In a recent work session of the Salida City Council, the city’s leadership heard two presentations related to city lighting, including a solar Street Lighting Evaluation Update and a Dark Sky Presentation. The session was arranged to help staff plan potential next steps related to city energy use and lighting improvements.
Prior to the past year when the city, together with consulting firm Clanton & Associates (C&A) worked to develop standards for solar lighting options, the consultant had presented an overview of how to manage public and private lighting within the city limits. The city council has also expressed interest in learning more about “Dark Sky” initiatives in other Colorado communities and considerations if a program would be proposed here.
Solar Lighting Options
Salida began this review of the comparison of street lighting “on-grid” vs. solar costs with this fact: Xcel-owned streetlights have a significantly higher 15-year system cost than solar options.
C&A reviewed the pros and cons of solar lighting from two resources: Greenshine New Energy and ClearWorld. Greenshine is traditional solar lighting, consisting of an arm-mounted battery box and arm-mounted photovoltaic (PV) panel. It uses a lead-acid battery with a six-year life. It is considered “tried and true, but also might be more than necessary for a rural city.
The ClearWorld product is a pole wrap system, consisting of a 360-degree wrap of the pole. Most of the light pole is covered in a solar cell and there is no battery box or solar panel to deal with. It uses a lithium-ion battery, with a longer system autonomy. It was compared to a Tesla battery. This system is considered “luminaire-agnostic” — giving the city more flexible design options to fit the performance needs and aesthetics of each site. A luminaire’s function is to direct light to appropriate locations, without causing glare or discomfort.
During the discussion of the lighting system types, it was noted that the arm-mount PV panel lighting is slightly cheaper, but that in some shading situations (if there is nearby tree cover or building construction), the panel must be re-aimed. The protruding PV panel is subject to damage or wear from the high winds typical in Salida, battery life is shorter (increasing replacement labor costs), and there are limited luminaire options.
The ClearWorld system has no panel to aim and has a longer battery life. A big asset is that a historical type light fixture can be set on this type of pole, which would be in keeping with the historic district downtown. The downside: the initial cost is higher and the batteries are more expensive. Over a 15-year life, the total system operating cost is still lower than Greenview.
Both systems offer a Bluetooth-based monitoring system; meaning that a Salida Public Works staffer could walk up to it and set light levels, by daypart or area of town, and that helps manage the battery life, ensuring enough sun exposure to recharge. Both offer the possibility of technology expansion, referred to as a “smart city’ capability. These features could include 5G Cellular Antenna, Wi-Fi Hot Spots, Closed Circuit TV (CCTV) or Environmental Sensors.
Until recently it hadn’t been considered a worthwhile exercise to compare the costs of on-grid versus solar lighting, but that has changed. The battery replacements are a one-time larger sum, but they are considered attractively priced, taking onto account the overall long-term cost of operation. And as the consultants explained. ‘The extra cost for historical style fixtures is an investment in the quality of your city.”
Among questions from city officials, Treasurer Merrell Bergin asked which system is more robust in cold weather. The answer: the lithium-ion battery, because lead-acid batteries degrade faster in temperatures often seen in local winters here.
Regarding a question concerning responsibility for maintenance, it was confirmed that Xcel Energy would handle this, and would train the City of Salida staff to replace batteries. Because there have been significant improvements in LED lighting, moving in the direction of solar lighting means that it can become even more cost-efficient over time. Answering safety and environmental questions, the consultants stated that lithium-ion batteries in lighting systems also have fire suppression built into them (unlike those in phones or laptops), and the batteries are recyclable.
Clanton & Associates President Dan Saunders discussed historic fixtures and bulb choices, explaining that color and spectrum of light is important, adding that the blue spectrum of light impacts the human circadian rhythm, as well as animals in the wild. “Anything above 4,000K (Kelvin) is an impact. The first LEDs, were too high, up to 6,000K and that is too bright [and blue-ish]. Xcel Energy replaced yours with 3,000 Kelvin (Warm White) LEDs.”
“We ask – where is light needed?” he continued. “That’s at intersection and mid-block, or areas that are commercial, and have more pedestrians. There is no need to have a lot of light at 2:00 a.m., but provide just enough light so people can see, distributing it where people need it; this also saves a lot more energy.”
He went on to point out that business signage is a component of a city’s lighting plan. “Consider limits on the brightness of sign illumination. That big Palace Hotel sign [on lower F Street], the lights on your baseball field by the river — right now they aren’t dark sky-compliant.”
Dark Sky Community Certification Explained
A special presentation explaining how communities can qualify to become part of what is called “dark sky-certified” was also given by Dani Robben, Community Connections Coordinator from San Luis Valley Great Outdoors (SLV GO).
To begin, it was noted that there is a nearby precedent in Central Colorado; Custer County and Westcliffe have claimed to be the first international dark sky community. In fact, their campaign included Crestone, La Veta, Creede, Westcliffe and Silver Cliff and they won an international award for their efforts.
Robben stated that light pollution is increasing at twice the rate of global population growth, yet so is the popularity of dark sky gazing.
The current state however, is not favorable: 8 out of 10 people live under a light-polluted night sky, so much would need to be done. Robben went on to say that 30 percent of outdoor light is wasted in the United States, with a cost of 3.3 billion dollars annually. Further, Artificial Lighting At Night (ALAN), especially of the blue-white type is impactful to human and animal health.
San Luis Valley Great Outdoors, the group that has organized in the San Luis Valley to provide outdoor recreation is proposing a dark sky “reserve” in south-central Colorado. Called the Sangre de Cristo Dark Sky Reserve, the proposed concept would stretch from the southern portion of Chaffee County on the north to Huerfano and Saguache counties to the south. It could potentially be the largest dark sky reserve in the world; some 4,000 square miles.
Communities are given five years to satisfy the criteria. Every community in the reserve would need to adopt a Dark Sky lighting management plan – county and city ordinances regulate it, but there are shared standards across the reserve region. There are seven basic policies that impact whether a community or county can become a certified “dark sky” area, where light pollution does not obscure the night sky. They include:
- Public street lighting and private property controlled by a lighting ordinance
- Community commitment (5 years to get the certification)
- Broad stakeholder support
- Dark Sky education
- Demonstrated success
- A measurement program
- Dark Sky community signs
Many people don’t realize that lighting accounts for:
- 19 percent of global energy use
- 5 percent of global greenhouse gases
- Shielding light and lowering levels actually enhances safety by minimizing glare.
- High Kelvin (blue-rich) light causes harmful glare, and threatens people, animals, and birds; dark skies are important for bird migration.
Featured image: Sand Hill cranes migrate through the San Luis Valley. Photo by John Duncan for Unsplash