Why an energy cost for every property?
An EPC label tells you something about insulation, but not what you will pay at the end of the year. Two label-D homes can differ by hundreds of euros a year depending on size and heating. So we translate the label into an amount: that way you can fairly compare a well-insulated but pricier home with a cheaper one that burns a lot of energy.
1. The EPC score as the starting point
Every certificate carries a score in kWh per m² per year: the calculated primary energy use for heating, hot water, ventilation and cooling, determined by a certified expert under the Flemish method. We multiply it by the living area. If only the label is known, we use the middle of the label class and show a wider margin.
2. Calibration to real consumption
The score is a theoretical calculation with a standard occupant heating every room to a fixed temperature. In practice, people in poorly insulated houses heat fewer rooms and to lower temperatures. Research on almost 200,000 dwellings shows that actual consumption for a poor label is roughly half the calculated value, while for an excellent label it is slightly above it. The average Flemish house has a score of about 418 yet actually uses some 17,000 to 20,000 kWh of gas. We therefore apply a correction factor that depends on the score: from about 1.2 for label A to 0.35 for label F.
3. From score to euros
The score counts electricity with a factor of 2.5 (primary energy). For electric heating or a heat pump we divide by that factor before applying the electricity price; the heat pump's efficiency is already in the score. Natural gas is priced at the gas rate, heating oil at the oil rate (10 kWh per litre), pellets at a fixed price per kWh. If the heating type is unknown we assume natural gas and say so.
4. Household use on top
Cooking, laundry, fridge, lighting and TV are not in the EPC. That use scales with the number of occupants, which we derive from the number of bedrooms: 3 bedrooms count as a household of 3 to 4. We use the VREG average consumption per household size. With solar panels we deduct 30% of that cost for self-consumption.
5. Current prices, all-in
We use the average all-in prices per region from the monthly dashboard of the CREG, the federal energy regulator: energy, grid tariffs, levies and VAT together, for a standard household using 3,500 kWh of electricity and 17,000 kWh of gas. Tariffs are updated monthly and the date is shown with every estimate.
Tariffs of September 2026 (CREG).
Why a range rather than an exact amount?
Because your heating habits, your thermostat, your energy contract and the weather matter more than any formula can capture. We therefore show a margin of 20% below and above the mid value (30% when only the label is known). The amount is meant to compare homes with each other, not to predict your bill.
Sources
- CREG, monthly dashboard of energy prices for residential customers.
- VREG, average electricity consumption per household size.
- Flemish Energy and Climate Agency, EPC method and label classes; Walloon and Brussels PEB classes for properties outside Flanders.
- Majcen, Itard and Visscher (2013), theoretical versus actual energy consumption of labelled dwellings, 194,000 homes; Delghust et al. (2015) on the performance gap in Flanders.
The estimated energy cost is an indication based on public data and averages. ikzoek does not guarantee its accuracy and the estimate does not replace an EPC, a quote or an energy audit.