Frequently Asked Questions

Please contact us if you have a question or comment on one of the EPB standards…

In general, the National Standard Body can be contacted for information and comments on any CEN or ISO standard. A list of National Standards Bodies can be found here.

Specifically for the EPB standards:
Part of the services of the EPB Center is to collect presumed errors and questions on the content of EPB standards and their accompanying technical reports.

The EPB Center experts prepare, to their best knowledge, proposals for corrections and/or clarifications.
The EPB Center may communicate and publish these proposals, purely to support the implementation and application of these standards and technical reports in practice.
For such proposals the CEN/ISO commenting template will be used, to ensure an efficient communication with CEN and ISO.

In no way these proposals shall be regarded as formal corrigenda to the related CEN or ISO documents. It is up to CEN/ISO to decide upon the preparation of an amendment or revision of the document.

See also general disclaimer

• Already available: proposal for corrections and/or clarifications on ISO 52000-1.
• Coming soon: e.g.: proposal for corrections and/or clarifications on ISO 52016-1

In general, the choice to start the development of a new standard is up to the stakeholders.
The development of the set of EPB standards was originally initiated by the European Commission under mandate M/480, to support the energy performance of buildings directive, EPBD (link to EPBD).

Europe started to develop EPB-related CEN (=European) standards many years ago (read more). So it made sense to take these as the starting point.
However, in the area of thermal and solar properties of building components (including windows), energy needs for heating and cooling and climatic data a long years cooperation existed already between CEN and ISO, so these EPB standards were developed as EN ISO standards from the beginning. For instance: EN ISO 52016-1, as successor of the well-known EN ISO 13790:2008 on the calculation of heating and cooling needs.

Because each EPB standard leans strongly on the overarching EPB standard (EN ISO 52000-1), that standard has also been adopted at ISO level.

Some of the EPB standards dealing with heating and cooling systems and with building automation and control are currently being prepared to become global (EN ISO) standards. And in a few years the rest might follow.

Read more:

• ISO and CEN, the road ahead
• Background on the set of EPB standards

2019.07.22

By preparing the standard as a combined CEN and ISO standard, the final draft standard is subjected to parallel voting:

• by the ISO members to approve publication as an ISO standard, and
• by the CEN members to approve it as a CEN standard.

If the final draft is approved in ISO, but rejected in CEN, CEN may decide to develop a separate CEN standard on the same subject. This process ensures that the European interests are taken into account.

This is very important, because the European Standardization System is unique in the world. After the publication of a European Standard, each national standards body or committee is obliged to withdraw any national standard which conflicts with the new European Standard. Hence, one European Standard becomes the national standard in all the 34 member countries of CEN and/or CENELEC.

In addition, some CEN standards may also be made mandatory in the framework of EU legislation. However, this is not the case for the set of EPB standards.

Read more on ISO and CEN, the road ahead
See also Q&A: Is the set of EPB standards mandatory in Europe?

2019.07.22

No. The set of EPB standards was originally initiated by the European Commission for support the Energy Performance of Buildings Directive (EPBD).

The set of EPB standards is of equal relevance at global (ISO) level.

As a matter of fact, already one third of the EPB standards, for instance the overarching EPB standard (EN ISO 52000-1), are available as combined European (CEN) and global (ISO) standards.

Read more on ISO and CEN, the road ahead

2019.07.22

If a country adopts an EPB standard, it can make use of the specific degrees of freedom given in Annex A of that standard (template for national choices).
These choices are introduced to accommodate national/regional differences in climate, building tradition, policy and user behaviour. This is what is known as the National Annex or National Data Sheet.

The template of Annex A of a given EPB standard even allows to replace one or more references to other EPB standards by references to one or more national standards. The condition is that such national standard complies with the input/output connections to the other standards and EPB framework methodology. This option could be used for a step-by-step implementation of the set of EPB standards at national level.

Other changes would not be in line with the EPB standard.

