When developing new energy networks, setting up appropriate and transparent cost estimation methods is essential. Using standardised reference cost values can facilitate planning and assessment processes, increase their credibility and enable consistent comparisons across the EU.
Under the TEN-E Regulation (Article 11(9)), ACER is required to establish and publish a set of indicators and corresponding reference values every three years. These are used to compare unit investment costs (UICs) of comparable energy infrastructure projects falling within the categories listed in Annex II of the Regulation.
ACER published the first set of UIC indicators for the categories set out in points (1), (2) and (3) of Annex II (electricity, smart gas grids, hydrogen, electrolysers and carbon dioxide) in 2023. These values were updated in April 2026 following a new data collection exercise, which provided more recent cost information.
UIC indicators were specifically established for electricity infrastructure and related assets, based on data provided by project promoters. The indicators provide benchmark values for the average, median and first and third quartiles of UICs, enabling structured comparisons across projects.
The indicators and their reference values can be used for various planning and evaluation processes, including:
supporting the European Network of Transmission System Operators for Electricity (ENTSO-E) and Gas (ENTSOG) in carrying out the cost-benefit analyses for their EU-wide ten-year network development plans (TYNDPs);
assessing and selecting projects of common and mutual interest (PCIs/PMIs); and
Take a look at our latest report on European energy infrastructure UICs.
Infrastructure reference costs
Looking ahead
The 2026 UIC indicators provide an important benchmark for decision-making and infrastructure planning. However, they also confirm a substantial increase in costs, leading to a potential underestimation of the indicators. Further work is needed to better capture and reflect these cost increases in future updates.
A harmonised EU-wide methodology for cost benefit analysis
The Regulation on guidelines for trans-European energy infrastructure ('TEN-E Regulation') foresees the development of a harmonised EU-wide methodology for cost benefit analysis (CBA) of projects included in the future Ten Year Network Development Plans (TYNDP), and for selecting the Projects of Common Interest (PCIs) and Projects of Mutual Interest (PMIs) at European level.
The Regulation also foresees the use of this methodology for deciding on the cost allocation of cross-border infrastructure projects (CBCA). The CBA methodology is developed and improved over time by ENTSO-E and is approved by the European Commission.
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Cost-Benefit Analysis
What's the role of ACER?
Whenever an updated CBA methodology is proposed by ENTSO-E, ACER provides an opinion on it to ENTSO-E.
Cost-Benefit Analysis
What does ACER say?
In its latest Opinion, ACER notes improvements, which include:
the assessment of hybrid offshore projects (i.e. grid projects that serve a dual purpose, to connect offshore generation and interconnect two bidding zones);
the definition of the reference grid; and
the assessment of projects’ commissioning dates and the commissioning year of projects involving multiple investments.
However, important shortcomings are also identified, such as the need to extend the analysis of security of supply by considering future extreme weather events, to simplify the assessment of hybrid offshore projects, to foresee the identification of beneficiaries and cost bearers at national level, and the lack of concrete methodologies for the assessment of ancillary services’ benefits.
ACER urges ENTSO-E to adapt the draft CBA Guideline in line with the considerations included in its Opinion before submitting it to the European Commission for approval.
Developing new networks in Europe in order to facilitate cross-border flows requires a close coordination of several processes and actors.
A common EU-wide Cost-Benefit Analysis methodology was developed by ENTSO-E to be used for infrastructure projects assessment, and it is reviewed when needed.
Every two years, based on the scenarios on the future state of the electrical system, ENTSO-E assesses the projects included in the EU-wide Ten-Year Network Development Plan (TYNDP).
Network development
What's the role of ACER?
ACER is strongly involved in all network development aspects, assessing not only the methodologies and guidelines developed by ENTSO-E for the various elements of the TYNDP, but also how they are implemented for the project assessments in the TYNDP. The Agency also verifies the consistency of the TYNDP with national development plans and provides an overview of related infrastructure reference costs.
Network development
How can regulation incentivise efficient investments in electricity grids?
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Significant enhancement in electricity grid capacityis needed to realise Europe’s decarbonisation objectives and ensure a high level of security of supply. New grid build-out is just one way and proving to be the costliest way to do it. Despite their advantages, innovative solutions are not yet spearheading investment choices.
In the context of the European Commission’s EU Action Plan for Grids, ACER is looking at best practices to promote smart grids and network efficiency technologies through tariff design.
