Heating cost billing with heat pump: How to bill legally in multi-family buildings

Everything you need to know for legally compliant heating cost billing with heat pumps.

Heating bill with heat pump

Since October 1, 2025, heating costs in multi-family buildings with a central heat pump must generally be billed based on consumption. This leaves owners and property managers with the question of which measuring devices are required and how the requirements of the Heating Costs Ordinance can be implemented in a legally compliant manner.

Whether it's electricity meters, heat meters, or additional measuring points: the required measuring technology depends on the heat pump system design. This article explains the legal requirements, the necessary measuring equipment, and how to bill heating costs transparently and comprehensibly. Choosing a suitable measuring concept early on lays the foundation for legally compliant heating cost billing, avoids later inquiries, and simultaneously provides valuable data on the efficiency of the heat pump system.

What measuring instruments are needed for a heat pump?

The necessary measuring equipment depends on the operating concept of the heat pump. Guidance is provided by the German Heating Costs Ordinance (Heizkostenverordnung) and recognized technical guidelines. These describe how the required energy quantities can be measured for different system designs.

Basically, electrically operated heat pump systems can be divided into three typical variants:

• Heat pumps without heating element
• Heat pumps with electric heating element
• Heat pumps with an additional heat generator, for example a boiler

Specific measuring points are required for each variant in order to correctly allocate the costs for space heating and domestic hot water heating.

Separate electricity meters as the basis for heating cost billing

To ensure legally compliant distribution of heating costs, the costs of heat generation must be recorded separately and transparently. For heat pump systems, a separate electricity meter for the heat pump therefore forms the basis for billing. Additional electric heating elements, for example in the buffer or hot water storage tank, must also be taken into account when recording consumption. If multiple heat generators are used, such as a heat pump and a boiler, the respective energy consumption must be recorded separately. This ensures transparent and traceable tracking of the actual costs incurred for heat generation.

How are heating costs billed for different system designs?

The following diagrams show which measuring devices are required depending on the system design. This allows you to see at a glance which measuring technology is needed for legally compliant heating cost billing.

Recommended measuring equipment at a glance

For a legally compliant and as accurate a heating cost statement as possible, the following equipment is recommended:

Suggestions	Measuring equipment	Benefits
Always	Electricity meter for the heat pump	Recording electricity consumption
Recommended	Electricity meter for the heating elements	Separate measurement of the heating current for the heating element
mandatory	Heat meter for domestic hot water heating	Correct distribution of hot water costs
Recommended	Heat meter for space heating	Correct distribution of heating costs
Recommended	Heat meter after the heat pump	Determination of heat generation and seasonal performance factor

Why are electricity meters alone not enough?

The electricity meter only records the electrical energy consumed. For accurate heating cost billing, the amount of heat generated must also be measured. Only the combination of electricity and heat meters enables transparent cost allocation and the calculation of the annual performance factor.

What happens when heat pumps lack measuring technology?

If the required measuring equipment is not fully available, alternative methods can be used in certain cases. This allows for billing to still be generated, but only based on calculated assumptions and not on fully measured energy quantities.

The more values ​​that need to be replaced or calculated, the less accurate the cost allocation becomes. From a technical perspective, replacement methods are therefore not the preferred solution. They can also lead to queries, discussions, or legal uncertainties – especially if important measurement points are missing.

We therefore recommend installing the required heat meters early on. This creates a transparent data basis, reduces billing risks, and ensures that heating cost billing is as accurate and comprehensible as possible.

Efficiency test of the heat pump

A heat pump only operates economically if it generates as much usable heat as possible from the electricity it uses. To reliably assess this efficiency, it is advisable to install a heat meter directly behind the heat pump. Together with the separately recorded electricity consumption, this allows the calculation of the seasonal performance factor (SPF) – an important indicator for evaluating the system's energy efficiency.

Many heat pumps have integrated energy balance displays. However, these are usually not calibrated and offer only limited monitoring options. Furthermore, the integrated system cannot be easily replaced if necessary. Practical experience shows that such displays can sometimes deviate significantly from the readings of installed, calibrated heat meters.

A conformity-assessed heat meter therefore provides a reliable basis for evaluating the actual system performance. Without measurement data from real-world operation, efficiency can only be assessed using theoretical values, such as the calculated seasonal performance factor (SPF). This is less informative and makes it more difficult to optimize the system settings.

With suitable measuring equipment, owners and operators receive transparent data on the efficiency of their heat pump. This allows them to identify optimization potential, better assess operating costs, and more reliably meet the requirements for testing and optimizing the system.