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International Dark Sky Community:

Stärepark Pëtschent Municipality Putscheid, Luxembourg September, 2025

Executive Summary The municipality of Putscheid, nestled in the northern region of Luxembourg within the Our Nature Park, is applying for recognition as a Dark Sky International Community under the designation «Stärepark Pëtschent» (Star Park Putscheid). With its rural charm, minimal light pollution, and a strong commitment to sustainable practices, Putscheid offers an exemplary model for preserving the natural night sky. Putscheid, covering approximately 27.1 km² and home to 1,176 residents, is part of the Our Nature Park, a nature park dedicated to environmental conservation and sustainable tourism. The municipality, which has already made significant strides in light pollution reduction, has implemented a series of lighting management policies to minimize artificial light impacts. These include retrofitting streetlights to shielded LEDs, utilizing dimming capabilities for public lighting, and advocating for responsible private lighting among its residents. As part of its commitment to reducing light pollution, Putscheid has carried out various initiatives, such as a light pollution reduction study, with the help of drone technology and luminance mapping, and the establishment of permanent sky quality measurement tools. The Our Nature Park has also supported these efforts, creating a model for other regions to follow in combating light pollution.

The community is supported by various national and local authorities, including the Mayor of Putscheid, the Minister for Energy, and the Minister for Tourism, all of whom endorse the application. These efforts reflect Putscheid’s ongoing dedication to preserving the natural beauty of its landscapes and protecting its unique night sky, with the broader goal of becoming Luxembourg’s first Star Park. By achieving IDSC certification, Putscheid aims to enhance local biodiversity, reduce energy consumption, and serve as a model for sustainable development and environmental stewardship in the region. The present application is formally submitted based on the International Dark Sky Community (IDSC) Guidelines 2018, which provide the established framework and criteria for recognition, ensuring that the municipality’s measures are aligned with internationally acknowledged standards of night sky protection and sustainable lighting practices. This application was authored by the ECO department of the Syndicate for Development and Management of the Our Nature Park (Syndicat pour l‘Aménagement et la Gestion du Parc Naturel de l‘Our).

Additionally, the municipality has made strides in public outreach through educational programs, events, and a concerted effort to engage the community with campaigns on reducing light pollution. Putscheid also envisions the future development of «Light on Demand» systems to ensure energy-efficient, demand-responsive street lighting, which further aligns with DarkSky International principles.

For more information about the different projects and this application feel free to contact: Mr. GLIEDNER, Daniel Light consultant daniel.gliedner@naturpark-our.lu +352 621 575 263

Mr. HEINZIUS, Fabian Energy and climate consultant fabian.heinzius@naturpark-our.lu +352 621 966 036

We hope that this nomination application meets the requirements of the reader while providing enjoyable and informative read.

Adress Number, Street 12, am Parc Municipality Hosingen Postal Code L-9836 Country Luxemburg

LIGHTS OUT! International Dark Sky Community: Stärepark Pëtschent

Table of Contents 1

Scope and Motivation 1.1 Proposal 1.2 Motivation

4 5 6

2 Letter of nomination and letters of support 2.1 Nomination 2.2 Support 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6

Fabienne Sinnes-Huberty, Mayor of Putscheid 7 Emile Eicher, Chairman of the Our Nature Park 9 Lex Delles, Minister for Small and Medium-Sized Enterprises, Minister for Tourism 10 Claude Turmes, Minister for Energy ; Minister for Spatial Planning 11 Fernand Zanter, President of the Syndicat d ’Initiatives Stolzembourg 12 Partnership agreement between SEO and Our Nature Park 13

3 The Our Nature Park and the municipality of Putscheid 3.1 The Grand-Duchy of Luxembourg: A Land of Rich Heritage and Modern Marvels 3.2 The Our Nature Park 3.3 The municipality of Putscheid (Pëtschent) 3.3.1 3.3.2

General description Tourism & Industry

National Street lighting Municipal Street Lighting A video of the adaptive lighting in action can be found here. Private Lighting

5 Measurements of the night sky quality 5.1 Satellite Measurements 5.2 Permanent measure instrument: All Sky Camera 5.2.1

5.3

14 17 21

Telescope Encoder and Sky Sensor

30 30 30 31 38 39

43 43 43 45

Sky quality measurements

5.3.1

Professional SQM Measurement

6 Education, research and public outreach 6.1 Events 6.1.1

6.2 6.3

21 25

4 Community commitment 4.1 Examples of the Application of Lighting Management Policy 4.1.1 4.1.2 1.1.1 4.1.3

6 6 7

49 49

Other Conferences and Events

Brochures Articles and other publications

54 56

7 Appendix: A) Lighting Management Policy : original Lighting Management Policy : Translated version B) Lighting Inventory

57 57 72 88

International Dark Sky Community: Stärepark Pëtschent

Scope and Motivation

1.1 Proposal With the present application, the municipality of Putscheid, is applying for a certification as “INTERNATIONAL DARK SKY COMMUNITY” within the municipal boundaries of Putscheid. Putscheid is a rather small municipality located in between majorly light polluted regions of Europe, within the beautiful country of Luxemburg. A map of central Europe and Luxembourg’s location can be found in the chapter 3.1.

Light pollution map of central Europe with Putscheid int its centre (red pin) Source : Lightpollutionmap

International Dark Sky Community: Stärepark Pëtschent

In the event of a successful application, the municipality would like to call itself in Luxembourgish “Stärepark Pëtschent” (English: “Star Park Putscheid”). The municipality covers a territory of approximately 27,1 km² (approx. 10,47 sq mi).

