Airport Parking Garage Lighting Solutions (2015)

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28 4.1 Site Planning 4.1.1 Orientation on the Site It is unlikely that the lighting design will have control over the orientation of the garage on the site. This is usually driven by the site topography and available space after siting of the terminals and runways, etc. However, should there be some opportunity for siting, the lighting design should strive to take advantage of daylighting as described in the next section. In addition, from a photometric perspective, siting of the garage should take into account the light trespass onto the runways and aprons as well as other facilities. 4.1.2 Sunlight Capture Before the era of reliable artificial light sources, buildings were entirely naturally lit during daylight hours. Architectural design took into account all the ways light could come into a build- ing, be it directly from the sun, diffused through the sky, or reflected off the ground and neigh- boring buildings (Figure 21). The most effective designs also responded to differences in light quality coming from orien- tation. In the northern hemisphere, a southern exposure gets the most hours of direct sun, can use horizontal elements to control glare while preserving view, and receives varying amounts of light through the day. A northern exposure, by comparison, gets little direct sun, therefore seeing steady light through the day and requiring little control. Facades facing east and west get half a day of direct sun low on the horizon (Figure 22), often diminished by vertical elements that interfere with any view, and receive the most variable amount and quality of illumination in daylight hours. Even partially illuminating a parking garage with natural light would create several advan- tages. The design could conserve energy if controls reduce artificial lighting when enough natu- ral illumination is present. Daylight gives the best color rendering capability for viewing surfaces and people. The openings allowing daylight in provide views out. Well-designed natural light- ing can enliven the interior for visitors, lessening a sense of claustrophobia that can come from spaces with low structure overhead and deep floor plates. There would be disadvantages as well, primarily the potential for glare, either directly from the sun, or reflected off surfaces such as shiny metal or glass on vehicles. Contrast between the luminance of surfaces outside versus inside can interfere with visibility. The variability of direct and diffuse natural light with orientation, time, and weather makes control difficult. Drivers need their eyes to adapt to the difference in luminance when entering a parking garage during daylight hours. For a discussion of glare in airport operations, see the Light Trespass section in Chapter 3. C H A P T E R 4 Building Design Considerations

Building Design Considerations 29 4.2 Architecture 4.2.1 Top Level Most of the concerns relating to the top levels of the garage are covered in other sections such as Ramps and Light Trespass in Chapter 3. 4.2.2 Perimeter Garage structures typically exhibit low floor-to-floor heights between deep floor plates with extensive openings at the perimeter for ventilation. These openings provide opportunities to Figure 21. Sources of sunlight including direct from the sun. Source: Parsons Brinckerhoff analysis.

30 Airport Parking Garage Lighting Solutions take advantage of natural light but usually allow it to enter indiscriminately. The ratio of short opening head height to long floor depth can make it difficult to daylight much of the interior effectively. From viewpoints deep within the garage, the scene beyond an opening can appear bright enough to interfere with visibility inside. Mitigating these effects and making use of natu- ral illumination involves redistributing the daylight, making interior surface reflectances as high as practical, and controlling the luminance of the views out. Redistributing daylight typically requires a reflector or refractor at the perimeter opening to capture natural light incident on that aperture and direct it up and in toward the interior. The bottom of the reflector or refractor must be above average standing eye level to prevent glare. A reflector can take the form of a light shelf, that is, a single horizontal object mounted in the open- ing, or a set of louvers (Figure 23). The top surface of the shelf or each louver can be specular or diffuse. A specular (Figure 24) light shelf would get the deepest penetration but needs the most precise design effort and installation coordination. An advantage of a shelf over a louver system is that the shelf can shade the lower part of the opening, thereby reducing contrast. Louvers and light shelves for daylighting can now be purchased as standard products. If the louvers are move- able, they can be adjusted to varying natural light conditions. 4.2.3 Pavement and Vertical Surface Reflectivity Surface reflectances affect lighting design both quantitatively and qualitatively. The higher the average reflectance throughout a space, the less initial light is needed to produce a target illuminance. The higher the reflectance, the more uniform will be the light distribution. A space with all low reflectances and lighting directed mostly downward appears to have high contrast, producing reactions that vary from “dramatic” to “gloomy” or even “threatening.” A room of all high reflectances will feel bright, prompting responses that could range from “cheerful” to “sterile.” These effects might not be in proportion to the illuminance that could be measured. Light-reflecting elements can mitigate the effect of a bright view to the outside by simply blocking part of the view while redirecting natural light. If the redirected light illuminates a Figure 22. Effect of compass direction on the quality of daylight available. Source: Parsons Brinckerhoff analysis.

