Rate vs usage — diagnose first
| Scenario | Cause |
|---|---|
| kWh same, $ higher | Utility rate increase (call them, verify on the bill) |
| kWh higher, $ higher proportionally | Something in your house is using more — go to causes table |
| kWh much higher (50%+), $ way higher | Major appliance failure or heating/cooling issue — see causes |
The 8 causes ranked by kWh impact
| # | Cause | Typical kWh swing | Diagnose by |
|---|---|---|---|
| 1 | HVAC running excessively (extreme weather + dirty filter + closed registers) | +30-100% of total bill | Check filter, runtime hours, thermostat setpoint |
| 2 | Electric water heater element failure (sediment buildup) | +200-400 kWh/mo | Tank flush, element resistance test |
| 3 | Heat pump backup-strip running constantly | +300-800 kWh/mo | Set thermostat to EMERGENCY HEAT OFF; watch for short cycling |
| 4 | Refrigerator door seal failure or compressor going | +200-400 kWh/mo | Dollar-bill seal test; coil cleaning; replace if pre-2001 |
| 5 | Pool pump running 24/7 (was 12 hr) | +200-600 kWh/mo | Check pool timer schedule |
| 6 | Dehumidifier or space heater on continuously | +200-500 kWh/mo | Walk the house, check forgotten plug-in loads |
| 7 | Utility rate increase (especially time-of-use schedule change) | $ only, not kWh | Read the bill — rate change usually disclosed |
| 8 | Hidden draw — pool/spa heater failure, irrigation pump stuck on, electric vehicle charging schedule wrong | +100-1,000 kWh/mo | Whole-house monitor (Sense, Emporia) |
DIY diagnostic — the $25 Kill-A-Watt method
Buy a Kill-A-Watt P3 P4400 ($25 Amazon). Plug it between the outlet and the appliance. Log kWh per day for each major plug-in load:
- Refrigerator: should be 1-2 kWh/day for a modern unit. 4+ kWh/day = problem.
- Dehumidifier: 2-5 kWh/day on continuous run.
- Space heater: 12-24 kWh/day if used 8 hrs (1,500 W × 8 hr = 12 kWh; 1,500 W × 16 hr = 24 kWh).
- EV charger: 7-12 kWh per full overnight charge (varies by car).
- Pool pump: 10-30 kWh/day on 12-24 hr schedule.
The whole-house monitor option
For permanent installs: Sense Home Energy Monitor (~$300) or Emporia Vue Gen 3 (~$200). Clamps onto your main service feeders inside the panel. Shows real-time consumption by appliance (Sense uses ML to identify which device is running based on signature). Catches the "always-on phantom loads" totaling 5-10% of most bills. Installs in 30 min by an electrician.
FAQ
Why did my electric bill double in one month?
Rate increase, HVAC excess, water heater element failure, heat pump strip running, refrigerator seal failure. Compare kWh vs $ to identify which.
How do I find what's using all my electricity?
Kill-A-Watt meter ($25). HVAC 50%, water heater 14%, fridge 7%, laundry 5%. Whole-house monitor (Sense, Emporia $200-$300) for permanent visibility.
Could a neighbor be stealing my electricity?
Rare in single-family. In multi-unit: possible. Two tests: meter spins with all breakers off; neighboring outlet powered with your breakers off. Call utility for free audit.
Will replacing my refrigerator save money?
Pre-2001: yes, $135-$190/yr savings. Post-2010: probably not worth replacement alone.
Related guides
- Best heat pump water heaters 2026 — biggest single energy upgrade for most homes
- Heat pump short cycling — adjacent diagnostic that also runs up bills
- Heat pump vs furnace cost — annual operating cost comparison
Editorial standards: Reviewed by Al, Building Doctor — 30 years facilities energy auditing.