This month Nest announced several studies that have been conducted on its learning thermostat. One was conducted by MyEnergy, a Nest subsidiary that analyzes residential energy information. The others were conducted by the Energy Trust of Oregon and by Vectren Corporation, an Indiana-based holding company. The results boost Nest’s claims that the thermostat can pay for itself in only a year or 2.
Across the studies, evaluators found average annual reductions in electricity use between 13.9% and 15% for cooling and 10% and 12% for heating loads. For natural gas, the Vectren study confirmed an average annual reduction of 12.5%. In terms of cost savings, Nest states that adopters showed an average of 9.6% savings on their gas bill and 17.5% on their electric bill.
Last year, competitors EnergyHub and EcoFactor released third-party studies that indicated reductions in electricity use of 6% to 17% after thermostats controlled by their back-end platform were installed in users’ homes.
The Limits of Studies
Smart thermostats have become increasingly numerous in recent years. According to Navigant Research’s report, Smart Thermostats, North American household penetration of these devices is expected to exceed 20% by 2023. Until recently the market was concentrated in warm weather states, but adoption across colder climates is becoming more common, and utilities are becoming interested in smart thermostats for year-round energy efficiency and demand response (DR) programs.
Regardless, the high prices—$150 to $300 for the device alone—are still a barrier. Hence, smart thermostat vendors have trumpeted third-party studies that indicate positive return on investment (ROI) through energy bill savings. Analyses of products from EcoFactor, EnergyHub, and now Nest indicates annual energy savings in the 8% to 15% range.
But such studies can be interpreted in several ways. The most obvious conclusion is that the chances of incurring similar savings are good given the variety in the studies’ methodology and sample populations. On the other hand, factors like the locations of households, weather varying, and simultaneous energy efficient behaviors all affect study results.
Your Results May Vary
For states where heating and cooling are a small part of the utility bill, the savings from a smart thermostat will look different than those in an area where the costs are high. In such cases the results could be misleading.
The MyEnergy study included households from all over the country in its sample, and Nest claims that it is fairly representative of their adoption base—but is that representative of U.S. consumers as a group? The average reported savings might not fall in the middle of the spectrum of all consumers, so someone using this information as a basis for purchase of the $250 device could be anywhere from greatly or slightly disappointed to slightly or very pleased depending on how similar they are to the majority observed that indicated decent savings.
And if the consumer doesn’t really care enough to break down this information in the first place, much less nitpick findings from a variety of disparate studies? These types of adopters might be drawn to purchase the device simply for its user delight qualities. Nest has created an iconic device that by most accounts works really well and that has a lot of informational features designed to trigger more energy efficient behavior. That would be a great outcome.
Tags: Building Systems, Home Energy Management, Smart Thermostats, Utility Innovations, Utility Transformations
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