Primary Energy Factor

The Primary Energy Factor (PEF), or Primärenergiefaktor (fP), is a key energy-accounting metric for evaluating the real resource use of a heat pump system. It converts final energy such as grid electricity into primary energy, showing how much energy was originally extracted before generation, conversion, transport, and grid losses. For heat pumps, PEF connects SCOP, building energy certificates, EU energy labeling, GEG, OIB Guideline 6, SIA standards, and on-site photovoltaic self-consumption into one comparable framework. Unlike CO2 emission factors or carbon footprint metrics, PEF does not measure greenhouse gases directly; it measures upstream energy input, making it essential for planning, certification, subsidy eligibility, and fair comparison between electricity, gas, oil, biomass, and district heat.

What is Primary Energy Factor

The Primary Energy Factor (PEF), known in German as the Primärenergiefaktor (fP), is a dimensionless coefficient. It converts final energy — the energy actually delivered to a building or appliance, such as electricity from a socket — into primary energy, the energy content extracted from nature before any conversion, transport, or distribution losses are deducted.

The relationship is expressed as a simple multiplication:

Primary Energy = Final Energy × PEF

A PEF above 1 signals that upstream losses exist. Electricity typically carries a PEF above 1, because power plants lose energy converting fuel into electricity, and grids lose further energy in transmission. A PEF of 0 signals that no upstream primary energy input was needed, which is why self-consumed on-site photovoltaic electricity is usually assigned this value in building codes.

What is the Core Purpose of Primary Energy Factor

PEF exists to make different energy carriers comparable on equal terms. Electricity, natural gas, heating oil, biomass, and district heat all have different upstream conversion chains. Without a shared accounting unit, a kilowatt-hour of grid electricity cannot be fairly compared to a kilowatt-hour of gas, because the two carriers lose different amounts of energy before they ever reach the building.

PEF supplies that shared unit. Regulators use it to calculate a building’s primary energy demand for energy performance certificates, to set minimum efficiency thresholds for heating appliances, and to convert reported electricity savings into primary energy savings for national energy-efficiency obligations. Manufacturers use it to demonstrate how a heat pump’s high on-site efficiency translates into resource efficiency at the primary energy level.

What is the Need for Primary Energy Factor

Heat pumps consume electricity, and electricity has a deceptively simple final-energy profile: a heat pump might draw one kilowatt-hour of electricity to deliver four kilowatt-hours of heat, a ratio described by its coefficient of performance (COP) or seasonal coefficient of performance (SCOP). Judged purely on final energy, this looks highly efficient. Judged purely on primary energy, the picture needs one more step, because that one kilowatt-hour of electricity itself required more than one kilowatt-hour of primary fuel to generate and deliver.

PEF closes that gap. It prevents heat pumps from being unfairly credited with an efficiency figure that ignores upstream losses, and it prevents fossil-fuel heating systems from being unfairly credited with an efficiency figure that ignores the fact that gas and oil are combusted directly on-site with comparatively small upstream losses. The following consequences follow directly from this need:

• Building energy certificates use PEF-weighted primary energy demand, not raw final energy consumption, as the compliance metric.
• Product energy labels for heat pumps use a PEF-based conversion coefficient to translate laboratory SCOP results into a labeled efficiency class.
• National governments use PEF to convert electricity savings into primary energy savings when reporting progress against EU energy-efficiency targets.
• Grid decarbonization lowers the electricity PEF over time, which mechanically improves the reported primary energy performance of every electric heat pump already installed, without any hardware change.

What are the Key Features for Primary Energy Factor

PEF as a regulatory metric carries a consistent set of structural features across jurisdictions, even though the numeric values differ. Each feature governs how the coefficient behaves and where it applies. The list below names each feature; the detailed explanation follows in Section 5.

• Non-renewable and total variants — most codes publish two coefficients per energy carrier, not one.
• Energy-carrier specificity — each fuel or delivery form (grid electricity, gas, oil, biomass, district heat) receives its own coefficient.
• Jurisdictional specificity — the applicable value depends on the national or regional building code in force, not on a single EU-wide constant.
• Time variability — coefficients are revised periodically as the underlying electricity generation mix changes.
• On-site generation treatment — self-consumed renewable electricity is typically weighted at or near zero.