Clervaux

Planned DarkSky Community

Wiltz Vianden Esch/s/Sûre

Diekirch

Echternach

Mersch

Luxembourg

Esch/s/Alzette

Map of Luxemburg showing its legal boundaries with the municipality of Putscheid highlighted. Source: geoportail.lu

International Dark Sky Community: Stärepark Pëtschent

1.2 Motivation Due to its countryside location and the relatively low level of light pollution, Putscheid offers great potential for stargazing and observing the night sky. The remote region‘s efforts to minimize artificial lighting also aid in conserving natural darkness, providing glimpses of celestial marvels on clear nights. The letter of support from the municipality’s mayor sums up the motivation of the municipality. Here is an extract from the letter: “Putscheid Commune is blessed with breathtaking natural beauty and a commitment to sustainable development. The commune’s remote location, limited light pollution, and responsible outdoor lighting policies have already made it an appealing destination for nature lovers. By becoming an International Dark Sky Community, Putscheid can take a definitive step towards safeguarding its nocturnal environment and

showcasing its dedication to preserving the night sky. The advantages of being recognized as an International Dark Sky Community are numerous and far-reaching. Preserving dark skies benefits the entire ecosystem, as it reduces the disruption of nocturnal wildlife and protects migratory bird patterns. Moreover, it fosters a sense of wonder and inspiration among residents and visitors, leading to a greater appreciation of nature and the cosmos. The Commune of Putscheid already exhibits a strong commitment to environmental conservation and sustainability. This designation will further enhance the commune‘s reputation as a responsible and forward-thinking community. It will also encourage other neighbouring areas to follow Putscheid‘s lead, thereby creating a ripple effect of dark sky preservation efforts across the region.”

Symposium “Gutes Licht” (English: good light) as part of the NIGHT, Light & more festival program. Text on Screen: Let's switch the night back on!

International Dark Sky Community: Stärepark Pëtschent

Letter of nomination and letters of support

2.1 Nomination

Dr. Andreas Hänel

International Dark Sky Community: Stärepark Pëtschent

2.2 Support 2.2.1 Fabienne Sinnes-Huberty, Mayor of Putscheid

International Dark Sky Community: Stärepark Pëtschent

2.2.2 Emile Eicher, Chairman of the Our Nature Park

International Dark Sky Community: Stärepark Pëtschent

2.2.3 Lex Delles, Minister for Small and Medium-Sized Enterprises, Minister for Tourism

International Dark Sky Community: Stärepark Pëtschent

2.2.4

Claude Turmes, Minister for Energy ; Minister for Spatial Planning

International Dark Sky Community: Stärepark Pëtschent

2.2.5

Fernand Zanter, President of the Syndicat d ’Initiatives Stolzembourg

International Dark Sky Community: Stärepark Pëtschent

2.2.6

Partnership agreement between SEO and Our Nature Park

The partnership agreement below states: This award confirms that the partner demonstrates a strong commitment to sustainable regional development and is committed to protecting and enhancing the natural, cultural and intangible heritage of the region.

International Dark Sky Community: Stärepark Pëtschent

The Our Nature Park and the municipality of Putscheid

3.1 The Grand-Duchy of Luxembourg: A Land of Rich Heritage and Modern Marvels Nestled in the heart of Europe, the Grand Duchy of Luxembourg is a small yet captivating country that embodies the spirit of timeless charm and contemporary progress. With a history stretching back centuries, Luxembourg is a testament to resilience and cultural diversity. Its picturesque landscapes, stunning architecture and thriving economy make it a truly unique destination worth exploring. Luxembourg‘s history is a complex tapestry of conquests, alliances, and territorial shifts. Beginning

as a medieval fortress and emerging as a prominent European power in the 17th century, the country has witnessed the rise and fall of empires. It was once the centre of the powerful House of Luxembourg, which produced notable figures such as Holy Roman Emperor Charles IV. Throughout the centuries, various European powers have governed Luxembourg, resulting in an inheritance of castles, fortified walls, and historic monuments. The UNESCO World Heritage site, iconic Luxembourg

Map of Central Europe, Luxembourg encircled Source: Google Maps

International Dark Sky Community: Stärepark Pëtschent

City, is a living proof of its affluent history. Its striking fortifications, elegant bridges, and picturesque casemates recount tales of a long-gone era. Despite its small size, Luxembourg is a melting pot of cultures and languages. It embraces three official languages: Luxembourgish, French, and German. This linguistic diversity reflects the country‘s cosmopolitan character and fosters a sense of openness and inclusiveness.

Luxembourg boasts a thriving and multifarious cultural scene featuring a vast selection of museums, art galleries, and theatres. The renowned Philharmonie Luxembourg draws music enthusiasts worldwide to its exceptional performances. The cultural calendar showcases festivals celebrating music, film, and the culinary arts, affording visitors the opportunity to indulge in the country‘s cultural richness. Luxembourg possesses not only an abundance of historical and cultural riches but also breathtaking natural beauty. Its rolling hills, dense forests and meandering rivers create a picturesque landscape that attracts outdoor enthusiasts. The Mullerthal Region, aptly nicknamed „Luxembourg’s Little Switzerland,“

Panoramic view of Luxembourg city‘s Grund and its fortifications (UNESCO world heritage), at dusk, in Luxembourg. © Joshua Schoos / Ville de Luxembourg

International Dark Sky Community: Stärepark Pëtschent

amazes visitors with its stunning rock formations, richly mossed woodlands, and scenic trails leading to unparalleled vistas. The Moselle Valley, famous for its vineyards, offers visitors an opportunity to indulge in the finest wines while admiring the picturesque countryside. The country has an intricate network of hiking and cycling trails, allowing explorers to enjoy its scenic beauty at a relaxed pace. Luxembourg is not only known for its history and scenic beauty, but also for its remarkable global economic influence. The country‘s strategic positioning and business-friendly climate have propelled it to become a financial hub and international trade centre. With a steady economy and low taxation, the nation has allured multiple multinationals and institutions, thus substantiating its prosperity.

