Cisco Systems Inc. says that there's a lot of energy wasted in buildings today, and that its new EnergyWise product can help save a lot of it.  But just how much?

Glad you asked. The networking giant has put together a long list of examples of the economic and environmental benefits customers can obtain by using EnergyWise – which, by the way, is free for Cisco customers.

Take the first phase of EnergyWise, and the only function currently available from it -- controlling devices that get their power through Ethernet cables. That includes Internet protocol (IP) phones, wireless access points, clocks and a small but growing number of other devices.

Cisco looked at the example of a bank with 5,000 IP phones and 500 wireless access points that decided to turn off those devices from 7 p.m. to 7 a.m. Given electricity prices of 10 cents per kilowatt hour, that simple move would save the hypothetical bank about $37,000 a year in power costs, Inbar Lasser-Raab, Cisco's senior director of network systems, said.

It would also save enough electricity to power about 67 homes, she said. For a standard mix of power generation sources that includes coal-fired power plants, that's the same as cutting 185 tons of greenhouse-gas emissions per year, she said.

When Cisco starts adding the ability to control desktop and laptop computers, printers and other IT devices to EnergyWise this summer, those savings will expand, Lasser-Raab said.

Take an imaginary corporate office – one with 1,000 IP phones, 100 wireless access points, 700 laptops and 300 desktop computers – that decides it wants to use EnergyWise to shave power consumption during times of peak-demand pricing, she said.

That would include shifting unused phones to "sleep" mode, access points to low-power mode and laptops to battery mode. Taking those steps on an annual basis could save about $74,000 in energy costs and reduce the emissions of greenhouse gases by about 371 tons – the equivalent of taking 111 mid-sized cars off the road for a year, she said.

Given that information and communication technology electricity use produces about 2 percent of the world's greenhouse gas emissions – about as much as the global airline industry – there are certainly benefits to increased efficiency, both by turning off unused equipment and engineering it to use less power when it's on.

Industry groups like the Climate Savers Computing Initiative are calling for improved energy efficiency in the IT sector, and companies like IBM, Hewlett-Packard and Sun Microsystems are busy making more energy-efficient equipment.

But the really large reductions possible from EnergyWise are likely to come from its final phase. That's the expansion of networked monitoring and controls to a whole host of building infrastructure, from heating and air conditioners to lighting, building security and other systems.

After all, while IT equipment takes up about a quarter of a typical commercial building's energy, about 58 percent is used in heating, air conditioning and ventilation, Lasser-Raab said. Lighting accounts for another 11 percent or so, she said (see Will the Computer Giants Invade Lighting Too?).

Cutting energy use in buildings -- which take up about two-fifths of the country's energy –isn't something Cisco came up with on its own, of course.

The Electric Power Research Institute says that existing "continuous commissioning" projects – tracking building systems like air-conditioning to ensure they're being powered at their most efficient level – can help achieve savings of nearly 9 percent on a building's electric bill. Using "demand-response" systems to power down equipment to avoid blackouts or reduce the amount of power consumed at peak load times also help save energy (see EPRI Plugs Smart Grid for Energy Savings).

Companies like Cimetrics, Tririga and others are busily making software to help property owners measure and manage their power consumption. Cimetrics estimates that measuring and managing that consumption can yield 10 to 20 percent reductions in use (see Controlling Energy Consumption, A Million Square Feet at a Time).

For EnergyWise's potential impact, Cisco laid out a hypothetical 200-room hotel that had decided it would use EnergyWise to make sure that lights, heat and air conditioning, TVs, phones and other power-consuming devices were only on when the room is occupied. Hotels waste a lot of power on empty rooms, Lasser-Raab noted.

That simple measure saves about $400, or the equivalent of two tons of greenhouse-gas emission reductions, per room per year, she said. That 200-room hotel could end up saving $80,000 per year and reduce greenhouse-gas emissions by 396 tons, she said.

Ideas like this could be extended to the commercial space, said William Choe, product management developer for Cisco's LAN switching business unit. Imagine an office building with a security badge system that linked up to the phones, computers and lighting on an employee-by-employee basis. As the employee checks into the security system, the phone, computer and lights turn on, "and if you've left the building, you could set a policy in a centralize fashion to turn off or go into a low power mode," he said.

These are all discrete examples. But imagine, Lasser-Raab said, that all 79.5 million IP phones and 8.5 million wireless access points in the world were hooked up to EnergyWise today -- perhaps an unlikely scenario, but interesting for what it reveals about how much power these devices use.

Turning off one-fifth of them for four hours a day would lead to a 106-megawatt reduction in power demand, with a greenhouse-gas reduction equivalent to saving 12,000 acres of CO2-fixing forest, she said. Turning off two-fifths of those devices for eight hours a day equals 426 megawatts and the greenhouse-gas reduction equivalent to taking nearly 41,000 cars off the road.

And turning off half those devices for half a day could reduce power demand by 800 megawatts, or the power demand of more than 72,000 homes – and greenhouse gas reductions equivalent to not burning nearly 200,000 pounds of coal or saving enough forest to cover the state of Colorado, she said.

In the end, of course, how much power EnergyWise saves will be up to the customers using it, Lasser-Raab said. Many companies may be leery of leaving the control of computers, lights and heating up to automated protocols, and start with simple things like turning off IP phones and lights on weekends and nights, she said.

But once they get more comfortable with their analysis of their power usage, they can put together more sophisticated policies, she said.

"Many devices on the network need to be always available," she said. "But they don't necessarily need to always be on.