The project is organized in four Subtasks as follows:

• Subtask A: Technology Overview
• Subtask B: Optimization Methodology and Strategy Development
• Subtask C: Case Studies
• Subtask D: Policy Instruments, Stakeholder Dialogue, and Dissemination

Subtask A: Technology Overview

Leader:            Jorgen Rose (Danish Building Technological Institute - Aalborg University) 
Co-leader:       Tomas Matuska (CVUT, Czechia)

The aim of this subtask is to provide an overview on the available technology options for renovating building envelopes and for switching heating and cooling systems as well as domestic hot water systems into renewable energy based systems in districts.

Starting from a characterization of measures in single buildings (information readily available as already investigated in depth by other studies), a focus is put on identifying options for carrying out such measures at district level. Concerning energy efficiency measures on building envelopes, such options refer in particular to the cost-effective renovation of groups of buildings with a similar structure.

Concerning renewable energy measures, a distinction is made based on the question whether a district heating system is available in a given district, or whether heating and cooling is carried out decentrally. For existing district heating systems, measures are described for transforming them into renewable energy based district heating systems. For districts with decentralized heating and cooling, options are described for new high-temperature or low-temperature renewable energy based district heating systems.

A focus is thereby put on the large untapped potential for renewable energy use based on low-grade renewable energy from the ground or from hydrothermal resources such as rivers, lakes, groundwater, aquifers or the sewage system as well as on the use of solar energy. Large related energy potentials are available in most cities; however, so far, only few cities have made use of these opportunities. Novel technologies are characterized such as cascading heat pumps or high temperature heat pumps that can upgrade heat from low temperatures to high supply temperatures, which are often necessary in existing buildings and particularly in existing district heating systems. Furthermore, technology options are described including the use of new types of "cool" district heating systems, where the working fluid is distributed to buildings without any upgrading of the heat source (making use of decentralized heat pumps in buildings for upgrading the heat source to the temperature required in each building). Also, technology options using solar energy at district level, in particular in combination with storage capacities, are investigated. Within the framework of this work, information on various options previously identified in specific IEA projects and other research projects is brought together and characterized in a common format.

A typology of technology options to be investigated is developed. The technical, economic and ecologic characteristics of the technology options are determined. This includes in particular information on their efficiency, cost elements such as investment costs and operational costs taking into account economies of scale, as well as the embodied energy and the embodied emissions associated with these options. The interdependencies, obstacles and success factors for combining the technology options are also described.

The technology options are put into context with available potentials, and an outlook is made on their future developments.

Subtask A (STA) is organized in the following work packages (WP):

• WP A1: Identification of existing and emerging technology options (both envelope and systems and at both building and urban scale)
• WP A2: Characterization of technology options (cooperation with WP B1)
• WP A3: Interdependencies, obstacles, and success factors for combining energy efficiency measures with renewable integration
• WP A4: Potentials and future developments

Main products:

A Technology Overview Report will be prepared including the following main parts:

• Overview on state-of-the-art technology
• Techno-economic and ecologic characterization of technology options
• Identification of interdependencies, obstacles, and success factors for combining energy efficiency measures with renewable integration
• Outlook to potentials and future developments

Subtask B: Optimization Methodology and Strategy Development

Leader:             Roman Bolliger (INDP, Switzerland)

Co-leaders:     Jon Terés Zubiaga (University of Basque Country, Spain)
                         Andreas Rudena (StruSoft, Sweden)
                         Harald Walnum (SINTEF, Norway)

The objective of this subtask is to develop the methodology to define cost-effective strategies for renovating urban districts towards far-reaching objectives regarding the reduction of greenhouse gas emissions and energy use. The proposed Annex will build on the methodology previously developed for individual buildings in Annex 56 extending it to the level of groups of buildings. Furthermore, it will also make use of results from other related Annexes. The idea is to identify cost-effective strategies, as facilitated by the methodology to be developed, that will support decision makers in the evaluation of the efficiency, impacts, cost-effectiveness and acceptance of various strategies for renovating urban districts.

