Smart-ready service DHW-2b · Domestic hot water
Sequencing in case of different DHW generators
In short
- 1This page covers DHW-2b, a smart-ready service within the Hot water domain of the Smart Readiness Indicator.
- 2The service assesses how intelligently a building determines which hot water generator is activated at any given time.
- 3Functionality levels range from control based on operating hours to control that accounts for predicted demand and electricity grid signals.
The levels
Level 0
Priorities only based on running time
Level 1
Control according to fixed priority list: e.g. based on rated energy efficiency
Level 2
Control according to dynamic priority list (based on current energy efficiency, carbon emissions and capacity of generators, e.g. solar, geothermal heat, cogeneration plant, fossil fuels)
Level 3
Control according to dynamic priority list (based on current AND predicted load, energy efficiency, carbon emissions and capacity of generators)
Level 4
Control according to dynamic priority list (based on current AND predicted load, energy efficiency, carbon emissions, capacity of generators AND external signals from grid)
What exactly does DHW-2b measure?
DHW-2b is a smart-ready service within the Hot water domain of the Smart Readiness Indicator (SRI), the European system that measures the digital intelligence of buildings. This service examines buildings with multiple hot water generators, for example a combination of a heat pump, solar water heater and gas boiler.
The question is: on what basis does the building management system (BMS) determine which generator receives priority? This is called sequencing or prioritisation.
How do the functionality levels differ?
At level 0, only operating hours determine the sequence, without further logic. Level 1 uses a fixed priority list, for example based on the rated efficiency of each generator.
Level 2 works with a dynamic priority list. The system then considers the actual efficiency, CO2 emissions and capacity of each generator, such as solar energy, ground heat, combined heat and power (CHP) or fossil fuels.
Level 3 adds predicted demand to these factors. Level 4 is the highest level: the system uses the same data, supplemented with external signals from the electricity grid.
Why does this count toward the score?
Each smart-ready service is evaluated against impact criteria, such as energy efficiency and grid flexibility. DHW-2b contributes to the overall score of the Hot water domain.
This service is not part of method A, the streamlined assessment covering 27 services. It does count toward method B, the full assessment covering 54 smart-ready services.
How does this relate to European law?
The SRI is established in Delegated Regulation (EU) 2020/2155 and Implementing Regulation (EU) 2020/2156. The Energy Performance of Buildings Directive (EPBD IV), Article 15, currently makes the SRI voluntary.
The European Commission must adopt a delegated act by 30 June 2027. This is expected to make the SRI mandatory for non-residential buildings with installations above 290 kW.
Relevant for these building types
Next step
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