Simulation Results of Collectopia Cross-Simulation (EIFER-EDF-AIT)


Simulation Setup & Configurations

  • System Configuration: In a city in the North of France, the construction of an eco-district aims at promoting the solutions for sustainable and environmental-friendly cities. Collectopia roughly covers an area of 10 ha and contains several building like single houses, office buildings and a greenhouse. Heat, cold and hot water are generated by the green house and locally distributed back up boilers. An aquifer is used as long-term thermal storage device. The heat is transferred via a 4th generation district heating network, designed to work at lower temperatures of about 45 °C.
  • Use-case: In summer time, the local heat pump fulfill the cooling needs of the greenhouse. The heat energy is recovered at the condenser, injected to the low-temperature DHN and stored in the long-term storage tank. Domestic hot water (DHW) needs of the residential and tertiary buildings are covered by local heat pumps. All PV panels (on the residential and tertiary buildings) form a local distribution grid to enable collective self-supply. Small local buffer tanks are used to increase the self-consumption rate (daily cycles). In winter time, the heating demand (greenhouse, residential and tertiary buildings) is covered by the DHN and the local heat pumps. The long-term storage tank is used to increase the self-consumption rate (cycles over longer periods). Eifers’s ETEM-model for the strategic planning of Collectopia differs from the system configuration used by EDF and AIT (Fig. 4), as in the planning phase the technology and component choice was subject of the optimization. The contemplated time interval of the use-case covers seasons like summer or winter. The minimum simulation time step is in case of EIFFER’s simulation one hour, EDF updates its simulation every 72 hours and AIT every 15 minutes.


Cross-Simulation Goals

Goal of the Collectopia cross-simulation is to design the energy infrastructure of Collectopia in order to maximize the use of local energy (electricity from PV and excess of thermal energy from the greenhouse). Hence, the

  • Volume of the long-term storage tank
  • Volume of the local daily buffers
  • Size of the local heat pumps
  • Temperature levels of the energy carriers
  • Assess the use and role of additional decentralized phase change storages (PCM storages)

need to be optimized.

Especially, for the system design with the ETEM-tool Eifer uses, the optimization is based to minimize the net present value (NPV) of the whole of Collectopia. The NPV is described in Eq. 1. The NPV sums up all investment expenses (CAPEX), the operational and maintenance expenses (OPEX), the costs for the energy used in Collectopia (Import_costs) and subtracts the revenues in case energy is exported.


Description of Tasks and Workflow

In the Collectopia cross-simulation EIFER, EDF and AIT are merging their modelling and simulation expertise. EIFER specializes in designing districts, in choosing optimal technologies for these districts and in calculating optimal capacities for district energy needs, considering future economic trends and legislative and environmental constraints.

EDF provides expertize in the described use case as well as in the design and operation of DHN’s and heat pumps. AIT specializes in the development and integration of advanced storage technologies. Especially, in this case phase change storage are a possible means to be used as decentralized storages to cut peak loads, which is investigated in the study.