The Empire State Building has long been a signature feature of Manhattan’s skyline. But owners of the iconic edifice hope to convince investors and tenants that it’s what’s on the inside that really counts.


The 81-year-old New York tower has undergone a massive, three-year makeover designed to cut energy use, modernize office suites and attract tenants willing to shoulder higher rents.


The Empire State is the highest-profile project in a growing collection of renovations.


Johnson Controls Inc., a building efficiency systems supplier based in Milwaukee whose contract for the Empire State is worth about $20 million, estimates six jobs are created for every million dollars spent.


A renovation can boost rents, lead to longer leases, lower vacancy rates and attract larger, higher quality tenants.


In fixing the building, there were two things that could not change: the landmark’s Art Deco exterior and the 86th-floor observation deck, a cash cow for the business.

Those stipulations meant that much of the work must be done at night.

Plans mixed measures such as new lighting and new ventilation systems with a host of longer-term fixes, such as replacing or modernizing boilers and chillers.

The retrofit promises a steady payback, as building owners expect to shave $4.4 million a year off energy costs.

Johnson Controls expects the redo to deliver the promised 38 percent energy savings by next year.

And tenants are already paying more.

“I get a competitive advantage when big tenants come in here,” said Anthony Malkin, president of the Malkin Group that controls the Empire State Building.

Malkin added that average office rents in August 2006 were $26.50 per square foot, compared to high $40s to high $50s nowadays.