Primary energy

Primary energy refers to the energy contained in energy sources before any conversion takes place-that is, the energy derived from natural sources (coal, natural gas, oil, solar, wind, biomass). In building energy law, a building’s primary energy demand is a key metric: It takes into account not only the final energy demand required directly within the building, but also the losses incurred during the generation, conversion, and transport of the energy source, as represented by the primary energy factor.

Primary Energy Factor and Its Significance

Every energy source has a primary energy factor (fp), which indicates how much primary energy must be expended per unit of final energy. Electricity from the grid has a high factor due to losses during generation and transmission (currently approx. 1.8 in Germany, decreasing as the share of renewables grows). Natural gas is around 1.1; district heating varies depending on the source (0.3-1.8). Wood pellets have a very low factor (approx. 0.2) because they are made from renewable raw materials.

The primary energy factor is not static: it changes with the energy mix of the respective country and is regularly adjusted by the legislature. The national primary energy factor for electricity in Germany has fallen continuously over the past few years because the share of renewable energy in the power grid has increased. For heat pumps, this means an increasingly favorable balance: the higher the share of green electricity in the grid, the better the calculated primary energy requirement of a heat pump-even with constant final energy consumption. Owners who invest in a heat pump today therefore automatically benefit from every advance in the energy transition.

Primary Energy Requirement in the Energy Performance Certificate

In a building’s energy performance certificate (mandatory since EnEV 2002, now GEG), the primary energy demand is reported in kWh/(m²a). This value determines the building’s energy efficiency class (A+ to H). Low primary energy demand values indicate a modern, efficient building; high values point to a need for renovation. When buying or selling a property, primary energy demand is an important criterion that increasingly influences the purchase price.

Energy performance certificates are issued as either demand certificates or consumption certificates. While the consumption certificate is based on actual energy consumption over the past three years, the demand certificate calculates the theoretical energy demand based on building characteristics such as insulation, heating system, and window area. For buyers, the demand certificate is often more meaningful because it evaluates the building independently of the previous owners’ usage patterns.

GEG Requirements and New Construction Standards

The Building Energy Act (GEG) stipulates maximum primary energy demand values for new buildings that are significantly lower than those of older buildings. Since 2023, the “GEG Efficiency House 55” standard has been the minimum requirement for new residential buildings: the primary energy demand must not exceed 55% of the calculated reference building value. New buildings meeting the KfW 40 standard require only 40% of the primary energy amount defined in the GEG reference building. The use of renewable energy (PV, heat pumps) can further reduce primary energy demand-which improves eligibility for subsidies and increases the building’s value.

Starting in 2024, the 65% renewable energy requirement will also apply when replacing heating systems: New heating systems must generate at least 65% of their heat from renewable energy sources. This directly affects the primary energy factor, as heat pumps powered by green electricity or pellet heating systems with a low PEF can drastically reduce a building’s primary energy demand-often by more than half. Owners facing a heating system replacement should carefully assess the implications for the primary energy demand and, consequently, for their building’s energy performance certificate.

The EU Energy Performance of Buildings Directive (EPBD) also sets long-term framework goals: By 2050, all buildings in the EU are to be climate-neutral. Germany will translate these goals into gradually stricter GEG requirements. Owners who invest early in low primary energy consumption values protect themselves not only from rising energy costs but also from future renovation obligations and loss of value.

Practical Tip for Owners in Nuremberg and Franconia

Anyone looking to sell a property in the Nuremberg metropolitan region should know the building’s primary energy demand and have a current energy performance certificate on hand. Properties with low primary energy demand (classes A+ to C) are significantly more in demand among prospective buyers and fetch higher prices than unrenovated properties in classes F to H. Energy-efficient modernization before selling can therefore be worthwhile. We advise you on which measures offer the best cost-benefit ratio.

In Nuremberg, N-ERGIE, as the municipal energy provider, is an important partner for district heating connections, which can offer a very favorable primary energy factor. Especially in densely populated neighborhoods with an existing district heating network-such as the Südstadt or St. Leonhard areas-connecting to the district heating network can be a cost-effective alternative to replacing the heating system and can significantly improve primary energy consumption. We help you evaluate the technical and economic options for your specific property.

Anyone who wants to know in advance of a sale how a specific renovation measure will affect primary energy demand should consult a dena-certified energy consultant. A qualified renovation roadmap (iSFP) not only provides an assessment of the savings potential but can also serve as the basis for government grant applications and enhances the credibility of the energy performance certificate during the sales process.

Frequently Asked Questions

What is the difference between primary energy and final energy?

Final energy is the energy that reaches the consumer (e.g., electricity from the outlet, gas at the burner). Primary energy includes losses during generation and transport and is therefore always higher than final energy. The energy performance certificate lists both values; however, primary energy demand is the more relevant indicator in terms of energy policy.

Why does electricity have such a high primary energy factor?

Because significant energy losses occur during electricity generation from fossil fuels (power plant efficiency approx. 30-50%), which are “attributed” to the electricity as primary energy. As the share of renewable energies in the electricity mix grows, the national primary energy factor for electricity decreases-in Germany, it has already fallen to approx. 1.8 and is expected to drop to 1.2 by 2035.

How can I reduce my building’s primary energy demand?

The most effective measures are: thermal insulation of the building envelope, window replacement, switching to an energy-efficient heat generator (heat pump, pellet heating), and installing a PV system. Combining these measures can reduce the primary energy demand of an unrenovated older building by 70-80%.

How often does an energy performance certificate need to be renewed?

An energy performance certificate is valid for ten years. After this period expires or following major renovation work that alters the primary energy demand, a new certificate must be issued. Anyone selling a property with an outdated certificate risks both fines and a weaker negotiating position, because buyers cannot reliably assess the building’s energy performance.

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