Best Smart Thermostat: Checked Against the ENERGY STAR List and the Field Studies

Four are computed from the decode table lower on the page, two are the certified list itself, one is the certifying program's own bar, and two are field results that link to the report.

1. 19 of 22

   19 of the 22 bestselling smart thermostats on Amazon are on the ENERGY STAR certified list. The 3 that are not (LUX, Aqara, meross) are Matter or HomeKit devices sold on integration, and their listings make no ENERGY STAR claim. 4 listed models never mention the certification. ^[1]

   The top results for five Amazon searches on 2026-09-15, nine per search, deduplicated to 22 ASINs and matched by brand and model code against the 117-row ENERGY STAR connected-thermostat dataset pulled the day before.

2. 13 of 22

   A price on Amazon is often not Amazon's price. On the build date the buy box belonged to a third-party marketplace seller on 13 of the 22 listings, and 9 carried a future ship date rather than stock. The 22 listings also cover 17 distinct products: five are a second colourway of a unit already in the set, and one is a two-pack. ^[1]

   Buy-box seller and price as a shopper sees them on 2026-10-17; availability and parent ASIN from the Creators API item record the same day. Counts on this page are per listing, because the listing is what makes the claim; the product count is here so the denominator is not mistaken for a model count.

3. 4 of 22

   15 of the 22 listings say they work with a heat pump. None uses the words 'auxiliary heat' or 'emergency heat': three say 'heat pump with electric backup' and one says 'dual fuel'. That backup stage is where the money is. The independent evaluation of a 185-home Oregon pilot measured a 12% cut in electric heating, 781 kWh a year per home; the attribution of that cut to the thermostat's management of the stage is the maker's white paper, not the evaluator's own words, and ENERGY STAR makes every heat-pump-capable certified model log its run time by the hour. ^[2]

   Each listing's title and bullets read by hand for 'heat pump', 'auxiliary heat', 'emergency heat', 'electric backup' and 'dual fuel'; the quote behind every cell is in the decode file. The Oregon figure is the Energy Trust pilot as reported in the Nest 2015 white paper.

4. 8%

   ENERGY STAR's certification bar is at least 8% less heating run time and 10% less cooling run time, measured against a modeled baseline of the same home never setting back; its plain-language average is 8% of the heating and cooling bill, about $50 a year. 12 of the 22 listings print a savings figure: 7 say 23% or 26%, and both Nest Learning listings say up to 31%. ^[8]

   Program Requirements V1.0 and the Method to Demonstrate Field Savings V1.0, both read in full; the FAQ page for the $50 figure; listing text for the claims.

5. 12.5% vs 5.0%

   One randomized pilot put a smart thermostat against a standard programmable one in the same utility and the same season: 300 homes got a Nest and a separate 300 got a professionally installed programmable. The smart unit saved 12.5% of gas heating, the programmable 5.0%. On cooling the two were indistinguishable, 13.9% against 13.1%. ^[3]

   Cadmus evaluation for Vectren Energy, Indiana, 300 homes per arm, as reported in the Nest 2015 white paper.

6. 0%

   The largest randomized field experiment found no statistically or economically significant change in energy use across 1,385 households over 18 months; some specifications showed electricity up 2.3% and gas up 4.2%. The authors attribute the gap to occupants overriding the schedule; the analysis rests on more than 16 million hourly electricity readings. ^[14]

   Brandon, Clapp, List, Metcalfe and Price, NBER Working Paper 30482, abstract and the Becker Friedman Institute summary.

7. 0.8–5.2 yr

   At ENERGY STAR's national average of about $50 a year, the six picks pay for themselves in 1.6 years ($79.99) to 4.9 years ($246.99); ComEd's 2025 rebate of $75 would have covered all but $4.99 of the cheapest. EPA says in the same breath not to apply its national average to any one home, so read this as the shape of the decision, not a forecast: even the cheapest certified pick takes about 19 months to pay back, longer than the 18 months over which the largest randomized experiment measured nothing at all. ^[10]

   Sticker price ÷ $50/yr, the ENERGY STAR FAQ figure, and against ComEd's 2025 rebate of $75. Prices are Amazon's on 2026-10-17.

