Cave Lighting: a year under the French spotlight. Cave Lighting : The number one in France.

Part 1: French show caves Michel Renda - Expanding Cave Lighting in France

France is home to numerous show caves that are open to visitors and offer spectacular geological formations and prehistoric art. The country’s show caves are very well-organized under La Fédération Française du Tourisme et Patrimoine Souterrain, https://www.grottesdefrance.org/contact-federation-tourisme-patrimoine-souterrain/. FFTS includes around 80 members, encompassing mostly some of the most well known show caves in France and beyond.

Notables show caves in France :

Caves with Prehistoric art:

1. Grotte de Lascaux (Dordogne) - World-famous for its cave paintings, accessible only through replicas (Lascaux II and Lascaux IV).
2. Grotte Chauvet (Ardèche) - One of the oldest decorated caves (36,000 years old). The replica "Caverne du Pont d'Arc" is open to visitors.
3. Grotte de Niaux (Ariège) - One of the few caves where original prehistoric artworks can still be seen.
4. Grotte de Pech Merle (Lot) - Features prehistoric paintings and well-preserved traces of humans and animal activity.

Caves with spectacular speleothems:

1. Gouffre de Padirac (Lot) - A vast cave with an underground river navigable by boat.
2. Aven Armand (Lozère) - Famous for its "stone forest" of hundreds of stalagmites.
3. Grotte de Clamouse (Hérault) - Known for its intricate crystal formations.
4. Grotte des Demoiselles (Hérault) - A massive stalactite cave with stunning formations.
5. Grotte de Trabuc (Gard) - Notable for its rare "100,000 soldiers" rock formations.

Cave Lighting’s journey in France

Cave Lighting was first introduced to the French show caves in 2008, when Alexander and Luba Chrapko took part in the lighting tests in Grotte de la Verna. The company’s first major project in France came in 2010 with the lighting renovation of Grottes de Clamouse, where Cave Lighting handled the complete installation. Following this successful project, there was a long hiatus until 2017, when Cave Lighting met Michel Renda during the Chameau Cave project in Morocco.

Who is Michel anyway?

Michel Renda is a renowned French speleologist, explorer, topographer and photographer. A member of the Fédération Française de Spéléologie (FFS), Michel has discovered and explored numerous caves. His photography, capturing stunning cave formations and crystals from all around the world, has been showcased at international speleology conferences (E.G., Muotathal, Switzerland, 2012).

Michel Renda has also collaborated with other cave photographers to capture the beauty of underground worlds and founded an international team La Salle (https://www.lasalle3d.com/ ).

He started his collaboration with Cave Lighting in 2018. Over the past eight years, his reputation has helped Cave Lighting gain multiple access to multiple projects in France.

To date, Cave Lighting has been able to realize 13 different lighting projects in France, including 6 in 2024.

2024 - A remarkable French year for Cave Lighting

In 2024, Cave Lighting completed six lighting projects in France:

1. Grottes de Blanot
2. Grottes d’Azé Rivière
3. Grottes d’Azé Préhistorique
4. Grottes de Thouzon
5. Grottes de St. Christophe Supérieure
6. Grottes de St. Christophe Inférieure

Part 2: Grottes de Blanot and Grottes d’Azé

Project Background

The projects at Grottes de Blanot and Grottes de Azé Rivière and Préhistorique, were commissioned by the Département de Saône et Loire in 2022 with planning overseen by Agence Rossignol. Initial discussions proved challenging, it took Cave Lighting some convincing to steer the realization of the project in the right direction.

The primary goal was to:

• Highlight the caves’s natural beauty while implementing a sustainable and energy-efficient lighting concept.
• Equip this historically and archeologically significant caves with a lighting system suitable for both scientific tours and tourism.

2.1 General description

Grottes de Blanot.

Located in Burgundy, (Saône-et-Loire)  near the village of Blanot, 20 km southwest of Cluny, Grottes De Blanot is an impressive karst cave system with:

Characteristics of the caves

• Multi-level formations reaching over 80 meters deep.
• Diverse formations: stalactites, stalagmites and sinter pools.
• Underground rivers contributing to its development.