Read more on national annexes

2019.07.22

For filling in a National Annex or National Data Sheet following the template given in Annex A of each EPB standard, you find guidance in the general introduction of the Annex A itself.

Note that, for the same EPB standard, different National Annexes or National Data Sheets may be prepared, each for a different purpose. For instance depending on:

• Type of application according to national building regulation (e.g. EP certificate, building permit, use permit, incentives, etc.).
• Type of building;
• Climate zone;
• Etc.

In addition, a Guide how to fill in National Annexes or National Data Sheets is available (link).

More information:

• Page on national annexes
• Recording of presentation (20 min.): “General guidance and introduction to national options (choices“
  (from webinar: “Guidance and examples for the EPB standards’ flexibility“)

2019-07-22 (updated 2021-02-02)

Yes. For instance a value depending on the application or depending on specific conditions or year of construction. As long as the result is a value for the required input data.
Read more on flexibility / national choices

2019.07.22

Each country/region can make a specific set of choices, according to the template of Annex A of a given EPB standard, for the assessment of the energy performance. Or different sets, depending on the application.

Once this template of Annex A is filled in with the national data and choices, it can be published.

• If it is published by the National Standardization Body, as Annex to the standard, it is called a National Annex. This is the preferred option (most transparent and accessible).
• If it is published by a national/regional building authority, it is called a National Data Sheet.

So for the user it is only a matter of where to find it.
The National Annex can be found as Annex to the EPB standard and the National Data Sheet can be found e.g. embedded in regulations. There is no difference in the type of content, or template used.

Read more on national-annexes
Read more in EC Recommendation 1

2019.07.22

Annex A and B are part of the standard and will remain part of the standard. In addition to this, a National Standards Body or a Member state can decide to publish a National Annex or National Datasheet. These are separate documents, based on the template in Annex A, with content that may or may not be taken from Annex B.

2022-04-02

Yes, see FAQ “Are there specific guidelines about how to fill in a National Annex to an EPB standard?“

2022-04-02

Indeed, each country/region can make specific choices to accommodate national/regional differences in climate, building tradition, policy and user behaviour, as long as the template of Annex A of a given EPB standard is respected.

These choices are laid down in a National Annex or National Data Sheet on that standard.

Such a document is in itself informative and not mandatory. However, a National Annex or National Data Sheet can be made mandatory for use within a specific context. For instance, a public authority may issue a National Data Sheet or refer to a National Annex to the standard, containing the required parameters (“filled in” Annex A) for specific regulatory purposes (energy performance certificates (EPCs), building permit, use permit, incentives, etc.).

More information:

• Page on national annexes
• Recording of presentation (20 min.): “General guidance and introduction to national options (choices“
  (from webinar: “Guidance and examples for the EPB standards’ flexibility“)

2019.07.22 (updated 2021-01-22)

According to EPBD:2018, Annex 1, when EPB standards are not adopted in full by a EU Member State, then the Annex A of the standard should be used as a template to describe the national calculation methodology and national choices, ensuring compliance with the EPBD.
If a Member State is able to use the normative template, as presented in Annex A of a given EPB standard, to describe the corresponding part of their national methodology without any violation of the template, then the national method is fully in line with the EPB standard. In that case, technically speaking, the EPB standard is “de facto” adopted.

If this is not the case, there will be elements in the national calculation procedures that do not (or not fully) fit in the template. To respect the template as much as possible it is advised to clearly mark and explain the deviation at the highest level of detail possible.

The EPB Center is preparing examples and tips.
Please contact the EPB Center if you have a specific question on this issue!

