Sony accounts for almost 0.01 percent of the world’s greenhouse gases, says Mark Small, Vice President Corporate Environment, Safety and Health at Sony Electronics, or about 20 million tons of carbon dioxide a year.

But the difficult part comes in trying to reduce it. Only about 10 percent of the total comes from internal operations at Sony (7 percent) and transportation (3 percent) that Sony can control directly.

“Ninety percent of the emissions relate to consumer use,” he said. “It is an incredibly large footprint.”

Such is the life of a modern day sustainability officer, said panelists at during a session at the Enterprise Carbon Accounting conference sponsored by Greentech Media yesterday. On one hand, it is a fantastic job to have these days. Consumers are demanding environmental accountability from corporations and employees at all levels are willing to participate in gathering data and kick-starting recycling programs. Everyone is listening to you.

“More customers are asking questions about data centers and environmental issues. We compete with Google for talent, and they get in the paper all the time for putting up solar panels,” said Rupesh Shah, director of corporate sustainability at Intuit.

Corporate leaders are also ordering product managers and others to reduce energy consumption. At Applied Materials, for instance, there is a directive to reduce the power consumed by its products by 20 percent by 2012. The company makes things like chemical vapor deposition equipment that that need to heat metals to several hundred degrees Celsius.

“We have a number of products that have made significant improvement,” said Bruce Klafter said. He’s the  Senior Director, Environmental, Health and Safety at Applied Materials.

On the other hand, any actions that add costs are going to be scrutinized by the CFO. (At Intuit, for instance, Shah is a team of one.) And to top it off, the numbers behind carbon accounting can be large and difficult to determine.

Some carbon-intensive activities are also tough to eliminate. Air travel ranked as a large source of emissions for both Applied and Intuit. Air travel accounted for around 45,000 tons of Applied’s nearly 200,000 annual metric tons of carbon dioxide. Videoconferencing can get rid of some of this but when you sell large hardware systems, customers want to see an engineer in person, Klafter said.

When doing carbon footprint counts it is probably more important to get a somewhat accurate number, rather than the exact amount. Klafter also stressed the problem with eco labeling. There are about 330 different eco labels, and you can’t get them all.

“How much value do your customers put into them. Many companies are creating their own criteria, putting their own label on it. We participate in the programs that we as a company thinks has a value. The ones we respond to is the ones that already gained some traction in the market,” Klafter said.

“We did our first footprint count in 2004 and reported it in 2005. We only calculated it for four facilities but it was 75 percent of our impact. From my perspective, what we need to do is incorporate more of that information into the companies’ strategy. You can’t manage any of these things as long as you don’t know what your numbers are,” he continued.

When starting with carbon accounting, Intuit’s Shah had some tips. First thing, you need help. Just getting the data from all over your company is a hard task and Shah pointed out the fact that over 65 people from his organization is helping him with delivering different kind of data do be able to do the right accounting.

“The data is all over the place. I reach out to everyone, from the travel manager to the facility manager,” he said. “Get the numbers close, and then ask yourself, if we do this, how much money can we save? That’s the key question,” Shah said.

Companies also have to get a handle on suppliers. Sony reduced suppliers to 3,500 and conducts audits, said Small, although he also admitted it is not always easy to get an accurate picture or data from third parties.

“We work with tier one suppliers to approach their suppliers with greenhouse gas emissions reporting,” said Ellen Jackowski, Corporate Environmental Sustainability at HP.

“The recession started a wave of customer questions. The stimulus package was also another good opportunity for HP. We haven’t really cut back on any of our programs,” Jackowski added.