8. 0.04–2.59 W

   The 117 certified rows draw between 0.04 and 2.59 W in network standby, $0.06 to $3.63 a year at 16¢/kWh; the median row draws 0.60 W, $0.84 a year. The bestsellers span 0.10 to 2.59 W. It is the one running-cost number the certification publishes per model, and it is small. ^[12]

   Certified watts from the ENERGY STAR dataset × 8,760 h × $0.16/kWh, the standing electricity rate this site uses on every page so figures compare; your own rate is on your bill.

9. 10 of 22

   On the wire that powers the radio: 7 listings say a C-wire is required and offer nothing to get around it, 2 require one but put a free adapter or a voucher for it in the box, 2 include the adapter that creates one, 2 sell that adapter separately, 1 says only some wiring needs it, 7 say most systems manage without, and 1 does not say. Of the 7 that manage without, 4 name the exception in their own text: a heat pump, a heat-only or cool-only system, or a zoned system needs the wire anyway. ^[1]

   Listing text read by hand for each of the 22 ASINs, with the verbatim fragment recorded beside every cell in the decode file.

10. 0.06–1.79°F

    Certified temperature accuracy across the 117 rows runs from ±0.06°F to ±1.79°F, median ±0.52°F, against a program cap of 2.0°F. Among the bestsellers it runs ±0.09°F to ±1.28°F. A thermostat that reads low holds the house warmer than the number on its screen for the whole season, which is the same direction as the saving the certification measures and is not netted against it. ^[12]

    static_temperature_accuracy on every certified row; the bestseller range from the 22 decoded models. No study in our set measures what a given bias costs, so no dollar figure is attached to it here.

Left, heating savings by source with the sample behind each. Right, cooling. The two maker claims are plotted for scale; the randomized experiment that found nothing is in the caption, because zero does not draw a bar.

A smart thermostat is a radio and a screen that need continuous power. Whether your wall can supply it decides more than any feature. Count the wires behind your old thermostat before you shop: the C, or common, wire is the fifth one, and it is the one that carries power rather than a call for heat.

The thermostat is a switch for the low-voltage control circuit the equipment already has: the listings call it 'most 24 V systems', and ENERGY STAR certifies nothing above 30 V. The question for each system is whether that circuit is what controls it, and whether the thermostat can drive the stages the system has.

• Works Gas or oil furnace with central AC — The system every bestseller is designed around: one or two heat stages, one or two cooling stages, a fan. The 12.5% Indiana heating figure and the 13.9% cooling figure come from homes like this. Any listed unit works; the C-wire is the only wrinkle. ^[3]
• Works Heat pump with electric auxiliary heat — The one system where the thermostat's settings change the bill. The electric strips that back up the compressor use, in the Energy Trust of Oregon specification's words, substantially more energy than the heat pump technology, so what matters is a thermostat that keeps them off above a set outdoor temperature (the Energy Trust of Oregon specification uses 35°F) and recovers gently enough not to call them. Check the maker's own page for how it handles that stage: a listing that only says 'works with heat pumps' is not telling you. ^[19]
• Works Dual fuel (heat pump plus gas furnace) — Needs a thermostat that can switch between the compressor and the furnace at an outdoor temperature you set. One bestseller listing names dual fuel: ecobee's Essential. Honeywell's T6 Pro lists 2 heat / 1 cool heat-pump staging without naming dual fuel. Confirm on the maker's compatibility checker before buying. ^[1]
• partly Boiler, radiators or hydronic floor — Two-wire heat-only circuits run most smart thermostats, but heat-only is exactly the case where the 'no C-wire' units need a C-wire or adapter. Radiant floors respond over hours, so a setback saves less and costs more comfort than the same setback on forced air. ^[20]
• partly A whole-house humidifier, dehumidifier or ventilator on the same wiring — 70 of the 117 certified models sense humidity, but sensing is not controlling: only a handful state humidify, dehumidify or ventilation control as a feature, and the accessory needs its own terminal at the thermostat. Check the maker's wiring page for an ACC or HUM terminal before you assume the new unit will run what the old one ran. ^[12]
• Wrong tool Electric baseboard, wall heaters, line-voltage radiant — 120 or 240 V at the thermostat. None of the 22 bestsellers switches it and the ENERGY STAR program does not certify above 30 V. You want a line-voltage smart thermostat, one per heater, which is a separate purchase and a separate page. ^[8]
• Wrong tool Ductless mini-split or PTAC — Most carry their own controls and infrared or proprietary remotes, and a low-voltage wall thermostat does nothing unless the maker sells a wired interface. Two of the 22 bestsellers, the LUX TQX and the Aqara W200, do list PTAC compatibility; for everything else the route is the maker's Wi-Fi adapter or an infrared bridge.

