Publications || IEA EBC || Annex 75

General Publications

Success Stories of Cost-effective Building Renovation at District Level Combining Energy Efficiency & Renewables (PDF 8.26MB)
May 2023
Author(s): Silvia Domingo Irigoyen, Manuela Almeida, Ricardo Barbosa, Oskar Bell Fernández, Roman Bolliger, Henrik Davidsson, Giuliano Dall’Ò, Tiziano Dalla Mora, Kirsten Engelund Thomsen, Simone Ferrari, David Grisaleña Rodríguez, Bernhard Gugg, Juan Maria Hidalgo-Betanzos, Erik Johansson, Aurora Monge-Barrio, Fabio Peron, Piercarlo Romagnoni, Jørgen Rose, Jorge San Miguel-Bellod, Ana Sánchez-Ostiz, Inge Strassl, Lorenzo Teso, David Venus, Federica Zagarella
Editor(s): Manuela Almeida
Publisher: University of Minho
Fifteen success stories from seven European countries have been collected within the framework of IEA EBC Annex 75 (available online in an interactive map: https://annex75.iea-ebc.org/success-stories). These success stories are exemplary interventions (mainly publicly owned, which largely condition the results of this report) involving district-based solutions for renewable energy use and energy efficiency measures. The scope of the renovation varies from one success story to another, and, in some cases, it was limited to measures either on the energy systems or on the thermal building envelope. It is documented to what extent the combination of energy efficiency measures on the building envelopes and renewable energy systems has been considered in the selected cases investigated and to what extent grid-based solutions were considered advantageous concerning individual heating or cooling solutions in the district. A special emphasis on the decision-making process as well as on challenges and lessons learned regarding their implementation is made.
ISBN: 978-989-35039-7-3
Document Number: C1
The District as Action Level for Building Renovation Combining Energy Efficiency & Renewables - A Short Guide for Investors and Decision-Makers (PDF 0.47MB)
May 2023
Author(s): Hauke Meyer, Maximilian Pechstein, Manuela Almeida, Anita Tan De Domenico, Roman Bolliger, Bernhard Gugg, Uta Lynar, Harald Taxt Walnum, Jørgen Rose, Erwin Mlecnik, Thaleia Konstantinou
Editor(s): Manuela Almeida
Publisher: University of Minho
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.
ISBN: 978-989-35039-2-8
Document Number: D3b
The District as Action Level for Building Renovation Combining Energy Efficiency & Renewables - A Short Guide for Policymakers (PDF 0.4MB)
May 2023
Author(s): Hauke Meyer, Maximilian Pechstein, Manuela Almeida, Anita Tan De Domenico, Roman Bolliger, Bernhard Gugg, Uta Lynar, Harald Taxt Walnum, Jørgen Rose, Erwin Mlecnik, Thaleia Konstantinou
Editor(s): Manuela Almeida
Publisher: University of Minho
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 policymakers only.
ISBN: 978-989-35039-2-8
Document Number: D3a
The District as Action Level for Building Renovation Combining Energy Efficiency & Renewables: Making use of the Potentials – A Guide for Policy and Decision-Makers (PDF 0.95MB)
May 2023
Author(s): Hauke Meyer, Maximilian Pechstein, Manuela Almeida, Anita Tan De Domenico, Roman Bolliger, Bernhard Gugg, Uta Lynar, Harald Taxt Walnum, Jørgen Rose, Erwin Mlecnik, Thaleia Konstantinou
Editor(s): Manuela Almeida
Publisher: University of Minho
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.
ISBN: 978-989-35039-2-8
Document Number: D3
Barriers and drivers for energy efficient renovation at district level (PDF 1.23MB)
May 2023
Author(s): Erik Johansson, Henrik Davidsson, Erwin Mlecnik, Thaleia Konstantinou, Hauke Meyer, Juan Maria Hidalgo-Betanzos, Roman Bolliger, Silvia Domingo Irigoyen, Matthias Haase, Bernhard Gugg, Manuela Almeida, Anita Tan De Domenico
Editor(s): Manuela Almeida
Publisher: University of Minho
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.
ISBN: 978-989-35039-5-9
Document Number: C3
Cost-effective building renovation strategies at the district level combining energy efficiency & renewables – investigation based on parametric calculations with generic districts (PDF 5.64MB)
May 2023
Author(s): Toivo Säwén, Johnny Kronvall, David Venus, Jørgen Rose, Kirsten Engelund Thomsen, Ole Balslev Olesen, Tiziano Dalla Mora, Piercarlo Romagnoni, Lorenzo Teso, Teresa Blázquez, Simone Ferrari, Federica Zagarella, Manuela Almeida, Anita Tan De Domenico, Juan Maria Hidalgo, Raúl Briones Llorente, Henrik Davidsson, Erik Johansson, Roman Bolliger, Silvia Domingo Irigoyen
Editor(s): Manuela Almeida
Publisher: University of Minho
This report aims to study cost-effective strategies to combine energy efficiency measures and renewable energy use in building renovation at the district level and to investigate factors influencing the choice of a cost-effective strategy. This is done through generic district assessments, where hypothetical, “generic” districts are generated to model typical conditions in various European countries.
