The term Effizienzhaus (Efficiency House) designates a tiered energy-performance classification used in German building subsidy programs administered by KfW (Kreditanstalt für Wiederaufbau). Each class expresses a building's calculated performance as a percentage of a notional reference building defined under the Gebäudeenergiegesetz (GEG). Two parameters are compared: the annual primary energy demand (Jahres-Primärenergiebedarf, Q'P) and the specific transmission heat loss (spezifischer Transmissionswärmeverlust, H'T). A lower percentage indicates better performance than the reference building.
Standard Levels and Key Values
The common Effizienzhaus classes and their defining values relative to the GEG reference building are:
Effizienzhaus 100: 100% primary energy demand, 115% transmission heat loss.
Effizienzhaus 85: 85% primary energy demand, 100% transmission heat loss.
Effizienzhaus 70: 70% primary energy demand, 85% transmission heat loss.
Effizienzhaus 55: 55% primary energy demand, 70% transmission heat loss.
Effizienzhaus 40: 40% primary energy demand, 55% transmission heat loss.
Effizienzhaus 40 NH adds the sustainability class (Nachhaltigkeitsklasse, NH), requiring certification under the Qualitätssiegel Nachhaltiges Gebäude (QNG). This includes life-cycle assessment (Ökobilanzierung) of the building over its calculated service life, documentation of building materials, and compliance with defined limit values for global warming potential (GWP) per square meter of net floor area per year, in addition to the Effizienzhaus 40 energy criteria.
Funding Status
Subsidy eligibility for these classes has changed substantially since 2022. Funding for new-build Effizienzhaus 55 was discontinued effective 1 February 2022 after the program budget was exhausted; it is no longer available for new residential construction. Funding for new-build Effizienzhaus 40 without the NH add-on ended shortly before the introduction of the successor program. Since 1 March 2023, subsidies for new residential buildings are administered under the program Klimafreundlicher Neubau (KFN, KfW programs 297 and 298), which requires at minimum Effizienzhaus 40 combined with QNG certification (Effizienzhaus 40 NH) as the entry threshold for loan-based support.
For existing buildings undergoing energy retrofit (Sanierung), the Effizienzhaus classes 100, 85, 70, 55 and 40 remain relevant under the Bundesförderung für effiziente Gebäude (BEG), program KfW 261, together with the special category Effizienzhaus Denkmal for buildings subject to heritage protection or comparable constraints. The reference values for the Effizienzhaus classes in renovation are calculated against the same GEG reference building but applying a separate factor set for existing structures, reflecting the fact that retrofit targets differ from new-build targets.
Certification and Verification
Compliance is verified by an energy efficiency expert listed in the Energieeffizienz-Expertenliste (maintained by dena, the German Energy Agency) through calculation of Q'P and H'T using GEG-compliant methodology, plus, for NH classes, a QNG audit covering material selection, life-cycle assessment, and building documentation. The expert's report forms part of the funding application and is required for disbursement of the KfW loan or grant.