Until recently, many CIOs didn't know how much electricity their IT equipment used, and they didn't care.

The electric bill was someone else's responsibility -- usually the head of facilities -- so they didn't track it, and they weren't motivated to reduce it. They didn't factor energy efficiency into their IT purchasing decisions, either.

Now, with a stagnating US economy, CIOs need to squeeze every penny out of their IT operations, and that means choosing the most efficient servers and desktops, as well as data center power supplies and air conditioning systems.

CIOs are being hit from all sides to become environmentally savvy, not just because it sounds good but because it cuts costs, drives profitability and improves competitiveness.

We've put together a list of the Top 10 people who are pressuring CIOs to green up their IT practices.

1. CFOs

The No. 1 reason CIOs are greening up their IT operations is to save money.

By reducing the amount of electricity or chilled water used in their data center operations, CIOs can contribute money straight to the company's bottom line, and that's what the CFO wants to see.

"The whole notion of being green is associated with making some sort of a sacrifice ...one less shower, driving a smaller car, changing out light bulbs," says Albert Esser, vice president of power and infrastructure solutions at Dell. "For green IT, that is just not true. Anything you can do to be green in IT will help your bottom line, will help your operations and will help your service-level agreements...With green IT, there's no sacrifice involved."

Esser says CIOs can't afford not to be green. Dell, for example, has saved US$1.8 million and reduced its carbon emissions by 11,000 tons in one year by requiring 50,000 employees to put their desktop computers into sleep mode each night.

"Companies that are embracing green IT practices today will have stronger balance sheets in five to 10 years than ones that don't," Esser adds. Green IT "contributes to the bottom line and allows you as a company to be a more responsible citizen in the corporate world."

Cimarex Energy, a Denver oil and gas exploration company, recently bought two American Power Conversion (APC) InRow cooling solutions because the units allow Cimarex to pack more IT equipment into the floor space of a data center located on the 11th floor of a high-rise building in Oklahoma. The APC units use 50 per cent less chilled water and produce more cool air in a data center expansion than Leibert units in the original data center space.

"In our old room, we have 600 square feet and we can rack 35 servers because of the Leibert units," says Rodney McPhearson, project manager for Cimarex' enterprise infrastructure team. "Our new space is about 300 square feet, and with the APC units we can populate 112 servers."