History & Archaeology

• The caves have been used since prehistoric times, as archaeological finds
• They were discovered and explored by various speleologists in the 19th and 20th centuries.
• The caves are a protected natural monument and are used for guided tours.

Sightseeing & Tourism

• The guided tour covers 350 meters and requires a certain level of fitness from visitors.
• Guided tours are available seasonally, usually from spring to fall.
• A guided tour lasts approx. 45 to 60 minutes.
• The temperature inside is a constant 11 °C, warm clothing is recommended.

Grottes d’Azé

Also located in Burgundy, (Saône-et-Loire, France), Grottes d'Azé is one of the region’s most important prehistoric and geological sites, featuring:

Geology & Nature

• Karst cave system with multiple rooms and passages
• Underground river meandering through the cave
• Stalagmites formations (stalactites, stalagmites) in various colors
• Multiple cave entrances, including a large natural opening

Archaeological and paleontological significance

• Evidence of prehistoric human settlement (tools, fireplaces)
• Fossils of extinct animals such as the cave bear
• Discoveries dating back to the Paleolithic period

Sightseeing & tourism - Grottes de Azé Rivière

• The caves are open to visitors for guided tours
• The guide path is about 560 meters long, mostly horizontal with small ascents
• Duration of a guided tour: 1 hour
• Temperature: 11 °C - warm clothing is recommended
• Educational exhibits on geology, hydrogeology and geomorphology

Sightseeing & tourism - Grottes de Azé Préhistorique

• The caves are open to visitors for guided tours
• The guide path is approximately 190 meters long, mostly horizontal with small ascents
• Duration of a guided tour: 40 minutes
• Temperature: around 11 °C - warm clothing is recommended
• Educational exhibits on geology, archaeology and paleontology

2.2 Lighting installation

After some productive discussions, the project management decided that no torch lights, pit lights or colored DMX lights would be installed in the caves. Thanks to Cave Lighting, the caves now have a natural look, and visitors are delighted with the subtle and authentic lighting as well as the smart  switching system used in all three caves.

The installation in Grottes de Blanot began in autumn 2023, and was completed in April 2024. The work in Grottes d'Azé followed and was also completed in April 2024.

Our tried-and-tested lighting solutions were used for the installation, including LSQ2, LQP2 and LMT luminaires as well as CN2, CD2, MMC2 and CP2 control units.

• Grottes de Blanot was equipped with an analog system
• Grottes d'Azé was fitted with a PLC-controlled system with a fiber optic network.

The installation was overseen by our project manager Adrian Titus Kondacs, who led a five-person Cave Lighting team.

Part 3: Grottes de Thouzon

3.1 General description

The Grottes de Thouzon is an impressive stalactite cave near Le Thor in the Vaucluse department in the southern France. It was discovered by chance during quarry work in 1902 and has since become a popular tourist attraction.

Features of the cave:

• Natural beauty: The cave is remarkably well-preserved, featuring a vast array of stalactites and stalagmites that have formed over thousands of years.
• "Golden Cave": Due to the unique yellowish color of its stalactites, Grottes de Thouzon is often referred to as the "Golden Cave".
• Underground river: originally shaped by an underground river, traces of this water system are still visible today.
• Temperature: a constant 13°C throughout the year..

Visitor experience:

• The cave is open to visitors and can be explored on a 45-minute guided tour.
• The guideway extends approximately 180 meters.
• Impressive light installations enhance the beauty of the rock formations during the tour
• Knowledgeable guides provide fascinating insights into the geology and history of the cave.

Location and accessibility:

• Address: Le Thor, Vaucluse, Provence-Alpes-Côte d'Azur, France.
• Nearby towns: Avignon (~20 km away), L'Isle-sur-la-Sorgue.
• Ideal for a day trip, especially for families and nature lovers.

The Grottes de Thouzon offers visitors a stunning underground experience, providing valuable insights into the geological history of the region.

