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Energy Saving Guide · Heating

Winter electricity shock: what your heater is really costing you

By Masie Ralepelle · Published · Last reviewed · 4 min read

A glowing electric radiant heater in a living room in front of a leather sofa

June arrives, the Highveld nights drop toward freezing, and the heater comes out. Then July's bill or token run brings the shock.

A heater's cost is its wattage × the hours it runs. A 2 kW heater running 4 hours a night uses about 240 kWh a month, which is roughly R1 140–R1 229 at Tshwane's 2026/27 rates. Heating a smaller space, using a thermostat, and cutting an hour a night all add up. And July is also when the City's annual increase lands.

A 2 kW heater for four hours a night can cost more than R1 100 a month.

Why heaters are expensive

Plain electric heaters turn every unit into heat one-for-one. There's no trick that makes a bar heater "efficient". What you control is how much space you heat and for how long.

What Eskom recommends

  • Pick the right heater for the room. Eskom says a fan heater with a thermostat is the best choice to quickly heat an average room of 3 × 3 × 2.5 m, because it spreads heat evenly and switches off when the room is warm.
  • Don't heat empty rooms.
  • Aim for 18–20°C indoors in winter, and use warm clothes, blankets and hot-water bottles before reaching for the heater.

Keep the heat in

Close doors and curtains, block draughts, and heat the room you're in. A ceiling that isn't insulated lets heat escape upward; the building regulations (SANS 10400-XA) set insulation requirements for new buildings.

Heat the room you're in, not the house you're not.

Check the timing

If your bill jumped in July, two things happened at once: the cold, and Tshwane's annual increase (8.8% in 2026/27). Compare units, not rand, to tell them apart (see “Why has your bill suddenly increased? Check these 5 appliances first”).

Interesting things about heating

  • Underfloor heating is a big, often invisible load, because it runs on a thermostat under your feet. Ask an electrician what it's rated at and when it runs.
  • Air conditioners that heat (heat pumps) are covered by South Africa's energy-labelling rules (VC 9008), so look for the label if you're buying.

What fixing it could save

For a 2 kW heater (check yours; ratings vary):

  • 1 hour less a night: about 60 kWh a month, R285–R307 a month.
  • Using a thermostat so it cycles instead of running flat out: depends on the room. Measure it with a plug-in meter.
How we worked out these figures

2 kW × 4 h × 30 nights = 240 kWh. 240 × R4.75 = R1 140; × R5.12 = R1 229.

1 hour less: 2 kW × 1 h × 30 = 60 kWh → R285–R307.

Which rate. A saving comes off your top block. Most Tshwane homes using more than 400 units a month pay R4.75 a unit (401–650) or R5.12 (above 650), including VAT, in 2026/27. So we show savings as a range between those two rates.

The 2 kW figure is an example input, not a claim about any product. Use your heater's rating plate.

Heater safety: never cover a heater, never dry clothes on it, and keep it away from curtains and bedding.

Safety: don't open your distribution board, plugs or appliance wiring yourself. Electrical work must be done by a registered electrician, who issues a Certificate of Compliance (CoC) for fixed wiring.

Want a second pair of eyes? Lesedi Energy can help you read your meter data and check the electrical side of your home safely. We measure first and recommend only what's needed. Use the contact button on this page to get in touch.

Lesedi Energy: Smarter energy decisions start at home.

Sources (checked 16 Oct 2026)

  1. Fan heater with thermostat for a 3 × 3 × 2.5 m room; avoid heating unoccupied rooms: Eskom Energy saving tips: https://www.eskom.co.za/eas/energy-saving-tips/ (opens in a new tab)
  2. 18–20°C winter setting; warm clothes and blankets: Eskom factsheet: https://www.eskom.co.za/eas/wp-content/uploads/2021/04/RES-FACT-SHEET-USE-ONLY-Final.pdf (opens in a new tab)
  3. VC 9008 covers heat pumps and air conditioners: Acts Online: https://source.acts.co.za/national-regulator-for-compulsory-specifications-act-2008/n7859_4__specific_requirements.php (opens in a new tab)
  4. 8.8% 2026/27 increase: City of Tshwane: https://www.tshwane.gov.za/?p=102188 (opens in a new tab)
  5. Tshwane 2026/27 block rates (R4.75 for 401–650 units, R5.12 above 650, incl. VAT; City figures, gazette check pending): City of Tshwane: https://www.tshwane.gov.za/?p=102188 (opens in a new tab)
  6. All rand figures: calculated (method box above).