For the generic districts, relevant variables were defined to carry out parametric assessments, applying and testing the methodology developed in IEA EBC Annex 75. The generic districts were generated and selected based on the typical conditions in each country, and the hypothetical nature of the assessment allowed for studying different starting conditions and renovation measures. It is, in particular, investigated to what extent there are synergies and trade-offs for combining energy efficiency measures and renewable energy measures.
ISBN: 978-989-33-4464-4
Document Number: B3
Methodology for investigating cost-effective building renovation at district level combining energy efficiency & renewables (PDF 1.09MB)
May 2023
Author(s): Roman Bolliger, Jon Terés-Zubiaga, Manuela Almeida, Ricardo Barbosa, Henrik Davidsson, Kirsten Engelund Thomsen, Silvia Domingo Irigoyen, Simone Ferrari, Erik Johansson, Thaleia Konstantinou, Roland Limacher, Tomas Matuska, Erwin Mlecnik, Ove Christen Mørck, Walter Ott, Piercarlo Romagnoni, Jørgen Rose, Toivo Säwén, Harald Taxt Walnum, David Venus, Zeno Winkels
Editor(s): Manuela Almeida
Publisher: University of Minho
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.
ISBN: 978-989-35039-6-6
Document Number: B1
Overview of available and emerging technology for cost-effective building renovation at district level combining energy efficiency & renewables (PDF 4.66MB)
April 2023
Author(s): Ove C. Mørck, Jørgen Rose, Kirsten Engelund Thomsen, Tomáš Matuška, Sergio Vega Sánchez, David Venus, Fabio Peron, Piercarlo Romagnoni, Erwin Mlecnik, Harald Walnum, Manuela Almeida, Ricardo Barbosa, Juan Maria Hidalgo, Jon Terés Zubiaga, Erik Johansson, Henrik Davidsson, Roman Bolliger, Silvia Domingo-Irigoyen, Uta Lynar, Hauke Meyer
Editor(s): Manuela Almeida
Publisher: University of Minho
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.
ISBN: 978-989-35039-4-2
Document Number: A1 - 2nd edition
Business Models for cost-effective building renovation at district level combining energy efficiency & renewables (PDF 3.19MB)
April 2023
Author(s): Thaleia Konstantinou, Matthias Haase, Juan Maria Hidalgo-Betanzos, Emilia Motoasca, Mira Conci, Zeno Winkels, Erwin Mlecnik, Hauke Meyer, Erik Johansson
Editor(s): Manuela Almeida
Publisher: University of Minho
The present report aims to identify the key characteristics of business models important for upscaling business from the building to the district level. Understanding those characteristics and gaining insights about the opportunities the BMs offer for the different stakeholders will support the implementation of the renovation and the stakeholder dialogue. The methods implemented in the study included desk research and quantitative analysis of semi-structured interviews.
ISBN: 978-989-35039-3-5
Document Number: D2
Investigation of cost-effective building renovation strategies at the district level combining energy efficiency & renewables – a case studies-based assessment (PDF 9.72MB)
April 2023
Author(s): David Venus, Piercarlo Romagnoni, Tiziano Dalla Mora, Lorenzo Teso, Manuela Almeida, Anita Tan De Domenico, Álvaro Campos Celador, Jon Terés Zubiaga, Juan Maria Hidalgo-Betanzos, Henrik Davidsson, Erik Johansson, Roman Bollinger, Silvia Domingo-Irigoyen, Clint Christen, Harald Taxt Walnum, Paula van den Brom
Editor(s): Manuela Almeida
Publisher: University of Minho
This report aims to show, in selected case studies, the application of cost-effective strategies to combine energy efficiency measures and renewable energy use in building renovation at the district level, investigate factors influencing the choice of a cost-effective strategy, and gather related best-practice examples.
For selected case studies, the necessary data was gathered to carry out parametric assessments, applying and testing the methodology developed in IEA EBC Annex 75. It was intended to select, as case studies, existing urban districts in need of renovation where the results of the analysis of these case studies could guide the choice of an adequate renovation strategy for the respective district. It is investigated to what extent there are synergies and trade-offs for combining energy efficiency measures and renewable energy measures. It is envisaged to determine cost-effective renovation strategies for the investigated districts considering both energy efficiency and renewable energy measures.
ISBN: 978-989-33-4463-7
Document Number: C2
Annex 75 Calculation Tool - A75CT
April 2023
Author(s): Toivo Säwén
The Annex 75 Calculation Tool was developed as part of the IEA EBC Annex 75 project entitled ”Cost-effective
Building Renovation at District Level Combining Energy Efficiency & Renewables” with the purpose of conceptualising a calculation framework to optimise the cost and environmental impact of building renovation measures and district energy supply systems.

Access to the online tool: https://annex75.bim.energy
Document Number: B2
- Full Report (PDF 0.81MB)
Policy instruments for cost-effective building renovation at district level combining energy efficiency & renewables (PDF 1.86MB)
April 2023
Author(s): Erwin Mlecnik, Juan Maria Hidalgo-Betanzos, Hauke Meyer, Uta Lynar, Thaleia Konstantinou, Frits Meijer, Roman Bolliger, Matthias Haase, Erik Johansson, Henrik Davidsson, Jan Peters-Anders, Bernhard Gugg, Manuela Almeida, Anita Tan De Domenico
Editor(s): Manuela Almeida
Publisher: University of Minho
IEA EBC Annex 75 focuses on promoting cost-effective building renovation at the district level combining energy efficiency and renewable energy systems. The present report intends to explore suitable policy instruments that can support the development of building renovation at the district level, targeting various types of stakeholders.