Part 4: Grottes de St. Christophe

4.1 General description

• The Grottes de Saint-Christophe (Caves of Saint-Christophe) is an impressive cave system in the Savoie region of France. Located in the Massif de la Chartreuse between Chambéry and Lyon, it is a site of significant geological and historical importance.

Key features

• Natural caves: Carved into the limestone by the Guiers Vif river over thousands of years, these caves showcase spectacular rock formations.
• Archaeological significance: Evidence of prehistoric settlements and human use of the caves by various cultures.
• Historical passage: The caves are situated along an ancient trade and pilgrimage route that was used by the Romans.
• Pont Romain (Roman bridge): A historic stone bridge that was once served as an important link between Savoy and Dauphiné.

Visit and activities

• Guided tours: The caves can be explored with a knowledgeable guide guide who provides insights into their geological, historical and archaeological significance.
• Light and sound installations: Some areas of the caves are spectacularly illuminated to highlight the special rock formations.
• Hiking: The surrounding area offers scenic hiking trails with magnificent views of the Chartreuse massif.
• The Grottes de Saint-Christophe is a fascinating excursion destination, ideal for nature lovers, history buffs and adventure seekers

4.2 Realization of the project in Grottes de Saint-Christophe

This project marked the conclusion of Cave Lighting’s French year. The project ran from the end of August to the end of October and was managed by Adrian Titus Kondacs, who led a team of four. The project was commissioned by the municipality with documentation prepared by the planning office, and was overseen by Guillaume Vieu. The project involved two caves: Saint-Christophe Supérieure and Saint-Christophe Inférieure.

While these caves are not particularly complex, consisting primarily of meandering passages with a  few stalactites, they posed a unique challenge:

• Both caves are designated residential habitats for small bat colonies and are subject to strict conservation regulations imposed by DREAL (the French bat conservation authority).
• Local planners and authorities faced significant pressure to comply with DREAL conditions, as failure to do so, could have resulted in the caves being closed.

Cave Lighting’s approach

To navigate these restrictions, Cave Lighting implemented a strategic two-step approach:

• First we adhered to all initial conservation conditions.
• Then, we proposed alternative solutions, which were ultimately approved by bat conservation authorities.

By working collaboratively, we successfully achieved a win-win outcome, ensuring both the ecological protection of the caves and the successful implementation of the lighting system.

Implemented solutions:

• Path lighting: installed using warm white LED lights
• Accent lighting: a combination of warm white and neutral white LED luminaires was used to provide optimal visibility while maintaining a natural cave ambiance.
• Bat friendly approach: the living areas of the bats were left completely unlit to minimize disruption
• Zone lighting control: the cave was divided into separate lighting zones, with each zone controlled independently for better adaptation to conservation requirements

The execution of the project was so seamless that the caves were opened before the bat protection season for Halloween, allowing visitors to enjoy a new and enhanced experience in 2024.

Technical overview:

Two separate analog lighting systems with PWM control were installed. In the Supérieure cave, a DMX-controlled island solution was implemented in the large hall. The following solutions from Cave Lighting were used:

• LSQ2 LED lights
• LQP2 LED lights
• LMT LED lights
• EQP2 LED lights
• CN2 control units
• CP2 button controller
• MMC2 multimedia controller
• RR Radio radio receiver

5.2 Bat protection

Of the 6 show caves installed in France, 5 were under bat protection regulations. . Only Grottes de Thouzon was and is still not affected by this regulation.

In the following section we will briefly outline the reasons and regulations behind bat protection, while highlighting key points of attention and differences observed throughout the projects.

5.3 Key issues

At the start of the project in Grottes d’Azé, there were no bat protection regulations in place. The installation began in November 2023 but in January 2024, the authorities were informed about the presence of a few bats.

As a result, the authorities interrupted the project, causing it to come to standstill. Some rules were then negotiated leading to new restrictions:

• One zone in the middle of the cave had to be sealed off with polyurethane
• However, work at the far end of the cave was still permitted

Mistake or lack of knowledge?

In our view, it would have been beneficial for project management to consider bat protection measures from the outset. Incorporating break periods for bat into the timeline and budgeting for associated costs could have helped ensure a smoother integration of environmental considerations.