A typology of districts is established. The type of districts to be investigated is defined, indicating in particular the scope regarding the number of buildings to be taken into account as well as the mix of urban functions in these districts, such as residential and businesses. Tentatively it is expected that a flexible approach will be chosen, which can be applied both to small groups of buildings, as well as to larger groups of buildings amounting to districts. It is also taken into account that there are neighbourhoods where heat consumption is lower than what could be expected from the energy performance of the corresponding building envelopes due to energy poverty situations.

Furthermore, national framework conditions are defined, including expectations regarding their future development.

A life-cycle cost approach is to be applied, putting energy efficiency measures and renewable energy measures into perspective with each other and allowing to assess combinations of the two types of measures in a comprehensive framework.

The methodology will address the challenge that in districts, buildings have different starting situations, as well as the challenge that renovation cycles of the buildings' envelopes in a district are usually not synchronized. Furthermore, the methodology will provide guidance on how and up to what level of detail the energy needs of the district's buildings have to be determined for developing cost-effective strategies.

It is planned to identify and adapt one or more existing tools to support the application of the methodology in case-specific assessments. The resulting tool is intended to serve as a support tool for preliminary decisions, which does not just take into account fixed types of building typologies, yet can be adapted to fit the reality.

The methodology will be applied and tested in generic calculations in Subtask B and in parametric calculations based on case studies in Subtask C. Through the application of the methodology in such a way, it is intended to identify and characterize factors, such as energy density in a given area, affecting cost-effectiveness of renovation strategies for urban districts. In addition, it is in particular intended to investigate synergies as well as trade-offs between renewable energy measures and energy efficiency measures, and between individual and collective solutions.

Based on the results obtained, and taking into account results from other Subtasks, various strategies are described to transform existing districts into low-energy and low-emission districts in different country contexts, as well as the opportunities and risks of such strategies.

Subtask B (STB) is organized in four work packages (WP):

• WP B1: Methodological guidelines and framework conditions
• WP B2: Adaption or development of optimization tools
• WP B3: Cost optimization with respect to varying energy and GHG reduction targets for generic reference districts
• WP B4: Strategy development

Main products:

• Methodology Report on cost-efficient building renovation at district level:  A methodology in conformity with the methodology previously developed in Annex 56 at building level and extended, in order to assess the optimal balance between energy efficiency measures and renewable energy measures at district level;
• Assessment tools: identification and adaptation of one or more existing tools to support the application of the methodology in generic and case-specific assessments.
• Report on the application of the methodology in generic districts
• Report on strategy development

Subtask C: Case-Studies

Leader:            David Venus (AEE INTEC, Austria) 
Co-leader:       Silvia Domingo Irigoyen (INDP, Switzerland)

The objective of this subtask is to illustrate in selected case studies the development of cost-effective strategies to combine energy efficiency measures and renewable energy use in building renovation at district level, to investigate factors influencing the choice for a cost-effective strategy, and to gather related best-practice examples. It is also intended to obtain information regarding necessary framework conditions or policy instruments for facilitating the up-take of cost effective strategies for far-reaching renovations of districts. Furthermore, the role of co-benefits is also investigated.

In a first step, success stories involving district based solutions for renewable energy use and energy efficiency measures are gathered and characterized. This includes both the transformation of previously existing district heating systems, as well as the creation of district heating systems based on renewable energies in districts previously heated with decentralized installations. Furthermore, this includes success stories for the mass-renovation of thermal envelopes in a specific district. It is documented to what extent the combination with energy efficiency measures on the building envelopes has been taken into account in the selected cases investigated, and to what extent grid-based solutions were considered to be advantageous with respect to individual heating or cooling solutions in the district.

In a second step, for selected case studies, the necessary data is gathered to carry out parametric assessments, applying and testing the methodology to be developed by the Annex. It is intended to select as case studies existing urban districts with renovation needs where the results of the case studies can provide guidance in choosing an appropriate renovation strategy for the respective district.  It is in particular investigated to what extent there are synergies and to what extent there are trade-offs for combining energy efficiency measures and renewable energy measures. It is envisaged to determine cost-effective renovation strategies for the investigated districts taking into account both energy efficiency measures and renewable energy measures.