Heat leaves a house in proportion to the gap between inside and out, so every hour at a lower setpoint is an hour of smaller loss. A thermostat saves by cutting that gap while you are asleep or away and by not overshooting when you come back. On a furnace that is the whole mechanism. On a heat pump there is a second one, and it is bigger.

ENERGY STAR certification bar, heating

≥ 8%less heating run time than a modeled never-set-back baseline, lower 95% bound; 10% for cooling ^[8]

Second bar the program applies

80% of homesmust save at least 4% heating and 5% cooling ^[8]

Energy Trust of Oregon specification, auxiliary-heat lockout

35°Fthe strips stay off above it; the specification's words are that aux heat 'uses substantially more energy than the heat pump technology' ^[19]

Certified models

11784 models from 35 brands; 54 geofence, 54 take a remote sensor, 61 read outdoor temperature ^[12]

• The program ENERGY STAR's method compares each home's measured run time against that same home held all day at its occupants' own 90th-percentile heating setpoint. It is a 'versus never setting back' comparison, not 'versus a $25 programmable'. ^[9]
• The heat pump A large morning recovery on a heat pump can call the electric strips, which the Oregon program specification says use substantially more energy than the heat pump technology. Managing that call is what the maker's white paper credits for the Oregon pilot's 12%; a thermostat that only runs a schedule can cost you. ^[2]
• The person Every saving above assumes the schedule survives contact with the household. In the 1,385-home randomized experiment it did not, and the measured effect was nil. ^[14]

The field results that show savings came from thermostats whose schedules were set once and left alone, and, on heat pumps, from auxiliary-heat management. Those two conditions are the difference between the 12% pilots and the 0% experiment.

1. Before you buy Photograph the wires behind the old thermostat. Count them and read the letters. R, W, Y, G and C is the full set; four without C means you need an adapter-in-the-box unit, a 'works without' unit on a conventional furnace, or an electrician. Two wires (heat only) or a heat pump means you need C regardless of what the box says.
2. Install day Tell it the truth about the system. Heat pump or conventional, one stage or two, whether there is auxiliary heat and what fuel it burns. A heat pump set up as a conventional furnace runs the compressor and strips together on every call.
3. Install day, heat pumps Set the auxiliary and compressor lockouts. The Energy Trust of Oregon specification keeps the strips off above 35°F outdoor; set yours where the maker's own tool says, and never set the compressor lower than the unit is rated for. Keep the setback small enough that the house recovers without calling the strips. This stage is where the 12% came from.
4. Week 1 One schedule, modest setbacks, then hands off. On a furnace, the long-standing guidance is 7–10°F back for eight hours, which is where the 5–15% range comes from; we quote it as reproduced in the Nest 2015 paper, because DOE's own page would not load. On a heat pump, less. Every manual override is logged and, in the randomized experiment, overrides are where the savings went.
5. Month 1 Read the run-time report, not the savings badge. Certified units log heating and cooling run time; that number is what ENERGY STAR measures. A 'you saved 20%' badge is the maker's model, not a bill. Compare degree-day-adjusted run time against last year's bills if you have them.
6. Every heating season Re-check the heat-pump lockouts and the utility rebate. Of the two programs we read, ComEd's 2025 program paid $75 against the certified list and closed to applications on 28 February 2026; Duke Energy Progress pays $150 the first year for letting the utility nudge the setpoint on peak days, with no certification required. Check both kinds before you assume the list is the gate.

