How EnergyClass works
EnergyClass estimates the energy class of your property in seconds, starting from a small set of easily available data. The estimate is indicative — it does not replace a legal energy certificate (EPC, APE, DPE, Energieausweis).
The calculation method
The engine combines three main factors:
1. Building envelope
The quality of the envelope (walls, roof, windows) determines how much heat is lost in winter and gained in summer. We use thermal transmittances (U-values) typical for construction period and building type, derived from studies and national regulations. Wall insulation or an insulated roof significantly improves the estimate.
2. Heating systems
The type of heat generator (standard boiler, condensing boiler, heat pump, district heating) and the energy carrier (natural gas, LPG, oil, electricity, biomass) determine the conversion efficiency and emission factor. An old or low-efficiency system negatively impacts the final class.
3. Local climate
The heating degree days of the locality weight the energy needed according to the actual local climate. A house in southern Spain needs far less heating energy than the same house in northern Finland. Climate data comes from the Eurostat heating degree days dataset and national climate zones.
Official energy class bands
EnergyClass maps the calculation result (non-renewable primary energy demand, kWh/m²·year) onto the official national bands of the country where the property is located:
- Italy — scale A4–G (DM 26/06/2015; dual criterion EPgl,nren).
- France — scale A–G, dual criterion primary energy + CO₂ emissions (reformed DPE 2021).
- Germany — scale A+–H (EnEV/GEG).
- Spain — scale A–G (RD 235/2013).
- And so on for all supported European countries — exact thresholds are listed on the country pages.
Where applicable (e.g. France), the system also calculates estimated CO₂ emissions and reports both classes (energy + emissions).
What data is needed
To get the estimate you only need:
- Country and municipality (for climate data and national bands).
- Building type (apartment, detached house, etc.).
- Construction period.
- Floor area in m².
- Window type (single, double or triple glazing).
- Heat generator and energy carrier.
- Approximate age of the generator.
- Presence of wall insulation and/or insulated roof.
- Optional photovoltaic system (kWp) — it reduces the energy class.
Missing data is automatically estimated with typical values for the category.
What this estimate is NOT
EnergyClass does not produce a legal energy certificate. In Italy this is called APE (Attestato di Prestazione Energetica) and can only be issued by a qualified professional after an on-site inspection. In France it is the DPE (Diagnostic de Performance Énergétique), in Germany the Energieausweis. EnergyClass provides exclusively an indicative estimate, useful for getting a sense of where a property stands before buying, renting or planning a renovation.