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 offers an overview of the available technologies for energy renovation and renewable energy supply at the district level. As anticipated, this is the second edition of the Technology Overview Report published in 2020 (and made available on the IEA EBC Annex 75 website since then), completing the set of final reports developed by IEA EBC Annex 75. The first edition was the first of IEA EBC Annex 75 deliverables and documented the work of Subtask A – Technology Overview. It served as a necessary reference for other subtasks, providing helpful information for assessing district renovation examples, especially for the simulations of the case studies and generic districts used in this project to test and verify the developed methodology.@en

Renovation at district scale is a key strategy to reduce CO2 emissions by optimising the implementation of renewable energy sources and taking advantage of economy of scale. This paper focuses on analysing good practice examples on energy renovations at district scale. The paper adapts a qualitative research methodology in four phases, including the multi-perspective analysis of nine exemplary renovation projects in six European countries, including identification of drivers and barriers of different stakeholders.

It is found that the drivers for a district renovation are not restricted to energy savings, but typically also include improving the overall quality of life as well as the image and economic value of a district. Moreover, the need for financial models that can alleviate split-incentive problems between investors and resident organizations is identified.

Barriers for carrying out a district renovation include that there is a need to comply with energy standards, that the renovation scope had to be limited to avoid a noticeable rent increase and that resettling of tenants during the renovation is often not possible.

Lessons learned include that good communication amongst the different stakeholders, especially with residents, plays a key role for the success of the project. Furthermore, a strong leadership is needed to coordinate activities due to the great number of stakeholders.@en