The pairings cover the two things the thermostat cannot see on its own: the rooms it is not in and the equipment it is not wired to.

Sensor counts are from the listings and the certified list; savings from sensors are not established by any study in our set.

One listed unit per job: two by system type, the rest by wiring, budget and ecosystem. Each is here because it is on the ENERGY STAR certified list, had an Amazon price on the build date, and its own listing or maker page answers the question its job asks. The three unlisted bestsellers are not here; the cheapest of them, meross at $57.99, is $22 under the cheapest certified pick here and carries no certification for a rebate to check.

Every "Check price" link below is an affiliate link: if you buy, we earn a commission at no extra cost to you. It does not change which units are here — the picks are chosen on the certified data and the listing text, and no brand paid for a place.

1. 

   Most furnace-and-AC homes, four or five wires

   Google Nest Thermostat

   $99.99 · ENERGY STAR listed · 0.1 W standby ($0.14/yr) · C-wire: not required (most systems) — required on a heat pump · 2.0 yr at ENERGY STAR's $50/yr average

   Listed, 0.10 W standby, $99.99, and its listing says most conventional systems run it without a C-wire. No remote sensor and no learning, which the certification does not ask for either.

   Google Home app; it is Matter certified, so it joins an Apple or Samsung home through a Matter controller rather than natively.

   Check price on Amazon

2. 

   Heat pump with electric backup

   Google Nest Learning (4th gen)

   $233.99 · ENERGY STAR listed · 0.1 W standby ($0.14/yr) · C-wire: not required (most systems) · 4.7 yr at ENERGY STAR's $50/yr average

   Google's spec page states the staging in full: a heat pump up to three stages with one or two stages of auxiliary or alternate heat, and emergency heat. Honeywell's T9 page states emergency heat as well, so this is not a Nest-only capability — the Nest is the pick because the one independent field result on backup-heat management was measured on Nests. Listed, Matter, 0.10 W standby, sensor in the box, and its listing says most homes need no C-wire.

   $233.99, $134 more than the plain Nest Thermostat. The silver variant of the same unit lists at $229.99, also sold by Amazon. Its listing prints 'up to 31%', the largest claim in this set and the one with no published method. Certified accuracy ±0.09°F, second on the list to Vivint's ±0.06°F, which changes nothing about the bill.

   Check price on Amazon

3. 

   Cheapest listed unit

   Sensi Lite ST25W

   $79.99 · ENERGY STAR listed · 0.11 W standby ($0.15/yr) · C-wire: not required (most systems) — required on a heat pump · 1.6 yr at ENERGY STAR's $50/yr average

   $79.99, listed, 0.11 W standby, Amazon is the seller, and its listing says a conventional furnace runs it without a C-wire. The 23% on the box is Sensi's own figure; the certification behind it is the same one the $247 units carry.

   C-wire required on heat pumps and heat-only systems; no sensors.

   Check price on Amazon

4. 

   A four-wire wall, and you would rather not buy the adapter

   Honeywell Home X8S Premium

   $246.99 · ENERGY STAR listed · 2.59 W standby ($3.63/yr) · C-wire: required, adapter in box · 4.9 yr at ENERGY STAR's $50/yr average

   C-wire required, and if your system has none the box carries a voucher for a Honeywell C-wire adapter by mail at no cost. Its listing is one of only three in the set that names the heat pump's electric backup stage, it ships a room sensor, and Amazon itself is the seller.

   2.59 W standby, $3.63 a year — the highest in the set, about $3.50 a year more than a Nest. $246.99.

   Check price on Amazon

5. 

   Rooms that run hot or cold

   ecobee Premium

   $245.00 · ENERGY STAR listed · 1.83 W standby ($2.56/yr) · C-wire: adapter in the box · 4.9 yr at ENERGY STAR's $50/yr average

   Sensor in the box, listed, Siri and Alexa built in, and the Power Extender Kit for a four-wire wall. Buy it for the sensor if one room is the problem; no study in our set shows a sensor lowering a bill.