As a founding member of the European Union, Luxembourg has a crucial role in shaping Europe‘s affairs. It hosts various significant EU institutions, including the European Court of Justice and the European Investment Bank, ensuring its continued influence in the continent‘s political landscape. In conclusion, Luxembourg blends its rich historical heritage with modern advancements. The country boasts picturesque villages, magnificent castles, and lush landscapes that exude a fairy-tale charm. Additionally, the thriving economy and global significance of Luxembourg showcase its progress and standing on the international stage, making it a country of contrasts and harmonies. Visitors are invited to explore the diverse offerings and experience the timeless allure of this unique country.

Geosite Huel Lee in Berdorf, © Raymond Clement

International Dark Sky Community: Stärepark Pëtschent

3.2

The Our Nature Park

The Our Nature Park is a designated area located in northern Luxembourg. It is one of the three nature parks in the country, alongside the Upper Sûre Nature Parc and the Natur- & Geopark Mëllerdall. Established in 2005, its goal is to preserve and promote the region‘s cultural and natural heritage.

The Our Nature Park is situated in the northernmost part of Luxembourg, bordering Belgium and Germany. It covers an area of approximately 491 square kilometers, encompassing a diverse range of landscapes, including forests, meadows, rivers, and quaint villages.

Map of the Our Nature Park member municipalities, colored in green. Source: Our Nature Park

International Dark Sky Community: Stärepark Pëtschent

Lycaena phlaeas, spotted in the Our Nature Parc, © Raymond Clement

The park‘s diverse habitats sustain a thriving range of plant and animal life. Its woodlands house an assortment of arboreal species, including beech, oaks, and pine. The River Our and its tributaries furnish crucial aquatic habitats and act as a vital passageway for migratory species. The meadows and grasslands in the nature park accommodate a diverse range of floral and plant varieties, drawing in pollinators such as bees, butterflies, and other species. Additionally, the varied habitats offer nourishment and refuge for multiple animal species, including deer, foxes, wild boar, and various bird species.

The Our Nature Park is esteemed not only for its scenic splendour but also for its cultural significance. The area features charming villages, historical sites, and classic farm steads that offer insight into the countryside‘s traditions and history. Numerous locales have been diligently preserved as a reminder of the region‘s cultural legacy. The Our Nature Park provides visitors with an array of outdoor pursuits to appreciate and experience the region‘s natural splendour. The park has extensive hiking and cycling paths that traverse its scenic landscapes and picturesque towns. Additionally, guided nature excursions and educational programs are offered to raise awareness about the park‘s distinct ecosystems and conservation initiatives.

International Dark Sky Community: Stärepark Pëtschent

The Our Nature Park is dedicated to fostering sustainable tourism and safeguarding its natural resources. To this end, the park works closely with local communities, stakeholders, and environmental organizations to execute conservation measures and promote the responsible utilization of its natural assets. In line with this mission, the park maintains an intercommunal approach based on solidarity and cooperation, engaging actively with local partners and stakeholders. Over recent years, the Our Nature Park has grown to employ 29 staff members and now operates in dedicated departments, including the ECO Unit.

The ECO department (Energy Climate Our), established in 2021, is committed to climate protection by standardizing regional measures and acting as a local contact point for climate-related inquiries. Among other responsibilities, the ECO department supports the processes of the Climate Pact, engages in interregional and national dialogue, and serves as an advisory centre for municipalities on climate projects. By aligning with the Climate Pact, the Our Nature Park and its member municipalities aim to achieve both EU and Luxembourg national climate protection targets at a regional level. The ECO department also prioritizes reducing light pollution, a key aspect of its climate strategy.

“Ourtalschleife” in Bivels, © Raymond Clement

International Dark Sky Community: Stärepark Pëtschent

In combining efforts to combat light pollution with climate change mitigation, the ECO team was formed in 2021, supporting these objectives within the nature park’s framework.

For more information about the Our Nature Park, visit the following website: www.naturpark-our.lu .

ECO-Team of the Our Nature Park. © Patricia Lefèber

International Dark Sky Community: Stärepark Pëtschent

3.3 The municipality of Putscheid (Pëtschent) 3.3.1

General description

Key Data :

Putscheid is a small locality in the north of Luxembourg which is one of the municipalities within the Diekirch district and comes under the jurisdiction of the Canton of Vianden. The settlement sits amidst charming landscapes of the Ardennes region, enveloped by lush woodlands, undulating hills, and winding waterways. Putscheid covers an area of approximately 27 square kilometers and boasts a tranquil natural landscape. The municipality is near the borders of Germany and Belgium, allowing for convenient exploration of crossborder regions and attractions.

Number of Inhabitants

1.176

Area

27,1 km² (Approx. 10,47 sq mi)

Population density

43 inhabitants / km²

Altitude

220 – 550 metres above sea level

Total installed power for public lighting

4.334 W

Satellite picture (© geoportail.lu) of Putscheid

International Dark Sky Community: Stärepark Pëtschent

Within the district of Putscheid, seven attractive villages can be found throughout the landscape. These quaint villages retain their rural character and traditional architecture, offering visitors an authentic glimpse into the rural life of the region. The villages are immaculately maintained, with several showcasing historic buildings, village squares, and tranquil streets.

The villages of Putscheid and Stolzembourg are described below as examples to give the reader a better impression of the municipality of Putscheid.

