The thermostat, bill, or HVAC system mentions auxiliary heat, emergency heat, strips, or backup heat during a cold spell.
Backup electric heat can use much more electricity than normal heat pump operation. A cold snap, thermostat jump, or equipment issue can make the bill rise quickly.
Check first
Look for AUX, EM heat, heat strips, or backup heat on the thermostat or bill notes.
Check whether the thermostat was raised by several degrees at once.
Compare cold-snap daily kWh with a normal winter bill.
Review filter condition, outdoor unit airflow, and recent service issues.
Practical savings moves
Avoid large thermostat jumps that trigger backup heat when possible.
Keep filters and vents from restricting airflow.
Use the winter calculator to separate heating from billing days and rates.
Call a qualified HVAC professional when backup heat runs unusually often.
Avoid these mistakes
Do not disable safety or emergency heating controls to save money.
Do not blame rates first if daily kWh jumped sharply in cold weather.
Do not compare winter totals without checking service days.