Two years ago, Nest was told to modify its advertising claims about how much energy its learning thermostat can save. Now, the company is armed with data to back up its assertion of energy -- and dollars -- saved.

On Monday, Nest announced the results from three studies, two of which were independent. On average, the thermostat saved about 15 percent on cooling and 10 percent to 12 percent on heating. For the average home, Nest found that its $250 thermostat would pay for itself in about two years.

“We have found what we have long believed and modeled,” said Ben Bixby, Nest's general manager of energy services. “Nest saves people energy.”

Only two of the studies were fully published when Nest released its white paper on Monday: Nest’s own study using MyEnergy, which it acquired in 2013, and a study done by the Energy Trust of Oregon. The third study was by Vectren, a utility in Indiana.

The Oregon study found that the thermostats were equally suited to saving money for customers with heat pumps, which the DOE had cautioned in the past weren’t a good fit for smart thermostats.

As the smart thermostat market heats up, companies are eager to prove that their products save energy and money for consumers and utilities alike.

The study from Oregon had some other interesting findings that might not be unique to Nest, but may be more broadly applicable as utilities look at their different residential customers to determine who might benefit from smart thermostats.

The lowest-income group had the largest savings percentage of any subgroup among the 175 participants. Single-person households, including the elderly, did not save much, however. In the study, elderly participants had essentially zero savings. Unsurprisingly, homes with the highest electric bills had the highest overall savings.

Customers said that the energy savings was the best aspect, but the ability to remote control the device and the auto-learning feature were also popular. About one-third of customers felt the thermostat was worth the full retail price even if it didn’t provide energy savings (although participants in the study received the thermostat for free).

The Oregon study only looked at the savings for air-source heat pumps, as it noted the Nest was the only commercially available programmable thermostat that could lock out the resistance heat without using an outside temperature setting, although more will likely be coming to market.

Air-source heat pumps are growing as more people move to warmer climates that lack prolonged periods of sub-zero temperatures. Also, heat pumps have nearly doubled in efficiency in the past 30 years. But savings were also seen in homes with natural gas.

Another study of Nest thermostats in homes with natural-gas heat found savings of about 12 percent on heating use.

Nest also found about 15 percent savings for air cooling in the two other studies. In Nest’s study, it noted that there could be some measure of selection bias, because many participants had purchased a Nest thermostat and also signed up for MyEnergy. However, the other independent study in Indiana found similar savings.

Nest is not alone in trying to back up its marketing with data. Last year saw a flurry of white papers based on independent studies showing that smart thermostats save people energy when the AC season cranks up. More will be coming this year as the smart thermostat market grows stronger.

Nest continues to be a consumer favorite, but it has competition on all sides, including a sleek-looking thermostat that Honeywell introduced last year to offer a Nest-like product to its dealer network.