7 villages

MERSCHEID Mierschent BIVELS NACHTMANDERID E H C S G R U O B M E STOSLtZolzebuerg GRALINGEN Groljen PUTSCHEID WEILER Pëtschent Weller 2 „Lieu-dit“

Poul

G ro e s t a e n

International Dark Sky Community: Stärepark Pëtschent

The Village Putscheid Putscheid first appears in official records in 1502 under the name „Putscheyt“. The name Putscheid describes a place in a clearing near a spring or well. During the feudal period, Putscheid, together with Stolzembourg, was subordinate to the lords of Stolzembourg, Clervaux, Brandenbourg and Bourscheid. For some years now, Putscheid, the municipality‘s administrative centre, has been the smallest village in the municipality of Putscheid and the smallest administrative centre in the Grand Duchy of Luxembourg.

In the 1980s, Putscheid was home to around twenty people, with an average age of 55. Today, 130 people live here, with an average age of 22. This change is mainly due to the completion of the „Neit Wunnen“ ecological housing estate.

P U T S C H E ID Pëtschent

The village of Putscheid. ©municipality of Putscheid

International Dark Sky Community: Stärepark Pëtschent

The Village Stolzembourg This old postcard gives the reader a good impression of what Stolzembourg looks like. Stolzembourg is located in the charming valley of the Our, 6 km upstream from the tourist town of Vianden. The varied landscape invites all nature lovers to walk through vast forests and narrow valleys. In the village, the bell tower was built before 1585 and the church bear witness to the long history of the village and its parish. The castle itself lies on a rise in the village centre. For the first time, the castle was destroyed by the governor Antoine Croy in 1454, and in 1679, a second

time, by the troops of Louis XIV. It was rebuilt in 1898 in the Scottish style. Today, the castle is privately owned. Description of Stolzembourg as described on the website of the “Syndicat d’ Initiative Stolzembourg”: https://www.stolzembourg.lu/stolzembourg-tourism/

STOLZEMBOgURG Stolzebuer

Old postcard showing the village of Stolzembourg Source: https://www.stolzembourg.lu/stolzembourg-tourism/

International Dark Sky Community: Stärepark Pëtschent

3.3.2

Tourism & Industry

Putscheid is a delightful municipality in Luxembourg, where the beauty of nature intertwines with a rich cultural heritage. With its charming villages, diverse outdoor activities, and serene landscapes, Putscheid beckons travellers seeking an authentic and tranquil escape in the heart of the Ardennes. Whether exploring the wooded trails, embracing local traditions, or simply soaking in the peaceful ambiance, Putscheid offers a unique and refreshing experience in this beautiful corner of Luxembourg.

Putscheid‘s picturesque situation renders it an ideal spot for those keen on outdoor pursuits. The encompassing forests and rural landscapes present a plethora of chances for trekking, cycling, and nature strolls. Four official hiking paths (up to 15 km) invite to discover nature. The adequately demarcated paths facilitate visitors to discover the scenic allure of the Ardennes, and the innate serenity of the region makes it a flawless haven for those in pursuit of leisure.

The OURDALL Promenade / Map of the 35 km long cycling path in and around Putscheid

International Dark Sky Community: Stärepark Pëtschent

The Copper Mine 1.5 km away from Stolzembourg are the remains of the former copper mine. For more than 500 years, the copper-bearing veins of the „Klangbaach“ have attracted several investors to Stolzembourg, although it is far from any industrial district. The geological path permits the evaluation of the remains by putting back the mining site in its historical, geological and environmental state. In recent years, a part of the underground galleries has been made accessible to the public. 50 meters below ground, the visitors learn about the difficult degradation of the copper ore. Today, the copper mine is open for guided tours from Easter to the end of October. The visit includes access to a museum, which provides information about the region‘s geology, the mine‘s history, and the various mining periods. Between the museum and the copper mine is a geological trail which was recently renovated.

Map and picture of the copper mine © Syndicat d‘Initiative Stolzembourg

International Dark Sky Community: Stärepark Pëtschent

The entrance and the inside of the copper mine. © Syndicat d ‘Initiative Stolzembourg

International Dark Sky Community: Stärepark Pëtschent

Pumped-storage power plant The natural conditions offered by the Our valley enabled the construction of a pumped-storage power plant capable of storing excess energy and generating the energy that is lacking. On 29th May 1951, the Société Electrique de l‘Our S.A. (SEO), was formed upon the initiative of the government of Luxembourg. At times when consumption is low, e.g. at night, with the surplus energy of the base-load power plant, water is pumped from the lower basin to the upper reservoir. At times when demand increases, the stored water is drained via turbines.

With a total output of 1.300 MW in turbine mode and 1.040 MW in pump mode, the Vianden pumped storage power plant is the second largest in Europe, stabilizing the european interconnected power grid, trough the quick reactivity Even though the production headquarters are in the neighbouring municipality (Vianden), the visitor centre is in the municipality of Putscheid. The visitors‘ gallery and underground power station can be visited on demand.

Pumped-storage power plant now and then Power Station © SEO

International Dark Sky Community: Stärepark Pëtschent

Wind Park Pëtschent – Housen Not only hydropower but also wind power is used in the region of the Our Nature Park and therefore also in the municipality of Putscheid. The company SOLER operates a wind farm with a total production capacity of 16,7 MW on the territory of the municipality of Putscheid and the neighbouring municipality of Parc Hosingen.

