DIN V 18599-3:2016-10

The method described in DIN V 18599-3 can be used to determine the energy need for thermal air conditioning as well as the delivered energy for air transport in ventilation and air conditioning systems (VAC systems) which partly use external air.
The energy need is the total of energy required by the heating, cooling, humidification and dehumidification functions to condition external air in order to achieve the desired supply air properties. The electrical energy demand of air transport includes the energy required by the fan and the mechanical transmission systems and the energy required to generate the mechanical energy.
This document does not include ventilation systems and air heating systems for residential buildings; these systems are dealt with in DIN V 18599-6.
The energy need for thermal air conditioning can only be calculated if the basic thermodynamic process controls involved are known. The process controls are determined by the order of the components in the VAC systems and by the basic rules according to which the system is operated. Ideal process control modes are assumed in the calculations to determine the energy need.
For calculation of the delivered energy for air transport, the air system pressure losses shall first be determined or a maximum value of the air system pressure losses shall first be specified.
In order to determine the delivered thermal energy, the deviations of the actual application from the ideal process control assumptions, expressed in terms of energy expended, shall be added to the calculated energy need. This procedure is defined in DIN V 18599-7.
The scope of DIN V 18599-3 covers installations with basic ventilation functions and in which both the minimum external air volume flow rate and the supply air temperature are given independent of the thermal loads in the zone served by the system.
This basic ventilation function is frequently combined with an additional function to satisfy cooling requirements. Calculation of the energy need for this supplementary "space cooling" or "room conditioning" function requires a separate assessment procedure which includes energy balances of the respective building zones.
Here a distinction needs to be made between two different cases:
The space cooling function is provided by an additional energy carrier without using external air.
EXAMPLE Zone reheaters/zone recoolers; cooled ceilings; air recirculation systems; cooling coils within an induction system.
In this case, the energy need of the space cooling (room conditioning) system is deduced from the monthly balance calculations for the building or the building zone as described in DIN V 18599-2.
1. The space cooling function is achieved by increasing the volume flow of pre-conditioned external air into the space.
EXAMPLE Variable air volume systems (VAV). The determination of the energy need for space cooling (room conditioning) in systems using this type of cooling function is dealt with in this document. However, it can only be calculated if the energy balance of the space or building zone has already been calculated as described in DIN V 18599-2.
The most commonly used types of VAC system configurations can be modelled using combinations of basic ventilation systems and space cooling systems.
DIN V 18599-3 has been approved by NA 005-12-01 GA "Gemeinschaftsarbeitsausschuss NABau/FNL/NHRS: Energetische Bewertung von Gebäuden" ("Joint Working Committee NABau/FNL/NHRS: Energy performance of buildings") and published as a prestandard.