In the D2Grids project, 14 partners cooperate to introduce a new paradigm to create completely sustainable and circular heating and cooling grids: 5th generation district heating and cooling (5GDHC). In order to demonstrate this new concept, partners are working on 5 pilot sites across, The Netherlands, France, Germany and the UK. In the second part of 2020, the 5 principles of a 5GDHC network have been determined, as well as Key Performance Indicators (KPIs), quantifying each of the design principles. The next step is now to be able to objectively determine whether a network meets the 5G requirements and then to be able to say to what extent a network is 5G.
Although most pilot sites follow the 5th generation DHC design principles, the performance on the different KPI’s are not expected to be met for all pilots upon first commissioning. For example, a district heating system could meet all 5GDHC KPI’s apart from a heat and cold storage dimensioned to balance the heat and cold demand with 100% sustainable thermal energy sources. This does not imply however, that this district heating system can’t evolve to a 100% 5G district heating and cooling system, progressively implementing all features to meet all the KPI’s that have been defined. The system is thus not 5G at the start, but is “5G-ready” But what is the meaning and the value of 5G-readiness if -for example- the storage and/or the renewable energy production is never added to the system or if other KPI’s of one or more of the principles are not met (yet)?
The “Nill-on-the-meter” approach
In order for any concept to deliver a successful contribution to the energy transition, it should be clear what the performance criteria are and how the performance criteria are guaranteed over the life cycle of the concept. This holds for sustainable installations such as heat pumps, sustainable building concepts such as the Nill-on-the-Meter (NOM) renovation concept and sustainable district concepts such as 5G district heating systems. This is also the reason that certification systems such as the NOM-certificate, have become an important element to assess the KPI’s of concepts.
Since high ambitions have proven to be difficult to meet at once, the phrase ‘xx-ready’ has become an easy way out for mainstream actors. Thus, undermining the efforts and accomplishments of frontrunners in the energy transition. Recognizing this challenge has led to the introduction in the Netherlands for a NOM-ready certificate. In order for a building or renovation proposition to be recognized as truly NOM-Ready it consists of the following 3 elements:
- Both the first set of measures and the measures taking in next steps, leading to NOM at a later stage, lead to guaranteed functional performance improvements with respect to energy use, the indoor environment, building physics, living comfort and maintenance;
- A transferable and concrete action plan, with which all NOM performance characteristics (as defined in the NOM-certification system) can be realised without disinvestment, constructional or building physics-related risks and other limitations in living comfort at standard use patterns, is part of the proposition;
- Insight is provided to the purchaser of the building/renovation proposition what the impact is of the set of measures on the (change in) total living or facility expenses as far as they are related to operational energy costs, cost of system maintenance, financing costs (such as down payments and interest of a loan), replacement costs and end-of life costs.
Assessing the 5GDHC “readiness” of a project
Applying this approach for NOM-ready to 5G district heating systems, we formulate the following draft for 5G-ready district heating (& cooling) systems: A district heating (& cooling) proposition is 5G-ready if it consists of:
- A concrete proposition following the 5G design principles with performance guarantees on a discrete set of the 5G-KPI’s;
- A transferable and concrete action plan, which provides insight how the complete set of 5G-KPI’s will be met at a later stage without disinvestments on the district heating and cooling network, constructional risks or functional downgrading, is part of the proposition;
- Insight is provided in the economic impact, for all actors who are affected by the introduction of the 5G-ready district heating and cooling network, stemming from financing, operational costs (living expenses, cost of maintenance), replacement costs and end-of-life costs.
This definition could not only help the developers of 5GDHC-grids to improve their current concepts, but also provides a concrete framework along which local authorities can challenge the market. Moreover, it provides other actors affected by the introduction of a district heating and cooling network the required insight to support this introduction with trust that it will end up as a full 5G system.
 A house is Nill-on-the-Meter, if the yearly energy demand of a household (building-related and use for house-hold appliances) in standardised conditions (usage profile and climatic conditions) are in balance with the yearly energy produced on the premises of the house.
 For a buidling concept NOM, the building concept should not only meet the energy definition, but also meet minimum performance characteristics on other aspects, such as IEQ, comfort, safety, privacy&security proof monitoring, maintenance and nature inclusiveness.