Outdoor Lighting Retrofts A guide for the National Park Service and other federal agencies 1 Developed by the National Park Service and the California Lighting Technology Center, UC Davis © 2014, Regents of the University of California, Davis campus, California Lighting Technology Center Guide Prepared by: California Lighting Technology Center (CLTC) University of California, Davis 633 Pena Drive Davis, CA 95618 cltc.ucdavis.edu Project Partners: National Park Service U.S. Department of Energy Federal Energy Management Program (FEMP) Lawrence Berkeley National Laboratory Contributors The U.S. Department of Energy and its Federal Energy Management Program (FEMP) sponsored the creation of this guide. The Energy Department’s mission is to ensure America’s security and prosperity by addressing its energy, environmental and nuclear challenges through transformative science and technology solutions. Lawrence Berkeley National Laboratory (Berkeley Lab) also contributed support. Berkeley Lab conducts extensive scientifc research with an annual impact of $1.6 billion on the national economy. It has created 12,000 jobs nationally and saved billions of dollars with its energy-efcient technologies. This guide was prepared by the California Lighting Technology Center (CLTC) at the University of California, Davis, for the National Park Service. CLTC is a research, development and demonstration facility dedicated to accelerating the development and commercialization of energy-efcient lighting and daylighting technologies. The center develops technological innovations, conducts demonstrations of new and emerging technologies, and carries out education and outreach activities in partnership with utilities, lighting manufacturers, end users, builders, designers, researchers, academics, and government agencies. July 2014 2 Contents Part 1 Outdoor Lighting Goals 6 Energy Efciency 7 Reduced Maintenance Costs 8 Improved Visual Environments 8 Safer Outdoor Areas 10 Minimal Light Pollution and Light Trespass 10 Part 2 Best-Practice Strategies 12 Basic Steps 13 Lighting Design and Retroft Elements 14 Structures and Monuments 15 Softscape 16 Hardscape 16 Vehicle Spaces 17 Pedestrian Spaces 19 Part 3 Light Sources and Controls 20 Light Sources 21 Lighting Controls 2 Emerging Technologies 2 Part 4 Project Planning 30 Lighting Audit Guidelines 32 Relamping and Maintenance 34 Recycling and Waste Disposal 35 Cost-Beneft Analysis 35 Part 5 Meeting Federal Standards 38 General Outdoor Lighting Guidelines 39 Lighting Controls Requirements 40 Lighting Power Allowances 41 Part 6 Preserving Dark Skies 46 Resources 54 Glossary 59 3 Lighting constitutes a large portion of energy use at national parks. This guide provides assistance to facility managers who want to reduce lighting energy use while making parks safer and more visually appealing for visitors. Proper outdoor lighting increases safety and security, minimizes light pollution, and makes visitors’ experience of national parks more memorable. Illuminating key attractions with the right luminaires, equipped with the right lighting controls, can also reduce energy consumption. This guide is intended to make the selection of appropriate, energy-efcient outdoor lighting solutions easier and improve project outcomes. This guide provides an overview of outdoor lighting best practices as well as information on lighting technologies that can optimize energy, cost and maintenance savings. It ofers guidance for evaluating light sources, performing a lighting audit, and pairing lamps with lighting controls. In many cases, following best practices allows facilities to exceed federal standards for outdoor lighting energy efciency. While some traditional outdoor lighting products are relatively energy-efcient, most sacrifce light quality and control for the sake of energy savings. This compromise is no longer necessary. Many new types of high-quality, outdoor lighting solutions are both highly energy-efcient and compatible with advanced lighting controls. Lighting retrofts that utilize these new technologies can reduce lighting energy use immediately, often by 50% or more as compared to traditional solutions. 