energy efficiency, ressource efficiency, energy performance, ressource savings, cost savings, efficiency agency, energy consulting, energy consultancy, optimization, optimisation, process

Copyright 2023 - Richtvert | Andrej Jentsch, PhD


Provides an indicator of the theoretical transformability of the considered energy into work. Energy quality is a simplified term for transformability. The transformability concept is based on the exergy concept and has been developed in 2010 by A. Jentsch, PhD in his dissertation.

A combination of supply system (technology) and supply target (building or process).

Theoretical potential to generate work from a combined system of a mass or energy transfer under consideration and the environment. Simply put, exergy can be defined as the product of energy and energy quality.

Visual representation of required and provided energy and energy quality. The exergy pass allows a comprehensive visual evaluation of energy systems and their comparison. Publications (in English) which include a description of the exergy pass can be found here (page 88 ff. under its old name ExergyFingerprint) and here (page 167 ff.). 


Space heating has an energy quality of approx. 7 % at a temperature of the environment of 0 °C. Electrical current has an energy quality of 100 %.

Heated room with gas boiler

1 kW heat flow at

20°C is associated with 0,07 kW exergy flow (Reference temperature 0°C)


Energy quality:           

Energy system:


Exergy pass:                    


Supply system:

Supply target:

A process chain which transforms primary energy (e.g. natural gas) into effective energy (e.g. space heat).

An area or volume within which effective energy is required. A simplifying term for the supply target is the term „consumer“. Its properties define the required amount of energy and the required energy quality.

deutsch    english

Natural gas block CHP unit with a district heating network and the indoor heating system

Warm air in a room,
Lighting requirements,

Temperature in an industrial oven