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.
ISBN: 978-989-35039-1-1
Document Number: D1
Good practices and lessons learned to transform existing districts into low-energy and low-emission districts (PDF 0.89MB)
April 2023
Author(s): David Venus, Silvia Domingo-Irigoyen, Toivo Säwén, Johnny Kronvall, Henrik Davidsson, Erik Johansson
Editor(s): Manuela Almeida
Publisher: University of Minho
The objective of this report is to illustrate, in selected case studies, cost-effective strategies combining energy efficiency measures and renewable energy use in building renovation at the district level, investigate factors that influence the choice of these strategies and gather related best-practice examples (the so-called "successful stories").
ISBN: 978-989-35039-9-7
Document Number: C4
Strategies to transform existing districts into low-energy and low-emission districts (PDF 0.96MB)
April 2023
Author(s): Harald Taxt Walnum, David Venus, Jørgen Rose, Kirsten Engelund Thomsen, Tiziano Dalla Mora, Piercarlo Romagnoni, Lorenzo Teso, Manuela Almeida, Anita Tan De Domenico, Henrik Davidsson, Erik Johansson, Roman Bollinger, Paula van den Brom
Editor(s): Manuela Almeida
Publisher: University of Minho
This report aims to describe various strategies 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. The strategies build on the outputs of other work packages and subtasks associated with this Annex, namely the case study assessments of case studies and the generic district analyses.
ISBN: 978-989-35039-0-4
Document Number: B4
Definitions and Common Terminology on cost-effective building renovation at district level combining energy efficiency & renewables (PDF 0.38MB)
April 2023
Author(s): Juan Maria Hidalgo-Betanzos, Erwin Mlecnik, Thaleia Konstantinou, Hauke Meyer, Roman Bolliger, Manuela Almeida, Anita Tan De Domenico, Harald Walnum
Editor(s): Manuela Almeida
Publisher: University of Minho
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 publications.
ISBN: 978-989-35039-8-0
Tecnology Overview Report (PDF 8.56MB)
May 2020
Author(s): Ove C. Mørck, Jørgen Rose, Kirsten Engelund Thomsen, Tomas Matuska, Sergio Vega Sanchez
This report is the first of the deliverables from the IEA Annex 75 project. It documents the work of Subtask A – Technology Overview. As the title of the subtask indicates, the idea of this subtask was to create an overview of the available technologies for energy renovation and renewable energy supply at the district level.

The technical and economic characteristics of the technology options are also determined. This includes in particular information on their efficiency, cost elements such as investment costs and operational costs taking into account economies of scale. 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.

Success Stories

Success Story in Switzerland - Weggis (PDF 1.21MB)
December 2020
The document reports detailed information of a Sucess Story in Switzerland concerning neighbourhood renovation in Weggis
Success Story in Sweden - Hagalund (PDF 0.72MB)
December 2020
The document reports detailed information of a Sucess Story in Sweden, concerning neighbourhood renovation in Hagalund
Success Story in Portugal - Vila D´Este (PDF 5.5MB)
May 2020
The document reports detailed information of a Sucess Story in Portugal, concerning neighbourhood renovation in Vila Nova de Gaia.
Success Story in Portugal - Rainha Dona Leonor (PDF 5.43MB)
May 2020
The document reports detailed information of a Sucess Story in Portugal, concerning neighbourhood renovation in Porto.
Success Story in Portugal - Boavista (PDF 8.01MB)
May 2020
The document reports detailed information of a Sucess Story in Portugal, concerning neighbourhood renovation in Lisboa.
Success Story in Spain - Vitoria-Gasteiz (PDF 1.34MB)
March 2020
The document reports detailed information of a Success Story in Spain, concerning district renovation in Vitoria-Gasteiz
Success Story in Spain - Tudela (PDF 0.48MB)
February 2020
The document reports detailed information of a Sucess Story in Spain, concerning district renovation in Tudela.
Success Story in Italy - Valdastico (PDF 0.55MB)
February 2020
The document reports detailed information of a Sucess Story in Italy, concerning district renovation in Valdastico.
Success Story in Italy- Venice Campus (PDF 0.62MB)
February 2020
The document reports detailed information of a Sucess Story in Italy, concerning district renovation in the Venice IUAV Campu
Success Story in Italy - Sangallo (PDF 1.05MB)
February 2020
The document reports detailed information of a Sucess Story in Italy, concerning district renovation in Sangallo.
Success Story in Italy - Turin (PDF 0.47MB)
February 2020
The document reports detailed information of a Sucess Story in Italy, concerning district renovation in Turin.
Success Story in Austria - Strubergrasse (PDF 0.8MB)
February 2020
The document reports detailed information of a Sucess Story in Austria, concerning district renovation in Strubergrasse.