   1.83 W standby, about $2.56 a year; $245, sold on the build date by Cellular express, a third-party seller; Amazon itself had no offer.

   Check price on Amazon

6. 

   Alexa household, C-wire present, under $80

   Amazon Smart Thermostat

   $79.99 · ENERGY STAR listed · 0.89 W standby ($1.25/yr) · C-wire: required · 1.6 yr at ENERGY STAR's $50/yr average

   Listed, $79.99. Its page says both things about the money: the bullet credits EPA estimates for $90 a year, the body credits an Amazon study using EPA's method, and ENERGY STAR's own FAQ says about $50. It requires a C-wire, which the title says up front.

   Alexa app only; no sensors, no HomeKit, no Matter.

   Check price on Amazon

Prices and sellers are what the Amazon buy box showed on 2026-10-17; standby watts and accuracy are ENERGY STAR's. Every pick was buyable that day. The cheap way to solve a four-wire wall would be ecobee's Enhanced at $188 with the Power Extender Kit in the box, and it is not a pick: its offer on the build date came from a third-party seller (ANR TECH) with no ship date. The decode table below carries the same fields, plus the seller, for all 22 bestsellers.

Three lines on the listings do most of the selling. Each has a document behind it; here is what the document says.

Nest Learning listing, both variants

31%the largest claim in this set; the listing cites a footnote, and the maker's own spec page prints no percentage ^[1]

ecobee, on its own savings page

26%internal analysis, 'has not yet undergone independent third-party verification' ^[21]

ENERGY STAR, plain-language average

8% · $50/yrthe FAQ figure; the Amazon listing says $90 ^[10]

Indiana randomized pilot, heating

12.5% vs 5.0%smart vs standard programmable; cooling not distinguishable ^[3]

'No C-wire' units on a heat pump

C-wireNest and Sensi fine print: heat pump, heat-only and zoned systems need it ^[1]

• Maker The Nest Learning Thermostat can help save up to 31% on heating and cooling bills, from both Nest Learning 4th gen listings; Google's own spec page for the same unit states no savings figure at all. ^[1]
• Maker Save up to 26% per year on heating and cooling costs, from the ecobee Enhanced listing; ecobee's site: based on an internal analysis, not yet independently verified. ^[21]
• Maker According to EPA estimates, ENERGY STAR certified thermostats save an average of $90 on yearly energy bills, from the Amazon Smart Thermostat listing; the body of the same page credits an Amazon study using EPA's method, the two-pack listing of the same device says $50, and $50 is the figure on ENERGY STAR's FAQ. ^[10]
• Maker Designed to work without a C wire in most homes, but for some systems, including heating only, cooling only, zone controlled, and heat pump systems, you'll need a C wire or other compatible power accessory, from the Nest Thermostat listing. ^[1]

We took the top results for five Amazon searches (nine per search), removed duplicates, and looked each brand and model up in the 117-row ENERGY STAR connected-thermostat dataset. The table is what the listing claims beside what the list certifies.

ENERGY STAR listed

86%19 of 22 products

Says heat pump

68%15 of 22 products

Names the heat-pump exception

18%4 of 22 products

Remote sensor

41%9 of 22 products

Matter

50%11 of 22 products

• 19 of 22 are on the certified list; the 3 that are not are LUX, Aqara and meross. 4 listed units never mention the certification on the listing.
• 15 listings claim heat-pump compatibility. None uses the words auxiliary or emergency heat; three say 'heat pump with electric backup' and one says 'dual fuel'.
• 12 listings print a savings figure: up to 31% (both Nest Learning listings), 26% (ecobee Enhanced and Premium), about or up to 23% (four Sensi units and ecobee's Essential), 8–16% (Honeywell T5), and $90 and $50 a year (the two Amazon listings of the same device). The certification average is 8%, or about $50.
• Certified standby power among the listed bestsellers runs 0.10–2.59 W: the Nest units are lowest at 0.10 W, the Honeywell X8S pair highest at 2.59 W.

Standby cost = certified network-standby watts × 8,760 h × $0.16/kWh. Accuracy is ENERGY STAR's static temperature accuracy in °F.