More information:

• On National Annexes
• COMMISSION RECOMMENDATION (EU) 2019/786 of 8 May 2019 on building renovation

2019.07.22

If (a part of) a table in Annex A of the EPB standard is not applicable due to national choices that are in line with the standard, the corresponding (part of) the table in the National Annex or National Datasheet may be left blanc. It is strongly advised be stated explicitly why (the part of) the table is not filled in. For example:

• Case 1: table An EPB standard offers a choice between two methods (e.g. simplified or detailed, monthly or hourly time interval). If the national choice only allows one of the methods, then all tables about the other method are irrelevant and may be kept blank. In this case an explanatory note should be placed in or below these tables, for example: “According to Table NA.xx the national choice is for Method A. Tables A.xx – A.yy are only relevant for Method B.”.
• Case 2: Some tables are intended to offer the possibility to specify (national or regional and typically ‘conservative’) default values, in case project specific data are not or not yet available. If the national choice is not to provide default values, then the table may be left blank. In this case, an explanatory note should be placed in or below the table, for example: “No default choices: the choice is project dependent”.

See worked examples in the Guide on National Annexes

2020-03-03

A National Annex is filled in and published by a National Standards Body (NSB), as annex to the national implementation of the EPB standard. The NSB can choose to publish this stapled to the standard, or as separate document(s). Consequently, it is publicly available, but it may not be available for free.

A National Datasheet can be a separate document referred to by the building regulations, or an integral part of the building regulation implementing the EPBD. One may therefore expect it to be publicly and freely available.

Development of a National Annex or National datasheet is a critical process that may take some time. Although countries are working on it, at the beginning of 2021 there were only a few published.

A National Annex or National Datasheet to describe the national method in terms of the Annexes A of the five so called overarching EPB standards (acc. to EPBD:2018, Annex 1) may not be publicly available.

More information, including guidance and examples:

• Page on national annexes

2020-03-03 (updated 2021-01-22)

Not all countries publish national annexes, and not for all standards.
You are invited to read FAQ Are all National Annexes and National Datasheets publicly available? for more information on the process of preparing National Annexes.
Or see FAQ Where can I find an overview of the reports from the EU Member States… for the situation to describe a national methodology in terms of National Annexes of the 5 key EPB standards (related to EPBD:2018).

2022-04-02

National Annexes or National Datasheets to describe the national method in terms of the Annexes A of the five so called overarching EPB standards (acc. to EPBD:2018, Annex 1^*)) are included in the national report to the European Commission and not necessarily made publicly available.

^*): See also FAQ “How can EU Member States follow …”

If available and if publication is permitted, the reports will be made available at the EPB Center website.

NOTE: In order to improve comparability, it is recommended that Member States make the description of their calculation methodologies publicly available, e.g. by uploading the filled-in templates to a website or annexing them to their building codes, etc.

Making the calculation methodology publicly available will also help Member States to fulfil the EPBD requirement to ensure that the methodology applied for the determination of the energy performance of a building shall be transparent.

2020-03-03 (updated 2021-01-22)

At the page on National Annexes we are collecting examples, as far as made available for publication at the EPB Center website.

See also FAQs “Are all … available?” and “Where can I find …”

2020-03-03

Yes, an extensive guide how to fill in National Annexes or National Data Sheets is available at the website (link).

The Guide comprises tips (“do’s and don’ts”), worked out examples and tips.

The Guide also contains recommendations. e.g. on:

• How to differentiate national choices for different applications
• How to clearly mark the differences in national choices compared to the informative default choices in Annex B of each standard.
• How to clearly mark violations of the template (if unavoidable) in case of deviating national methodology.

Following these recommendations would strongly facilitate comparison with other countries.

Also available, upon request (let us know), a file with fillable Annexes B of (EN) ISO 52000-1. 52003-1, 52010-1, 52016-1 and 52018-1, in English only.

See also FAQs “Where can I find …” and “How can EU Member States follow …”

2020-03-03 (updated 2021-01-22)

If the template of Annex A of the EPB standard can be filled in without any violation of the template and without de facto altering the provisions of the EPB standard, a National Annex or a National Datasheet may be used. See FAQ on the difference between these two options.

A National Annex to the EPB standard is not an option if the template is violated or if the filled in national choices lead to de facto alterations of the normative provisions of the EPB standard. In that case the only choice is a National Datasheet.