Success Story in Italy - Modena (PDF 0.69MB)
February 2020
The document reports detailed information of a Sucess Story in Italy, concerning district renovation in Modena.
Success Story in Denmark - Aalborg (PDF 1.02MB)
February 2020
The document reports detailed information of a Sucess Story in Denmark, concerning district renovation in Aalborg
Success Story in Sweden - Lund (PDF 1.27MB)
May 2019
The document reports detailed information of a Sucess Story in Sweden, concerning district renovation in Lund.
- (PDF 1.27MB)

Articles

Streamlining Building Energy Modelling Using Open Access Databases—A Methodology towards Decarbonisation of Residential Buildings in Sweden
February 2023
Author(s): Rafael Campamà Pizarro, Ricardo Bernardo and Maria Wall
Publisher: Sustainability 2023, 15(5), 3887, MDPI
The building sector is a major contributor to greenhouse gases, consuming significant energy and available resources. Energy renovation of buildings is an effective strategy for decarbonisation, as it lowers operational energy and avoids the embodied impact of new constructions. To be successful, the energy renovation process requires meaningful building models. However, the time and costs associated with obtaining accurate data on existing buildings make large-scale evaluations unrealistic. This study proposes a methodology to streamline building energy models from open-access datasets for urban scalability. The methodology was tested on six case study buildings representing different typologies of the Swedish post-war construction period. The most promising results were obtained by coupling OpenStreetMap-sourced footprints with energy performance declarations and segmented archetypes for building characterisation. These significantly reduced simulation time while retaining similar accuracy. The suggested methodology streamlines building energy modelling with a promising degree of automation and without the need for input from the user. The study concludes that municipalities and building owners could use a such methodology to develop roadmaps for cities to achieve carbon neutrality and evaluate energy renovation solutions. Future work includes achieving higher accuracy of the generated energy models through calibration, performing renovation analysis, and upscaling from individual buildings to neighbourhoods.
- Full Report (PDF 7.56MB)
The Balance between Energy Efficiency and Renewable Energy for District Renovations in Denmark
October 2022
Author(s): Jørgen Rose, Kirsten Engelund Thomsen and Ole Balslev-Olesen
Publisher: Sustainability 2022, 14(20), 13605, MDPI
Emissions can be reduced by increasing the energy efficiency of buildings and supply systems or increasing the share of renewable energy in the energy system. Denmark has a long tradition for district heating and today it supplies more than 65% of dwellings, which indicates that a major part of the transition from fossil fuels to renewables can be achieved at the supply system level rather than on the individual building level. This paper presents calculations performed on a generic Danish district undergoing major renovation. The generic district is based on an existing district in Aalborg and consists of 1019 dwellings spread over three different building typologies. The purpose of the investigation was to determine which combination of energy saving measures would achieve the optimal level of energy efficiency. Calculations were made with average data for district heating in Denmark, district heating based on natural gas, and district heating from renewable energy sources, such as solar heating, biofuels, and heat pumps, respectively. The calculations include costs for investment, maintenance, and operating as a function of the primary energy needs. Global warming potential (GWP) was calculated and included CO2 emissions from space heating, domestic hot water, and electricity for operation and household. The calculations show that for the generic Danish district, which is already connected to a district heating network, the optimal solution is to add 200 mm insulation to roofs (in total 300 mm) and 150 mm insulation to walls (in total 200 mm) and replacing the existing windows with new three-layer low energy windows. Furthermore, the calculations show that in a future scenario with a significantly higher level of renewable energy in the energy system, a shift to individual heat pumps can reduce total emissions by up to 1.5 kg CO2 eq/m2 per year (20% reduction) at an additional cost of EUR 8.0/m2 per year (40% increase). The calculations described in this paper are part of a larger investigation carried out in IEA EBC Annex 75.
- Full Report (PDF 2.79MB)
Renovation of near 20% of existing building stock to zero-carbon-ready by 2030 is ambitious but necessary
Part of Technology and innovation pathways for zero-carbon-ready buildings by 2030
September 2022
Author(s): Manuela Almeida, Anita Tan De Domenico, Takao Sawachi
Publisher: Internation Energy Agency (IEA)
Renovating the existing building stock to a zero-carbon-ready level is a key priority for achieving the sector's decarbonisation targets for 2030 and 2050. However, the retrofitting of buildings is a significant challenge since at least 40% of buildings floor area in developed economies was built before 1980, when the first thermal regulations came into force. Retrofitting 20% of the existing building stock to a zero-carbon-ready level by 2030 is an ambitious but necessary milestone toward the Net Zero Emissions by 2050 Scenario (NZE Scenario). To achieve this goal, an annual deep renovation rate of over 2% is needed from now to 2030 and beyond.
Taking advantage of new technology opportunities and construction practices, cost-effective renovation solutions that combine energy efficiency and renewable sources are being explored at the building, and cluster and district levels. In addition to meeting climate resilience, building energy renovation is increasingly relevant to ease energy security concerns and as a means to create jobs. However, for this to happen swiftly and effectively, a strong political will is required, and policy, legal, regulatory, and administrative support frameworks need to be developed.