Wind Park Housen-Pëtschent S.A. 4x Enercon E115 High of 135 meters Rotor diameter 115 meters Power 3 MW 2x Enercon E 92 High of 138 meters Rotor diameter 92 meters Power ,35 MW Total power of 16,7 MW producing 35,9 Milliounen kWh ~ 8000 households Which leads to a CO2 savings of 23.500 tons per year

www.soler.lu

Wind turbine in the municipality of Putscheid © SOLER

International Dark Sky Community: Stärepark Pëtschent

Community commitment

4.1 Examples of the Application of Lighting Management Policy 4.1.1

be in 2.200 K, to reduce light pollution, protecting wildlife, supporting human health, accepting a higher energy consumption of approximately 15% compared to 3.000 K LED.

National Street lighting

For the purposes of clarity and comprehension, it is essential to understand that in Luxembourg, the responsibility for public street lighting is divided between two principal entities: The lighting of roads of national importance is the responsibility of Ponts et Chaussées, while the lighting of municipal roads is the responsibility of each municipality. As Ponts et Chaussées is a national institution, the country-wide standards established by this entity are applied to all national roads. This results in the use of 3.000 K LED lighting. However, with the support of the former Minister for Energy and Spatial Planning, the municipality of Putscheid was able to negotiate with Ponts et Chaussées that all future new or retrofit lighting would

2025

SON-T* 70W

SON-T 100W

Corr. Color Temperature

20002200K

Power in W

120

LED 30W

To avoid conferring an advantage on any particular municipality, the national lighting of one municipality is not replaced in its entirety at one time, but rather in discrete blocks, with each municipality receiving replacement lighting in a staggered fashion. In accordance with this approach, Ponts et Chaussées initiated the replacement of public lighting in 2019, which has resulted in the current situation outlined in the table below. From 2019 to the end of 2022, Ponts et Chaussées replaced 93 streetlights with fully shielded LEDs (3.000 K), representing 34% of the municipal street lighting owned by Ponts et Chaussées. In July 2023, Ponts et Chaussées presented an update on the ongoing replacement program:

LED 30W

730/3000K 830/3000K 33

LED 40W

LED 40W LED 40W

730/3000K 830/3000K 44

Total

2200K 44

Quantity: Bivels

Gralingen

Merscheid (Putscheid)

Nachtmanderscheid

Poul

Putscheid

Stolzembourg

23 30

Stolzembourg Centrale SEO

Weiler (Putscheid)

Total Amount (pcs)

58 21

275

Total Power (W)

2.552

7.320

264

198

3.476

308

2.552 924

17.594

*SON-T: Tubular High Pressure Sodium Discharge Lamp

International Dark Sky Community: Stärepark Pëtschent

Ponts et Chaussées has indicated its intention to replace the old SON-T lamps with 2.200 K LEDs commencing in 2026. As evidenced in the table, all lighting owned by Ponts et Chaussées is already within the 3.000 K range or below.

4.1.2

Municipal Street Lighting

To comply with the lighting management plan, multiple upgrading projects have been executed in the municipality over the past few years. Further projects are currently in the planning stages. The following two examples illustrate the completed relamping/ upgrading projects. Relamping Projects: Gralingen The first village to benefit from the changeover to LEDs was Gralingen. This campaign was launched by the state authority Ponts et Chaussées, which, as described above, is responsible for the national roads (e.g. „Rue Principale“). The municipality has joined the campaign and at the same time refurbished the lighting on the municipal roads. The recently installed municipal road lighting is equipped with automatic dimming functionality. This dimming capability was pre-programmed at the factory.

The village of Gralingen Source: Google Maps

Up to +- 2019

From +- 2020 National Road

SHP-T* 100 W

Thorn Isaro Pro

115 W

40 W

2.000 K

3.000 K

10.700 lm

4.639 lm

16.000 h of usage

> 100.000 h of usage Municipal Road

SHP-T* 70 W

Thorn Isaro Pro -

85 W

19 W

2.000 K

2.700 K

6.500 lm

2.770 lm

16.000 h of usage

> 100.000 h of usage

*SHP-T : Tubular High Pressure Sodium Tubular Lamps

International Dark Sky Community: Stärepark Pëtschent

Profil de dimming programmé suivent demande client : Allumage - 20h00 :

100%

20h00 - 23h00:

70 %

23h00 - 06h00:

35 %

06h00 - 07h00:

70 %

07h00 - extinction:

100%

Dimming profile of municipal lighting in Gralingen Source: Invoice from Kaufmann & Bissen

By the conclusion of 2022, the municipality of Putscheid, in collaboration with Ponts et Chaussées, had resolved to extinguish all illumination between the hours of 1 a.m. and 4:30 a.m. Consequently, the previously described dimming profile is no longer wholly accurate with respect to the specified time frame.

landscapes by identifying and mitigating excessive artificial light sources.

Aerial Night Flights for Light Pollution Assessment: Methodology and Purpose To evaluate the impact of lighting infrastructure upgrades on light pollution, the company xirrus GmbH was commissioned to conduct measurements in the villages of Nachtmanderscheid and Gralingen. This initiative was part of the Naturpark Our‘s broader engagement in the European INTERREG project Night Light, which aims to preserve the integrity of nocturnal

Comparative measurements were carried out before and after the lighting upgrade using a commercially available drone (DJI Phantom 4), equipped with a precalibrated luminance camera. Calibration was achieved through reference to known light sources previously measured with a professional luminance meter (Gossen Mavospot-2). A Lambertian light panel (Dörr LT-6060) served as a ground-based calibration reference during each flight and was included in every captured image to ensure measurement accuracy. Images taken during the flights were analysed by identifying the top 95% of the brightest pixels and calculating their average luminance, resulting in absolute brightness values. These values enabled a direct comparison of the lighting conditions before

