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(ii) Estimation of distribution costs and identification of promising technologies and
network geometries

In the previous subsection it has been cleared how a reasonable estimation of thermal energy end
uses could be obtained, classified by type of costumer (centralized/punctual, i.e. “large scale”,
and distributed/residential, i.e. “small scale” user) and energy request (domestic hot water, space
heating and space cooling). In the present section the methodological approach followed to
identify reasonable technological solutions to develop the district heating and/or cooling
networks and their geometry will be discussed in details.
First of all, let us define a possible set of options/scenarios to be investigated, that are classified
as follows:
a. Interconnection level: two alternative scenarios are considered, respectively based on
assuming:
- a very high interconnection level of the networks, with the densely populated/built areas
entirely covered by the hot/warm/cold fluids distribution network and the consequent
possibility, for any centralized or residential customer, to be connected to the DH
network upon request. This design option is illustrated, for an exemplificative island with
two densely populated areas “1” and “2”, in Figure 8.a;
- a very low interconnection level of the network, based on assuming the installation of a
limited number of pipes/branches, sufficient only to distribute the hot/warm/cold fluids
toward the largest centralized/punctual customers. This option is illustrated in Figure 8.b;

a. b.

Figure 8. Representation schema of district heating networks characterized by different
interconnection levels: a. high interconnection level, b. low interconnection level

b. Energy uses to be supplied and consequent temperature levels of the distributed fluid. Three
scenarios could be in principle considered:
- Distribution of low grade heat for space heating and DHW uses and distribution of cold
water for space cooling loads;
- Distribution of high grade heat (via superheated water supply) to supply space heating
and domestic hot water and to drive on-site (i.e. within the served buildings) thermally-
activated chillers, like single-effect absorption units, to produce cold water for space
cooling purposes;
- Distribution of low-grade heat for space heating and domestic hot water uses only.

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