Renovating Building Groups in the Mediterranean Climate: Cost-Effectiveness of Renewable-Based Heating Alternatives in the Italian Context
September 2022
Author(s): Teresa Blázquez, Tiziano Dalla Mora, Simone Ferrari, Piercarlo Romagnoni, Lorenzo Teso and Federica Zagarella
Publisher: Sustainability 2022, 14(19), 12303, MDPI
District level approaches for the renovation of the building stock boost the implementation of energy efficiency measures (EEMs), taking advantage of the economies of scale. International Energy Agency Annex 75 aims to assess the cost-effectiveness of renovation strategies at the district level, combining EEMs and renewable energy sources. For this goal, a building energy model is simulated with the Energy Plus dynamic calculation engine for assessing the generic district of the Italian case study, representing the residential stock from 1960 to 1980, placed in two prevailing space-heating dominated climates; then, a cost-effectiveness evaluation of each scenario is conducted to support stakeholders’ decision making. In particular, envelope insulation is cost-effective only in northern zones, while new decentralized thermal systems are not convenient in any case with current envelopes. Once the envelopes are insulated, decentralized low-temperature air-to-water heat pumps with PV can cover all of the buildings’ energy needs, even implying a small increase in annual costs. The switch to district net scenarios is cost-effective only if coupled with PV. A rise in energy prices brings PV-based strategies under a 10-year PBT, except for solar thermal DH in northern areas, as well as non-PV-based options such as low-temperature HPs or biomass-fuelled DH in warmer and colder zones, respectively.
- Full Report (PDF 3.93MB)
Chances for the upscaling of living-cost neutral renovations in the Netherlands
2022
Author(s): Erwin Mlecnik
Publisher: IOP Conference Series: Earth and Environmental Science, Volume 1085, SBE22Delft - Innovations for the Urban Energy Transition: Preparing for the European Renovation Wave 11/10/2022-13/10/2022 Delft, Netherlands
Many multi-owned condominiums need an energy renovation, but in practice the number of such renovations is low. Dutch policy emphasizes the need to search for cost-neutral renovation solutions. This study therefore examined how the number of living-cost neutral renovations of buildings owned by assemblies of homeowners in the Netherlands can be increased by means of an integrated unburdening offer that includes energy performance guarantees and supply chain integration. The study uses scientific literature, project experiences and in-depth interviews with experts to examine how policy, demand and supply currently play a role in the upscaling of living-cost neutral renovations. The study finds that customized guidance is needed for condominium associations to steer their maintenance decision processes towards deep renovations. Also chances are detected to link living cost neutrality with energy neutrality, while developing an integrated supply chain that takes into account full process guidance including the provision of performance guarantees. This is now already successfully implemented in a new non-profit service desk and a new process model will be tested in multiple regions.
- Full Report (PDF 0.97MB)
Policy instruments for energy-efficient renovations at district level
2022
Author(s): Erwin Mlecnik and Juan Maria Hidalgo-Betanzos
Publisher: IOP Conference Series: Earth and Environmental Science, Volume 1085, SBE22Delft - Innovations for the Urban Energy Transition: Preparing for the European Renovation Wave 11/10/2022-13/10/2022 Delft, Netherlands
IEA EBC Annex 75 aims to investigate, amongst other policy for reducing carbon emissions and energy use in buildings at district level, combining both energy efficiency measures and renewable energy measures. Particularly policy instruments deployed at the local level targeting owners and investors could increase residential building renovation and renewable energy systems to a district scale. A desk and empirical research using 38 expert interviews from 8 European countries was used to investigate the use and development of various types of policy instruments, including regulations, incentives, communication and facilitating instruments. The research confirms interest of frontrunners to use or develop specific policy instruments further, such as enforcement of energy standards and inspections, financial incentives for district stakeholders and for groups of homeowners, renovation services and energy desks, digital communication and network meetings in districts. It also finds that low relative advantage for some stakeholders, lack of good examples, an incompatible legal or national framework and high complexity are serious risks that can further hinder adoption of energy efficiency and renewable energy systems in districts. Renovations at district scale including energy efficiency and renewable energy can benefit from adapted or improved regulations, incentives, communication and facilitation to better support renovations at district scale including energy efficiency and renewable energy systems.
- Full Report (PDF 0.84MB)
Comparative Analysis between Dynamic and Quasi-Steady-State Methods at an Urban Scale on a Social-Housing District in Venice
August 2021
Author(s): Tiziano Dalla Mora, Lorenzo Teso, Laura Carnieletto, Angelo Zarrella, Piercarlo Romagnoni
Publisher: Energies 2021, 14(16), 5164, MDPI
The residential building stock represents one of the major players in energy use and greenhouse gas emissions; thus, it is fundamental to reduce the energy used. Simulation tools are becoming more and more accurate in compliance with the new requirements both at the single-building and at the district scale, although they are not affordable by non-specialist users such as policymakers. The research concerns the evaluation of the energy demand for space heating for a historical district that is representative of the Italian building stock. The work compares dynamic and specialist-oriented urban scale tools such as Energy Urban Resistance Capacitance Approach (EUReCA) and City Energy Analyst (CEA)) as well as a quasi-steady-state calculation method (Excel spreadsheet), which is more affordable for non-specialist users. The work was carried out to assess the possible deviation of the results between the dynamic and quasi-steady-state calculation methods, as well as to identify any limits and opportunities in the application of the latter procedure, which is currently the official national calculation tool for the implementation of Directive 2010/31/EU. The study shows how the quasi-steady-state method predicts a reliable building energy demand, in line with the results obtained by the two dynamic tools, when considering only geometry and infiltrations as input. However, the limits of the quasi-steady-state method emerge when introducing internal loads, significantly underestimating the energy demand compared to CEA and EUReCA simulations. The results underline the potential application of the quasi-steady-state method to predict energy demand, although dynamics tools are more reliable but far more complex. Major findings through two methods concern the impact of solar heat gains on the overall heating demand at both the single building and the district scale. The different results between the tools provided evidence of a gap in the use of the simplest tool and demonstrated the accuracy and reliability of the proposed approach with a lower computational effort.