Retrofitted fixtures in Nachtmanderscheid Source: Google Maps

International Dark Sky Community: Stärepark Pëtschent

Retrofitting an existing lighting fixture with a downwards inclined metal bracket to achieve ULR = 0% © Daniel Gliedner

and after the intervention. From the aerial images, semi-automated light emission maps were produced, including High Dynamic Range (HDR) representations that accurately depict luminance gradients. Additionally, false-colour RGB visualizations were used to facilitate the interpretation of spatial light distribution. The comparison revealed a significant reduction in light pollution following the lighting upgrade in Gralingen, with emissions decreasing by approximately 40%. This measurable improvement highlights the effectiveness of targeted lighting interventions in minimizing artificial skyglow. In addition to drone-based measurements, satellite data from the Suomi NPP were used to identify areas that appeared anomalously bright during new moon Up to 2019

phases—specifically, those exceeding three-quarters the brightness of a full moon. While some bright spots could be directly linked to known sources, others required on-site inspections to determine their origin. Based on these findings, the report outlines recommendations for further mitigation efforts and provides a foundation for discussions with stakeholders responsible for excessive illumination. In order to select an energy-efficient LED that remains within the low blue-light „warm white“ spectrum of light colours, an LED with a colour temperature of 3.000 K was chosen. The following table provides a comparative overview of the characteristics of the existing and the new lighting system.

From 2020

SHP-T 70 W

Lightronics MAK LEDWELL2

85 W

11,7 W

2.000 K

3.000 K

6.500 lm

1.800 lm

16.000 h of usage

> 100.000 h of usage

Dimming profile of municipal lighting in Gralingen Source: Invoice from Kaufmann & Bissen

International Dark Sky Community: Stärepark Pëtschent

It is crucial to note that the existing light pole is not compatible with the objective of reaching ULR = 0%, as the lighting fixture has a 15°upwards tilt which is non adaptable. This particular type of street lighting is unfortunately quite specific and prevalent in Luxembourg, particularly in rural areas. The municipality of Putscheid still has approximately 70 poles in use. Considering the adverse environmental impact of these poles during their production and the high value placed on them by the inhabitants the municipality of Putscheid, the decision was taken not to replace them, even though they do not reach the desired ULR = 0%. To achieve this objective, the lighting fixture was modified. A “minus” 15-degree metal bracket was incorporated into the fixture to offset the 15-degree tilt of the lampshade.

Retrofitting an existing lighting fixture with a downwards inclined metal bracket to achieve ULR = 0% © Daniel Gliedner

International Dark Sky Community: Stärepark Pëtschent

Re-lamping Projects: Area - wide upgrading of the municipal lighting system In the period after the two retrofit projects previously described, the initial discussions commenced regarding the comprehensive upgrading of the municipality‘s lighting to achieve Dark-Sky conformity. The definitive decision was taken in 2022. The tender documents explicitly delineated the following criteria: Criteria

Functional lighting

Decorative lighting

ULR

< 0,5 %

CCT

2.200 K

Ra(CRI)

Minimum 70

Efficiency

>100 lm/W

Off-peak adaptation

between 0% and 100%.

In the event of failure, the LED module is easily accessible and interchangeable

2W maximum

Service life

L80B10 after 90,000h

L80B10 after 100,000 h

Interface

2 Zhaga connectors Dali driver

LED module

Stand-by power

The following luminaire was installed for the functional lighting:

Installed functional lighting in the municipality with corresponding polar distribution curve

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The following luminaire was installed for the decorative lighting:

Installed decorative lighting in the municipality with corresponding polar distribution curve

The municipal-wide re-lamping project is now in its final stages, with most luminaires already installed and operational. The luminaires were equipped with Zhaga connectors and DALI drivers, thus most of the hardware for the forthcoming „light on demand“ project is already in place. Adaptive Lighting

Pilot project Light on Demand (Outlook)

Two significant alterations to the municipal approach to street lighting have been introduced following the completion of the upgrading projects in Gralingen and Nachtmanderscheid.

In Luxembourg, the duration of darkness is approximately 4,200 hours per year, during which the street lighting infrastructure is operational. This is regardless of whether light is actually required. In some municipalities, the street lighting infrastructure has been switched off between 1 a.m. and 4:30 a.m. at the end of 2022 until today.

•

Dimming: The state-owned street lighting is dimmed by 30% (emitting only 70% of its initial value) between the hours of 10 p.m. and 5 a.m. The municipality-owned street lighting is dimmed in accordance with the above-described regimes. Night Shut-Off: The municipality of Putscheid was among the first to adopt the Ministry of Energy‘s night-time switch-off of street lighting, which was implemented at the end of 2022. Since then, all street lighting has been shut off between 1 a.m. and 4:30 a.m.

The project involves the conceptualization of a sustainable transformation of street lighting in the municipality of Putscheid, with the objective of implementing demand-responsive lighting systems. This approach guarantees that illumination is only provided when required, thereby optimizing energy consumption. A comprehensive analysis will be undertaken to ascertain the optimal times and conditions for street lighting, integrating technologies such as motion sensors and smart control systems. Test installations in the Our Nature Park area have demonstrated the potential for significant energy savings through demand-based lighting over the past

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three years. These installations have shown that with an optimal design, approximately 70 to 90% of the burning hours can be saved if the lighting is demandbased.

comprehensive community engagement activities to gather feedback from residents, address their concerns, and ensure their support. This will involve public consultations, surveys, and information campaigns to educate the inhabitants about the benefits of demand-responsive lighting and how it contributes to sustainability goals.

This initiative will consider several key factors, including public acceptance, nature conservation, energy efficiency, and the reduction of light pollution. Public acceptance is a crucial factor in the success of this project. To conclude, the project will include

The following budget table provides an overview of the upcoming tasks.

