Client: Gut Rantzau GmbH & Co. KG, Berlin
Architect: URBANSKY ARCHITEKTEN PartGmbB, Berlin
Lighting Design: Ulrike Brandi Licht
Feasibility Study: 2022

Nature Conservation Through Strategic Lighting: Gut Rantzau as a Model

Gut Rantzau is being transformed into a vacation and recreation destination. Bats, birds, insects, hedgehogs, and other species will continue to be part of the estate. The lighting is designed to protect this wildlife, not displace it.

The new development is modeled after the historic buildings. Plans include hotel rooms, vacation apartments, restaurants, workspaces, and wellness facilities. Since the estate is surrounded by nature reserves, a conscious and economical use of light is essential.

The low lighting levels create a stark contrast to bright cities. This allows visitors to experience darkness, and the starry sky remains visible. The goal is to keep bat roosts dark, attract as few insects as possible, uphold the “dark sky” concept, and use light only where it is truly necessary.

Nine of the fifteen native bat species live on the estate. Their habitat must not be disturbed. For this reason, dark alternative roosts and dark corridors are being created between habitats and foraging areas. In these areas, the illuminance does not exceed 0.1 lux. Low-intensity, warm-white light sources with a color temperature of 2,700 Kelvin are suitable.

Insects are also sensitive to light. Warm-white LED lights without UV components attract them less than neutral- or cool-white ones. Low-level light sources, low brightness, and precise light control are also important. For this reason, stray light is avoided, and uplights are not used at all. Demand-controlled lighting further preserves darkness and saves energy.

There is no vehicle traffic on the paths. Therefore, low illuminance levels are sufficient for orientation on foot. The main axis in the center is illuminated with an average of 5 lux, side paths with 2.5 lux, and the path to the sauna with 1 lux. Low-profile bollard lights are used there.

The sauna area is located less than ten meters from the protected biotope along the Kossau. Inside, dimmed, warm-white light with an average of 20 lux creates a safe and peaceful atmosphere. Colored lighting is not used. Only at low illumination levels is the view from the panoramic window into the dark natural surroundings preserved. When the sauna is not in use, the lights remain off. The garden shed is also located near the protected biotope.