ACER has thus commissioned the Florence School of Regulation (FSR) to conduct a study on existing regulatory frameworks and how regulators could incentivise a more efficient use of existing and future electricity grids.
Building on the previous research conducted by FSR on behalf of ACER, the report presents a new regulatory scheme which focuses on the value projects bring (i.e. benefit) and not on their costs. By sharing this benefit between the grid user and grid operator, a stronger incentive for technology-neutral solutions is created while mitigating the tariff increase (in comparison to the business as usual, e.g. investing into infrastructure alone).
Maximising cross-zonal trading opportunities is a core element to ensure an efficient internal electricity market. It is also important for meeting a number of future challenges in Europe's energy trajectory, including the decarbonisation targets.
The Clean Energy Package offers a new opportunity to increase the capacity offered for cross-zonal trade. In particular, Transmission System Operators are required to ensure that at least 70% of the transmission capacity is offered for cross-zonal trade, while respecting operational security limits.
For more information about the 70% minimum target, read our dedicated Q&A.
Why 70% grid capacity target is needed for renewable goals
What's the role of ACER?
The minimum 70% target has become a key element of market integration, which requires intensive monitoring. To ensure a harmonised approach on how to monitor the achievement of the minimum level of available cross-zonal capacity (MACZT), ACER is monitoring the MACZT in relation to the 70% target.
The results are published yearly in dedicated reports.
Electricity transmission networks, once developed purely for national requirements, have become increasingly interconnected across Europe, creating one of the largest electricity transmission systems in the world. The system enables the operation of the Internal Energy Market (IEM), requiring coordinated actions of all Member States in terms of its development and operation.
To facilitate the integration of the IEM, individual Transmission System Operators (TSOs) cooperate under the umbrella of the European Network of Transmission System Operators for electricity (ENTSO-E) when developing new infrastructure assets.
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Infrastructure
What's the role of ACER?
ACER plays a crucial role in overseeing all aspects of network development by:
Reviewing the draft Union–wide Ten-year Network Development Plan prepared by ENTSO-E every two years, assessing its consistency with the national Ten-year Network Development Plans, and monitoring its implementation
Coordinating National Regulatory Authorities' work on establishing and making publicly available a set of indicators and reference values of unit investment costs of infrastructure projects
Supporting the selection of priority projects in Europe, by providing its views on the biennial draft regional lists of Projects of Common Interest, and by monitoring annually their implementation
Monitoring the implementation of the Inter-TSO compensation mechanism
Deciding on some cross-border issues, such as the allocation of the investment costs of projects of common interest or on granting exemptions from third party access in case NRAs fail to agree
Striving towards efficient and cost reflective network tariffs, by reviewing the appropriateness of transmission charges to be paid by generators and identifying best practices of transmission and distribution tariff methodologies
Ensuring the efficient use of congestion revenues, by approving the methodology proposed by all TSOs
Providing views on ENTSO-E's work planning and Innovation activities
ACER can issue non binding opinions and recommendations to national energy regulators, transmission system operators, and EU institutions.
ACER can also take binding individual decisions in specific cases and under certain conditions on cross-border infrastructure issues.
On request from the European Commission, the Agency submits draft framework guidelines which serve as basis for the drafting of network codes. The network codes only become binding after comitology procedure involving Member States and the European Commission.
Consult the ACER work programme for a detailed list of ACER tasks and deliverables.
Would you like to invite an ACER speaker to your event?
Thank you for your interest in the EU Agency for the Cooperation of Energy Regulators (ACER).
While the Agency is committed to attending external events related to its field of work and competences, it is obliged, due to the limited resources at its disposal, carefully to select the events in which its staff members participate.
A decision is taken based on the event in question, as well as on the availability of staff members on the date(s) of the event.
In order for us to make an informed decision about the event at which you would like an ACER staff member to speak, we kindly ask you to send us a request with details about your event to press(at)acer.europa.eu.
The NC IMG used to oversee the implementation and implementation monitoring of electricity network codes and gas network codes in the EU. Network codes and guidelines are rules to harmonise technical, operational and market rules governing the EU's electricity grids and gas networks, making an integrated EU internal energy market possible.
The NC IMG is no longer operational and its work has been discontinued in 2020.
Information on implementation and implementation monitoring
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The Gas Network Codes Functionality Platform (FUNC) is managed by ACER and ENTSOG with the support of the European Commission. The platform allows stakeholders to report cross-border, regional and European issues related to the implementation of gas network codes and guidelines. This cooperation facilitates ACER and ENTSOG to find solutions to the cross-border, regional and European issues identified.
