Smart Thermostat Savings Calculator
Calculates certified energy savings from smart learning and WiFi setback thermostats (such as Google Nest Learning Thermostat or Ecobee Smart Thermostat Premium) utilizing automated occupancy sensors, geofencing, and night setbacks under EPA Energy Star verified testing.
Formula
Annual Savings = Annual HVAC Spend × Savings % (8% to 12%); Break-Even Months = (Thermostat Cost ÷ Monthly Savings)
1. Savings Percentage: Away Day = 10%; Work from Home = 7%; Vacation/Airbnb = 16% 2. Annual Dollar Savings = Annual HVAC Spend × Savings Percentage 3. Monthly Average Savings = Annual Dollar Savings ÷ 12 4. Thermostat Purchase Cost = $180 (e.g. Nest / Ecobee) 5. Local Electric / Gas Utility Rebate = ~$50 to $100 instant rebate 6. Months to Pay Off = ((Thermostat Cost - Utility Rebate) ÷ Monthly Savings)
Inputs
- Estimated Annual Heating & Cooling Spend ($)
- Household Daytime Occupancy
Worked example
Installing a Nest Learning Thermostat with automated 7-degree workday and night setbacks.
Outcome: Saves 10% on heating and cooling demand = $150 saved per year ($12.50/month). A $180 smart thermostat with an $85 local electric utility rebate has a net cost of $95, paying for itself in under 8 months.
Do smart thermostats require a "C-Wire" (Common Wire)?
Most modern WiFi thermostats require a dedicated 24VAC C-wire (Common Wire) to supply continuous power to the WiFi radio and color screen. If your old thermostat wiring only has 4 wires (R, W, Y, G), you can use a Fast-Stat power extender kit or Ecobee's included Power Extender Kit (PEK).