In the late 1960s, the small metal boxes on walls that users manually adjusted for indoor conditioning evolved into the first programmable thermostats. Advances in technology and the Internet, as well as greater access to digital connectivity, are now giving rise to new types of intelligent systems that boost energy efficiency and automate user comfort.
“Once thermostats could be put on the network, it opened the doors to creative pathways for what we can do,” says Delia Hansen, marketing solutions manager at Crestron Electronics, headquartered in Rockleigh, N.J. Not only can homeowners control thermostats remotely, but thermostats in turn “have become very smart energy managers that react in real time to the environments around them.”
Heating and air conditioning units are by far the most expensive home appliances to operate, says John Peil, thermostat product manager of Chatsworth, Calif.–based Venstar. As a result, better management of these systems is critical. “The U.S. Environmental Protection Agency,” he says, “estimates that simply installing a programmable thermostat can save from $100 a year in Los Angeles to more than $600 a year in Barrow, Alaska.”
The new generation of thermostats can offer additional energy savings by gathering temperature, humidity, and occupancy data from sensors placed in interior and exterior zones. Photocell occupancy sensors can also help save energy incrementally. Because homeowners’ unpredictable schedules may mean that a programmed system operates while the house is empty, occupancy sensors might save a few additional hours of power consumption a week.
Thermostats may also utilize adaptive technology. As occupants set their preferred environmental conditions, the thermostats use sensors to gauge indoor and outdoor temperatures and humidity levels in conjunction with user preferences. After some time, these systems learn how to achieve the residents’ comfort levels without user intervention. For example, if an occupant turns up the temperature when humidity is low and the outdoor temperature is 70 F, but dials it down when humidity is high and the indoor temperature is in the high 60s, the thermostat remembers these adjustments and programs itself to maintain similar conditions on a long-term basis.
According to Mark Rehley, senior manager of emerging technology at Northwest Energy Efficiency Alliance in Portland, Ore., these advances are essential. “Programmable thermostats had become so complex that very few people could figure them out,” he says. “Shifting schedules often meant that many homeowners overrode the program.” If one-third of the households in four Northwest states (Oregon, Washington, Idaho, and Montana) can reduce their energy usage by 5 percent, Rehley estimates, nearly 600 megawatts per year—enough to power approximately 500,000 more homes—would be saved. “That’s a significant impact,” he says.
Thermostats may contribute to energy efficiency, but architects can have a bigger influence through good planning and design. Jay Waterman, an associate at Thornton Tomasetti in Portland, Maine, notes that thermostats cannot help save energy if the building isn’t designed well. “Architects need to make the thermal envelope as energy efficient as possible, and then right-size the HVAC system and understand how passive solar gain works,” he says. “Intelligent systems may kick on the air conditioning if there’s solar gain—potentially even in the winter—and that could expend rather than conserve energy.”
Although mechanical contractors generally specify the HVAC systems for residences, clients may ask designers for recommendations on thermostat selection. Because residential heating and cooling options have increased over time, some thermostats are compatible with newer technologies such as radiant floor heating, heat pumps, and dual-fuel systems. With the array of choices, it’s important to steer clients toward thermostats that can handle the system requirements.
The growing emphasis on user engagement means that thermostats are more intuitive now. Many have software that creates a heating and cooling program based on the occupants’ responses to lifestyle questions, such as the times at which they wake up, eat, and return home from work. “How user-friendly the interface is can be a market differentiator,” says Andre DeBar, AIA, senior green building consultant at Portland, Ore.–based Earth Advantage Institute. “Manufacturers have caught on to this and are developing tools that are more attractive and easy to use.”
For homeowners with a high design sensibility, manufacturers are incorporating architectural elements and design customization into their products. Architects engaged in selecting the thermostat can chose among products with slim profiles, contoured edges, and custom color displays that can complement or contrast with the interior palette. “It offers a pleasing aesthetic to the client’s wall,” says Mike Hoppe, senior product manager at Honeywell in Golden Valley, Minn. “Other improved features, such as easy-to-read screens, high-resolution imagery, menu-driven one-touch buttons, and displays that tell the outdoor temperature and humidity, create an interactive user experience.”
Flexibility in installation may also be helpful. Some thermostats can be located completely out of sight, such as inside a closet, and use sensors that can be painted to match the walls. The discreet thermostats are then controlled wirelessly via phone, tablet, or computer.
In fact, remote interfacing is giving homeowners enhanced control over their thermostats while away from home. The EverSense technology by Austin, Texas–based Allure Energy combines global positioning systems with phone applications to detect the homeowners’ proximity to the home. When the system reads that an occupant’s mobile phone is approaching the house, it moderates the indoor temperature to meet their preference so the house is ready when they arrive.
The convergence of digital technologies has also enabled thermostats to become integrated with larger building management systems. Some manufacturers have created software that manages thermostats along with lighting, skylights, shades, humidifiers, and dehumidifiers. Thermocouples can tell the system to close the shades when it’s too hot or to open a skylight to let in fresh air.
Building systems integration requires early planning among the entire project team, DeBar says. “Make sure the system is well conceived and planned before everything is closed and the finishes are in,” he says. “You can add data points after the fact with wireless systems, but getting the heating and cooling where you need it could be difficult if it wasn’t pre-planned.”
Although the complexity of past thermostat models could require the expertise of a mechanical contractor or multiple calls to customer service during installation, many of today’s thermostats have no special wiring. Online tutorials and videos are often available to clarify installation procedures, so clients can choose to install thermostats after the design or remodel is complete.
Some concern remains on whether the systems’ expanded capabilities will live up to their promises. For example, occupancy sensor technology might backfire if the heating system shuts off while someone is napping. This is particularly a challenge when the installed HVAC system has a slow response time, as in the case of radiant flooring and hot water baseboards. “A bit of skepticism is a good thing,” Rehley says. “There’s a lot of innovation happening in this emerging field and not all the kinks have been worked out. But a few bright spots are already delivering real value.”
