The bright lights of the big city are getting a little bit duller  with just a hint of green.

Motion sensors ensure that unoccupied offices, storerooms and canteens go dark after workers and cleaning crews leave at night. Dimmers soften overhead lights that once could burn only bright or not at all. Timers guarantee that buildings fade to black while the city sleeps.

Gone are the days when cheap electricity, primitive lighting technology and landlords’ desire to showcase their skyscrapers kept floor after floor of the city’s highest towers glowing into the night. Now, rising energy costs, conservationism, stricter building codes and sophisticated lighting systems have conspired to slowly, often imperceptibly, transform Manhattan’s venerable nightscape into one with a gentler glow.

Instead of tower after tower shining at all hours  the World Trade Center stayed aglow long after its occupants went home  the skyline is becoming a patchwork of sparsely sparkling buildings decorated with ornamentally lighted tops.

“The tall tower with the illuminated floors on all night long is probably a thing of the past,” said Randy Sabedra, the owner of RS Lighting Design, who is helping to create a new map of the city’s most prominently lighted buildings. “You’re not relying on the glowing floors to have the building presence. It is relying on the crown of light.”