scope:

The standard specifies the calculation of the energy effort for generation, i. e. generation of heat and cold. These terms, albeit actually incorrect from the viewpoint of thermodynamics, are brief technical terms subsuming extraction processes by which the usefulenergy types (target energies) heat or cold are made available for the purpose of space heating, potablewater heating or cooling. The extraction processes do not always, and not always only, comprise an energy conversion process; they can also act as energy transfer (overview see Figure 1). Input energies can be extracted from the environment, or they can take the form of fuels (solid, liquid and gaseous) or electrical energy.

In most cases, like benefit transfer and distribution, the generators are a subsystem of an overall installation, which means they are indirect-acting (e. g. using water as heat transfer medium in hot-water heating); however, they are also used directly for benefit transfer (e. g. as stove). When used indirectly, they can be combined with supplementary units, and such combinations shall then be treated jointly in the energy performance evaluation because of the repercussions on the operating behaviour of the generator. Examples of supplementary units are buffer storage tanks or hydraulic switches and central or distributed potablewater storage tanks.

The standard applies to all generators and their control systems as well as to combinations with supplementary units and to multiple-generator systems or generator combinations. It can be used for the energy performance evaluation of both new and existing generators. The specific numerical values given, however, refer exclusively to generator sets currently offered by manufacturers.

This standard forms a system along with the other parts in the series of standards VDI 2067 and shall be applied in conjunction with these. Basic principles and the calculation procedure are explained using the example of a boiler with continuous fuel supply. Specific features of other heat generators such as

• central-heating boilers with (discontinuous) manual charging,
• heat pumps,
• combined heat and power systems,
• systems for solar heating support (solar heating systems),
• electric central-heating boilers,
• district heat transfer stations,
• distributed heat generator systems for individual space heating and
• chiller systems,

are addressed in Section 5, Section 8 and Section 9.

The common special terms pertinent to each generator type are listed separately in Section 3.