Annex to the Information Sheet Energy-Efficient Building (153)
Order number 600 000 3465, status 04/2016
Technical Minimum Requirements
Technical minimum requirements and supplementary information for the new construction of a KfW Efficiency House
The energy standard of a KfW Efficiency House is achieved through structural and technical measures to improve energy efficiency as well as the integration of renewable energies. The following minimum requirements must be met and the "List of Technical Frequently Asked Questions (FAQ)" must be observed.
Requirements for a KfW Efficiency House
Proof of the energy standard of a KfW Efficiency House 40, 40 Plus or 55 is provided by an energy demand calculation. Alternatively, the KfW Efficiency House 55 can be verified by compliance with reference values.
For the calculation of the energy level of a KfW Efficiency House, the accounting regulations of Section 3 paragraphs 1 to 3 of the Energy Saving Ordinance (Energy Saving Ordinance) are to be applied, taking into account the provisions of this annex and the "List of Technical Frequently Asked Questions (FAQ)." Section 3 paragraph 5 (Energy Saving Ordinance, simplified verification method (Energy Saving Ordinance Easy)) is not applicable.
The interpretations of the expert committee “Building Technology” of the Conference of Ministers of Construction regarding the Energy Saving Ordinance (Energy Saving Ordinance), see there under “Energy Saving Ordinance, Interpretations,” are to be applied when calculating a KfW Efficiency House, insofar as no separate regulations exist according to this annex and the "List of Technical Frequently Asked Questions (FAQ)."
The annual primary energy demand (QP) and the transmission heat loss (H’T) related to the heat-transferring envelope surface of the building for the new construction project must be calculated based on the planned measures according to the Energy Saving Ordinance (Energy Saving Ordinance). The corresponding energy key figures of the reference building (QP REF; H’T REF) must be determined according to Annex 1, Table 1 (without applying line 1.0) of the Energy Saving Ordinance (Energy Saving Ordinance).
The calculation rule for the reference building for electric domestic hot water preparation according to Annex 1, number 1.1, paragraph 2 of the Energy Saving Ordinance (Energy Saving Ordinance) has not been applicable since 01.01.2016, neither for the Energy Saving Ordinance (Energy Saving Ordinance) nor for a KfW Efficiency House.
The calculated values for the annual primary energy demand (QP) and the transmission heat loss (H’T) for the new construction project must not exceed the percentage maximum values given in the above table in relation to the respective values of the corresponding reference building (QP REF; H’T REF).
At the same time, the transmission heat loss of the new construction object must not be higher than permitted according to Annex 1 Table 2 Energy Saving Ordinance (Energy Saving Ordinance).
For a passive house, proof must be provided in accordance with the accounting regulations for KfW Efficiency Houses. This means that the annual primary energy demand (QP) and the transmission heat loss (H’T) related to the heat-transferring envelope surface of the building of the new construction project must be determined according to the accounting regulations for a KfW Efficiency House 40, 40 Plus or 55. Alternatively, a passive house can also be verified as a KfW Efficiency House 55 by reference values.
For the new construction of a KfW Efficiency House, a hydraulic balancing of the heating system must always be carried out. The implementation must be demonstrated on the current confirmation form of the VdZ - Forum for Energy Efficiency in Building Technology e. V. and the documentation must be retained.
Requirements for the airtightness of the building envelope according to Annex 4 Energy Saving Ordinance (Energy Saving Ordinance) do not apply, provided no ventilation system is installed and no reduced air exchange rate is set in the efficiency house verification. However, the airtightness of the building envelope of a KfW Efficiency House must be determined by measurement. If a mechanical ventilation system is installed, the airtightness of the building envelope must be proven by measurement according to Annex 4 Energy Saving Ordinance (Energy Saving Ordinance).
Alternative proof of a KfW Efficiency House 55 by reference values
The requirements for a KfW Efficiency House 55 are met if the following structural and technical requirements (reference values) are implemented. In this case, a computational proof for the KfW Efficiency House 55 is not required.
