Primary energy demand

Primary Energy Demand - Primary energy demand indicates the total amount of energy a building requires when, in addition to final energy demand (heating, hot water, ventilation, cooling), the upstream processes of energy generation, conversion, and distribution are also taken into account. It is expressed in kilowatt-hours per square meter per year (kWh/m²·a) and is the key metric in the Energy Performance Certificate and the Building Energy Act (GEG).

Calculation and Primary Energy Factors

The primary energy demand is calculated by multiplying the final energy demand by the primary energy factor (PEF) of the energy source used. This factor accounts for losses during generation, transport, and conversion. The PEFs are specified in the GEG: Natural gas 1.1 - Heating oil 1.1 - Electricity (grid) 1.8 - Wood pellets 0.2 - District heating 0.3-1.3 (depending on generation) - Solar energy 0.0 - Heat pump (electricity × 1.8, but a high coefficient of performance reduces the final energy demand). A building with pellet heating therefore has a significantly lower primary energy demand than one with oil heating, even with the same final energy demand.

This calculation logic has important practical implications: A poorly insulated building with pellet heating can, on paper, have a lower primary energy demand than a well-insulated building with an old gas boiler. Primary energy demand therefore does not measure building quality alone, but always the interaction between the building envelope and the energy source. Owners who want to reduce their primary energy demand therefore have two options: reduce the final energy demand (insulation, windows) or choose an energy source with a lower primary energy factor.

Limit Values According to the GEG

The Building Energy Act (GEG) sets maximum values for primary energy demand in new buildings. The reference value is based on the Efficiency House 55 (since 2023): A new building may have a maximum of 55% of the primary energy demand of the reference building. For existing buildings, requirements apply in the case of major renovations: If more than 10% of the building envelope is replaced, the affected building components must meet the GEG minimum requirements. When replacing a heating system, the 65% renewable energy requirement will take effect starting in 2024, which indirectly reduces primary energy demand.

Further tightening of regulations is foreseeable in the coming years. The EU Energy Performance of Buildings Directive (EPBD) requires member states to gradually introduce minimum standards for existing buildings as well. Germany will transpose these requirements into national law, which means: Owners of buildings with very high primary energy demand will face pressure to renovate in the medium term. Those who act today avoid future pressure for mandatory renovation and position their property advantageously for sale.

Primary Energy Demand and Financing Implications

Lending institutions are increasingly taking primary energy demand directly into account in their financing assessments. Some banks and subsidy programs (e.g., KfW BEG) explicitly link favorable terms to specific energy-efficient building standards. In addition, financial advisors and appraisers are increasingly required to include the energy performance of the property being purchased in their risk assessment. A building with high primary energy demand may therefore not only command a lower market price but also be more expensive to finance.

The EU Energy Performance of Buildings Directive (EPBD) also requires member states to gradually introduce minimum standards for the primary energy demand of existing buildings. Germany will implement these requirements step by step in the coming years. Owners who invest now are not only acting economically wisely but are also positioning themselves early on in a favorable regulatory environment.

Some commercial banks have also begun integrating primary energy demand as a standalone risk parameter into their lending models. The rationale behind this is the so-called stranded asset risk: properties that do not meet future minimum energy standards could lose value and thus be less suitable as collateral. This effect is currently still moderate but will gain significance as regulations progress.

Practical Tip for Property Owners in Nuremberg

We recommend that property owners in the Nuremberg metropolitan area take targeted steps to reduce their property’s primary energy demand-not only for environmental reasons, but because it directly influences the market value. Properties with a primary energy demand exceeding 200 kWh/m²·a (energy class G-H) already command 10-20% lower selling prices in Nuremberg than comparable renovated properties. The most effective lever is switching the energy source: A heat pump or a district heating connection (available in Nuremberg via N-ERGIE) drastically reduces primary energy demand due to its low PEF. Combining this with photovoltaics (PEF 0.0) further enhances the effect.

We also recommend having the energy performance certificate checked for up-to-date and accurate information by a dena-certified energy consultant before a sale. Incorrect or outdated information in the energy performance certificate can lead to claims for reimbursement from future buyers. At the same time, a well-presented, up-to-date energy performance certificate with low primary energy demand can be a decisive marketing argument-especially for renovated older buildings whose good energy performance is not immediately apparent.

A qualified renovation roadmap (iSFP), prepared by a licensed energy consultant, outlines step by step which measures reduce primary energy demand and by how much, as well as which government subsidies can be utilized. For owners preparing to sell, an iSFP can significantly strengthen their negotiating position because it gives prospective buyers a clear picture of the renovation potential and costs.

Frequently Asked Questions

What is the difference between primary and final energy demand?

The final energy demand indicates how much energy actually reaches and is consumed by the building-that is, the amount of gas, oil, or electricity you pay for. The primary energy demand additionally accounts for losses during extraction, transport, and conversion of the energy source. The final energy demand is more relevant for estimating your heating costs, while the primary energy demand is key for GEG compliance and the overall ecological balance.

What is the primary energy demand of a typical unrenovated building?

An unrenovated single-family home or apartment building from the 1960s to 1970s with oil heating typically has a primary energy demand of 250-400 kWh/m²·a (energy class G-H). After a comprehensive energy-efficient renovation (facade insulation, new windows, heat pump, solar thermal), this figure can drop to 40-80 kWh/m²·a (energy class A-B). The renovation costs for a single-family home in Nuremberg are approximately 80,000-150,000 euros, but are partially offset by KfW and BAFA subsidies.

Does the property listing have to specify the primary energy demand?

Yes. Since 2014, it has been mandatory to include the primary energy demand (or consumption) and the energy efficiency class in real estate listings (§ 87 GEG). Violations can be punished with a fine of up to 10,000 euros. The energy performance certificate must be presented during viewings. Buyers should use primary energy demand as an important comparison criterion-it provides a more reliable overview of overall energy efficiency than final energy demand alone.

Does a photovoltaic system reduce primary energy demand?

Yes, a PV system reduces primary energy demand-but only to the extent that the electricity generated is consumed within the building itself. Self-consumed PV electricity is assigned a primary energy factor of 0.0 under the GEG, thereby significantly reducing the calculated total demand. In combination with a heat pump that uses this electricity for heat generation, primary energy demand can drop to values below 30 kWh/m²·a-which corresponds to energy efficiency class A or A+.

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