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BACnet Insight
The table on p. 23 below shows an overview of the
requirements. A tick stands for legally unambiguous
requirements. A question mark is shown where there is
room for legal interpretation. Where there is a horizon-
tal bar, there are no legal requirements based on § 71a.
Existing Non-Residential Buildings
If the nominal output of the heating/air conditioning sys-
tem in an existing building does not exceed 290 kW, no
legal requirements based on § 71a must be observed.
If this threshold value is exceeded, energy monitoring
Mit dem GEG 2024 wurde für Nichtwohngebäude erstmals ein Mindest-Automatisierungsgrad eingeführt.
The German GEG 2024 introduced a minimum level of automation for non-residential buildings for the first time. technology including data exchange via company and
manufacturer-independent interfaces must be guar-
anteed in any case. It is unclear whether the “automa-
Heating directly support a standardized communication protocol tion level B or better” must then also be implemented.
Automated room temperature control with or be converted to standardized communication proto- According to the BMWK’s statement, this is not neces-
communication (e.g. time programs, flow temperature cols via gateways or corresponding controllers. sary and if this level of automation is not introduced out
adaptation) of own motivation (reduction of operating costs), it is
Heat transfer for hall heating systems: Time program The issue of defining the central communication proto- advisable to make a note in the file with reference to this
with optimized on/off switching col is therefore of particular importance. The difference BMWK statement. However, if a major renovation of the
Demand-driven flow temperature control between interfaces and the actual communication proto- heating or cooling system is to be carried out in an exist-
Regulation or control of the circulation pumps: cols should be emphasized here. Interfaces include, for ing BMS – e.g. replacing an oil boiler with a heat pump
Differential pressure control example, Ethernet or RS 485; however, these are quite – the planner should also explicitly agree with the client
Heat generation: Weather-compensated control universally applicable and the definition of one or the the extent to which the degree of automation should be
including room temperature activation other is not sufficient! It is not only important to spec- taken into account.
ify that systems and applications can transfer data, but
Cooling also that the content of the data is interpreted correctly. New non-residential buildings
Cold transfer (intermittent operation): Time program Protocols such as Modbus, OPC UA, MQTT or BACnet
with optimized on/off switching should be mentioned here. BACnet has the advantage of If the nominal output of the heating/air conditioning sys-
Partial interlock between heating and cooling a consistent focus on the requirements of building auto- tem in a new building exceeds 290 kW, automation level
Demand-driven flow temperature control mation with different interface support (e.g. as BACnet B and cross-system and cross-manufacturer communi-
Regulation or control of the circulation pumps: Differ- MS/TP, BACnet/IP or BACnet/SC). cation between all technical building systems and appli-
ential pressure control cations must be clearly guaranteed.
Cooling generation: Demand-driven control Requirements According to GEG 2024
If the value falls below this threshold, the question arises
AHU/air conditioning The legal requirements are listed in the GEG in § 71a. as to whether the listed requirements also apply. Accord-
Presence-dependent air volume flow control Unfortunately, there are different legal interpretations of ing to the BMWK, this should not be the case, but as
Cooling load-dependent variable volume flow and the wording. before, this is not legally binding and could be decided
demand-controlled temperature with communication differently in court. It is therefore advisable to make a
The BMWK (Federal Ministry for Economic Affairs and note in the file and provide an exact description or exclu-
Lighting/Shading Climate Protection) has published a statement on the sion of the automation requirements between the client
Daylight-dependent dimmed lighting (switches off, legally ambiguous requirements, which unfortunately and the planner.
switches on again automatically) with presence detector begins with the note that this is not a legally binding
Automatically operated sun and glare protection with statement and may be decided differently in court. This Comprehensive White Paper on the Topic
slat tracking means that a certain amount of uncertainty will remain
until the first court rulings are made, but this should be Further information and the exact wording of the BMWK
Technical Facility Management kept under control by taking appropriate notes or clarify- (Federal Ministry of Economics and Climate Protection)
Central adaptation of user requirements ing matters with clients. statement are available in a free White Paper – download
at www.big-eu.org/resources.
Data Communication
In addition, the GEG 2024 requires communication
between the technical building systems and the appli-
cations, even with different proprietary technologies; Prof. Dr. Michael Krödel
for this purpose, the integrated components must either
Professor für Gebäudeautomation und -technologie
bei der Technischen Hochschule Rosenheim
michael.kroedel@th-rosenheim.dewww.th-rosenheim.de
18 BACnet Europe Journal 41 09/24