Detailed Feature Explanation for Primary Energy Factor

Non-Renewable and Total PEF

Definition: Building codes typically split PEF into a total value (all upstream energy, renewable and non-renewable) and a non-renewable value (PEFne, excluding the renewable share).

Purpose: The split isolates the portion of primary energy demand that depletes finite resources, since renewable primary energy is not scarce in the same sense.

Benefit: Policymakers can set compliance thresholds specifically on non-renewable primary energy, rewarding systems that draw on renewable-heavy grids or on-site generation.

Example: Germany’s GEG Annex 4 (Anlage 4) publishes PEFne values, not total values, as the figure used in statutory primary energy demand calculations.

Energy-Carrier Specificity

Definition: Every energy carrier used in a building’s heating, cooling, or hot water system receives its own coefficient, derived from that carrier’s specific upstream chain.

Purpose: A single blended coefficient would obscure the real difference between, for example, direct on-site oil combustion and grid electricity generated from a mixed thermal and renewable fleet.

Benefit: Designers can model hybrid systems — a heat pump paired with a gas boiler, for instance — with each carrier weighted correctly rather than averaged.

Example: German GEG Annex 4 lists distinct coefficients for grid electricity, heating oil, natural gas, biomass, biomethane, and district heat, each with its own justification.

Jurisdictional Specificity

Definition: No single PEF value applies uniformly across the EU; each member state, and in Austria and Switzerland each sub-national authority, sets or adopts its own applicable coefficient.

Purpose: Electricity generation mixes differ substantially by country and even by region, so a nationally or regionally derived coefficient reflects local upstream reality more accurately than an EU average.

Benefit: Compliance calculations stay grounded in the actual grid a building draws from, rather than a theoretical EU-wide average that may not apply locally.

Example: Germany applies GEG Annex 4; Austria applies OIB Guideline 6 as adopted into each federal state’s building code; Switzerland applies SIA 380/1 or the separate Minergie weighting system, depending on the certification target.

Time Variability

Definition: PEF coefficients for electricity are not fixed constants; they are revised as the share of renewables in the generation mix grows and upstream losses fall.

Purpose: A static coefficient would eventually misrepresent the real primary energy cost of electricity, understating the benefit of grid decarbonization or, if left too low, overstating it.

Benefit: Periodic revision keeps the metric aligned with physical reality and creates a policy lever that automatically improves electric heating’s reported performance as the grid decarbonizes.

Example: The EU default electricity PEF fell from 2.5 (set under the original 2006 framework and carried into the 2012 Energy Efficiency Directive) to 2.1 under the 2018 revision, and to 1.9 under Commission Delegated Regulation (EU) 2023/807, based on the average projected value for 2024–2025.

On-Site Generation Treatment

Definition: Electricity generated on-site from a renewable source and consumed directly, without passing through the public grid, is typically assigned a PEF of zero.

Purpose: The coefficient rewards self-consumption of on-site renewables by removing any upstream energy penalty from the calculation.

Benefit: It creates a direct, quantifiable compliance incentive to pair a heat pump with an on-site photovoltaic system.

Example: Under German GEG Annex 4, self-generated and directly consumed PV electricity is credited with fP = 0, while any electricity exported to the grid loses that treatment and no longer counts as self-generated.

Types and Regulatory Models

PEF is not one number; it is a family of coefficients defined by different regulatory instruments, each serving a different compliance purpose. Understanding which model applies to which task is a precondition for correct use.

