The U.S. government is going to ask its suppliers to disclose their greenhouse gas emissions. It’s not going to require it. It won’t happen right away. But this is a big deal.

It’s a big deal because the government is by far the nation’s largest single buyer of goods and services: It occupies nearly 500,000 buildings, operates more than 600,000 vehicles, employs more than 1.8 million civilians, and purchases more than $500 billion per year in goods and services. The General Services Administration, which is more or less the government’s purchasing department, buys more than 12 million products and services, an astonishing number when you stop and think about it. And almost 600,000 companies are registered to do business with the government. Yes, 600,000!

In any event, although they won’t be required to disclose their greenhouse gas emissions, and although it’s not clear when or how or even if the government will give preference to companies or products with a lower carbon footprint, you can be sure that many, if not most, of those 600,000 companies will soon think seriously about counting carbon. Once they do, they’ll begin to look at opportunities to curb their energy use–by operating more efficiently, opting for greener offices, promoting telecommuting, whatever.

To learn more about how this might work, I spoke by phone with Steve Leeds (left), who is the Senior Counselor to the Administrator for the U.S. General Services Administration as well as the GSA’s senior sustainability officer. He is

leading GSA’s efforts under Executive Orders 13423 and 13514 to fulfill GSA’s responsibilities and opportunities under those EOs as well as assisting GSA’s Federal agency customers with solutions to help them integrate sustainability throughout their agencies and achieve their sustainability goals.

His job of greening GSA’s supply chain is complicated by the fact that

The procurement of goods and services by the U.S. Government is a unique activity that is governed by a web of specialized rules, regulations, statutes, and policies outside of the realm of commercial contract law. These rules arise out of the nature of the Government as a contracting party and the distinctive forms and procedures used in the procurement process. The rules governing this process are contained in statutes, regulations, and decisions, many of which are designed to protect the public‘s interest and assure fair treatment of companies that enter contracts with the Government. Most of these rules apply to all agencies, but some are specific to a certain agency.

Unhappily, this is the language that your government speaks. Fortunately, Steve, who is 64 years old and a real estate lawyer from Atlanta, speaks English, so I was get some sense from him of what is really going on.

Last October, President Obama signed an executive order on sustainability that set ambitious goals for the government’s operations. It requires agencies to meet energy, water and waste reduction targets, among them:

• 30% reduction in vehicle fleet petroleum use by 2020;
• 26% improvement in water efficiency by 2020;
• 50% recycling and waste diversion by 2015;
• 95% of all applicable contracts will meet sustainability requirements 

But, of course, the devil is always in the details, and so the White House asked GSA to look into what is feasible and practical under Section 13 of the order, which is about “Vendor and Contractor Emissions,” i.e., the government’s supply chain.

“This is a real opportunity for the federal government to look at everything we do through the lens of sustainability,” Leeds says. The government will re-examine workplace design, video conferencing and telecommuting, among other things.