Individual consumption-based heat billing for domestic and commercial premises has been a regulatory requirement in Germany for decades [1]. The original technology used for heat cost allocation was based on the evaporation principle, but over the last 15 years this has been replaced by electronic devices, and today radio technology is increasingly used to communicate readings. Through these technical advances, the maintenance and meter reading of the devices has become more customer friendly. Today there are further benefits in accuracy, availability of data, and functionality based on technical improvements.

The fundamental reason for requiring heat cost allocation or - to put it more simply - users paying for their proportion of a shared building’s energy costs, is to reduce the overall energy consumption for the shared building. It is human nature that where individual users are responsible for their own energy costs they will use energy more conservatively, and this change in user behaviour is evident where consumption-based heating bills for individual users is introduced for the first time. (cp. [2, 3])

Individual heat consumption is predominantly measured with heat cost allocators. These devices enable an aggregated energy bill for a large building to be allocated to individual parts of the building, such as apartments or commercial units, in proportion to the heat they use. The development of the devices started with evaporative heat cost allocators, which used the principle of an evaporating liquid to measure the heat being used. Later these devices were replaced by electronic heat cost allocators, and today by heat cost allocators that incorporate a radio device to allow meter readings to be transmitted automatically, avoiding the need for meter readers to enter premises and take manual readings.

These modern technologies enable more frequent and more accurate energy consumption information to be provided to energy users, and this has made possible the introduction of new services to monitor and control energy consumption and energy costs as part of a modern energy management system.


Energy consumption for new buildings has been reduced significantly over recent years. However, temperature control (and therefore energy consumption) in newer, highly insulated buildings is often sensitive with regard to the user behaviour (cp. e.g. [6]). Inefficiencies caused by poor ventilation systems, for instance, can have a similar effect on energy losses as poor insulation in older buildings. Regarding the heating consumption, the user’s influence is even greater than in conventional buildings.

For buildings with low heat energy consumption, the benefits of technologically developed metering systems are obvious. They give the user more information about his heating behaviour than is possible with conventional heat cost allocators. By providing relevant information, the user can easily control his consumption through better understanding of his usage behaviour.

For large buildings with combined residential and commercial users of heat, energy can be controlled and monitored at individual user level. Small business users in commercial properties may have less time to look at energy consumption; however larger companies become more and more interested in effective control of energy, because of increasing energy costs. Most large corporations have their own energy manager.

In the near future national legislation will encourage companies to manage their energy usage economically.


The Government’s initiatives and regulations on the reduction of energy consumption have the primary aim of reducing dependency on energy imports. At the same time, the pollution by CO2 and the resulting greenhouse effect has been recognised as a serious problem. This has led to the international agreement (the Kyoto-Protocol [5]), in which the signing states commit to reductions in CO2 emissions. For the European Union the reduction by 2010 is 8% compared to 1990 emission levels.

To translate this aim into action, the European guideline for the total efficiency of buildings was enacted in 2002 [6]. An integral part of this guideline covers aspects of energy management or ‘energy identification’ and it includes energy ratings for buildings, in which the energy efficiency is listed. Energy identification consists of log-books to record the energy consumption of the building and the technical equipment, metered values for the energy consumption of the complete building, and particular consumption sectors (heating, air-conditioning, lights). According to national law, the implementation of the guidelines is scheduled to be completed by January 2006.

Figure 1 - Possible displays for energy monitoring.

Figure 1 – Possible displays for energy monitoring. The first graph shows meter readings for different rooms in an apartment, and the second shows monthly consumption compared with consumption from the previous year.

A further proposal concerning energy efficiency and energy services has existed since December 2003 [7]. Its aim is to improve the approach to energy efficiency by co-ordinating the energy service with quality requirements. For the end user of energy services such as heating, the benefit is a measurement of quality which introduces quality control. Through better control, it is possible to achieve the same room comfort with a reduced use of energy. This is attractive for the customer, because he can reduce his energy costs. This approach also improves transparency in the market by addressing the energy delivery and the technology that is employed (in this example the control) together.

Even though there is still discussion about the implementation of this regulation, it is likely that the requirements in the approach to measuring energy consumption will be implemented in some form. The total energy efficiency is a combination of energy management and cost control. Measuring points for individual system components with appropriately frequent data resolution could make a major contribution to enable energy users to implement improved quality initiatives of this nature.

There is still discussion about the implementation of this regulation; it is clear that the requirements in measuring techniques will change dramatically. The total energy efficiency is a combination of energy management and cost control, and an adequate number of measuring points with a high frequent data resolution could contribute towards this.


Modern metering devices have a communication interface. There is an increase in fully automated meter reading today, with electronic heat cost allocators. Devices are equipped with a radio-interface. With the symphonic radio system from Viterra Energy Services, the meter data is sent via short-wave radio to a data concentrator memonic and collected in a database. The system also includes water, heat, electricity and gas meters. To make data available for effective energy controlling the memonic is read in short term intervals via modem.

Figure 2 - Structure of an Internet-based energy-monitoring solution

Figure 2 – Structure of an Internet-based energy-monitoring solution

Together with the Technical University Munich (TU) Viterra Energy Services conducted a research project on energy monitoring called ISOTEG [8]. The system that was developed as a result is a demonstration application using a central apartment display, which shows the heat consumption of individual rooms. In addition other information, such as cold and hot water consumption or electricity and gas consumption, can be seen (see Figure 1).
A simple graph represents the current state of the heat consumption for individual rooms in an apartment. The user sees the accumulated heat consumption since the last effective day, and recognises the main point of consumption in his apartment.

An Internet-based energy monitoring system was developed, in the belief that there will be large increases in Internet applications in the future. In addition it allows comfortable and flexible user interfaces to be achieved easily.

The Internet energy monitoring system, which visualises the consumption data, consists of three large sections that work separately. The function groups are the data collection, in the form of a client that collects and transmits the data, and a server that saves, edits and displays the information collected (see Figure 2).

The user data which is transmitted from the measurement points is received from the client and transmitted to the server via Internet, where it is collected in a database. This allows the data to be evaluated statistically (temporal development of consumption, consideration of the climatic conditions, comparison of the consumption of rooms with the same use or from different buildings). An interface to the billing system is needed for consumption-based billing. The server also edits the data for the display that has been selected, and the user accesses his data via the Internet.


  1. Verordnung über die verbrauchsabhängige Abrechnung der Heiz- und Warmwasserkosten (Verodnung über Heizostenabrechnung – HeizkostenV) vom 20. Januar 1989.
  2. Hilberg, M.: Einfluß des Nutzerverhaltens auf den Heizwärmeverbrauch. Jahrbuch 1994, VDI-Gesellschaft Technische Gebäudeausrüstung, S. 90-111. VDI-Verlag GmbH, Düsseldorf 1994.
  3. Mügge, Günter: Die Bandbreite des Heizenergieverbrauchs – Analyse theoretischer Einflußgrößen und praktischer Verbrauchsmessungen, Dissertation TU Berlin, VDI-Verlag, Düsseldorf 1993.
  4. Loga, Tobias; et. al.: Der Einfluss des Gebäudestandards und des Nutzerverhaltens auf die Heizkosten. Institut Wohnen und Umwelt, Darmstadt 2003.
  5. Kyoto Protocol to the United Nations Framework Convention on Climate Change, 10.Dec.1997, Annex B
  6. Directive 2002/91/EC of the European Parliament and of the Council of 16 December 2002 on the energy performance of buildings, Official Journal L 001 , 04/01/2003 P. 0065 – 0071
  7. COM (2003) 739 Proposal for a DIRECTIVE OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on energy end-use efficiency and energy services.