• EU default electricity PEF (Energy Efficiency Directive, Article 31 and Annex V): Currently set at 1.9 by Commission Delegated Regulation (EU) 2023/807, down from 2.1 under the 2018 revision and 2.5 under the original 2012 framework. Member states may apply this default or justify a different national coefficient.
• Germany — GEG Annex 4 (Anlage 4 GEG): Sets the statutory non-renewable PEF for grid electricity at 1.8, a value carried forward from GEG 2020 into the current GEG 2024 framework. A separate, lower coefficient of 1.2 applies specifically to grid electricity used to operate large heat pumps feeding district heating networks, effective since January 2023.
• Austria — OIB Guideline 6 (OIB-Richtlinie 6): Defines PEF and CO2eq conversion factors for Austrian building energy certificates, with editions from 2015, 2019, and 2023. Adoption into binding law happens at the federal state (Bundesland) level and has historically varied — the 2019 edition, for example, was not adopted in every state — so the applicable coefficient must be confirmed against the specific state building code in force, not assumed from the OIB edition alone.
• Switzerland — SIA 380/1 and SIA 2040, or Minergie national weighting factors: Switzerland runs two parallel systems: the SIA norms, which publish separate total and non-renewable primary energy factors, and the Minergie label, which applies its own national weighting factors — for example, weighting electricity roughly twice as heavily as gas. Cantonal building codes determine which system a given project must satisfy.
• Ecodesign and Energy Labeling Conversion Coefficient (CC): A separate coefficient, functionally equivalent to a PEF, used specifically to convert a heat pump’s SCOP into its labeled seasonal space heating energy efficiency (ηs). Under current EU Ecodesign Regulations (813/2013 and 2016/2281), this coefficient is fixed at 2.5. A Commission proposal to lower it to 1.9, aligning it with the revised EED default, is part of the pending Ecodesign Lot 1 revision; as of July 2026 this revision, like the related A–G energy label rescaling, has not been adopted, so 2.5 remains the figure in force for compliance purposes.

Use Cases

PEF is not a theoretical construct; it enters concrete compliance and design workflows at several distinct points. Each use case applies a different regulatory instance of the coefficient described above.

• Building energy performance certificates: Primary energy demand (Q_P) is calculated as final energy demand (Q_E) multiplied by the applicable PEF, forming the headline figure on an Energieausweis or equivalent certificate.
• New-build and renovation compliance: Standards such as Germany’s Efficiency House 55 or 40 (Effizienzhaus 55/40) cap allowable primary energy demand as a percentage of a reference building, making the choice of heating system’s PEF-weighted performance decisive for compliance.
• Heat pump energy labeling: A heat pump’s seasonal space heating energy efficiency (ηs), the figure shown on its EU Energy Label, is derived by dividing SCOP by the Conversion Coefficient (ηs ≈ SCOP / CC), directly linking laboratory performance to primary energy accounting.
• National energy-savings reporting: Under the Energy Efficiency Directive, member states convert reported final-energy savings in kWh of electricity into primary energy savings using the applicable PEF, for obligation-scheme reporting to the European Commission.
• Subsidy and funding eligibility: Programs that gate funding on a building’s or system’s primary energy performance — rather than final energy or emissions alone — apply PEF as the qualifying calculation basis.

Benefits

Correct application of PEF delivers benefits at three levels: technical accuracy, policy consistency, and commercial positioning.

• Fair cross-technology comparison: PEF prevents electric heating from being penalized for high final-energy draw when its primary-energy performance is favorable, and prevents fossil systems from appearing more efficient than their upstream fuel chain justifies.
• Renewable self-consumption incentive: Assigning a near-zero PEF to self-consumed on-site electricity creates a quantifiable, code-recognized reason to pair a heat pump with photovoltaics.
• Automatic performance improvement from grid decarbonization: As national electricity PEF values fall — as the EU default has, from 2.5 to 1.9 — every installed heat pump’s reported primary energy performance improves without any change to the physical installation.
• Regulatory transparency for planning: Correctly identifying which PEF applies to a project — EU default, national building code, or Ecodesign Conversion Coefficient — avoids compliance errors during permitting and certification.

