A stadium innovation beneath the surface

Image: Rhenac

As part of its transformation into a multi-use venue, Real Madrid has reimagined the Santiago Bernabéu, not just above ground, but deep below. At the heart of this change is a technological first: a fully automated underground greenhouse using Rhenac Sports LED’s Complete Light Spectrum (CLS) system to maintain perfect pitch conditions, even when the turf is stored out of sight.

The stadium’s new retractable pitch system allows the grass to be rolled underground to accommodate concerts and other non-sporting events. But taking the pitch out of the sun for days or weeks introduces serious challenges: reduced light, airflow, and environmental stress threaten turf quality. Rhenac’s CLS system addresses this with an intelligent, programmable lighting setup designed to mimic natural conditions across the turf’s full lifecycle.

Housed in a 30-metre-deep hypogeum, the system forms a self-contained biosphere. LED units recreate any part of the solar spectrum, from germination-supporting red light to disease-preventing blue, while infrared warmth is added only when needed. Sensors constantly monitor temperature, moisture, and nutrient levels, feeding data into software that can auto-adjust lighting, heat, irrigation, or fertilisation. The entire process is remotely operable, giving groundskeepers unprecedented control.

This is the first time such a sophisticated spectrum-based lighting system has been used in a retractable stadium pitch. Real Madrid’s ambition, to host frequent non-sporting events while preserving world-class pitch conditions, required a new standard in turf care. With over 6,000 luminaires and 750,000 LEDs across 51 programmable zones, the CLS solution provides precision without compromise.

The system’s flexibility also extends above ground. Mobile rigs replicate the hypogeum lighting spectrum during periods when the pitch must remain in place, ensuring consistent growth and stress-free transitions.

Image: Rhenac

Jose Maria Fernandez, Head Groundsman, explains: “We simulate outdoor conditions as closely as possible. During growth, we run 16-hour lighting cycles, gradually increasing and decreasing intensity to mirror sunrise and sunset.”

Built on 12 years of research in collaboration with the Technical University of Munich, the CLS system isn’t just a grow light, it’s a climate control platform for elite sports turf. From rapid pitch deployment post-football season to long-term sustainability goals, the integration at Bernabéu has already delivered tangible results: healthier root systems, lower energy use, and the ability to host back-to-back events without sacrificing turf quality.

The Santiago Bernabéu’s underground greenhouse may be out of sight, but it’s at the forefront of a growing shift, where smart, sustainable stadiums don’t just accommodate the future. They grow it!

Image: Rhenac

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