ACER and ENTSO-E co-organise three European Stakeholder Committees (ESCs), one for each family of electricity codes (market codes, operational codes, and connection codes).
They complement, rather than replacing, the legal obligations to consult and inform stakeholders during the implementation of electricity network codes.
At ACER we value diversity and make no distinction on the grounds of sex, race, colour, ethnic or social origin, genetic features, language, religion, political or any other opinion, membership of a national minority, property, birth, disability, age or sexual orientation.
ACER currently employs twenty different nationalities and is committed to fostering a culturally diverse work environment.
The Agency guarantees respect for everyone at the workplace and it is committed to prevent any psychological or sexual harassment.
A rainbow of activities shows Diversity and Inclusion (D&I) in action in ACER:
Training
Human Resource (HR) policies and practices
D&I resource library
Dedicated D&I section in the Staff Newsletter
Fostering a culture of inclusion through a dedicated D&I group (pro-actively led by ACER’s staff)
the adoption the EUAN Charter on Diversity and Inclusion (May 2021);
information sharing and awareness raising activities e.g. through workshops/on-line talks on D&I issues to share good practices;
ACER’s internal D&I survey inspired a common D&I survey template for use across the EUAN, ensuring an effective data collection on D&I matters. Read more on the EUAN website.
Representing diversity and respecting dignity at the workplace
Flexible work arrangements, days of leave and public holidays
ACER strongly supports and encourages a healthy work-life balance. The Agency introduced flexible and core working hours, so that Staff members and SNEs are free to choose the beginning and the end of their working day while ensuring their office presence during core hours.
Telework is also supported for Staff and SNEs, so to carry out their duties outside the Agency's premises.
ACER has between 17 and 19 days of public holidays spread across the calendar year.
Staff members and SNEs are entitled to annual leave of 2 days per month.
Wellbeing
At ACER, we CARE!
The Agency offers annual medical checks to staff and organises seasonal vaccinations. It also offers the possibility of specific and ad hoc medical and consultation services concerning physical and mental health.
The Agency also subsidises several sport activities, such as football, yoga, fitness, climbing, Pilates, and many more.
Any newcomer can also benefit from the Welcome Buddy programme helping new colleagues to get a good start with their new life at ACER and in Ljubljana, as well as to integrate quickly in the new environment.
ACER's employees are also supported by the Staff Committee (SC), acting as a bridge between the staff and the management and ensuring the interest of staff is represented.
Learning and Development
Our learning and development portfolio ranges from language courses, own initiative learning, in-house courses, to specific training in partner institutions such as the European Commission, Florence School of Regulation, European School of Administration, and many more.
Remuneration, allowances, and other benefits
ACER offers a competitive remuneration scheme and several allowances.
Remunerationincludes basic salary, family allowances and other benefits (compensation of costs related to entry into service, installation, annual travel and removal), depending on the individual situation.
If you are an expat with an employment contract of at least one year, you will also be entitled to the VAT exemption during your first twelve months in Slovenia.
Health insurance is provided by the European Commission - Joint Sickness and Insurance Scheme (JSIS), starting with the first day of your employment at the Agency. It can also be extended to your family under certain conditions.
ACER offers also external legal service for its staff, exclusively available for personal purposes. The service provides free-of-charge legal advising in various areas of Slovene law, such as consumer rights, property law, or tax law. The main purpose is to facilitate the integration of staff and families in Slovenia, as the host country.
Office facilities
In the heart of Ljubljana, ACER welcomes its staff and guests in modern and well-equipped offices. The most important services, facilities, shops and restaurants are at a walking distance from ACER offices.
Life in Ljubljana
Ljubljana is the green capital of a green country and is considered to be a yet undiscovered gem of Europe. It is one of the smallest European capitals, with less than 300.000 residents. Awarded the title of European Green Capital 2016, the city features a widely pedestrianized city centre, well-developed cycling networks and a substantial presence of green areas, distinguishing itself for its high liveability and security levels.
Ljubljana is located in the heart of Slovenia, making it a perfect starting point for any trip. The country represents an earthly paradise for outdoor lovers offering a wide range of activities: from skiing to rafting, from climbing to cycling and horse-riding, In Slovenia, due to its relatively small size, you can swim in the sea and climb mountains on the same day.