Selection Criteria

Choosing the correct PEF value is a matter of matching the coefficient to its regulatory context, not selecting a single “correct” number. Four questions determine which figure applies:

• What is being calculated? Building-level primary energy demand for a certificate uses the building code’s PEF (GEG, OIB, SIA); a heat pump’s energy label uses the separate Ecodesign Conversion Coefficient.
• Which jurisdiction governs the project? Germany, Austria, and Switzerland each apply a different instrument, and Austria and Switzerland further require confirmation at the state or cantonal level.
• Which edition or delegated act is currently in force? PEF values are revised periodically; using an outdated figure — for example, the pre-2023 EU default of 2.1 instead of the current 1.9 — produces an incorrect result even if the calculation method is right.
• Is on-site generation involved? Self-consumed renewable electricity typically requires a separate, near-zero coefficient rather than the standard grid-electricity value.

Comparisons

PEF is frequently confused with adjacent metrics that measure related but distinct things. Distinguishing them precisely avoids both calculation errors and content redundancy across this hub’s clusters.

• PEF vs. CO2 Emission Factor: PEF quantifies upstream energy input per unit of delivered energy; the CO2 emission factor quantifies upstream greenhouse gas output per unit of delivered energy. The two are usually published side by side in the same national datasets — Germany’s GEG Annex 4 and Austria’s OIB Guideline 6 both list both figures — but they measure different physical quantities and can move independently of one another.
• PEF vs. Carbon Footprint: Carbon Footprint, covered in its own cluster on this hub, is a broader lifecycle metric spanning production, installation, operation, and end-of-life emissions. PEF addresses only the operational-phase energy-conversion step, and only from an energy-accounting perspective, not an emissions perspective.
• PEF vs. Final Energy Demand: Final energy demand is the delivered energy a building or system actually consumes, before any upstream weighting. PEF is the multiplier applied to that figure to arrive at primary energy demand; the two describe different points in the same supply chain.
• PEF vs. SCOP / JAZ (Seasonal Performance Factor): SCOP measures a heat pump’s own on-site conversion efficiency — useful heat delivered per unit of electricity consumed. PEF measures something upstream of the heat pump entirely: how much primary energy that electricity itself cost to produce and deliver. Ecodesign labeling combines both, dividing SCOP by the Conversion Coefficient to produce a single primary-energy-adjusted efficiency figure.

Integration with Other Systems

PEF does not function as an isolated figure; it is one input among several that determine how a heat pump system is certified, labeled, and financed. Within this hub, it connects directly to the CO2 Emissions and Carbon Footprint clusters, since national datasets typically publish PEF and CO2 conversion factors together, even though the two remain separate entities. It also connects to the Energy Labeling cluster, since a heat pump’s labeled efficiency class is a direct function of the Conversion Coefficient described in Section 6.

At the building level, PEF integrates into the energy performance certificate workflow alongside U-values, ventilation heat losses, and renewable energy share calculations required under national building codes (GEG, OIB Guideline 6, SIA 380/1). At the product level, it integrates with SCOP and COP documentation, since a heat pump’s real-world primary energy performance depends on achieving its rated SCOP in practice, not just in laboratory conditions. iDM’s Navigator 2.0 control system is built around this link: by managing flow temperatures, defrost cycles, and hydraulic balancing to keep real operating SCOP close to its rated value, it protects the primary-energy-efficiency figure that building certificates and energy labels are built on. iDM’s AERO ALM and SLM air source systems and TERRA SW and AL brine and water source systems are engineered around the same principle — because PEF for electricity is well below the equivalent conversion efficiency of direct fossil combustion once SCOP exceeds roughly 1.5–2.0, a properly sized and controlled heat pump clears the primary energy threshold of a fossil boiler by a wide margin, and gains further ground as national electricity PEF values continue their downward trend.

The Primary Energy Factor helps explain why heat pumps can achieve strong primary-energy performance even when they use electricity with upstream conversion losses. By multiplying final energy demand by the correct PEF value, designers, certifiers, and homeowners can compare heating technologies on a shared energy basis and avoid confusing primary energy demand with CO2 emissions or lifecycle carbon footprint. Because electricity PEF values fall as grids decarbonize, efficient heat pumps paired with smart controls and on-site solar power become increasingly favorable in building compliance, energy labels, and long-term environmental performance. For any heat pump project, the right PEF depends on the calculation purpose, the jurisdiction, the regulation in force, and whether renewable self-consumption is included.