Lesson 5 of 5 5 min read

Measuring Your Actual Savings

Why Measurement Matters

It's easy to install smart devices and assume they're saving energy. But without actual measurement, you're just guessing. Real data helps you identify which automations deliver the most savings and which devices are costing more than you think.

Whole-Home Energy Monitoring

A whole-home energy monitor gives you a real-time view of your total electricity consumption. The most popular options:

  • Emporia Vue — $35-150 depending on model. Clamps onto your electrical panel. Per-circuit monitoring available with the Gen 2 model. Excellent Home Assistant integration.
  • Sense — $300. Uses machine learning to identify individual devices by their electrical signatures. Takes weeks to learn your devices but provides impressive detail.
  • IoTaWatt — $100-200. Open-source, local-only monitoring. 14 circuit inputs. Great for privacy-focused users.

Device-Level Monitoring

Smart plugs with energy monitoring let you track individual devices. Look for plugs that report watts, kilowatt-hours, and voltage:

  • TP-Link Kasa KP125 — WiFi, energy monitoring, affordable
  • Zooz ZEN15 — Z-Wave, great for high-draw devices up to 15A
  • Shelly Plug S — WiFi, compact, excellent Home Assistant support

Focus monitoring on your biggest consumers first: HVAC, water heater, dryer, EV charger, and entertainment systems.

Calculating Your Savings

To calculate actual savings from your smart home:

  1. Establish a baseline — Compare your utility bills from before your smart home to after. Use the same months year-over-year to account for weather differences.
  2. Track automation impact — Monitor specific automations. If your smart thermostat reduces HVAC runtime by 2 hours per day and your system draws 3 kW, that's 6 kWh/day saved.
  3. Calculate phantom load elimination — If smart plugs cut 200W of standby power for 16 hours daily, that's 3.2 kWh/day or about 96 kWh/month.
  4. Multiply by your rate — At $0.15/kWh, 96 kWh saved is $14.40/month just from phantom loads.

Building an Energy Dashboard

The most actionable tool is a dashboard that shows real-time and historical data. Home Assistant's built-in Energy Dashboard is excellent for this. It tracks:

  • Total consumption over time (daily, weekly, monthly)
  • Solar production vs consumption
  • Grid import and export
  • Per-device consumption via smart plugs
  • Cost calculations based on your utility rates

Even without Home Assistant, most energy monitors provide their own dashboards and mobile apps that show trends over time.

Common Savings Benchmarks

Based on real-world data from smart home users:

  • Smart thermostat — 10-15% HVAC savings ($100-200/year for most homes)
  • Smart plugs eliminating phantom loads — $50-150/year
  • LED + smart lighting automation — $30-80/year
  • EV off-peak charging — $600-1200/year vs peak rates
  • Solar + battery optimization — 20-40% improvement in self-consumption
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