Operational building energy has long been recognized as both a major contributor of as well as an opportunity to save carbon emissions. To do so, one may follow two paths, reduce the energy use in buildings (demand) or provide the required energy in more efficient ways (supply). In the literature, extensive research has been made on both fronts and at different levels of detail resulting in a myriad of tools unique to specific stages in the development timeframe of a district energy project. This manuscript describes a modeling workflow based on a new Rhinoceros-based plugin that combines an Urban Building Energy Model with a network topology optimization and a heat generation scenario model bridging the gap between the planning phase and the design phase. The new plugin builds on the foundation of umi, a Rhino-based link to Radiance and EnergyPlus developed at the MIT Sustainable Design Lab, as an addition to the demand simulation module. A demonstration project shows how the workflow serves as a stepping stone from the design environment of Rhinoceros to the technical environment of TRNSYS, thus enabling a more streamlined process to use different modeling strategies for different purposes, within the same design workflow. (C) 2018 Elsevier Ltd. All rights reserved.