The certification program, two utilities that pay for the thermostat, four editorial tests with named authors, six maker pages and three community threads, in one table. Every row links to the page it came from. The C-wire stance each takes is plotted in the findings above; the savings figure, where one is printed, is in the Recommends column.

Harvested from the subreddits where people ask what to buy and what went wrong, then filtered to the comments that name a thermostat or a thermostat brand. The shares below are of those comments, not of the whole harvest — a Home Assistant recommendation in a thread about door locks is not a thermostat buyer asking for local control. Every quote is verbatim and links to the comment.

Reddit search across the six communities, then each thread's comments read from the rendered page; 280 threads and 5,393 comments were harvested, of which 1,395 name a thermostat or a brand and are the denominator here. Themes are keyword matches over that set, each one's quote being the highest-scoring comment that carries both the thermostat term and the theme term. Reddit rate-limited the JSON endpoint partway through; the remainder was read from the HTML page, and 225 thread fetches could not be completed and are not represented.

• Daniel Wroclawski Senior Home & Appliances Writer, Consumer Reports (lab testing credited to Kathleen Halevah and Joe Chin)
  Most smart thermostats require a C-wire so they can receive constant power. Consumer Reports, "8 Best Smart Thermostats of 2026, Lab-Tested and Reviewed" · 2026-01-01 ↗
• Paul Rankin Contributing Writer & Editor, Bob Vila (co-bylined with Tony Carrick, Jasmine Harding, and Glenda Taylor)
  Smart thermostats require more electricity than either manual or programmable thermostats to power their network connections and GPS functions. This means the model you select may require a common wire (also known as a C-wire) that runs from the thermostat to the HVAC system. Bob Vila, "The Best Smart Thermostats of 2026" · 2026-01-13 ↗
• Rachel Murphy Editor, Home, Reviewed (USA Today) (co-bylined with Dr. Dave Ellerby, Chief Scientist, and Marc Saltzman, Contributing Writer)
  Most smart thermostats require a C-wire. Some thermostats will work without it or may require a separate conversion kit Reviewed.com, "10 Best Smart Thermostats: Keeping home comfortable" · 2026-04-02 ↗
• Austin Palmer Senior Review Analyst, TechGearLab (contributors David Wise and Katie Melynn)
  All of the thermostats we tested have great temperature accuracy TechGearLab, "The Best Thermostat, Lab Tested & Ranked" · 2025-10-01 ↗

Cited without a named author: ENERGY STAR (three pages), ComEd, Duke Energy Progress, Google Nest, ecobee, Honeywell Home, Copeland Sensi and Amazon; their pages are in the sources list. Community threads (r/homeautomation, r/smarthome, r/hvacadvice) are quoted in the consensus panel; individual Reddit usernames are not treated as verifiable published positions and are not listed here.

How much does a smart thermostat actually save?

ENERGY STAR's average is 8% of the heating and cooling bill, about $50 a year, and its certification bar is at least 8% less heating run time than never setting back. The independent numbers run 5–15% on heating: 12.5% for a Nest against 5.0% for a standard programmable thermostat in the same Indiana pilot, and 12% on heat-pump electricity in Oregon. The largest randomized experiment, 1,385 homes over 18 months, measured no significant change at all, because occupants overrode the schedule. The 23%, 26% and 31% on the listings are the makers' own analyses; ecobee says on its site that its figure is not independently verified, and the 31% listings publish no method. ^{[10][3][14][21]}

Which smart thermostat is best for a heat pump?

One whose own documentation says how it handles the electric backup heat, because those strips use substantially more energy than the heat pump technology itself, in the Oregon program's words, and it is the only mechanism here with an independent field result attached: a 12% cut in electric heating across 185 Oregon homes running Nests, with the causal attribution coming from the maker's white paper rather than the evaluator. Google's spec page states heat-pump staging with auxiliary and emergency heat; Honeywell's X8S pair and the RTH9600WF say 'heat pump with electric backup' on the listing. None of the 22 listings uses the words 'auxiliary heat' or 'emergency heat', so the listing is not where you will find this: check the maker's own compatibility page. The Energy Trust of Oregon specification keeps the strips off above 35°F outdoor. ^{[2][19][1][4]}

Do I need a C-wire?

