Puerto de la Cruz, Canary Islands, Spain

PUERTO DE LA CRUZ CITY, CANARY ISLANDS, SPAIN

Bright stars in a dark sky

By Chus Rodríguez

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© Enrique Lledó

© Juan Aroca

The Spanish town of Puerto de la Cruz Spanish, a tourist hotspot in the Canary Islands, needed to upgrade its lighting to LEDs to reduce its energy costs, improve its citizens’ quality of life, and reduce light pollution — all while maintaining the area’s continued international recognition for the quality of its night-time sky for astronomical observations. Signify and the Canarian Institute of Astrophysics made this possible by using the ClearStar system to reduce the levels of light emitted in the blue spectrum.

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© Enrique Lledó

High levels of light in the night skies of cities all over the world cause problems both for scientists and for astronomy lovers.

Observing the Milky Way is becoming increasingly difficult because excessive light pollution is hiding it from human eyes. The Canary Islands host unique observatories unparalleled anywhere else on the planet, and these provide exceptional opportunities for observing the stars. The islands want to care for this open window to the universe and maintain their status as some of the world’s best sites for astronomical observation. Therefore, the Institute of Astrophysics of the Canary Islands (IAC) well-known in the international scientific community — is striving to avoid light pollution as far as possible.

In the very popular tourist area of the Spanish municipality of Puerto de la Cruz (located in the north of Tenerife), Signify had a project that involved more than just the standard conversion of the city’s streetlights to LED technology. It also had to innovate in order to adapt the entire design to fulfill the strict ‘Heaven’s Law’ (Ley del Cielo). This

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pioneering law — designed to protect the quality of night skies for astronomical observation — was implemented in 1988 and is recognized worldwide as the most complete set of light, radioelectric, and atmospheric pollution regulations.

According to Javier Diez de Castro, IAC’s technical director, “The regulations for astronomical observation require the replacement of all polluting lighting, to prevent contaminating light reaching the observatory and adversely affecting the observations. The streetlights have been replaced with LED lamps which emit a light spectrum unaffected by blue light and which now include filters that minimize blue light as much as possible”. This forced the Signify team, in collaboration with the IAC, to find the right balance between the lighting needs of the urban population and respecting the need for celestial darkness.

This contrast led Signify to create its own ‘light recipe’, made possible by using filters that stop the blue light in the spectrum — the main source of light pollution.

Finding perfect harmony between Canarian citizens’ needs, commercial and ‘star’ tourism, and the requirements of the scientific community, guided by the need to respect Heaven’s Law, was a huge challenge. The municipality of Tenerife, whose previous lighting system had been installed in the 1950s, now sees the change as an ‘added value’. This relatively small island destination did not have to sacrifice its popular tourist industry in order to continue being an international point of reference for astrophysical observation.

As Lope Alfonso, former mayor of Puerto de la Cruz, put it, “The Canaries are unique for astronomical observation and so we must take care of this place. We tried to make sure the streetlights had the least possible impact on our citizens. This work was very difficult because we had to try to get the LEDs to emit a very specific spectrum of light resembling that of the sodium lamps we had had up until then.

An academic study of the changeover in Puerto de la Cruz highlighted that this municipality had reduced its levels of light

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By August 2018 the following two light recipes have been certified: Light recipe

Ra

Tc (K)

Recipe 518

48

1800

Recipe 420

36

2000

Light spectrum Recipe 518

360

400

450

500

Spectra: Recipe 420

550

600

650

700

750

800

360 400

Spectra: Recipe 518

360 400

450

500

Light spectrum Recipe 420

550

600

650

700

750

800

360

400

450

500

550

600

650

700

750

800

Wavelength (nm)

Wavelength (nm)

The luminaire efficiency is 24% higher compared to amber polycarbonate solutions. This luminaire efficiency depends on the type of luminaire, as shown in these two examples:

Recipes 518 and 420, certified in August 2018, met the IAC’s requirements and provided quality lighting for observers, city inhabitants, tourists, and drivers alike, all with a 24% higher performance than that of the previous amber polycarbonate streetlights.

pollution the most of all the islands. It was very beneficial.” He added. “If all the lighting on the island were changed, we would have a much cleaner sky.”

For Mar Gandolfo, Signify’s training manager and a specialist in the preservation of dark night skies for the Spanish Lighting Committee (CEISP), the project was about going further. “We have been working with the Astrophysical Institute of the Canary Islands for many years”, she said. “We want to understand our client’s needs and respond to them with our energy-efficient products and in doing so, also preserve the night sky. This time we developed a more complex product than those previously available. We had to do a lot of work to find the balance between the best energy-efficient option and the best night sky quality in the Islands”, she went on.

The project, which played a part of the greater goal of making Puerto de la Cruz a smart city, included a total of 6,000 light points distributed throughout pedestrian areas, especially on the coast (where tourism is most concentrated), high

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450

500

550

W

Wavelength (nm)

Luminaire

Luminaire efficiency Recipe 518 (lm/W)

Luminaire efficiency Recipe 420 (lm/W)

ClassicStreet

59-63

77-83

DigiStreet

79-86

99-108

mountainous areas, rural areas, and on to respond to citizens and therefore also ring roads.

Signifyrecipe chose Philips Luma and to well-being”. Lope Alfonso added, The light is available intheir combination Classic Street with LED technology for “Current management systems allow with various Philips LED luminaries 4,500 of these streetlights and maintained specific levels to be recorded before and sodium vapor lighting for the remaining after midnight, thus reducing light pollution”. designed and urban applications 1,500 lights. They for are allroad connected to the Interact City system, which allows each recipe developed for Puerto are certified by the InstitutoThe delighting Astrofísica point to be controlled individually. The de la Cruz by Signify achieved the timing the lighting can be adapted, objectives and made it possible to de ofCanarias (IAC). or even made sensitive to pollution levels reconcile these with citizens’ everyday or to public-road, parking, irrigation, lives and the thousands of tourists that gardening, and traffic-light systems. This visit every year. They also fit in with resulted in savings of more than 60% the suggestions from the IAC and the and gave the municipality complete different observatories in the region, management control of its lighting system. thus demonstrating that a smart city can serve its citizens while also protecting Such management possibilities have very the environment. useful maintenance advantages because they provide detailed information ClassicStreet Villa LED about Harmony LED Quebec LED incidents and information consumption in real time. As the City Council itself declared, “Interact is intelligent and efficient. It allows us to leverage resources to provides services to citizens while spending as little as possible. For Puerto de la Cruz, the commitment to Signify represents an advance and an improvement in the quality DigiStreet ClearWay gen2 LumiStreet and of the night sky as well asLuma in our ability UniStreet

Javier Diez de Castro, IAC technical director

© Juan Aroca

© Juan Aroca

© Juan Aroca

“The streetlights have been replaced with LED technology lamps which emit a light spectrum unaffected by blue light”

Client Municipality of Puerto de la Cruz Astrophysics Observatory of Canary Islands – IAC Lighting designer Yanes Ingenieros Installer Imes APi Lighting solutions Philips Luma Philips ClassicStreet Philips Villa LED Philips MileWide Lighting system Interact City Websites www.puertodelacruz.es www.iac.es www.yanesingenieros.es www.lighting.philips.com www.interact-lighting.com

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