4 Photo: Nimish Gogri 5 Part 1 Reasons for Outdoor Lighting Retrofts 6 After the sun sets, people rely on outdoor lighting for safety, security, wayfnding, Figure 1. Satellite imagery of the Earth at night reveals the density of electric lighting and recreational activities, but excessive lighting often obstructs views of the in developed areas. night sky and can negatively impact ecosystems. Recent advances in light sources, controls and luminaires have made it possible to focus lighting only where and when it is needed, reducing light pollution. Advances in outdoor lighting technologies are also increasing energy savings, reducing maintenance costs, improving visual environments, and enhancing safety. These improvements, coupled with a nationwide push to increase energy efciency, have prompted the development and deployment of many lighting retroft programs. Energy Effciency Lighting retrofts can lower energy use and costs without sacrifcing light levels or quality. Switching to more advanced technologies may also allow users to implement lighting controls more successfully, which further increases energy savings. Outdoor lighting presents an excellent opportunity for national parks to reduce their energy use. Case study summaries presented throughout this guide illustrate the energy savings that can be achieved with outdoor lighting retrofts. When replacing older technologies, it is important to select fxtures, light sources and controls suited to each site. Proper selection requires consideration of many factors. This guide is intended to assist facility managers during the process. It includes instructions for conducting a lighting audit and guidelines for determining which lighting system components might be best suited to diferent applications. 7 Photo: NASA Earth Observatory/NOAA NGDC Reduced Maintenance Costs Correlated Color Temperature (CCT) A lighting retroft can often deliver reduced maintenance Correlated color temperature (CCT) indicates the color costs over the life of the new lighting system as compared to appearance of a light source and is measured in Kelvin (K). costs to maintain old or outdated components. For example, CCT is calculated by measuring the apparent color of light improvements in lighting technologies have led to increased emitted by a source then correlating that color to that of an lifetimes for many types of products. This lengthens the idealized reference light source, called a blackbody radiator. time between maintenance tasks such as lamp replacement, The color of light emitted by a blackbody radiator depends which reduces labor costs and other expenses. In addition, exclusively on its temperature. As a blackbody radiator heats up implementing a routine maintenance program simplifes or cools down, the color appearance of the light it emits varies. maintenance and further reduces operational costs associated The higher the temperature of the blackbody radiator, the with sustaining lighting systems. “cooler” the color appearance of the light it emits (see fgure 2). Maintenance savings may also help ofest some the initial High-pressure sodium lamps, for example, have a relatively cost of a lighting retroft project. For example, prices for low CCT (~ 2000 K), and deliver orange-yellow light. In LED sources continue to decrease, as their efcacy continues contrast, most general illumination LED sources have high to increase, resulting in greater energy savings and a better CCTs (5000 – 6000 K) and deliver white light that is relatively return on investment. cooler in appearance. Improved Visual Environments Lighting retrofts can help address general lighting quality problems. For example, new technologies can ofer lighting with better color rendering characteristics and reduced ficker and audible noise. When discussing outdoor lighting characteristics, two metrics are commonly used: correlated color temperature (CCT) and color rendering index (CRI). In addition, surrounding visual conditions infuence the way we perceive light in the outdoor environment. WARM COOL Figure 2. CCT indicates the warmth or coolness of a light’s apparent color. Note how the high-pressure sodium light on the left in this photo has a warm CCT while the metal halide lighting on the right has a cooler CCT. 8 Photo: Kathreen Fontecha / CLTC, UC Davis Figure 3. CIE 1931 x,y chromaticity (color) space, with the Figure 4. These photos were taken before and after a streetlight chromaticities of blackbody light sources of various temperatures retroft in San Jose, CA. The pre-retroft low-pressure sodium lights shown as the locus plot. (top) have a low CRI while the post-retroft LED lights (bottom) have a high CRI. A more in-depth perspective on color specifcation uses the International Commission on Illumination (CIE) 1931 x,y chromaticity diagram (fgure 3). Here, specifc color matching can be achieved by plotting the chromaticity coordinates of light sources and comparing how close those points are to the reference light source (represented by the black line cutting through the middle of fgure 3). Color Rendering Index (CRI) The color rendering index is used to describe how accurately a light source renders colors. CRI uses eight standard color samples to compare the color rendering ability of a light source (such as a fuorescent or HID lamp, etc.) to that of a reference light source. The color of each sample