Usually. Of the 22 bestsellers, 10 need one: 7 say so flatly, 2 include a free adapter or a voucher for it, and 1 says only some wiring needs it. 2 ship the adapter that creates one, 2 sell it separately, 7 say most systems manage without, and 1 does not say. Of the 7, 4 name the exception themselves: a heat pump, a heat-only or cool-only system, or a zoned system needs the wire. Count the wires behind your old thermostat first — five with a C is the easy case. ^[20][1]

Is the Nest Thermostat better than the Nest Learning Thermostat?

For the bill, no. Both are on the ENERGY STAR list, both draw 0.10 W in standby, and the certification does not distinguish learning from a set schedule. The Learning 4th gen adds a sensor in the box, Matter, the documented heat-pump staging and a certified accuracy of ±0.09°F (second on the list to Vivint's ±0.06°F) for $134 more. If you will set a schedule and leave it on a furnace, the $99.99 unit earns the same result. ^[12][1]

Is ecobee better than Nest for a heat pump?

On the pages we could fetch, Google's is the more specific: its spec page states heat-pump control up to three stages with auxiliary or alternate and emergency heat. ecobee keeps its compatibility and threshold detail in an interactive checker and support pages that would not load for us, so we do not state its settings here. Neither is certified as saving more than the other — the certification is granted to the product, not to a feature — so decide on documentation you can read and on the ecosystem you already own. ^[4][5][8]

Why is the Sensi Lite so cheap, and is it any good?

It is $79.99 because it has no sensors and no learning. It is on the ENERGY STAR list, draws 0.11 W in standby, and its listing says a conventional furnace runs it without a C-wire. The certification is identical to the $247 units'. Its own bullets say a C-wire is required on a heat pump or a heat-only system. ^[12][1]

Does the Amazon Smart Thermostat really save $90 a year?

Its page says both things. The bullet credits EPA estimates for the $90; the body of the same page credits an Amazon study using EPA's ENERGY STAR methodology. ENERGY STAR's own FAQ says about $50, and the two-pack listing of the same device says $50. The device is certified; the $90 is a marketing figure, not a certified one. ^[10][1]

Will a smart thermostat work with electric baseboard heat?

No, not any of the 22 bestsellers. Baseboards and wall heaters switch 120 or 240 V; these thermostats switch the low-voltage control circuit the listings call 'most 24 V systems' and the ENERGY STAR program does not certify above 30 V. You need a line-voltage smart thermostat, one per heater. ^[8]

Do remote sensors save energy?

Not that any study in our set shows. 9 of the 22 bestsellers take a sensor and 54 of the 117 certified models list the feature, but no field study we found isolates its effect on the bill. Buy the sensor for the room that runs hot or cold, not for the saving. ^[12]

Will my utility pay me for one?

Often, and in two ways. ComEd's 2025 program paid $75 for a thermostat on the ENERGY STAR certified list installed on one of four system types, and closed to applications on 28 February 2026, so check the current year. Duke Energy Progress pays $150 the first year and $50 after for enrolling in demand response, which lets the utility nudge your setpoint on peak days and does not require certification at all — its list is ten compatible brands, Lux among them. So of the three unlisted bestsellers, Lux qualifies at Duke; Aqara and meross qualify at neither. Check your own utility for both kinds. ^[11][6][7]

• Best cold-climate heat pumps — the systems where the aux-heat setting matters most
• Furnace filters by MERV — the other thing on the schedule
• Best mini-splits — which carry their own controls
• Best air purifier — the same decode method on the AHAM directory
• Operating cost calculator — what the run time costs at your rates

1. 1

   Decode of 22 Amazon smart-thermostat bestsellers against the ENERGY STAR list (this page's table)

   Verified HVAC Data · verifiedhvacdata.com · 2026

2. 2

   Energy Trust of Oregon, Nest Learning Thermostat heat-pump pilot (as reported in the Nest 2015 white paper)

