Frequently asked questions

The energy class summarises the non-renewable primary energy demand of a building per square metre per year (kWh/m²·year). It ranges from the most efficient class (A4, A+ or equivalent depending on the country) to the least efficient (G). A high class (A) means low energy consumption and lower CO₂ output; a low class (G) means high energy costs.

The estimate is indicative, not certified. The typical error compared to a real EPC is ±1 energy class. The estimate is more accurate for "average" buildings (1970s–1990s construction, not renovated) and less precise for very recent buildings with complex systems or unusual detached houses. Use it for orientation, not for legal or contractual decisions.

No. EnergyClass produces only an indicative estimate. To sell or rent a property in most EU countries a legal energy performance certificate is required, issued by a qualified professional after an on-site inspection (APE in Italy, DPE in France, Energieausweis in Germany). EnergyClass has no legal or contractual value.

Each EU Member State has transposed the EPBD (Energy Performance of Buildings Directive) through national legislation with its own class thresholds. Germany uses the A+–H scale, Italy A4–G, France A–G with a dual energy+CO₂ criterion. EnergyClass applies the official bands of the selected country, so the same physical house may have a different class label depending on the country.

They are all national energy performance certificates for buildings: the APE is the Italian certificate (issued by registered professionals), the DPE is the French one (mandatory since 2006, reformed in 2021 with a dual energy+CO₂ criterion), and the Energieausweis is the German one (required for sales and rentals). All are based on primary energy demand but use different calculation methods and scales.

Yes, significantly. Electricity (used by heat pumps) has a lower primary energy conversion factor than natural gas, which is better than heating oil or non-certified biomass. A heat pump, even if it consumes more kWh of electricity, often results in a better class because the associated non-renewable primary energy is lower.

Yes. Electricity produced on-site by a PV system is subtracted from the net demand, lowering the EP index and potentially improving the class by one or two levels, depending on the system size and the building floor area.

You can use it as a rough reference to estimate future energy costs and assess whether a property is worth its asking price. However, for any purchase or rental contract, always request the original energy certificate from the seller/landlord — it is a legal obligation in most EU countries and must be attached to the contract.

The form data (building type, period, area, etc.) is saved anonymously to generate the aggregate statistics visible in the "Explore" section. We do not collect full addresses or personally identifiable data. Each estimate is linked to a unique URL token: anyone who knows the link can view it, but it is not indexed by search engines (noindex).

Heating degree days (HDD) measure the heating demand of a location: the higher the value, the colder the climate and the more energy is needed to maintain a comfortable indoor temperature. A city with HDD 3000 (e.g. Turin) needs roughly twice the heating energy of a city with HDD 1500 (e.g. Naples) for the same building. EnergyClass uses official HDD values for each municipality or climate zone.

Because the class depends on the specific context: an apartment in a 1960s building in Milan without insulation will likely be class G, while the same apartment retrofitted with wall insulation and a condensing boiler could be B or C. The energy class is not an abstract property of the building type, but of the specific building with its systems, envelope and local climate.

Yes, completely free and with no sign-up required. No account is needed to get an estimate. The site is an open-source, independent project.