This report, therefore, focuses on the following objectives:
- Give an overview of various policy options that could target the district level, considering existing and emerging policy instruments with the potential to be successfully applied within that context, and how policy challenges specifically occurring in an urban context can be overcome;
- Develop, test and use a methodology which can be applied to identify best-practice policy instruments for specific districts by evaluating stakeholder’s acceptance of proposed policy instruments and the effects and impacts stakeholders expect for reducing carbon emissions and energy use in buildings in cities at the district level, combining both energy efficiency measures and renewable energy measures;
- Illustrate the development and assessment of innovative local policy instruments that could target the district level for achieving energy renovations and renewable energy systems;
- Provide the necessary background for recommendations to policymakers and their key partners on how they can influence the uptake of cost-effective combinations of energy efficiency measures and renewable energy measures in building renovation at the district level.

Worldwide, cities are nowadays formulating their own sustainability goals, including ambitious targets related to the generation and consumption of energy. In order to support decision makers in reaching these goals, energy experts typically rely on simulation models of urban energy systems, which provide a cheap and efficient way to analyze potential solutions. The availability of high-quality, well-formatted and semantically structured data is a crucial prerequisite for such simulation-based assessments. Unfortunately, best practices for data modelling are rarely utilized in the context of energy-related simulations, so data management and data access often become tedious and cumbersome tasks. However, with the steady progress of digitalization, more and more spatial and semantic city data also become available and accessible. This paper addresses the challenge to represent these data in a way that ensures simulation tools can make use of them in an efficient and user-friendly way. Requirements for an effective linking of semantic 3D city models with domain-specific simulation tools are presented and discussed. Based on these requirements, a software prototype implementing the required functionality has been developed on top of the CityGML standard. This prototype has been applied to a simple yet realistic use case, which combines data from various sources to analyze the operating conditions of a gas network in a city district. The aim of the presented approach is to foster a stronger collaboration between experts for urban data modelling and energy simulations, based on a concrete proof-of-concept implementation that may serve as an inspiration for future developments.