Description / €

Phase 1 20232024

Phase 2 20242025

Phase 3 End of 2025

Total

Infrastructure Technical upgrade of municipal streetlights with communication and sensor modules in the seven villages of the municipality of Putscheid (196 light points)

60.000

Installation of municipal control cabinets equipped with a gateway for autonomous demand control of lighting (1 per village)

40.000

15.000

Training for operators

5.000

Monitoring and optimization of the system during operation

5.000

Monitoring the impact of optimization measures with regard to light pollution

5.000

Municipal, regional, and national communication of actions and results (editing, layout, printing costs, presentations, visits, etc.)

5.000

Activities to raise public awareness

2.000

100.000

25.000

12.000

137.000

External Consulting and Experts Professional planning network design engineering costs project setup

Communication

Total

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The project benefits from 50% co-funding from the Luxemburgish Ministry of the Environment, Climate and Biodiversity By the end of 2024, 40% of the existing lighting has been upgraded to the Light on Demand system, and it is expected that the upgrade will be completed by mid-2025. Some villages have already been completed,

and the first conclusions can be drawn: for example, in the village of Weiler, it can be shown that in the first 30 days, 85% of the energy was saved, which means that only 15% of the working hours the lights were switched on. This is shown in this extract from the lighting management tool.

Extract from the light on demand management tool

Figure Legend: The blue bars represent the current energy consumption, while the green bars indicate the corresponding energy savings. The black curve illustrates the percentage savings relative to the total energy usage which are constantly above 80%. A video of the adaptive lighting in action can be found here.

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4.1.3

Further information and a brochure on the topic can be found at: https://www.liichtberodung.lu/de/documents

Private Lighting

Inhabitants – new buildings The requirements for the private lighting systems of Putscheid’s residents are listed in the Lighting Policies. In principle, every private developer receives an explanation of these requirements when collecting a building permit and is verbally reminded of the most important requirements for residents: •

•

Demand control should be implemented via motion sensors or timers and operating times should be restricted. Uplights must be avoided as they contribute directly to brightening the sky and disturb the night-time rest of flora and fauna in green areas. The light colour of each light source must be equal or below 3.000 K.

Thank you for your help and we look forward to a clear starry sky! With kind regards Your municipal administration Industry : SEO There is currently only one company in Putscheid that operates outdoor lighting: SEO is the operator of the pumped-storage power plant. The employee and visitor car park, as well as the outdoor facilities are illuminated.

Inhabitants – existing buildings Now that the municipality has implemented the projects described above and can set a good example, the involvement of private individuals should be increased. Several articles and events are planned specifically for the municipality of Putscheid. With the upcoming campaigns tailored to the inhabitants of the municipality of Putscheid, we hope to be able to report on upgrading successes in lighting of private households in the activity report. Here is an example of an appeal that was recently sent to all households (translated into English): Dear fellow citizens, Our municipality is planning to apply to become Luxembourg‘s 1st star park in order to protect the night sky and preserve the natural light conditions. A star park is an area where the night sky is particularly dark and therefore ideal for observing the stars. This park will not only be a place of peace and wonder but will also contribute to the preservation of biodiversity and natural biorhythms. We are asking for your support so that we can successfully realize this project. Please only install star park-friendly outdoor lighting in the future. This is characterized by warm, downward-directed light and causes little or no light pollution. In this way, together we can help to preserve the starry sky above our municipality and enjoy the beauty of the night.

Aerial view of the SEO production site at day and night ©: Google Maps / xirrus GmbH

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In 2020, SEO undertook a project to replace its outdoor lighting with LED technology in collaboration with the national lighting consultant Daniel Gliedner.

At this juncture in the project, procuring new luminaires would have been an inefficient use of resources.

A comprehensive lighting master plan was developed for the site in this regard.

To reduce the impact of the incorrect coloured LEDs, the decision was taken to dim the light as much as possible outside the working hours.

It is regrettable that the SEO had already purchased 4.000 K LEDs prior to consulting with the Our Nature Park.

All luminaires are dimmed to a minimum of 10% of their nominal output during nocturnal hours (22:30–5:00), with some reaching as low as 5%.

The following table provides an overview. Placement

Count Mounting

Type

Dimming %

Off-Peak hours

Feuerwehrgebäude

Wandmontage

Philips Decoflood

BVP636 64LED-HB/ NW DW AL 4000K

22:30h - 5h

Einfahrt zum Zufahrtsstollen 1

Wandmontage

Philips Speedstar

BGP322 T35 GRN881740 DW

22:30h - 5h

Parkplatz Nähe Zufahrt

Mastmontage Ansatz Philips

22:30h - 5h

Parkplatz hinter Verwaltungsgebäude

Mastmontage Ansatz Philips Speedstar

BGP322 T35 GRN881740 A

22:30h - 5h

Parkplatz hinter Verwaltungsgebäude

Wandmontage

Philips Speedstar

BGP322 T35 GRN881740 A

22:30h - 5h

Belüftungsstollen

Wandmontage

Philips Speedstar

BGP321/BGP322GRN88-2S740

22:30h - 5h

Trafostollen

Wandmontage

Philips Speedstar

BGP321/BGP322GRN88-2S740

22:30h - 5h

Auslaufbauwerk M11

Mastmontage Ansatz Philips Speedstar

BGP323 GRN1852S740 159W 4000K

22:30h - 5h

Eingang M11

Mastmontage Ansatz Philips Speedstar

BGP323 GRN1852S740 159W 4000K

22:30h - 5h

Zufahrtsstollen 2

Wandmontage

Philips

22:30h - 5h

Gebäude Baukolonne

Wandmontage

Philips

22:30h - 5h

Gebäude Baukolonne

Mastmontage Ansatz Philips

22:30h - 5h

Gebäude Baukolonne Treppe Bergseite

Wandmontage

Philips

22:30h - 5h

Zufahrtsweg Baukolonne zur Garage

Mastmontage

Philips

22:30h - 5h

Abfahrtsweg Baukolonne Ecke M-Werkstatt

Mastmontage

Philips

22:30h - 5h

Abfahrtsweg Baukolonne Weg mitte

Mastmontage

Philips

22:30h - 5h

Abfahrtsweg Baukolonne Weg unten

Mastmontage

Philips

22:30h - 5h

Parkplatz gegenüber Verwaltungsgebäude

Mastmontage Ansatz Philips

22:30h - 5h

Speedstar

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In addition to the primary site, SEO has a second outdoor area where an additional turbine is operational.