Enabling factors and obstacles for the implementation and replication of successful case studies for transforming existing districts into low-energy and low-emission districts are assessed in various country contexts, taking into account also co-benefits as well as results on investigations on user acceptance from previous studies.

Results obtained and lessons learned are used to prepare a good practice guidance for low-energy and low-emission districts.

Subtask C (STC) is organized in four work packages (WP):

• WP C1: Success stories
• WP C2: Parametric assessment of selected case studies
• WP C3: Enabling factors and obstacles for replicating successful case studies
• WP C4: Good practice guidance for transforming existing districts into low-energy and low-emission districts

Main products:

• Report on parametric assessments of case studies: case studies on cost-effective combinations of energy efficiency measures and renewable energy measures in building renovation at district level
• Online documentation of good practice examples: a collection of good examples for successful implementation of strategies on transforming existing urban districts to low-energy and low-emission districts, combining energy efficiency measures and renewable energy measures or waste heat, including aspects relating to stakeholder dialogue and acceptance by building owners
• Report on enabling factors and obstacles to replicate successful case studies
• Good practice guidance: Guidance for transforming existing districts into low-energy and low-emission districts

Subtask D: Policy Instruments, Stakeholder Dialogue, and Dissemination

Leader:            Erwin Mlecnik (TU Delft - Faculty of Architecture and The Built Environment)
Co-leader:       Hauke Meyer (German Association for Housing Urban and Spatial Development)

The objective of this subtask is to give recommendations to policy makers and local energy related companies about how they can influence the uptake of cost-effective combinations of energy efficiency measures and renewable energy measures in building renovation at district level. The subtask also aims to provide guidance to building owners, as they are the main decision-makers and investors for building renovation.

This will on the one hand be reached through the identification of suitable policy instruments. This will include recommendations regarding subsidy programmes, mandates or obligations for energy companies or contractors, structures of energy tariffs, links to energy planning and contests for encouraging market up-take of cost-effective strategies for the renovation of urban districts. On the other hand, this will be reached through the development of business models for the renovation of districts and for putting them into perspective with individual solutions. Expert interviews are planned to take place with policy makers and stakeholders to identify such policy instruments and business models. A cooperation is thereby in particular sought with local authorities from cities in which case studies are carried out within the framework of the Annex.

Based on the results of the Annex, guidelines will be prepared for policy makers, municipalities, and energy related companies on how to encourage the market take-up of cost-effective strategies combining energy efficiency measures and renewable energy measures for the transformation of existing districts into low-energy and low-emission districts. The guidelines will also include aspects on stakeholder dialogue. Furthermore, guidelines will be prepared for building owners.

For the dissemination of the project, an Annex website will be created as the main information point for various target groups and interested persons in general. Furthermore, Annex Newsletters will be prepared and sent out regularly. Results from the research carried out, apart from their presentation in reports, will also be published in scientific journals. Preference is given to open-access publications. The project is furthermore presented at international conferences. In each of the countries participating in the Annex, regional workshops are going to be carried out for disseminating the results of the Annex. These workshops will involve policy makers and stakeholders, to present and disseminate in particular the guidelines and other results of the project.

A particular element of the dissemination activities will be to explore possible connections to Annex 74 on the Energy Endeavour initiative.

Subtask D (STD) is organized in four work packages (WP):

• WP D1: Policy instruments
• WP D2: Business models and models for stakeholder dialogue (including user acceptance)
• WP D3: Guidelines
• WP D4: Dissemination

Main products:

• Report on policy instruments, including recommendations for subsidy programmes and for encouraging market take-up through contests
• Report on business models and models for stakeholder dialogue
• Guidebooks: Guidelines for policy makers and energy related companies on how to encourage the market take-up of cost-effective strategies combining energy efficiency measures and renewable energy measures or waste heat  for the transformation of existing districts to low-energy and low-emission districts; guidelines for building owners/investors  about cost-effective renovation strategies, including district-based solutions
• Annex Website and Annex Newsletters
• Scientific publications, presentations at international conferences
• Carrying out of regional policy conferences with participation of international guests
• Regular communication through social media