How to measure heating consumption over 7 days
A week of records gives you a reference for your own home. Track energy, operating hours and comfort together, rather than comparing only the total on two bills.
Prepare a simple diary
Choose seven consecutive days. At the same time each day, record opening and closing kWh readings, heating hours, rooms used, target temperature and observed indoor temperature. Add outdoor conditions and unusual activities such as more occupants, clothes drying or prolonged oven use.
Date · opening/closing kWh or kg used · hours · rooms · indoor temperature · outdoor conditions · notes
Keep the diary privately; WattRumo does not need your address, customer number or bill. If you use the household meter, label the result as whole-home consumption.
For electric heating
Subtract opening from closing energy readings. For example, 1,248.6 − 1,243.2 = 5.4 kWh. At €0.22/kWh, that costs approximately €1.19. A display in W or kW shows power at that moment, not accumulated energy.
At constant electrical power, kWh = kW × hours. A 2 kW heater drawing that power for three hours uses 6 kWh. If its thermostat cycles, three hours plugged in does not mean three hours at rated power. A heat pump’s advertised heating output is not its electrical input. Virginia Cooperative Extension explains the power–time–energy relationship.
Use equipment energy data or a compatible energy meter where available. Whole-home readings also include cooking, hot water and other appliances, so do not assign the entire increase to heating. Dedicated monitoring of fixed circuits requires a suitable professional; this diary does not require opening electrical panels or adapting connections.
For pellet heating
Record fuel added and account for the hopper’s opening and closing levels. Adding 15 kg does not establish that 15 kg burned if some fuel remains. Starting and finishing at similar levels reduces that error.
Suppose 30 kg is consumed over seven days, with 15 kg bags costing €5.40. Fuel costs €10.80 per week, about €1.54 per day. This excludes stove electricity, maintenance and delivery. Converting fuel weight into useful heat would also require fuel energy content and applicable efficiency.
Calculate the weekly result
| Record | Total | Energy cost |
|---|---|---|
| Dedicated electricity | 42 kWh | €9.24 at €0.22/kWh |
| Pellets | 30 kg | €10.80 at €5.40/15 kg |
42 kWh over seven days is 6 kWh/day. Extending that to 30 similar days gives 180 kWh and €39.60. The calculation assumes similar use and weather; it is not a guaranteed monthly bill.
Compare comfort as well as cost
Two systems are not directly comparable if one heated only the living room and another heated several rooms, or if indoor temperatures differed. Repeat the diary and note changes. Similar weather and schedules improve the comparison without removing every source of uncertainty.
In the advanced calculator, enter the area actually heated, your schedule and a suitable electricity price. If an estimate differs from the diary, review these inputs and the comfort achieved first. Do not change COP merely to force agreement: electrical energy alone does not measure delivered heat.
Keep a useful reference
Save the energy total, price, heated rooms and comfort notes. A second comparable week is more informative than presenting a single day as a universal normal consumption figure.