Design Tool 2dâ26 minutes for both wide-body and narrow- body aircraftâcan be used. Turn times should then be averaged for each gate over the reporting period and entered (in minutes) into Column D. For example, if the reporting period is 1 week, the turn times per day should be recorded and then averaged over the week. Columns E through H will automatically populate once data have been entered into Columns C and D, but each step is described as follows.
56 Optimizing the Use of Electric Preconditioned Air (PCA) and Ground Power Systems at Airports Step 5. Calculate the average amount of time per day, in minutes, that aircraft are at each gate. This number is calculated by multiplying the average number of daily operations per gate by the average amount of time (in minutes) that aircraft are at each gate per turn. The resulting number is the average total time per day (in minutes) that aircraft are at each gate. This informa- tion will automatically populate in Column E. Airport operators may wish to calculate a weighted average utilization rate if some gates have significantly more operations than others. However, the accompanying Excel spreadsheet does not automatically do this. Step 6. Calculate the minimum APU run time per gate. The minimum APU run time per gate is obtained by multiplying the average number of turns per day (Column C) by 7 minutes. The FAA VALE Program Technical Report, Version 7, uses a default assumption for the minimum amount of time an aircraft APU must be used during gate-in and gate-out operations of 7 minutes. Since this is also the value used by air- ports for VALE reporting purposes and because actual APU use data are more time- and resource-intensive to gather, the methodology uses the 7-minute default figure, as well. This information will automatically populate in Column F. If the user has actual APU use time available, those data can be included for each gate in Column F instead of the default time of 7 minutes per turn. To include these data, the user should first ensure that the worksheet is unlocked (follow steps in Section 5.1.1). Then, the user should enter the amount of time that aircraft APUs were in use at each gate during the reporting period (total APU use during the reporting period divided by number of days in the reporting period). Step 7. Calculate the maximum amount of time (in minutes) per day that electric PCA and ground power could be in use by aircraft. This is calculated by subtracting APU run time per day (Column F) from amount of time per day aircraft are at each gate (Column E). PCA and ground power are generally not needed when APUs are in use, so the amount of time APUs are in use (Column F data) is subtracted from the total amount of time aircraft are at the gate. This information will automatically populate in Column G. Step 8. Convert Column G to hours. Convert the maximum amount of time PCA and ground power systems could be in use from minutes to hours by dividing the number of minutes in Column G by 60. This information will automatically populate in Column H. Step 9. Determine average daily time (in hours) ground power equipment is in use. For each gate listed, data from the hour meters on the electric ground power equipment should be recorded at the beginning and at the end of the reporting period. The number on each meter at the beginning of the reporting period should be subtracted from the number at the end of the reporting period to get the total number of hours the ground power equipment was in use (for each selected gate). That number should be divided by the number of days in the reporting period to get the average number of hours the ground power equipment was in use per day. This number should be entered into Column I. The total average daily hours that ground power equipment was in use for each terminal will automatically populate (the gray rows). Step 10. Review utilization rate for ground power equipment. The utilization rate for 400 Hz ground power (or both 400 Hz and 28 VDC) at each gate will automatically be calculated in Column J. The utilization rate is calculated by dividing the hours
Utilization Tracking Methodology 57 of actual ground power use (Column I) by the maximum time ground power equipment could be used (Column H). The average utilization rate for all gates in a given terminal will appear in the last row of that section (in the Example worksheet, the average utilization rate for Terminal A appears in Cell J14). Column K provides the weighted utilization rate based on number of operations per gate. This information will calculate automatically. The utilization rate for gates with a higher number of turns per day will be weighted proportionally more than the utilization rates of gates with fewer operations. This column is not useful on a per gate basis but is important for the terminal as a whole. In the Example worksheet, Cell K14 contains the adjusted utilization rate for Terminal A. The Example worksheet shows a slightly higher ground power utilization rate in Cell K14 com- pared to the unadjusted rate in Cell J14. This accounts for the high utilization rates for Gates A7 and A8 being weighted more heavily, given their higher number of daily operations. Step 11. Determine percentage of time ground power equipment was out of service. Column L is optional, but it can be used to help interpret utilization rates. If the airportâor equipment maintainer, if other than the airportâhas sufficient maintenance data available to determine the approximate percentage of time the ground power equipment was out of service (due to maintenance needs, replacement, and so on), the data should be entered in Column L. The user can then compare utilization rates by gate (or terminal) to the percentage of time the equipment was unavailable for use due to maintenance needs. While these two variables are not always correlated, they do provide a starting point for airports or equipment users to investigate possible causes of low utilization. Step 12. Determine the percentage of time that cooling or heating is needed. Aircraft heating and cooling is not needed at all times. FAA assumes that aircraft heating is necessary when ambient temperatures are below 45Â°F, and cooling is needed when temperatures are above 50Â°F (FAA 2010). Therefore, the maximum amount of time that electric PCA systems are needed to provide heating and cooling is dependent on the weather. Users should determine the percentage of time during the reporting period that ambient temperatures were either below 45Â°F or above 50Â°F and enter that figure as a whole number into each row in Column M. If the airport uses a different temperature range for determining heating and cooling modes, the airport-specific range should be used instead of the default temperature range. If the PCA system provides ventilation during periods when neither heating nor cooling is needed, then the system might be in use even when temperatures are in the neutral range. In this case, the airport may consider that PCA is needed 100 percent of the time for utilization rate calculation. If so, then the user should enter 100 for each gate in Column M. Another consideration is the frequency of flights when PCA is needed compared to frequency of flights when PCA is not needed. If the airport determines that temperatures during the study period necessitate PCA use consistently during the times of day when flights are most frequent, and if flights are relatively infrequent during times of day when PCA is not needed (such as at night), then the airport may wish to enter â100â for each gate in Column M, recognizing that for the majority of flights PCA is needed 100 percent of the time, based on weather. Alternatively, airports may wish to set up two study periods: one during times of day when temperatures necessitate the use of PCA and one during times of day when temperatures are within the neutral range. Although the percentage of time that temperatures warranted either heating or cooling will be the same for all gates, it must be entered into each row for the formula in the adjacent column to work properly.