- Full Report (PNG 0.19MB)
WNR: Kansen voor de opschaling van Woonlasten-Neutraal Renoveren in Nederland
July 2021
Author(s): Erwin Mlecnik
Publisher: Delft University of Technology
Een groot bestand van gebouwen in Nederland is in eigendom van Verenigingen van Eigenaren (VvE’s) en is toe aan renovatie en energetische verduurzaming. Het aantal grondige renovaties van dergelijke gebouwen is in de praktijk nog laag, mede door een trage ontwikkeling van het Nederlands renovatiebeleid, een gebrek aan motivatie van bewoners om te investeren in verduurzaming, en de trage opbouw van een integrale bouwketen die is afgestemd op deze doelgroep.
Deze studie onderzocht daarom hoe woonlasten-neutrale renovaties van gebouwen in eigendom van VvE’s in Nederland kunnen worden opgeschaald d.m.v. een integraal ontlastend aanbod m.i.v. energieprestatiegarantie en ketenintegratie. De studie maakt gebruik van wetenschappelijke literatuur, projectervaringen en diepte-interviews met koplopers in deze sector om te onderzoeken hoe het beleid, de vraag en de markt momenteel een rol spelen bij de opschaling van woonlasten-neutrale renovaties.
De studie vindt kansen om woonlasten-neutraliteit te koppelen met energie-neutraliteit, een ontlastend aanbod, publiek-private partnerschappen, prestatiecontracten, vraagbundeling en ketenintegratie. In het bijzonder bieden sociaal gestuurde beslissingsprocessen ook nieuwe kansen om bewoners te overtuigen. Het opschalen van deze processen vergt garanties voor de procesbegeleiders en wettelijke aanpassingen voor de soms nog onbestaande of gebrekkig functionerende VvE-besturen.
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Building renovation at district level – Lessons learned from international case studies
May 2021
Author(s): Jørgen Rose, Kirsten Engelund Thomsen, Silvia Domingo-Irigoyen, Roman Bolliger, David Venus, Thaleia Konstantinou, Erwin Mlecnik, Manuela Almeida, Ricardo Barbosa, Jon Terés-Zubiaga, Erik Johansson, Henrik Davidsson, Mira Conci, Tiziano Dalla Mora, Simone Ferrari, Federica Zagarella, Ana Sanchez Ostiz, Jorge San Miguel-Bellod, Aurora Monge-Barrio, Juan Maria Hidalgo-Betanzos
Publisher: Sustainable Cities and Society Volume 72, September 2021, 103037, Elsevier
Cost-effective building renovation at district level combining energy efficiency & renewables
Methodology assessment proposed in IEA-Annex 75 and a demonstration case study
October 2020
Author(s): Jon Terés-Zubiaga, Roman Bolliger, Manuela G. Almeida, Ricardo Barbosa, Jørgen Rose, Kirsten E. Thomsen, Eduardo Montero, Raúl Briones-Llorente
Publisher: Energy and Buildings Volume 224, 1 October 2020, 110280, Elsevier
Building renovation plays a key role in reducing greenhouse gas emissions and achieving the climate pro-tection goals. The district scale approach is one of the most effective approaches to accelerate this processof reducing the energy consumption in the building sector as increasing its renovation rates. In this con-text, the Energy in Buildings and Communities Programme of the IEA, IEA-EBC started in 2017 the project‘‘Annex 75: Cost-Effective Building renovation at District Level Combining Energy Efficiency andRenewables” aiming to explore optimal opportunities of district renovations from a cost-benefit perspec-tive. IEA Annex 75 is a co-operative effort of participants from 13 different countries: Austria, Belgium,China, Czech Republic, Denmark, Germany, Italy, The Netherlands, Norway, Portugal, Spain, Swedenand Switzerland. In this paper, key elements of the methodology developed in Annex 75 project are pre-sented. This methodology aims to facilitate the identification of optimal solutions in different Europeancountries, enabling to explore similarities and differences amongst them, with a particular focus on thebalance between energy efficiency measures and renewable energy measures. After a detailed descrip-tion of the developed methodology, it is also applied to a case study located in Portugal and resultsobtained are analysed in detail. The paper demonstrates the usefulness of the methodology for evaluatingand identifying optimal solutions in renovations at district scale, as well as for successfully addressing theresearch questions investigated by the Annex 75 project. They also provide some insights regarding thespecific case study, showing that, although district systems are not usual in the current Portuguese con-text, these centralised solutions in renovations at district level are cost-effective interventions that canlead to significant reductions of greenhouse gas emissions and non-renewable primary energy use.
