Two new wind turbines were recently installed along The Eiffel Tower’s lower deck. Perched 122 meters (400 feet) above the ground atop a second-level restaurant, the composite turbines from Urban Green Energy (UGE) are part of a broader effort to make Paris’ most iconic monument more eco-friendly.

The 5.2-meter (17-feet) VisionAIR5 turbines provide enough electricity to power the tower’s first-floor commercial areas — about 10,000 kWh per year. Jan Gromadzki, an engineer who oversaw the project for UGE, says that’s enough to power an average American family’s home for one year. But “it’s just a small drop in the ocean” for the Eiffel Tower, which consumes an estimated 6.7 GWh a year. “This installation is definitely more symbolic,” Gromadzki says. “But it is still significant because the merchant spaces on the first floor do consume energy, and being able to offset that consumption is something people can really assimilate and understand.”

The curved, tri-blade turbines were designed and installed by UGE. Each blade had to be hoisted by hand and pulley up to the second floor, and secured within the building’s tight lattice structure along its southwest corner. The entire installation had to be done at night, since the Eiffel Tower is open to the public until 11 p.m. seven days a week.

The Société d’Exploitation de la Tour Eiffel, the organization that manages the Eiffel Tower, wanted “something that would make a visual statement,” Gromadzki says, without distracting from its distinct silhouette. So the glass fiber blades were painted in a brown-grey hue to match the building, and extra vibration dampeners were added to make sure the turbines wouldn’t disturb diners at the Jules Verne restaurant below. When running at full speed, the turbines only produce about 40 decibels of sound.