Airport Parking Garage Lighting Solutions (2015)

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55 9.1 Parking Garage Lighting Comparison A sample lighting design has been prepared that will allow for a direct comparison of the light sources. This design was prepared to meet the requirements of RP-20. A typical parking structure has double loaded bi-directional travel aisles, creating a situation where pedestrians must pass both between the parked cars and across travel lanes. The surfaces of a garage tend to have low reflectance, the maintenance is difficult at times, and ceiling heights tend to be low, requiring luminaires that provide both horizontal and vertical illuminance while minimizing excessive direct glare. A 60-ft by 50-ft area made up of two structural bays with a floor-to-ceiling height of 14 ft 3 in. and a structural depth of 2 ft 6 in. is illustrated in Figure 27. There are many options for the construction of a garage. In this case, a precast structural TT slab—a floor slab with two reinforcing vertical webs that in cross-section resembles two T’s placed side by side—would allow luminaires to be raised into the structure, limiting direct glare. To accurately model the parking garage lighting from the various light sources, an LLF is to be established that takes into account the differences in the sources’ operating characteristics, luminaire efficiency, and maintenance cycles for cleaning the facility. The LLFs used in this comparison are shown in Table 18. A comparison layout of four luminaires placed over the travel line at the edges of the parking stripes was used to generate a series of relative comparisons of calculated lighting. The lighting on the surfaces in the calculation represents horizontal illumination on the floor plane and ver- tical illumination in each direction at 5 ft above the finished floor. The OLED and LEP sources were omitted from the calculation comparison because neither source has a practical luminaire for garage lighting. The results are shown in Table 19. The comparison reveals the benefits of the alternatives. The LED system had the highest relative efficiency compared to the fluorescent. Similarly, the LED had the best uniformity. It did, however, have the lowest average horizontal illuminance. The other technologies provided higher average illuminance levels with a higher power consumption. 9.2 Bi-Level Lighting Savings Example California State University, Sacramento (CSUS), and the University of California, Santa Bar- bara (UCSB), conducted two case studies for bi-level lighting systems. CSUS and UCSB con- ducted the case studies in partnership with the California Lighting Technology Center (CLTC), UC Davis, and the California Energy Commission’s Public Interest Energy Research (PIER). Neither case study evaluated people’s responses to or feelings about the parking garage lighting. C H A P T E R 9 Case Studies

56 Airport Parking Garage Lighting Solutions Figure 27. Parking lot structure for design comparison. Source: Created by Parsons Brinckerhoff. SOURCE COMPARISON – LIGHT LOSS FACTORS (LLF) Source FL IFL HPS CMH LED OLED LEP LLF .63 .67 .62 .66 .68 .63 .70 Source: Compiled by Parsons Brinckerhoff Table 18. Light loss factors for compared light sources. SOURCE COMPARISON – Calculated Values for Identical Layouts SOURCE FL IFL HPS CMH LED Horizontal Illuminance (fc) MAX 4.8 5.7 5.8 6.3 3.8 MIN 1.1 1.7 2.6 2.6 1.7 MAX/MIN 4.36 3.35 2.23 2.42 2.24 Vertical Illuminance EAST-(fc) MAX 3.8 5.2 6.5 7.6 4.4 MIN 0.6 0.9 1.5 1.1 0.8 MAX/MIN 6.33 5.78 4.33 6.91 5.5 Vertical Illuminance NORTH-(fc) MAX 4.8 5.4 7.1 6.7 4.4 MIN 1.1 1.9 2.9 3.2 2.3 MAX/MIN 4.36 2.84 2.45 2.09 1.91 Vertical Illuminance SOUTH-(fc) MAX 4.7 5.4 7.1 6.8 4.4 MIN 1.1 1.9 3.2 3.5 2.1 MAX/MIN 4.27 2.84 2.22 1.94 2.10 Vertical Illuminance WEST-(fc) MAX 3.8 5.2 6.5 7.6 4.4 MIN 0.6 0.9 1.5 1.1 0.8 MAX/MIN 6.33 5.78 4.33 6.91 5.50 Total Load - W (4 Luminaires) 240 W 347 W 412 W 444 W 196 W Relative Efficiency FL = 100% MIN(fc)/W 100% 106% 137% 128% 189% Source: Parsons Brinckerhoff analysis Table 19. Light source comparison in sample garage calculations.