Although the site in question is already situated within the boundaries of the neighbouring municipality, it is nevertheless pertinent to provide a concise description of the measures implemented therein, as they serve to illustrate the commitment of the company based in Putscheid. To reduce the effects of light pollution, SEO has decided to renovate the street lighting on the access road to Machine 11 on its own initiative. The recently installed LED luminaires were equipped with Zhaga communication modules and two motion detectors, one situated at the commencement of the street and the other at its conclusion. The installation of a central control system at the light points was financed entirely by SEO with the objective of protecting the surrounding natural environment. There was no standard or national requirement that necessitated this action; the initiative was inspired by the Our Nature Park. It is estimated that the lighting system is operational for less than 365 hours per year due to the motion detectors.

Picture: Map of SEO locations Source : https://www.seo.lu/Kontakt/Kontakt

Access road to machine 11. © Daniel Gliedner

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Outlook for SEO: The efficacy of this solution is currently being evaluated, as illustrated in the photograph below. The filters were affixed to the interior surface of the cover glass. The light colour was thus reduced to 2.000 K.

As previously stated, the CCT of the luminaires utilized by SEO does not align with the DarkSky International guidelines. To comply with those, the SEO company and the Our Nature Park are currently looking into retrofitting the existing light fixtures with coloured filters from the entertainment industry, or coloured lenses.

Together with SEO, we aim to convert all luminaires to be Dark Sky compliant within the next five years, that is, by 2030 — either through the complete replacement of fixtures purchased over the past ten years or, in extreme cases, by using color filter film.

Colour Adaptation of an existing LED – Lamp © Daniel Gliedner

This solution hasn’t been employed yet on a large scale, we are working on it!

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Measurements of the night sky quality

5.1 Satellite Measurements The „Radiance Light Trends“ application provides a convenient platform for users to select a region or site and analyze trends in light emissions detected by satellites since 1992. The web application was developed under the guidance of Dr. Christopher Kyba of the German Research Centre for Geosciences (GFZ)

in Potsdam, Germany. The app was developed as part of the GEOEssential project, which is funded by the European Union‘s Horizon 2020 program. The trend line indicates a reduction in radiant flux of between six and nine percent per annum.

Light trends chart for the area of the municipality of Putscheid. Source: Lighttrends

5.2 Permanent measure instrument: All Sky Camera On Monday 25 September, the Our Nature Park inaugurated Luxembourg‘s first ‚All Sky‘ camera. This innovative technology offers a fascinating insight into the night sky and promises to enhance our comprehension of the universe. In addition to the customary meteorological observations, the camera also furnishes clear, highresolution images of the entire night sky above the Nature Park. In conditions of optimal transparency, the camera can discern a multitude of astronomical phenomena, including the configuration of the

constellations, the trajectory of the Milky Way, and the positions of the planets. The system is employed for the purpose of monitoring the brightness of the sky, thereby facilitating longterm observation of the extent of light pollution. Concurrently, the system enables more precise identification of artificial light sources through photographic means. Furthermore, the images can be utilized to identify transient phenomena such as satellites and meteors.

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Daniel Gliedner and Claude Turmes, former Minister for Energy and Spatial Planning © Liz Hacken September 25, 2023

The All Sky camera made it possible to capture the rare occurring event of an aurora borealis. The project is funded in equal parts by the Ministry of the Environment, Climate and Biodiversity and the Our Nature Park.

Aurora Borealis captured by the All-Sky Camera Putscheid on Mai 10, 2024

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5.2.1

Telescope Encoder and Sky Sensor

The data was downloaded and imported into Excel for more detailed analysis. Completely or partially clear nights around the new moon were selected to derive the zenith brightness. Clear nights can be selected by the uniform trend of sky brightness, see figure below.

In conjunction with the All Sky camera, a TESS (Telescope Encoder and Sky Sensor) was installed, which is designed to continuously monitor sky brightness, ambient conditions, and sky temperature. The data can be consulted here. After a full year of measurement, an assessment was written by Doctor Andreas Haenel.

As can be seen in the figure above, the sky brightness decreases during the night by about 0.2 - 0.3 mag/ arcsec² due to the shutdown, with the darkest values measured after midnight.

The data of the TESS-W Stars938 for the year 2024 till mid Dec 2024 from the https://tess.dashboards.stars4all.eu

The values for clear moonless nights in 2024 are shown in the table below. The darkest nights have been observed in spring when the Milky Way is low in the sky. date 2024

Zenith sky brightness between 8 – 14 May, 2024 (new moon was on 8th May), the time scale is Central European Summer Time (CEST). The uniform trend of the nights 8/9, 9/10 and 11/12 indicate clear nights, while the night 10/11 was cloudy. Zenith sky brightness (in mag/arcsec²) of clear partial or total dark nights in 2024 as measured with the TESS-W Stars938, time is given in Ventral European Time (CET).

time [CET]

mag

10.1