More info in the Guide

2020-03-03

If a certain part of the national calculation procedures is fully based on the relevant EPB standards, then the national choices logically follow the template of Annex A of the relevant EPB standards.

In other cases this may not be 100% possible. Nevertheless, it is important to follow the template as much as possible, because:

• It greatly facilitates analysis.
• It facilitates comparison between countries.
• It helps to show the elements where the EPB standards could not be followed. This is important feedback to CEN and ISO, for future improvement and further harmonization of the EPB standards.
• The template provides clear and consistent choices. For instance, if the tables to provide primary energy conversion factors (EN ISO 52000-1) are followed, ambiguities in the national choices will be automatically revealed. The template thus helps to create consistent national choices. This is demonstrated in one of the worked out examples in the Guide on how to fill in National Annexes or Datasheets (see FAQ “Is there a Guide…“)

See also FAQs Is there a Guide… and “How can EU Member States follow…”

2020-03-03 (updated 2021-01-22)

Annex B is and remains an informative Annex to the EPB standard. The National Annex can be annexed to the national implementation of the EPB standard or published as separate document see FAQ “Are all …. publicly available?”). So, an EPB standard will have Annex B with default European choices and might also have an Annex NA with the national choices.

The same situation in case the national choices are laid down in a National Datasheet: Annex B says where it is. It is part of the standard.

2020-03-03

If at national level it is not possible to fill in the Annex A according to the rules it is a strong indication that the national procedure doesn’t follow the procedures included in the set of EPB standards.

2022-04-02

The responsible organizations for publishing National Annexes are the National Standards Bodies and/or the national or regional authorities. Preferably it should be the National Standards Body (NSB). See FAQ Are all National Annexes and National Datasheets publicly available? for an extensive explanation of the different options.

The actual development of the National Annexes for the NSBs or authorities is typically the work of experts who are also involved in the development of national and/or international energy performance methodologies, together with all stakeholders concerned.

Note that the development of NAs involves interconnecting national standardization committees on heating, cooling, ventilation, thermal insulation, lighting, overall EPB, etc. So attention should be given to establishing a strong relation between these national focus groups.

They usually have close contact with the public authorities for regulatory purpose. The NAs only focus on the assessment method, the public authorities will set the minimum EP requirements. But these are two sides of the same coin (see FAQ Why is international harmonization of energy performance calculation methods important? on the importance of international harmonization of the EP calculation procedures).
So, in case the NA -if intended to be used for regulatory purpose- is published by the NSB, interaction between the NSB and public authorities is essential.

Sometimes the national association of building engineers/consultants takes the lead, or a national or regional energy agency In other countries an educational institute or research organization is asked to take the lead.

In most cases the funding comes (directly or indirectly) from the national or regional authority responsible for the building regulations. However, there is a wide variation in funding, depending on the country, on the way the National Standards Body is financed, on the involvement of stakeholders, etc.

2022-04-02

Examples of currently published publicly available NA’s and ND’s can be found on the EPB Center website,

Further to this, there are a few NA’s and ND’s that we are not allowed to share, because of copyright issues.
You are invited to read FAQ Are all National Annexes and National Datasheets publicly available? for more information on the process of preparing National Annexes.

But see also FAQ Where can I find an overview of the reports from the EU Member States..? for the situation to describe a national methodology in terms of National Annexes of the 5 key EPB standards (as required by the EPBD:2018, Annex 1). The National Annexes prepared for this purpose need to be reported to the European Commission. The EU Member State may decide to keep this report to the EC confidential.

