The pitch is that the Internet of Things will make our world a greener place. Environmental sensors can detect pollution, the voices say. Smart thermostats can help us save money on our electric bills. A new breed of agriculture tech can save water by giving crops exactly the amount they need and no more.

But this vast network of new online devices could also end up harming the environment. Manufacturing all those gadgets means expending both energy and raw materials. In many cases, they will replace an older breed of devices, which will need to be disposed of (so long, non-smart thermostat). And eventually, every IoT device you buy–and people are predicting there will be hundreds of thousands–will need to be retired too. Since all these devices will connect to the net, we should even consider the energy used by the data centers that drive them.

"The Internet of Things, for us, is a way for people to get reconnected with where their energy comes from," says Greenpeace IT analyst Gary Cook. "But it could also drive more consumption, which won't help us."

None of these problems are insurmountable. But with more networked devices being released everyday, it's time to start thinking about what the real environmental impact of these devices will be–and how we can minimize it.

Shrinking the Footprint

Earlier this year, Nest claimed on its company blog that it takes only eight weeks for its thermostat to save enough energy to become carbon neutral, based on the amount of energy it takes to manufacture and distribute devices. That's a good return on investment, but the Nest thermostat is specifically designed to save energy. Other products–such as fitness trackers, kitchen appliances, and home security systems–may have heavier footprints.

>In many cases, the companies that make and sell electronics don't know how much energy they're using.

The problem, Cook says, is that it's hard–if not impossible–for consumers to get a sense of the lifetime environmental impact of any given product. There just aren't enough standards and certification bodies to provide accurate information. RoHs labels provide assurances about the amounts of toxic materials like cadmium and lead used in a product, and Energy Star can give you an idea of a product's energy efficiency. But neither label gives you much insight into the manufacturing process or the overall lifecycle of a product. In many cases, the companies that make and sell electronics don't know how much energy they're using, since many components that go into a product are manufactured by other companies entirely.

Greenpeace is trying to help out in this regard with its Cool IT Challenge campaign to encourage companies not just to change their own practices but to use their influence to drive change in the industry. The campaign also includes a leaderboard that ranks how well companies are doing. "We've been evaluating companies both on their use of toxic chemicals in their products and how they use energy," Cooks says. "Something we were trying to measure in the leaderboard is how much homework companies are doing."

Perhaps the biggest environmental issue regarding network connected devices is the amount of energy used by the servers they connect to. Although big data center operators try to use as little electricity as possible–and there are more products than ever available to help these companies bring their power bills down–Cook says it's about more than just using less energy. Companies need to be using clean energy as well.

In recent years, many major cloud companies–including Google, Rackspace, and Salesforce–have disclosed their energy usage information and pledged to eventually power their data centers exclusively with renewable energy. But Amazon, the largest cloud computing provider in the U.S., hasn't cooperated by releasing data about its environmental impact. That worries Cook. "If Amazon doesn't pivot to take the challenge as seriously as Google, Apple and Microsoft, it could lower the floor for everyone," he says.

Long Lifespans, Please

But we also have to worry about all these devices being dumped into the landfill. Many communities have companies or non-profit organizations that recycle electronic waste. But it would be better if the devices had long lifespans. That's a tall order in the era of planned obsolescence. Companies want you to buy new versions of their products every few years, or perhaps more often.

>It's inevitable though that some products are going to end up in the landfill, so it's important to make sure they do as little harm as possible once they're there.

Adding more smarts and a network connection to devices means that companies can more easily sell software upgrades to customers, instead of entirely new devices. That could help extend the lifespan of products–at least for companies willing to support older devices. But the fact of the matter is that many companies will cut devices loose after a while. Dan Geer, chief security officer at the Central Intelligence Agency's venture firm, In-Q-Tel, is encouraging IoT companies to build a "self-destruct" function into devices so that older devices, which are more likely to have un-patched security issues, can't be used after a certain date.

That means open source software will be extremely important for keeping connected devices going and out of landfill, says Michael Richardson, the co-chair of an Internet Engineering Task Force work group standardizing wireless networking for the IoT. If devices use open source code, the broader community of developers can help keep them going. "If an IoT device is not running open source, it means that as soon as someone comes up with a security problem, it's going in the trash because major companies aren't going to want to upgrade lightbulbs," he says. "It's going to end up creating more waste, more garbage."

But it's inevitable that some products are going to end up in the landfill, so it's important to make sure they do as little harm as possible once they're there. Adam Dunkels, the co-founder of Thingsquare, a cloud service for IoT developers, says one of the most important things that companies developing IoT products can do is to avoid using disposable batteries, to reduce the size of the batteries that the devices use, or even possibly create new types of batteries that are less toxic.

The Net Good

In the end, Dunkels thinks that the IoT will be a net benefit for the environment. "If you're attaching a sensor to something that allows you to inspect this thing from afar, then you don't need to go see it, so you don't need to drive a car to get there," he says. "So you spend some energy in a data center, but you don't have to use the car ride for that."

He also points out that the biggest potential for the IoT isn't consumer devices, but for industrial automation, building automation, traffic light control, and other less visible but highly important applications that will ultimately save electricity.

But that doesn't mean we should ignore the other problems. Companies that are promising a new, connected future must o do more to ensure this future is a sustainable one. And that's going to mean releasing more information to the public–at the very least.