New York ? When owners of the Empire State Building decided to blanket its facade this year with thousands of insulating windows, they were only partly interested in saving energy. They also needed tenants.

After 78 years, Manhattan’s signature office building had lost its sheen as one of the city’s most desirable places to work. To get it back, the owners did what an increasing number of property owners have done — they went green, shelling out $120 million on a variety of environmental improvements.

In recent years environmental retrofits have begun to pay off for owners and tenants alike. Higher-profile companies are seeking out more efficient office space, and new technology at older buildings has started to translate into higher property values, leases and occupancy rates.