   Energy Trust of Oregon; Apex Analytics · energytrust.org (evaluation report); figures as reported in the Nest 2015 white paper · 2014

3. 3

   Evaluation of the Vectren programmable and smart thermostat pilot, Indiana (as reported in the Nest 2015 white paper)

   Cadmus Group · as reported in the Nest 2015 white paper (puc.pa.gov copy) · 2015

4. 4

   Nest Learning Thermostat (4th gen), tech specs and wiring compatibility

   Google · store.google.com, read 2026-09-15 · 2026

5. 5

   Smart Thermostats: Premium, Enhanced and Essential compared

   ecobee · ecobee.com, read 2026-09-15 · 2026

6. 6

   ENERGY STAR Smart Thermostat rebate application, 2025 program year

   Commonwealth Edison · comed.com (PDF) · 2025

7. 7

   EnergyWise Home smart thermostat enrollment, Duke Energy Progress

   Duke Energy Progress · greatergrid.com, read 2026-09-15 · 2026

8. 8

   ENERGY STAR Program Requirements for Connected Thermostat Products: Partner Commitments and Eligibility Criteria, Version 1.0 (Rev. Jan 2017)

   U.S. EPA ENERGY STAR · energystar.gov · 2017

9. 9

   ENERGY STAR Connected Thermostat Products: Method to Demonstrate Field Savings, Version 1.0 (rev. Dec-2016)

   U.S. EPA ENERGY STAR · energystar.gov · 2016

10. 10

    ENERGY STAR Smart Thermostats FAQs for EEPS

    U.S. EPA ENERGY STAR · energystar.gov · 2026

11. 11

    ENERGY STAR Smart Thermostats Key Product Criteria

    U.S. EPA ENERGY STAR · energystar.gov · 2026

12. 12

    ENERGY STAR Certified Smart Thermostats dataset (Socrata 7p2p-wkbf, 117 models pulled 2026-09-15)

    U.S. EPA ENERGY STAR · data.energystar.gov · 2026

13. 13

    Energy Savings from the Nest Learning Thermostat: Energy Bill Analysis Results

    Nest Labs · Nest Labs white paper (hosted by PA Public Utility Commission) · 2015

14. 14

    The Human Perils of Scaling Smart Technologies: Evidence from Field Experiments

    Brandon A, Clapp CM, List JA, Metcalfe RD, Price MK · NBER Working Paper 30482 (rev. Nov 2024), doi:10.3386/w30482 · 2022

15. 15

    Research summary: The Human Perils of Scaling Smart Technologies

    Becker Friedman Institute for Economics, University of Chicago · bfi.uchicago.edu · 2022

16. 16

    Managing thermal comfort in contemporary high-rise residential buildings: Using smart thermostats and surveys to identify energy efficiency and comfort opportunities

    Stopps H, Touchie MF · Building and Environment 173:106748, doi:10.1016/j.buildenv.2020.106748 · 2020

17. 17

    Load shifting and energy conservation using smart thermostats in contemporary high-rise residential buildings: Estimation of runtime changes using field data

    Stopps H, Touchie MF · Energy and Buildings 255:111644, doi:10.1016/j.enbuild.2021.111644 · 2022

18. 18

    UL 60730-1, Edition 6: Automatic Electrical Controls – Part 1: General Requirements

    UL Standards & Engagement · shopulstandards.com · 2024

19. 19

    Auxiliary heat lockout settings vital to energy-efficient operation of heat pump equipment

    Energy Trust of Oregon · insider.energytrust.org · 2026

20. 20

    Everything You Need to Know About a C-Wire

    Honeywell Home / Resideo · honeywellhome.com · 2026

21. 21

    ecobee Savings

    ecobee Inc. · ecobee.com (internal analysis, April 2021, not independently verified) · 2021

22. 22

    This site's own ENERGY STAR Certified Smart Thermostats pull (verifiedhvacdata.com data corpus)

    Verified HVAC Data · verifiedhvacdata.com/data/research/gold/energystar-smart-thermostats.json · 2026