Example with a constant electricity price
Illustrative figures, not a current tariff or measured appliance: 2 kW for 5 hours at €0.30/kWh gives 10 kWh and €3. Use your bill’s consumption-based price, including applicable taxes and variable charges. Fixed fees and the heater’s purchase price are excluded. If the tariff changes during use, calculate each price period separately.
Allow for thermostat cycling
A thermostat can interrupt heating once the set temperature is reached. Its effect depends on the room, insulation and temperature setting; do not assume a fixed percentage saving. In a simplified example with 3 hours of full-power heating within 5 hours, the heating element uses 6 kWh, costing €1.80. Any fan or control consumption is additional. This is an illustration, not a forecast for your room.
Check comparable days with meter readings
Read the same electricity register at the same time each day. In Energy Detective, open Meters, select your electricity meter and add the reading with a photo. Put the exact time, heating schedule, temperature setting, weather and other major loads in the note. Subtract consecutive readings and compare equally long periods. A whole-property meter includes other appliances, so its difference is not the heater’s consumption alone. Keep calculated examples out of your measured history.
Keep the test safe
Plug a portable heater directly into a wall socket, not an extension lead or power strip. Keep it at least 1 metre from combustible materials, or farther if the manual requires. Follow the manufacturer’s instructions and turn it off before sleeping or leaving it unattended. Do not alter wiring for this check.