Building Design Considerations 31 surface near the perimeter opening, then contrast between the inside and outside is reduced. Shaping the structure and infill so that surfaces are angled toward the opening can encourage this reduction in contrast (Figure 25). For the lower part of an exterior opening, decorative screening can reduce the brightness of the view out while allowing the necessary ventilation. For daylighting, once the light is redirected from the perimeter, it is most useful if diffused. The best diffusion comes from high reflectance matte surfaces (Figure 24). That means flat white Figure 23. Utilizing reflective surfaces to increase the amount of daylighting. Source: Parsons Brinckerhoff analysis. Figure 24. Specular versus diffuse reflection, direct versus diffuse transmission, direct versus reflected glare. Source: Parsons Brinckerhoff analysis.

32 Airport Parking Garage Lighting Solutions paint on as much of the garage structure and infill as possible, especially the underside of floor slabs and the sides and bottoms of beams. If the columns and floors can be similarly coated, then so much the better. Standard reflectances of surfaces in a garage tend to be those of bare concrete, which is usu- ally in the range of 20% to 30% when new. Paint for concrete and masonry is readily available with reflectance of 80% or higher. These values will decrease over time with the accumulation of dirt but can be recovered if the surfaces are cleaned. The common combination of low surface reflectances, light directed almost entirely downward, and multiple shadows from vehicles can result in an environment that feels insecure to users, especially to those unfamiliar with it. Allowances need to be made with regard to the reflectance of the pavement for both sunlight and luminaire performance. Since the goals of garage lighting are to illuminate the roadway, pedestrians, and so forth, the reflectance properties of the pavement will affect how well a driver or pedestrian can see the pavement as well as drive lane and parking spot markings. In general, concrete surfaces provide a more diffuse reflection than asphalt. In addition, the darker the pave- ment type, the more illuminance will be required to provide the lighting needed. The lighting recommendations in this guide were developed with respect to a medium concrete surface. Adjustments up or down need to be made for other pavement types as provided in RP-8. 4.2.4 Stairwells/Elevators Refer to RP-20 guidance. Current practice seems to follow RP-20 and no reason was found to provide differing guidance. 4.2.5 Ramps, Entrances, and Exits Again, RP-20 guidance appears to be working well for transitioning from bright outdoors into the darker interior of airport parking garages. Be careful of not introducing glare with the Figure 25. Shaping of openings to reduce contrast between indoors and out. Source: Parsons Brinckerhoff analysis.

Building Design Considerations 33 relatively bright lighting of an entrance by using vertical cutoffs (luminaire or architectural) to limit the vertical illuminance directed toward the drivers. 4.2.6 Pedestrian Exits/Entrances Current practice seems to follow IESNA RP-20 with no complaints from garage patrons. 4.2.7 Signage Signage is very important to wayfinding for both pedestrians and patrons. The authors found that in some situations, due to the large size of the garage, some patrons had a difficult time determining which direction to head to find the terminal. Utilizing lighting to highlight the existing signage will attract the attention of the patrons and enable improved wayfinding. Glare to Airfield Operations This is covered in the Light Trespass section of the Designing for Lighting Performance chapter. 4.3 Retrofit Issues 4.3.1 Available Electric Power In most cases, technology transition will enable more efficient lighting to be installed lowering the electrical load in the garage overall. Airport authorities should consider this an opportunity to provide increased services or comforts for airport garage patrons in order to attract more customers. New services might include parking spots for electric vehicles with dedicated char- gers for the various styles of connection. Increased lighting can be implemented in areas such as walkways to the terminals, as well as in the rental car and/or loading and unloading areas. 4.3.2 Available Electrical Circuits Adding electrical circuits may be required for certain lighting control technologies. In some cases this may be cost-prohibitive. There are wireless and automated control technologies that install at each luminaire, enabling individually addressable control and or occupation/daytime control for energy savings as described in the next chapter.