This report describes the methodology for identifying and assessing cost-effective strategies for renovating urban districts towards far-reaching objectives regarding reducing carbon emissions and energy use. The report proposes different scenarios considering boundary conditions and different interventions on building envelopes and thermal systems. The proposed methodology builds on the methodology previously developed for individual buildings in IEA EBC Annex 56 (developed by the same main authors of this report), extending it to the level of districts/groups of buildings. Furthermore, it also makes use of results from other related Annexes. The idea is that the methodology supports decision-makers in evaluating the efficiency, impacts, cost-effectiveness and acceptance of various strategies for renovating urban districts, and in identifying suitable renovation strategies. The methodology defines the boundary conditions set for the assessments carried out, the research questions/hypotheses mainly investigated with the assessments, and the type of outputs generated from the assessments. It is intended that, based on the methodology developed, existing tools can be identified, or existing tools can be adapted to support the application of the methodology in case-specific assessments. In addition, an online Calculation Tool (Annex 75 CT) was developed to support the application of this methodology, which is available at: https://annex75.bim.energy and at https://annex75.iea-ebc.org/publications.@en

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.@en

The present report provides guidance on the main concepts regarding building renovation and aims to set a common language for communication between local authorities, professionals, researchers, inhabitants and, in general, all the stakeholders and international partners. Each term is defined in the context and scope of IEA EBC Annex 75, namely building renovations at the district level, and combines definitions from the European legal framework, common definitions of English dictionaries, related projects, research papers, and other professional@en

This report aims to identify both barriers that hinder energy-efficient renovation of buildings and drivers enabling the implementation of energy and cost-effective renovation of buildings and energy supply systems at the district level. Fifteen success stories regarding barriers and drivers were analysed in the first step. These success stories consisted of projects from seven European countries (Austria, Denmark, Italy, Portugal, Spain, Sweden and Switzerland) where energy-efficient and/or renewable energy measures had been successfully implemented at the district level. In the next step, different stakeholders involved in energy renovations at the district level were interviewed about their experiences to identify barriers and drivers. In total, 39 in-depth interviews from eight countries (Austria, Belgium, Germany, Netherlands, Portugal, Spain, Sweden and Switzerland) were carried out. The stakeholders included policymakers, renovation solution suppliers, energy solution suppliers, clients and beneficiaries, financing intermediaries and other intermediaries. The barriers and drivers were divided into the following categories: policy, legal aspects, economic aspects, social aspects, communication, technical aspects, and knowledge and training.@en

The guidebook illustrates that the district, as an action level for building renovation, allows for synergies through combinations of energy efficiency measures and measures that promote the use of renewable energy and opportunities for stakeholders to cooperate, compared to an individual building approach. But building renovation at the district level also presents challenges. These include high upfront costs, a long payback time, and risks of not being implemented due to a potential withdrawal of some building owners at different stages. However, the studies also show that often the opportunities are greater than the challenges in district approaches, even if the cost-effectiveness of certain measures may not necessarily be one of these opportunities. One main conclusion from IEA EBC Annex 75 is that assessments must be carried out for each district renovation project since no "ready-made" or "one size fits all" solutions exist. Still, several techno-economic potentials for district solutions are apparent. Furthermore, the research indicates that the best renovation solutions for a district-level renovation depend on the district's starting situation. The building insulation level, the installed heating/cooling systems, the availability of renewable energy sources and the possibility of integrating renewable energy are determining factors.@en

A comprehensive and detailed Guidebook was prepared to provide target group-oriented recommendations for policymakers and investors/decision-makers. As a supplement to this Guidebook, two complementary versions offer more straightforward guidelines oriented to each target audience, with a summary of the main recommendations. This document provides guidance for policymakers only.@en

A comprehensive and detailed Guidebook (Meyer et al., 2023) was prepared to provide target group-oriented recommendations for policymakers and investors/decision-makers. As a supplement to this Guidebook, two complementary versions offer more straightforward guidelines oriented to each target audience, with a summary of the main recommendations. This document provides guidance for investors and decision-makers only.@en