1.) The following requirements for the individual components of the thermal building envelope must be met. The requirements for the execution of thermal bridges as well as for the airtightness of the building envelope must be observed.
Roof surfaces, top floor ceiling, dormer: U ≤ 0.14 watts per square meter and kelvin (W/(m²·K))
Windows and other transparent components: Uw ≤ 0.90 watts per square meter and kelvin (W/(m²·K))
Exterior walls, floor ceilings downward towards outdoor air: U ≤ 0.20 watts per square meter and kelvin (W/(m²·K))
Other opaque components (basement ceilings, walls and ceilings to unheated rooms, wall and floor surfaces towards soil, etc.): U ≤ 0.25 watts per square meter and kelvin (W/(m²·K))
Doors (basement and exterior doors): UD ≤ 1.2 watts per square meter and kelvin (W/(m²·K))
Avoidance of thermal bridges: ΔUWB ≤ 0.035 watts per square meter and kelvin (W/(m²·K))
Airtightness of the building envelope: n50 ≤ 1.5 h-1
2.) For building services, one of the 6 following system concepts must be implemented. The location of the heat generator or heat transfer station must be within the thermal building envelope and a central domestic hot water preparation must be present. Domestic hot water circulation is permitted.
Condensing boiler, solar domestic hot water preparation (standard values according to DIN V 4701-10), central ventilation system with heat recovery (heat supply rate > 80 %)
District heating with certified primary energy factor fp ≤ 0.7, central ventilation system with heat recovery (heat supply rate > 80 %)
Central biomass heating system based on wood pellets, wood chips or firewood, central exhaust air system
Brine-water heat pump with surface heating system for heat transfer, central exhaust air system
Water-water heat pump with surface heating system for heat transfer, central exhaust air system
Air-water heat pump with surface heating system for heat transfer, central ventilation system with heat recovery (heat supply rate > 80 %)
A central exhaust air system can be replaced by a ventilation system with heat recovery. Deviations beyond the stated requirements for the components and the listed system concepts are not permitted for this verification procedure. Additional heat generators for heating or domestic hot water are not permitted, not even as supplementary heat generators. Where appropriate, the concepts can be supplemented by solar thermal systems (heating support, domestic hot water preparation) or photovoltaic systems.
Additional requirements for a KfW Efficiency House 40 Plus
A KfW Efficiency House 40 Plus meets the requirements of a KfW Efficiency House 40 and includes the following plus package:
A power-generating system based on renewable energies
A stationary battery storage system (electricity storage)
A ventilation system with heat recovery
A visualization of power generation and power consumption via a corresponding user interface
The electricity attributable in the balance from renewable energies must be generated on the property in the immediate spatial connection with the building or its ancillary structures (garage, carport, shed, etc.). Examples include electricity from photovoltaic systems or small wind turbines or combined heat and power plants that operate 100 % with renewable energies.
The electricity generated at the building or its ancillary buildings should be predominantly used in the building itself. Self-consumption of electricity must be ensured by a priority control. There must be a physical connection between producers, storage and consumers (heating, ventilation, lighting, household processes and household appliances). For grid-feeding photovoltaic systems, the maximum power feed-in at the grid connection point must be limited to 60 % of the installed capacity.
The ventilation system with heat recovery must have a heat supply rate of at least 80 %. The ventilation system must be able to reliably ensure the design outdoor air volume flows (nominal ventilation) according to DIN 1946-6 for the entire balanced building useful area. The ventilation system must be adjusted. The airtightness of the building envelope must be proven by measurement with n50 ≤ 1.5 h-1 (recommendation: n50 ≤ 0.6 h-1).
The annual electricity yield to be generated must be determined depending on the number of residential units and the building useful area and must be at least the sum of 500 kilowatt hours per year (kWh/a) per residential unit and 10 kilowatt hours per square meter per year (kWh/m² a) related to the building useful area. The electricity yield of the power-generating system must be accounted according to DIN V 18599: 2011-12 and the further regulations of § 5 Energy Saving Ordinance (Energy Saving Ordinance).
