Do you know how much that 3 p.m. bag of vending machine potato chips costs you?

Probably about 85 cents.

But there’s an additional price: the health of the Earth.

Vending machines are notorious energy-guzzlers. After all, they operate 24 hours a day, cooling cans of Diet Coke and shining just the right light on that Snickers bar.

The average vending machine consumes about 3,400 kilowatt-hours of energy each year — more than $300 in energy costs per machine, according to the Environmental Protection Agency.

So it seems natural that when Chief Administrative Officer Dan Beard began to implement the Green the Capitol Initiative, he would look to replace the House’s 84 older vending machines with more energy-efficient models.

That happened this week, when Restaurant Associates took over as the primary food vendor for House cafeterias. Along with the new menus came new vending machines, affixed with the EPA’s coveted Energy Star logo and provided by RA’s partner company Compass.

The machines offer basically the same thing as before — Pepsi and Coca-Cola products, coffee, bottled water and a range of chips, sandwiches and candy.

But there’s also a machine that serves hot dogs, fresh (well, sort of) off the grill, er, microwave cooking unit. And there’s even a machine that has nothing to do with food — a DVD rental machine.

“What we’re doing is providing energy-efficient products and vending machines, and we’re providing services to our work force to make it a comfortable environment,” Beard said. “I think they’re terrific.”

The vending machines installed in the House buildings save energy a number of ways, according to Gina Zimmer, vice president of marketing and communications for Restaurant Associates.

Some machines feature programming that allows them to shut down at night, Zimmer said. Others have the capability to control lighting, and soda machines, which are programmed to 40 degrees, can be programmed to sit at 65 degrees for five hours at night.

“We save energy while not compromising the product,” Zimmer said.

Zimmer also said it isn’t known how much energy will be saved until data start to roll in. But EPA case studies provide clues.

When the State University of New York at Buffalo installed 132 new Energy Star vending machines on its campus in 2004, they saved 261,849 kilowatt-hours of energy annually, according to the EPA. That’s $20,948, or about $160 per machine.

At the University of Michigan, administrators also installed 132 Energy Star machines and ended up saving 224,400 kilowatt-hours of energy, which added up to $19,800 in savings. “We should have some pretty exciting results in a few months, if not weeks,” Zimmer said.

By Wednesday afternoon, the vending room located near in the Longworth Cafeteria was up and running, with Energy Star- labeled machines offering Doritos and other chips for 85 cents, Pepsi and Coke products for $1.25 and Wolfgang Puck coffee for $1 to $1.75.

The cafeteria’s hot dog vending machine clearly already has been a popular choice. With items such as a $2 Oscar Meyer “All-American Classic” and the $3 Hillshire Farm “CheddarWurst,” it was little wonder that the machine had stopped working by 3 p.m. Wednesday — there were no more buns.

The DVD rental machine hadn’t been stocked yet. But when it is, staffers can use their credit cards to rent movies for $1.79 for the first night and 99 cents for any additional night. When finished with a flick, renters just drop the movie through a return slot.

Not everybody is a fan of the new machines, however.

“This is exactly what every Hill staffer needs and what every American taxpayer wants to subsidize — hot dogs and movies in the workplace,” said Brian Kennedy, a spokesman for House Minority Leader John Boehner (R-Ohio). “All we need now is a few more clowns, some cotton candy vendors and a striped tent — then we’ll have a full-blown circus.”

But Beard said the machines are provided at no cost to the Capitol. The DVD and hot dog machines, for example, allow busy staff to grab a bite and movie on their way home.

“I think Mr. Boehner and the Republican leadership do support us having energy operations that do everything possible to make the work-life balance on Capitol Hill as comfortable as possible,” Beard said. “These things didn’t cost us a cent.”