After 18 months of gutting and retrofitting the infrastructure of New York’s 1909 landmark Argonaut building in Manhattan, the $20 million green renovation will be complete this summer. The overhaul of the former General Motors building at West 57th Street and Broadway is likely to pass muster with Mayor Michael Bloomberg.

On April 22, the mayor proposed sweeping legislation that seeks to reduce carbon emissions from the city’s commercial buildings. If passed, New York City’s largest building owners would be required to conduct energy audits and make energy-efficient retrofits.

The devil is likely to be in the details. Little has yet been specified including when the legislation will go into effect or what rating systems or measurements will be used to ensure compliance, says Leslie Lisser, senior asset manager for FirstService Williams, leasing and asset manager for the Argonaut. The project is pursuing LEED core and shell gold certification from the U.S. Green Building Council.

The Argonaut’s new energy-efficient systems — from HVAC to electric and plumbing — could be a model for Bloomberg’s plan, which includes four pieces of legislation that will reduce greenhouse gas emissions from existing government, commercial and residential buildings.

The first hearing for the bills will be June 11, followed by a second later in the summer. The City Council expects the proposed legislation to come up for a vote this fall. If passed, the laws could take effect as early as 2013. The bills include:

• legislation that creates a New York City Energy Code that existing buildings will have to meet whenever they undergo renovations.

• legislation that requires owners of buildings that are 50,000 sq. ft. or larger to conduct an energy audit once every 10 years and make any improvements that can be paid for within five years.

• legislation calling for buildings of 50,000 sq. ft. or more to include energy-efficient lighting systems, which can be paid for through energy savings.

• legislation that requires owners of buildings 50,000 sq. ft. or more to conduct an annual benchmark analysis of energy consumption. By doing so, building owners can better understand what steps they need to take to increase efficiency.

Other measures in Bloomberg’s plan include an employment program that would create as many as 19,000 green construction jobs. It also features a financing program that utilizes federal stimulus dollars to provide loans for efficiency upgrades.

Many leading New York developers, owners and property managers, however, are already retrofitting the buildings in their portfolios to achieve greater energy efficiency in advance of the proposed requirements.

New York-based FirstService Williams, for instance, has begun the process of benchmarking its 8 million sq. ft. owned portfolio, primarily in New York. Benchmarking allows building owners to compare a building’s energy performance to relative periods.

SL Green, New York’s largest office owner with 29 office properties totaling more than 23 million sq. ft., also is ahead of the curve. The office REIT currently has 19 buildings slated for LEED certification and recently announced a companywide energy conservation initiative. For instance, through the initiative all trash is recycled off-site with approximately 80% of all waste being diverted from landfills.

Given SL Green’s efforts toward greater sustainability over the past few years, the REIT is watching Bloomberg’s proposed legislation with interest, according to the firm’s executive vice president Edward Piccinich.

“The best way for building owners and public officials to reach a consensus is to agree on timing,” says Piccinich. Against the backdrop of the recession, forced compliance “would put a significant burden on many owners and managers.”

Despite existing rebates and incentives from the New York State Energy Research and Development Authority, Con Edison as well as potential stimulus financing, Lisser of FirstService Williams notes that upfront retrofit costs could create stress for smaller building owners. “It costs a lot of money to go in and initially do an audit,” says Lisser. “It could cost $5,000 to $10,000, so in the case of a smaller building that money could be problematic.”