The electricity storage must have a usable storage capacity according to manufacturer specifications at least corresponding to the power of the power-generating system (for example peak power Ppk of the photovoltaic system) multiplied by one hour. The basis for dimensioning is the power required to ensure the required minimum yield of the power-generating system for the Efficiency House 40 Plus. For grid-feeding power-generating systems, these and the storage must have a suitable and open interface for remote parameterization and remote control.
Proper and safe commissioning must be confirmed by a suitable specialist and evidence of this must be provided (specialist contractor’s declaration). Alternatively, confirmation by the suitable specialist can be based on the photovoltaic storage passport (“storage passport”).
Further requirements for the calculation of the reference building are given in the "List of Technical Frequently Asked Questions (FAQ)" with regard to building envelope components and system assessment.
If technical building components are used in residential buildings for which no recognized rules of technology or, according to § 9 paragraph 2 sentence 2 half-sentence 3 Energy Saving Ordinance (Energy Saving Ordinance), published reliable empirical values exist for their energetic evaluation, then alternatively to Annex 1, Number 2.1.3, Energy Saving Ordinance (Energy Saving Ordinance), components with equivalent or poorer energetic properties may be used.
If heat supply is provided by district heating, the primary energy factor for the heat network must be entered as the table value according to DIN V 18599-1: 2011-12. The use of the calculation procedure described in the standard to determine primary energy factors is not permitted in this context. Alternatively, a primary energy factor can be used which is confirmed by a certified expert according to the AGFW, Energy Efficiency Association for Heat, Cooling and Combined Heat and Power (CHP) e. V. working sheet FW-309 Part 1 and published on the website of the AGFW, Energy Efficiency Association for Heat, Cooling and Combined Heat and Power (CHP) e. V.
If a central heating system is present, manually fed single stoves that are not integrated into the circulation system cannot be taken into account. For central heating systems with integrated biomass-fired single stoves as well as automatically fed pellet primary stoves, a maximum coverage share of 10 % of the useful energy demand can be assumed.
For calculations according to DIN V 4701-10, the coverage share of a solar system for heating support can be a maximum of 10 % without a separate proof if the collector area meets the corresponding requirements of DIN V 4701-10. Otherwise, the coverage shares are to be determined on the basis of a solar thermal simulation for the respective building in compliance with the boundary conditions for the public-law verification according to Energy Saving Ordinance (Energy Saving Ordinance).
In the proof for the KfW Efficiency House, the regulation of § 5 Energy Saving Ordinance (Energy Saving Ordinance) for the crediting of electricity from renewable energies may be applied.
The system performance factor fPerf of photovoltaic systems must be at least 75 % according to DIN V 18599-9: 2011-12.
In calculations according to DIN V 4108-6 / DIN V 4701-10, the air change rate n = 0.7 h-1 is to be used as standard. The assumption of a reduced air change with n = 0.6 h-1 for natural ventilation/window ventilation or with n = 0.6 h-1 or 0.55 h-1 for buildings with ventilation systems may only be applied if after completion of the construction project the airtightness of the building required according to Annex 4 Energy Saving Ordinance (Energy Saving Ordinance) is demonstrated by an airtightness measurement. In this case, particular attention must be paid to airtightness from planning through construction execution.
For the thermal bridge surcharge, only the provisions of § 7 paragraph 2 Energy Saving Ordinance (Energy Saving Ordinance) must be observed, i.e., the influence of constructive thermal bridges on the annual heating demand must be kept as low as possible according to the rules of technology and the economically justifiable measures in each individual case. The remaining influence must be taken into account.