Other Considerations 57 In the case of UCSB, 30 existing fluorescent fixtures in a parking garage were retrofitted. The resulting energy consumption and savings can be seen in Figure 28 and Table 20 (PIER, 2009). In the case of CSUS, 30 high pressure sodium luminaires were retrofitted with LED luminaires. The resulting energy consumption and savings can be seen in Figure 29 and Table 21 (PIER, 2008). 9.3 Effects of Various Surface Reflectances A model of a portion of a typical garage similar to the one at Boston’s Logan Airport Terminal B was adjusted and calculated with surface reflectances varied for comparison on the ceiling, walls, beams and columns. This was modeled using AGI32 software which allows calculation of W AT TS Figure 28. Approximate energy-consumption levels for fluorescent and bi-level fluorescent lighting systems. Source: Created by VTTI from PIER 2009 data. System size (Watts) Lifecycle energy cost (energy at $0.128/kWh) (20 yr life) Lifecycle maintenance cost (labor at $100/hr) (lamp cost $2.65) Total lifecycle cost Standard Fluorescent 58 $33,174 $7,898 $41,071 Bi-Level Dimmable Fluorescent 54 $25,638 $7,898 $33,533 Savings $7,538 $7,538 Source: VTTI compiled from PIER 2009 data Table 20. Savings from using bi-level dimmable fluorescent lamps versus standard fluorescent lamps.

58 Airport Parking Garage Lighting Solutions the effects of reflectance, luminaire distribution, and shadowing. The calculation results can be seen in Table 22, Table 23, Figure 30, and Figure 31. FC is the illuminance in foot candles, and AFF stands for “above the finished floor.” Comparing the measurement results to calculations performed for Boston Logan’s B termi- nal garage (Table 22), the measured illuminances were quite a bit higher than those predicted. Virginia Tech Transportation Institute measured 111 lx average horizontal and 104 lx average vertical illuminances. This is higher than the calculations of 59 lx and 40 lx for low reflectivity. This could be due to higher reflectances from the vehicles occupying the space, especially since RP-20 and the model assume no vehicles in the garage. It could also be due to a difference in spacing between the luminaires in the model and the as installed luminaires or running the lumi- naires at a higher current level. Figure 32 illustrates a real-world application of low reflection illumination. As can be seen, the ceiling is shadowed and darker than the floor, similar to the illustration in Figure 30. Also, similar to the model, the vehicles and pedestrians are in positive contrast to the background. Figure 29. Bi-level energy consumption (PIER, 2008). Source: VTTI compiled from PIER 2009 data. System size (Watts) Lifecycle energy cost (energy at $0.128/kWh) (20 yr life) Lifecycle maintenance cost (labor at $100/hr) (lamp cost $100) Total lifecycle cost HPS 189 $2,419 $210 $2,629 LED 165 $1,661 $150 $1,811 Savings $758 $60 $818 Source: VTTI compiled from PIER 2008 data Table 21. Savings from using LED lamps versus HPS lamps.

Other Considerations 59 Calculation with reflectances of 10% Average Minimum Max:Min Horizontal illuminance, 0’ AFF 5.50FC (59lx) 2.9FC (31lx) 2.52 Vertical illuminance at low hor. illum., 5’ AFF 3.76FC (40lx) 0.9FC (9.7lx) 8.78 Source: Parsons Brinckerhoff analysis Table 22. Boston Logan Terminal B model calculations with low reflectance. Calculation with reflectances of 80% Average Minimum Max:Min Horizontal illuminance, 0’ AFF 6.27FC (67lx) 4.2FC (45lx) 1.88 Vertical illuminance at low hor. illum., 5’ AFF 4.38FC (47lx) 1.9FC (20lx) 4.42 Source: Parsons Brinckerhoff analysis Table 23. Boston Logan Terminal B model calculations with high reflectance. Figure 30. Surface reflectances at 10%. Source: Parsons Brinckerhoff analysis. Figure 31. Surface reflectances at 80%. Source: Parsons Brinckerhoff analysis.

