Anthony Rowe is working on a killer app. When he leaves his house each day, he doesn't worry whether he left the iron on or the television blaring. This Carnegie Mellon computer engineer and doctoral student can keep an eye on his home from almost anywhere he happens to be. His apartment is brimming with sensors he's designed. Some plug right into wall outlets to monitor the electrical usage of individual household gadgets and appliances. All he needs is his iPhone or laptop to see what's running and what's not.

"We've developed a sensor device which can, if you plug an appliance into it, sense how much energy the appliance is using and allow you to remotely turn the appliance on and off," says Rowe.

To demonstrate, Rowe opens his laptop and clicks an "off" button on the screen and a light next to him turns off. He highlights the word fan on his computer screen, clicks "on" and a fan sitting next to him turns on. He does the same for the lights in his apartment, five miles away.

"The idea behind this project is to give people in their homes visibility about how much energy they're consuming. We see our monthly power bills," he explains, "but we don't necessarily know what appliances are using the energy."

"Each one of the devices actually has a small radio inside it that talks from one device to the next, forwarding messages back to a gateway system," he explains. "The unique property of this system is the fact that since these devices are wireless, it makes it very easy to install at home. You don't have to run any cabling."

The data is transmitted via wi-fi and Rowe can access it over the Internet. With support from the National Science Foundation (NSF), he has also developed software to chart the output.

"I can actually very quickly see a bar graph and a pie chart showing which devices are consuming the most amount of energy," says Rowe.

For example, one day, he noticed the refrigerator was using more electricity than usual. Come to find out the refrigerator door was ajar. Easy to go undetected had it not been for the spike on the energy chart.

"You know it can happen. If you're in a hurry, you don't notice the door is completely closed."

"If I click on 'TV,' I can see when my TV was consuming power and how much power it's consuming. If I look at my living room lamp, I can even remotely turn that on and off."

Recently, he noticed his printer guzzling energy and learned something new about printer behavior.

"My printer, when it runs out of toner, it goes into a mode that it no longer sleeps, it's just awake. There's a huge amount of energy wasted there. Things I wouldn't have known unless I had some energy feedback."

He's also invented what he calls environmental sensors.

"It's similar to the outlet devices," he says and picks up a cube shaped device, "except this one will measure environmental values like light, temperature and humidity. It can also detect the accelerations if you mount it on machinery. It can tell if the machinery is operating or not. It can give you an idea of how well the heating and air conditioning systems are performing."

Rowe's main objective is to give people an easy way to monitor their power consumption and their carbon footprint. His ultimate goal is to save energy.

"People can typically save 10-20 percent on their electric bill through awareness about where the energy is going," says Rowe. "Of course, by saving energy, we help the environment and we also reduce costs."

Rowe's inventions may one day be the killer app that not only helps save energy but reduces worry that the toaster oven or iron has been left on after you leave the house.

This story was originally written for Science Nation and was republished with permission here. Video: Science Nation, Miles O'Brien/Science Nation Correspondent, Ann Kellan/Science Nation Producer.