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O potencial das intervenções de renovação a nível urbano para edifícios nZEB (PDF 0.5MB)
Portuguese national journal article
Author(s): Manuela Almeida and Ricardo Barbosa
Publisher: Edifícios e Energia

Newsletters

Annex 75 Newsletter - September 2021
September 2021
Annex 75 Newsletter - December 2020
December 2020
Annex 75 Newsletter - March 2020
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Annex 75 Newsletter - July 2019
Annex 75 Newsletter - November 2018
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Conference Papers

Experiences from Local Authorities Stimulating the Adoption of Low-Carbon Technologies by Homeowners
2022
Author(s): Erwin Mlecnik
Publisher: EuroSun2022 conference, 25-29/09/2022, Kassel, Germany
To meet carbon reduction goals, local authorities aim to achieve a market acceleration for owner-occupied single-family home renovations by increasing awareness of – and enabling access to – low-carbon technologies for homeowners in target areas. In this framework, this research summarizes and examines project experiences of seven local authorities in Belgium, France, The Netherlands and the UK in the period 2017-2021. These cover the use of different models of demo exemplars and pop-up consultancy centres in target areas, web module developments and the use of Home Energy Monitoring Systems by local authorities. The results show that local authorities can benefit from using an innovation adoption model to develop an integrated mix to support homeowners throughout their whole renovation journey. Depending on their context, local authorities can focus on specific customer segments and target areas to support adopting new technologies, renovation measures at district level, deep renovation, phased retrofits and any combinations thereof. Physical and digital communication can be tailored to (pop-ups in) specific target areas, customer segments and local actors. Local authorities can work more closely together with intermediaries, also to achieve more renovations, group buying actions, specific energy coaching for groups of homeowners and Integrated Home Renovation Services.
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Cost optimal investment in energy efficiency measures and energy supply system in a neighbourhood in Norway
March 2021
Author(s): Harald Taxt Walnum, Marius Bagle, Åse Lekang Sørensen and Selamawit Mamo Fufa
Publisher: E3S Web of Conferences, Volume 246, 2021, Cold Climate HVAC & Energy 2021
Building renovation is a key measure to reduce energy consumption and Greenhouse gas (GHG) emissions, and ease the transition to a fully renewable energy system. This paper applies the IEA EBC Annex 75 methodology for investigating the cost optimal and environmental trade-off between investment in energy efficiency measures on the building envelope and energy supply, on a residential neighbourhood in Norway. Combination of different energy efficiency measures and energy supply systems are investigated with an optimal investment model. The cost and environmental impact of the combinations are evaluated. An important outcome is that within the evaluated combinations, the choice of energy supply system has little impact on the cost effectiveness of the energy efficiency measures. However, it has a significant impact on the GHG emissions. The results also highlight the importance of performing energy efficiency measures in coordination with other renovating measures, both regarding cost effectiveness and environmental impact. The results will not give a finite answer to what is the best solution but serves at a useful set of inputs for overall evaluations.
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Neighbourhood consultancy centres for the adoption of low-carbon technologies by homeowners: experiences from Dutch initiatives (PDF 0.48MB)
March 2021
Author(s): Erwin Mlecnik,Oubbol Oung, Ariane Lelieveld, Marianne de Snoo, Coen Vos
Frontrunner local authorities aim to achieve a market acceleration in the owner-occupied single-family home renovation sector by increasing awareness of – and enabling access to – low-carbon technologies in residential target areas. With their easy availability, adaptability, and possible mobility, pop-up consultancy desks can provide local outreach in target areas for achieving home renovation measures.
This research looks into the adoption, use and effectiveness of fixed or mobile energy consultancy desks in target areas organized by local authorities. Local authority initiatives are described, compared and evaluated regarding various parameters. For two local authorities in the Netherlands, Rotterdam and Breda, pop-up initiatives are elaborated upon, examining the number of visitors, needed resources and experienced barriers and opportunities.
The results show that both longer-term fixed and short-term mobile consultancy pop-ups can be suitable for providing energy awareness and consultancy in target areas, and for stimulating the local adoption of low carbon technologies. The results clarify pros and cons of both approaches and the elements of business models that can be used by other local authorities.
Recommendations for business models for self-supporting consultancy in target areas and guidelines for local authorities are planned. For sustaining the pop-ups, collaboration is recommended with other partners.
Business models for Energy Master Planning of communities and districts
January 2021
Author(s): Matthias Haase
Publisher: 11th International Conference on Improving Energy Efficiency in Commercial Buildings and Smart Communities (IEECB&SC’20), Online, 1-2 December 2020. Conference Organizer: European Commission, DG JRC
In the introduction, Energy Master Planning (EMP) in the context of spatial and urban planning is discussed. This includes spatial planning and the EMP process and the stakeholders involved, how to shape good framework conditions for the energy master planning, practical experience from spatial and Energy Master Planning, decision making in EMP, soft and hard constraints for the EMP, integrating constraints into EMP and in the Design phase.
