Last summer, Benedict called on Christians to unite to take "care of creation without squandering its resources and sharing them in a convivial manner." He said lifestyle choices were damaging the environment and making "the lives of poor people on Earth especially unbearable."
The modernistic hall, at the southern end of Vatican City, was built in 1969, designed by architect Pier Luigi Nervi.
The auditorium "was born half-ecological," Cuscianna said, noting that Nervi used cement panels on its 6,000-square-yard flattened vaulted roof in part to help keep pilgrims cool.
The new roof panels will be the same shape and almost the same color as the cement panels they are replacing, minimizing the aesthetic impact, Cuscianna said.
Weathering has deteriorated the condition of the cement panels, which needed replacement, so Cuscianna thought it was the right time to make the move to solar in Mediterranean Italy, which enjoys many sunny days.
The Vatican is considering the installation of photovoltaic cells on roofs of other Holy See buildings, although centuries-old landmarks like St. Peter's Basilica won't be touched.