If a thermal bridge surcharge Δ UWB < 0.10 watts per square meter and kelvin (W/(m²·K)) is applied, this must be calculated or proven separately according to the rules of technology. § 7 paragraph 3 Energy Saving Ordinance (Energy Saving Ordinance) is not applicable. The preparation of an equivalence proof is always required when using the flat thermal bridge surcharge of Δ UWB = 0.05 watts per square meter and kelvin (W/(m²·K)). In addition, the procedures described in the leaflet “KfW Thermal Bridge Assessment” "Extended Equivalence Proof" and "KfW Thermal Bridge Short Procedure" can be applied.
Services of the expert
The expert must provide at least the following services in the context of energetic specialist planning and support of the construction measure and confirm their program-compliant implementation for the new construction of a KfW Efficiency House (including KfW Efficiency House 55 according to reference values).
If partial services are provided by third parties (e.g., specialist planners or supervising architect), these must be checked by the expert within his overall responsibility.
Development and planning implementation of an overall energetic concept for the structural thermal protection and the energetic system technology as well as execution of the efficiency house calculation (exception: implementation of a KfW Efficiency House 55 according to reference values); if necessary, consulting on implementation options
Provide planning to minimize thermal bridges (thermal bridge concept) and for building airtightness (airtightness concept)
Check the necessity of ventilation measures (e.g., using DIN 1946-6) and inform the client about the results. The client is responsible for commissioning the implementation of ventilation measures
Confirm the planned energy level on the KfW form "Confirmation for the application (BZA)"
Participate in tendering or obtaining offers and check offers for compliance with scope and quality of the planned energetic measures
Conduct at least one on-site inspection before execution of plastering or application of later coverings to visually check energetically relevant, especially later no longer accessible components (such as thermal protection component structure) as well as the implementation of the thermal bridge concept, airtightness concept and system components
Check the implementation of ventilation measures (if conducted)
Check the execution of an airtightness measurement
Check the materials, products and components installed on the building envelope and the energetic system technology for compliance with the planned energetic measures according to the efficiency house calculation
Pass on the energetically relevant building parameters to the heating engineer for the dimensioning of the heating system (and if applicable the thermal solar system), check the proof of hydraulic balancing and adjustment of the system (if applicable heating and ventilation system), check the handover of the energetic system technology (if applicable with supplementary technical instruction)
Document the energetic specialist planning and the support of the construction measure
Confirm the implementation of the funded project on the KfW form "Confirmation after completion"
Issue the energy certificate according to Section 5 Energy Saving Ordinance (Energy Saving Ordinance) for the completed building and hand it over to the client
Necessary proofs and documents for a KfW Efficiency House to be retained by the client
Complete documentation of the efficiency house proof according to § 3 Energy Saving Ordinance (Energy Saving Ordinance) or proof of implementation of a KfW Efficiency House 55 according to reference values including detailed heat transfer coefficient (U-value) calculations for individual components of the thermal building envelope and the existing/planned technical system All plans of the KfW Efficiency House (floor plans, elevations, sections, site plan) on the basis of which the primary energy demand proof according to Energy Saving Ordinance (Energy Saving Ordinance) was prepared; the thermal building envelope underlying the calculation must be marked
All plans of the KfW Efficiency House (floor plans, elevations, sections, site plan), the thermal building envelope must be marked
Other planning documents relevant for the efficiency house proof (e.g., thermal simulation of solar systems, proof of product-specific system technical key figures, thermal bridge proof, certificate of primary energy factor for district heating according to AGFW, Energy Efficiency Association for Heat, Cooling and Combined Heat and Power (CHP) e. V. working sheet FW-309, etc.)
Confirmation of a specialist company about the execution of the hydraulic balancing using the confirmation form of the VdZ - Forum for Energy Efficiency in Building Technology e. V.
Measurement protocol of the airtightness measurement
Other documents created within the framework of energetic specialist planning and construction supervision (e.g., airtightness concept, ventilation concept)
Energy certificate on the basis of the energy demand according to Section 5 Energy Saving Ordinance (Energy Saving Ordinance) for the completed building.
Source kfw.de