Then, possibilities for an evaluation of cost-effectiveness of community projects is given. A short introduction to economic decision-making criteria with focus on Life-Cycle Cost calculation (LCC) for EMP, multiple benefits (bankable LCC on the building level), bankability and risk mitigation of multiple benefits, and cost-effectiveness. Investment costs and capital expenditures are discussed followed by a determination of technical concept and investment costs is given. This is based on gathering of accurate investment costs, developing detailed energy demand and supply scenario by simulation and specific risks in the calculation of investment costs which can be used for an optimization of investment cost.
Finally, issues like energy savings, avoided maintenance and repair costs, operation cost reduction, insurance costs, building comfort and Green Neighborhood Value are discussed. This leads to risks and De-Risking methods and tools (with a discussion of the structure and several lines of defence and the introduction of Key Risk Factors (KRF) and Key Risk Indicators (KRI) in general and in EMP for building clusters in particular.
The presentation ends with a brief description of de-risking measures in the EMP process and resulting business models, with an introduction of required services for EMP and their allocation in two practical experiences with business models.
Potential of building renovation at district level for reducing CO2 emissions and fostering urban regeneration. IEA-EBC Annex 75 (PDF 0.56MB)
October 2019
Author(s): Jon Terés-Zubiaga, Manuela G. Almeida , Ove Mørck, Roman Bolliger, David Venus
Publisher: Proceedings of 10th EUROPEAN CONFERENCE ON ENERGY EFFICIENCY AND SUSTAINABILITY IN ARCHITECTURE AND PLANNING, VITORIA-GASTEIZ, 2019
La edificación es uno de los principales sectores con mayores emisiones de CO2 en Europa. Así, uno de los objetivos principales en los edificios existentes es la reducción del consumo energético (y emisiones asociadas) de una forma coste-efectiva, siendo el principal reto (especialmente en ciudades) la transformación de dichos edificios en edificios de bajo consumo y bajas emisiones. Al mismo tiempo, existen oportunidades de desarrollar y aprovechar el potencial de soluciones a escala de barrio para acelerar la consecución de dicho objetivo. En este contexto, el Proyecto de la Agencia Internacional de la Energía Annex 75 (“Cost-effective Building Renovation at District Level Combining Energy Efficiency & Renewables”), iniciado en 2017 y que se prolongará hasta el año 2021, y en el que participan 25 entidades de 13 países diferentes, tiene por objetivo desarrollar diversos enfoques y metodologías dirigidas a identificar soluciones coste-efectivas que combinen tanto la implementación de medidas de eficiencia energética como el suministro de energía desde fuentes renovables a escala de distrito. La primera sub-tarea, “Revisión de las tecnologías existentes y emergentes” compuesta por 4 paquetes de trabajo, tiene por objetivo realizar un análisis exhaustivo de las distintas opciones tecnológicas disponibles dirigidas a la rehabilitación de la envolvente del edificio y a la sustitución de los sistemas energéticos (para calor, refrigeración y ACS) en sistemas suministrados por fuentes renovables a escala de distrito. La segunda sub-tarea, “Metodología de optimización”, compuesta a su vez de otros 4 paquetes de trabajo, se centra en el desarrollo de una metodología para definir e identificar estrategias coste-efectivas para la renovación de distritos con objetivos de superar los objetivos de reducción de gases de efecto invernadero y consumo energético. Esta sub-tarea tomará como referencia el trabajo desarrollado en el Annex 56, donde se desarrollaba una metodología similar dirigida en ese caso a edificios individuales. La sub-tarea C, “Casos de estudio”, tiene por objetivo mostrar y evaluar las estrategias coste-efectivas de combinación de renovables con medidas de eficiencia energética en grupos de edificios, investigar factores que afectan a la elección de una determinada estrategia y recoger ejemplos de buenas prácticas. Para ello se vale de una selección de casos de estudio ubicados en distintos países europeos. Finalmente, la sub-tarea 4 “Instrumentos políticos, diálogo entre los distintos agentes y diseminación”, tiene por objetivo identificar cómo desde los distintos agentes se puede promover y fomentar las combinaciones coste-efectivas de medidas de eficiencia e implementación de energías renovables a escala de distrito. Esta comunicación presentará los principales avances del proyecto hasta la fecha, así como los primeros resultados obtenidos, con especial atención al apartado de metodología y casos de estudio.

Fact Sheet

Factsheet: Cost-effective Building Renovation at District Level Combining Energy Efficiency & Renewables (PDF 0.83MB)
June 2023
Author(s): Annex 75
Buildings are a major source of greenhouse gas emissions and cost-effectively reducing their energy use and associated emissions is particularly challenging for the existing building stock, mainly because of the existence of many architectural and technical hurdles. The transformation of existing buildings into low-emission and low-energy buildings is particularly challenging in cities, where many buildings continue to rely too much on heat supply by fossil fuels. However, at the same time, there are specific opportunities to develop and take advantage of district-level solutions at urban scale. In this context, the project aims to clarify the cost-effectiveness of various approaches combining both energy efficiency measures and renewable energy measures at the district level. At this level, finding the balance between renewable energy measures and energy efficiency measures for the existing building stock is a complex task and many research questions still need to be answered.