How much can a smart thermostat save on energy bills?

Most studies show 10-15% savings on heating and cooling bills ($100-$200+/year for the average home). Some studies (including Nest's own data) show up to 23% savings. The savings come from: automatic setback when you leave (geofencing), learning your schedule, and optimizing run times. A $200 smart thermostat typically pays for itself in 1-2 years. Savings vary based on: local energy costs, your current thermostat habits (if you already manually adjust, savings are less), and climate (bigger savings in extreme climates).

Do I need a C-wire for a smart thermostat?

Most smart thermostats require a C-wire (common wire) for continuous power. Many older homes do not have one. Check: look at your current thermostat wiring. If there is a wire connected to the C terminal, you have one. If not: options include an add-a-wire kit ($25-$50, adds a C-wire using existing wires), a C-wire adapter (some Nest models include one), or having an electrician run a new C-wire ($100-$200). Some smart thermostats (like some Nest models) can work without a C-wire by harvesting power from other wires, but this can cause issues with some HVAC systems.

What temperature should I set my thermostat to save money?

Summer: 78°F when home, 85°F when away. Winter: 68°F when home, 60°F when sleeping or away. The key rule: set back 7-10°F for 8+ hours/day (saves up to 10% annually). Every 1°F of setback saves 1-3% on energy. Use a programmable or smart thermostat to automate these changes. Do NOT turn the thermostat off completely when away (extreme temperatures can damage pipes, cause humidity problems, and the system works harder to recover).

Smart thermostat vs programmable: which is better?

Programmable saves money IF you program it and stick to the schedule. Problem: studies show most people never program their programmable thermostat (they use it like a manual thermostat). Smart thermostats are better because: they learn your schedule automatically, adjust when you leave (geofencing), can be controlled from your phone (adjust remotely if plans change), provide energy reports, and integrate with smart home systems. The extra cost ($100-$200 more than a programmable) is recovered in 1-2 years of additional energy savings. For most homeowners: a smart thermostat is the better investment.

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Thermostat Guide: Types, Smart Features & Energy Savings

Lumberama Editorial Team, Home HVAC & Energy Efficiency Specialists Jun 22, 2026 12 min read

Thermostat Types

Manual (non-programmable): Simple dial or digital display. Set the temperature and it stays there until you change it. No scheduling. Cheapest ($15-$30) but the least energy-efficient (you have to remember to adjust it when leaving or sleeping). Being phased out in favor of programmable and smart models.

Programmable: Set a schedule (different temperatures for wake, leave, return, and sleep times). The thermostat automatically adjusts. 7-day programming is the most flexible (different schedule each day). The EPA estimates a programmable thermostat saves 8% on heating and cooling bills when used properly ($50-$100+/year). Cost: $25-$75.

Smart thermostat: Wi-Fi connected, app-controlled, with advanced features: learning (learns your schedule and preferences over time), geofencing (detects when you leave and return based on your phone's location), remote sensors (measure temperature in multiple rooms), energy reports (show how much energy you use and how to save), and integration with smart home systems (Alexa, Google Home, Apple HomeKit). Cost: $100-$300.

Top Smart Thermostats

Google Nest Learning Thermostat: The original smart thermostat. Learns your schedule and adjusts automatically. Sleek design. Home/Away detection. Energy history. $180-$
2
5
Best for: people who want a set-it-and-forget-it experience.

Ecobee Smart Thermostat: Includes a remote room sensor (monitors temperature in another room). Built-in Alexa speaker. Excellent multi-room temperature balancing. $170-$
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5
Best for: homes with hot/cold spots and multi-story homes.

Honeywell Home T9: Remote room sensors. Smart alerts (filter reminders, temperature alerts). Good for traditional HVAC systems. $150-$200.

Google Nest Thermostat (budget): Simplified version of the Learning Thermostat. No learning feature but has scheduling, app control, and energy savings. $90-$
1
3
Best for: budget-conscious buyers who want smart features.

Energy Savings Tips

The #1 energy-saving thermostat rule: set it back 7-10°F for 8 hours a day (when sleeping or away from home). This saves up to 10% annually on heating and cooling. Recommended settings: Summer: 78°F when home, 85°F when away. Winter: 68°F when home, 60°F when away and sleeping. Every degree of setback saves 1-3% on energy costs.

Smart thermostats amplify savings by: automatically adjusting when you leave (geofencing), learning your routine (no need to remember to adjust), and providing energy reports that identify waste. Most smart thermostat users report 10-15% savings on heating and cooling (some studies show up to 23%).

Installation

Most thermostat replacements are simple DIY projects (15-30 minutes). Turn off HVAC power at the breaker. Remove the old thermostat. Label and photograph the wires before disconnecting. Mount the new thermostat base plate. Connect the wires (follow the new thermostat's instructions — wire colors and terminal labels vary by system). Attach the thermostat to the base plate. Restore power and configure. Important: Check that your system has a C-wire (common wire — provides continuous 24V power). Smart thermostats require a C-wire. Many older systems do not have one. Solutions: use an add-a-wire kit ($25-$50), install a C-wire adapter (provided with some Nest models), or have an electrician run a C-wire ($100-$200).