What does a plug-in heater cost in a rented room?

01The arithmetic

An electric heater turns every kilowatt-hour fully into heat, so the consumption is simple to work out: power times hours. A 2 kW heater that runs at full power for 6 hours a day uses 12 kWh a day. If the heater has its own thermostat that switches it off now and then, this is the maximum. At an electricity price of €0.29 per kWh, roughly the Dutch average for a variable contract in August 2026, that is €3.48 a day, or about €106 a month.

Cost per month (30.4 days) at €0.29 per kWh. Use your own rate: at €0.35 per kWh, a 2 kW heater running 6 hours a day costs €128 a month.

Over a heating season of seven months, that is about €740 for one heater. With four heaters in a portfolio of 40 rooms, it comes to over €420 a month in electricity that nobody sees. Work it out for your own houses with the calculator on the home page.

02Why tenants top up the heating

A heater is often a symptom. The most common reasons:

• The room really is cold. A radiator that does not work properly, a valve that is closed, or a thermostat in the living room that cannot get the north-facing bedroom up to temperature.
• Different hours. Someone on shift work is at home and asleep exactly when the heating schedule is set low.
• Different habits. What one resident finds warm enough, another finds cold.
• No reason to save. If energy is included in the rent or in a fixed deduction, the resident never notices what they use.

That is why it pays to look at two things at once: rooms that are too cold, and rooms that are warmer than the central heating allows. A room that sits below 17 °C for days and then suddenly reaches 24 °C tells the whole story: first a fault, then a heater.

03More than the bill: safety

Several heaters on one circuit, extension leads and power strips: that is how a circuit trips, or worse. Version 7.3 of the Dutch SNF standard for worker housing contained the requirement, for good reason, that there is no visible overloading of the electrical supply. A heater you find early is also a risk you remove early.

04How to find a heater without walking into every room

The energy bill only shows the total per house, and often only at the annual statement. An announced inspection does not help much either: a heater is in the wardrobe within a minute. What a heater cannot hide is the temperature of the room.

If the central heating is set to 21 °C and a room stays above 23.5 °C for a full hour during the day, or above 22.25 °C in the evening and at night, that room is being heated by something else. Because the lowest reading of the whole hour is used, a hot shower or sun on the window does not cause a false alarm. In warm weather (18 °C or more outside, or 21 °C or more in the last 5 hours) no alert is sent: then the warmth is the weather. eyesonrooms runs exactly that check for every room and sends an alert with the address and the room, so the visit is targeted.

05Frequently asked questions

06Sources

• Pure Energie: electricity price per kWh in 2026 (average about €0.29 incl. VAT and energy tax, August 2026; Dutch)
• SNF: Norm voor huisvesting van arbeidsmigranten (housing standard for labour migrants), version 7.3 (pdf, Dutch, via the municipality of Vlissingen)

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