60 Airport Parking Garage Lighting Solutions 9.4 Sample Benefit-Cost Calculation A simplified benefit calculation is shown in Table 24 to highlight some of the concepts dis- cussed above. This example considers only two quantified benefits: cost savings due to decreased demand for electricity and the associated reduction in CO2 emissions. The example uses a 15-year lifecycle starting in FY 2014. A 7% discount rate is used to compute the present value of the lifecycle benefits. The energy savings for the entire lighting installation has been estimated at 92,843 kWh per year. This amount is assumed to remain constant throughout the lifecycle. Figure 32. Boston Terminal B illustrating low reflectance lighting in application. Source: VTTI. Year Energy Savings (kWh) CO2 Reduction (metric tons) Utility Rate (FY14 $/kWh) Energy Savings (FY14 $) CO2 Reduction (FY14 $) Total Benefit (FY14 $) Present Value (FY14 $) 2014 92,843 64 $0.1000 $9,284 $278 $9,563 $9,563 2015 92,843 64 $0.1012 $9,395 $278 $9,674 $9,041 2016 92,843 64 $0.1025 $9,519 $278 $9,797 $8,557 2017 92,843 64 $0.1036 $9,623 $278 $9,901 $8,082 2018 92,843 64 $0.1049 $9,739 $278 $10,018 $7,642 2019 92,843 64 $0.1061 $9,852 $278 $10,131 $7,223 2020 92,843 64 $0.1074 $9,970 $278 $10,248 $6,829 2021 92,843 64 $0.1086 $10,087 $278 $10,366 $6,455 2022 92,843 64 $0.1099 $10,206 $278 $10,485 $6,102 2023 92,843 64 $0.1112 $10,326 $278 $10,605 $5,768 2024 92,843 64 $0.1125 $10,448 $278 $10,727 $5,453 2025 92,843 64 $0.1139 $10,571 $278 $10,850 $5,155 2026 92,843 64 $0.1152 $10,696 $278 $10,974 $4,873 2027 92,843 64 $0.1166 $10,822 $278 $11,100 $4,606 2028 92,843 64 $0.1179 $10,950 $278 $11,228 $4,354 Total: 1,392,644 960 $151,489 $4,176 $155,665 $99,704 Source: MCR Federal analysis Table 24. Sample benefits calculation.

Other Considerations 61 In this example, the decrease in energy consumption is converted to a reduction in CO2 using the average EPA value of 6.8927 × 10-4 metric tons of CO2 per kWh of electricity generation (EPA, 2014). CO2 reductions are monetized at $4.35 per metric ton of CO2 (Potomac Econom- ics, 2014, p. 8). The price of CO2 is assumed to remain constant throughout the lifecycle. The example assumes an electricity cost of $0.10/kWh, with an annual escalation of 3%. How- ever, since the BCA methodology requires the benefit streams to be expressed in real dollars, the resulting utility rate has been normalized using GDP deflators. This corrects the cost of electric- ity for inflation. The resulting utility rate is shown in constant (i.e., real) FY 2014 dollars. In this case, the monetized benefit is the sum of the electrical cost savings, computed by apply- ing the utility rate to the energy saved per year, and the monetized value of the associated reduc- tions in CO2 emissions. These yearly sums are then converted to a present value benefit stream using the FAA standard 7% discount rate. The conversion from real to present value dollars accounts for the opportunity cost of money. Since the discounting is compounded throughout the lifecycle, the impact of the conversion to present value dollars is substantial. This is especially true for benefits near the end of the lifecycle. Figure 33 plots the total benefits before and after discounting, to illustrate the impact of this conversion. While this highly simplified example omits many of the benefits that would be expected in a next-generation lighting installation, such as maintenance and replacement cost savings, it illus- trates the key principles of monetizing benefits. As discussed, the example also demonstrates the impact of using the present value of the monetized benefits. Also notable is the relatively minor monetary contribution of CO2 reductions relative to the economic value of the associated sav- ings in energy costs. Not shown in this example is the risk adjustment that would normally be conducted in order to account for uncertainty in key benefit drivers. A number of other factors have the potential to substantially affect the results. In a real-world application, ranges of low, best, and high values would be established for these drivers, for a probabilistic analysis of risks. Key drivers from this example that are candidates for risk adjustment include: • Annual energy savings, • Utility cost and/or escalation rate, and • Monetization of CO2 reduction and its escalation rate (assumed to be zero in the example). Figure 33. Total benefits before and after discounting (7% discount rate). Source: MCR Federal analysis.