58 Optimizing the Use of Electric Preconditioned Air (PCA) and Ground Power Systems at Airports Weather data can be obtained from the National Oceanic and Atmospheric Administration National Weather Service or from airport records. Step 13. Calculate maximum amount of time electric PCA could be used, adjusted for temperature. Next, for each row (i.e., for each gate) users should multiply the data in Column H (the maximum number of hours per day that electric PCA and ground power equipment could be used) by the percentage of time heating or cooling was needed during the reporting period (Column M). This information will be automatically calculated in Column N of the Excel file. Step 14. Determine average daily time electric PCA equipment is in use (in hours). For each gate listed, data from the hour meters on the electric PCA equipment should be recorded at the beginning and at the end of the monitoring period. The number on each meter at the beginning of the recording period should be subtracted from the number at the end of the recording period to get the total number of hours the PCA equipment was in use (for each selected gate). That number should be divided by the number of days in the recording period to get the average number of hours the PCA equipment was in use per day. This number should be entered into Column O by the user. The total average daily hours that PCA equipment was in use for each terminal will automatically populate (the gray rows). Step 15. Review utilization rate for electric PCA equipment. The utilization rate for electric PCA equipment will automatically be calculated in Column P. The utilization rate is calculated by dividing the hours of actual PCA use (Column O) by the maximum time PCA equipment could be used (Column N). Column Q provides the weighted utilization rate based on number of operations per gate. This information will calculate automatically. The utilization rate for gates with a higher num- ber of turns per day will be weighted proportionally more than the utilization rates of gates with fewer operations. This column is not useful on a per gate basis, but it is important for the terminal as a whole. In the Example worksheet, Cell Q14 contains the adjusted PCA utilization rate for Terminal A. The Example worksheet shows a slightly higher PCA utilization rate in Cell Q14 compared to the unadjusted rate in Cell P14. This accounts for the high utilization rates for Gates A7 and A8 being weighted more heavily, given their higher number of daily operations. Step 16. Determine percentage of time PCA equipment was out of service. Like Column L, Column R is optional, but it can be used to help interpret utilization rates. If the airportâor equipment maintainer, if other than the airportâhas sufficient maintenance data available to determine the approximate percentage of time the PCA equipment was out of service (due to maintenance needs, replacement, and so on), the data should be entered in Col- umn R. The user can then compare utilization rates by gate (or terminal) to the percentage of time the equipment was unavailable for use due to maintenance needs. While these two variables are not always correlated, they do provide a starting point for airports or equipment users to investigate possible causes of low utilization. 5.3 Next Steps The Excel-based tool allows users to catalog existing data to better understand and improve utilization of gate electrification systems. The tool is based on metrics and methodology avail- able in the FAA VALE Program Technical Report, Version 7, and may assist operators in pin- pointing high-level faults in their system; thus, enabling them to improve system reliability. The tool can also provide a general understanding of gate electrification system availability. System
Utilization Tracking Methodology 59 availability is a function of both reliability (time between failure) and maintainability (average time necessary to make repairs); thus, representing the percent of time that units are available for use by aircraft. Once utilization rates have been obtained for multiple reporting periods, the rates can be compared and tracked for internal benchmarking purposes. The utilization rates for ground power and PCA for multiple reporting periods can be combined to estimate an average annual utilization rate, for example. Anomalies can be further examined to determine what may be causing higher or lower utilization at different gates during different times of the year, based on maintenance records and so on. The methodology is intended as a starting point for discussions between airports and airlines, system owners, maintainers, and operators to determine how to improve overall utilization.