Energy system integration between district heating and electrical domains is required for harvesting potential flexibility arising from sector coupling and support the transition to smart energy systems. This work presents a use case for using excess compressor capacity in refrigeration systems to locally couple district heating and electrical distribution networks by providing heat peak-shaving services to the district heating network. A tool-chain for explicit modelling of the electrical, thermal, and control domain using co-simulation is presented. It is based on a quasi-static electrical load flow model, a dynamic thermal-hydraulic district heating model and dedicated controller simulators integrated into the co-simulation information flow. The use case is implemented using the tool-chain and studied for different peak-shaving services request levels. The result shows that the proposed tool-chain is suitable for studying operational aspects of domain-linking components both at the network and the unit level. It is shown that the refrigeration unit can provide peak-shaving services while satisfying the primary cooling needs. Providing heat peak-shaving services allows distributed feed-in into the district heating network and potential new revenues. However, the refrigeration cycle coefficient of performance decreases as its operation changes from air/air to air/water mode.