"What if the renewal of Rinkeby-Kista, Stockholm, were to make it part of a 2 kW Society?" Renewal of the city district's 25 000 flats from the 1970s is due and a network organisation, "Järva Boost" is established. A cross-disciplinary team of KTH researchers develop a computerised model to simulate energy efficiency gains resulting from actors' decisions. Inputs are measures that building owners, energy providers, residents, planners etc. might propose. They can be technical institutional or socio-cultural. Outputs are energy use in kW/person and CO2 emissions. To guide model development, an "ideal type" usage situation is outlined. The energy system is modelled "upstream" from end use, to identify larger efficiency potentials. The model interface is designed to enable the "staging" of actors' negotiations: The manager influences the properties of the climate shell, the residents the energy used for cooking, and the energy provider the primary energy mix. The concepts of "Household Activities System" and "Energy Usage Systems" give theoretical framework for modelling. The former conceptualises residents' activities, the latter the technology providing services to the activity. Simulations give contrasting outcomes: "business as usual" vs. "most favourable". Used in practice, simulations might simplify negotiations and coming to agreement.