is measured under the test light source and the reference light source, both with the same CCT. The degree of color shift between the two sets of measurements is calculated and grouped as an average. This average is subtracted from 100 to produce the CRI value. CRI is expressed as a number on a scale with no units. CRI ratings range from 1 to 100. A CRI rating (above 80) denotes more accurate color rendering ability. Any light source appears to emit a single color, but in reality, a light source emits a broad range of colors that the eye blends together. This spectrum deconstructed into its individual colors is called spectral power distribution, or SPD. SPD is usually represented as wavelengths in the visible spectrum. The visible spectrum of light wavelengths ranges from approximately 380 – 780 nm. CCT and CRI are two ways of distilling a light source’s SPD into a single number. 9 Photo: International Commission on Illumination Photo: Pacifc Gas and Electric; Energy Solutions Photo: Pacifc Gas and Electric; Energy Solutions Visual Conditions: Scotopic, Photopic and Safer Outdoor Areas Mesopic Efciency Functions An outdoor lighting retroft can improve the visual environment How the human eye perceives the SPD of a light source is also and make outdoor spaces feel safer and more secure. Many critical. This perception is, in part, dependent on the SPD of people assume that “brighter is safer,” but studies have shown the source and the surrounding visual conditions. There are that increased illuminance is not always benefcial. three general types of visual conditions: photopic, scotopic Too often, excessive lighting can lead to glare and and mesopic conditions. overillumination. When designing outdoor lighting systems, Photopic conditions account for the majority of applications, the quality of light, not just the quantity of light, is important including all applications occurring under moderate to for safety. Outdoor lighting designs should aim to reduce well-lit conditions; scotopic conditions occur at very low light glare, employ appropriate contrast ratios, and create “zones of levels, such as occur in a forest on a cloudy night; and mesopic recognition” in order to increase safety and perceived security. conditions occur somewhere in between. Mesopic conditions The visual needs of the area’s intended occupants should account for the majority of nighttime lighting conditions in also determine what type of illumination is installed. suburban and urban outdoor environments. The color temperature and quality of diferent light sources Viewing-condition efects are captured through a luminous can also afect people’s perception of brightness. As a result, efciency function, which is applied to the SPD to get it is important to understand who will use the space being lit, a representation of what the human eye actually sees under when they will use it and for what tasks or purposes. real-world conditions. There are three diferent luminous efciency functions, one for each of the three diferent visual conditions. Minimal Light Pollution and Light Trespass Light pollution and light trespass occur when nighttime Photopic and scotopic luminous efciency functions are well lighting strays from its intended target, spreading into the defned, although the photopic luminous efciency function sky or intruding on surrounding areas. Research continues is the only function accepted for use in standard lighting to indicate the adverse efects of light pollution on people practice. The mesopic luminous efciency function is more and wildlife. An important reason for completing an outdoor complex. Work is ongoing to better defne and account for lighting retroft is to reduce the negative environmental visual conditions in the mesopic range. impacts of an existing lighting system. More on this topic, and Light level measurements are calculated based upon the important role that national parks can play in reducing application of the luminous efciency function to the SPD light pollution, is provided in the section on “Preserving Dark of a particular light source. Application of one function or Skies,” presented in Part 6 of this guide. the other has the efect of biasing the measured light level; thus, it is important to understand which function has been applied to obtain a particular light output value. The lighting industry usually provides light output values using the photopic luminous efciency function. Figure 5 shows the scotopic and photopic luminous efciency functions. Figure 5. Scotopic and photopic luminous effciency functions 1.00 0.08 SCOTOPIC 0.60 PHOTOPIC 0.40 0.20 505 nm 0.00 400 500 600 70 0 WAVELENGTH (NANOMETERS) Source: The Lighting Handbook, 10th edition, Illuminating Engineering Society, Figure 5.5 10 LUMINOUS EFFICIENCY