Have a Smart Thermostat? Now It’s Time for Smart Air Vent. by Stacey Higginbotham @FortuneMagazine November 24, 2015, 6:54 PM EST E-mail Tweet Facebook Linkedin Share icons Once you’ve purchased a connected thermostat, this New York-based startup wants you to think you’re only halfway done with making your HVAC system more intelligent. Keen makes a connected vent that opens or closes when it detects people in the room, or when it senses that the room is too hot or cold. The idea is that a homeowner would pay $80 per vent (the initial kit with a vent and bridge to connect the vents to a Wi-Fi network costs $120) and eventually your home becomes so smart that it only heats or cools rooms based on occupancy and their temperature. I’ve been waiting for Keen to get these vents to the market ever since meeting them in March of 2014. As of Friday, they will finally be in Lowe’s stores and on Amazon.com. The battery-powered vents are compatible with both the Lowe’s Iris hub and the SmartThings home automation hub. They have sensors that detect both occupancy and temperature and communicate that back to a hub. From there, the system runs algorithms to determine whether or not the room should be cooled or heated. You can also control the temps of a group of vents from the app on your smartphone. It can work with a thermostat on one for the aforementioned smart home hubs or alone. Of course, bringing the average home up to an energy-saving intelligence standard is going to be expensive. Counting up vents in my own home, which is 2,500 square feet, brings the tally to 18. However, Keen says that not every vent needs to be replaced. A calculator on its site says mine will need 6 based on the number of bathrooms and bedrooms it has. That’s $520 in vents. This does not include the cost of thermostats or my home automation hubs. Surprisingly, Keen is not the only company out there that wants to help you replace your existing wall vents. Startup Ecovent has also raised capital to take on the same task. The market to tweak HVAC systems in residential homes is vast and filled with both startups like Keen and Ecovent, but also larger firms such as Emerson, which is pioneering a different type of efficiency play. Emerson is creating a service sold to HVAC installers that relies on sensors placed inside your existing ductwork and AC units that will ensure that your current system runs optimally. Most HVAC installers I have chatted with say that any sort of vent blocking system could potentially compromise the efficiency of your system because blocking the airflow is bad for the AC units. However, both Ecovent and Keen have responded to those accusations with claims that their algorithms account for that. At a certain point, arguments over airflow algorithms become too much for the average consumer to worry about. The real issue here will likely be one of cost, and whether or not the consumer wants a system they install themselves and pay for one or if they want to pay a recurring service fee to an installer, as they would for the Emerson offering, which can cost $10 or so a month. Sign up for Data Sheet, Fortune’s daily newsletter about the business of technology. For more about connected homes, watch this Fortune video: Updated: This story was updated on Nov. 25 to clarify that you do not have to replace all the vents in your home with Keen vents.