Key elements of the retrofit include refurbishing the building's 6,500 windows to reduce summer heat load and winter heat loss, adding insulation behind the radiators, upgrading the lighting in tenant spaces, replacing the air handling units, retrofitting the chillers, upgrading the building control system, introducing demand-control ventilation and incorporating individualized energy management systems for tenants. The integrated approach means, for example, that the existing chillers could be upgraded rather than replaced outright because the window retrofit reduces the load on the chillers, Quartararo tells GlobeSt.com.

Although JLL has been involved with high-profile new green construction such as the Bank of America tower at One Bryant Park, Quartararo says "it's a bigger challenge to build an economic model with existing buildings." Malkin, president of W&M Properties, which manages the Empire State Building and indirectly owns it, said at Monday's conference that the retrofit will save $4.4 million in energy costs annually by 2013. He said he hopes that its example will influence lawmakers and other building owners.

At the same time, Malkin said he believes a greener 350 Fifth will be "more desirable in the marketplace." A fact sheet on the project lists marketability as one of the top three goals, along with reducing energy use and improving tenant comfort.

The link between green and profitability was made repeatedly at the Empire State Building event. "We will never conquer climate change until we prove it's good business to do so," said former President Bill Clinton, who founded the CCI. Clinton said that while developing electric cars and harvesting energy from wind farms are important, "you have to be able to pick the low-hanging fruit."

Greening the building is projected at $13.2 million in incremental costs and $20 million total costs, above and beyond the $500-million capital program. Malkin said his company is doing without financing on the retrofit because it's in a position to pay cash.

Since not all landlords could swing a sustainability program without obtaining credit, the project's partners are also working to devise a series of financing mechanisms that building owners could tap into. Based on meetings with lenders and other potential stakeholders, the partners hope to announce a financing blueprint within 60 to 90 days, Quartararo tells GlobeSt.com.

Quartararo says one way to help line up financing on a green project is to obtain a performance guarantee from the consulting company. Johnson Controls, which is providing energy services on the retrofit, has signed a contract guaranteeing that 350 Fifth's greenhouse gas emissions will be reduced by 105,000 metric tons over the life of the contract, VP Iain Campbell said Monday.