2022-04-02

The reason we can’t simply replace the EPB (Energy Performance of Buildings) standards with widely available dynamic building simulation tools lies in several key factors:
1. Regulatory Consistency and Comparability
The EPB standards provide a harmonized framework that ensures consistent and comparable energy performance assessments across different buildings, regions, and countries. If everyone used different simulation tools, the results would vary significantly, making regulatory enforcement, benchmarking, and policy implementation difficult.
2. Consensus-Based and Internationally Recognized
The EPB standards are developed under CEN (European Committee for Standardization) and ISO (International Organization for Standardization) through a consensus-based process involving experts, industry representatives, and policymakers from different countries. This ensures that the methodologies are scientifically sound, widely accepted, and aligned with policy goals. In contrast, commercial dynamic simulation tools are developed independently, without the same level of broad stakeholder agreement.
3. Simplicity and Practicality
Dynamic simulation tools require detailed input data and expert knowledge to operate correctly, which is not practical for widespread regulatory use. The EPB standards offer tailored but reliable calculation methods that make compliance feasible for a wide range of professionals, including those without specialized simulation expertise.
Moreover, special attention is paid to the availability and reliability of input data, particularly regarding internationally harmonized product and component data (e.g., insulation materials, HVAC systems, glazing properties). The EPB standards ensure that these data are standardized and accessible, reducing uncertainty and avoiding the need for complex, often unavailable, or inconsistent input parameters that are typically required for dynamic simulations
4. Transparency and Reproducibility
The calculation methods in the EPB standards are well-documented, standardized, and transparent, making them easier to verify, audit, and reproduce. Many dynamic simulation tools use complex and sometimes ‘black box’ algorithms that vary between software providers, making it difficult to ensure full transparency, comparability and validity over the full range of applications.
5. Computational Efficiency
Dynamic simulation tools can be computationally intensive, requiring longer processing times and more resources. The EPB methods, on the other hand, use a balanced set of dynamic approaches that provide results efficiently while maintaining sufficient accuracy for regulatory purposes.
6. Policy and Legal Framework Alignment
The EPB standards are designed to align with EU directives and national regulations, ensuring compliance with legal requirements. Many commercial simulation tools are developed for broader purposes (e.g., design optimization) and may not fully align with the specific requirements of regulatory frameworks.
As CEN or ISO standards they are consensus based.
Conclusion
While dynamic building simulation tools are useful for design optimization and advanced studies, the EPB standards serve a different purpose: providing a regulated, transparent, and practical approach to assessing energy performance that is consistent, comparable, and enforceable across different regions and projects.

Updated 2025-02-05

Spreadsheets are used to ensure consistency, coherence, and accuracy across all EPB standards. Developed alongside each calculation standard, they provide a transparent, step-by-step demonstration of the process, making it easy to trace, verify, and understand calculations—even when dealing with complex equations.
Though not designed for daily professional use, spreadsheets are valuable for:
• Software developers verifying algorithms.
• Generating reference cases to validate application software.
• Conducting detailed case studies.
While calculations may take a few minutes, spreadsheets offer unmatched traceability and allow input/output consistency checks across multiple EPB standards.

Updated 2025-02-05

Spreadsheets are primarily used for demonstration and validation, as explained in another FAQ. Their key advantage is accessibility—anyone can scroll through and examine formulas, making the entire calculation process transparent and easy to follow step by step.
Spreadsheets also provide immediate access to all intermediate results for each equation and calculation step.
For practical applications, a programming language like Python would be more suitable, but that serves a different purpose.

Updated 2025-02-05

Yes, the plan is to upgrade the set of EPB standards from being individually “software proof” to become individually and as a set “software ready”. How? By making all input and output data in each EPB (calculation) standard fully explicit, including all non-numeric choices and to mark these up and link them to a repository of uniquely identified variables. This will enable to track and trace all input/output links between the EPB standards for consistency, gaps, loops, etc. It will also show which input data are expected to be supplied as input data by the user (EPB assessor) or as national choice.
More information: see the 2024 CEN/ISO Roadmap.

2025-02-05

International standards in general are a valuable tool for facilitating cross-border trade and knowledge exchange, thus stimulating the implementation of novel technologies.
Standards promote innovation, because they consolidate the latest knowledge into agreed assessment procedures and it is the policy of both ISO and CEN to periodically update their standards.
The set of EPB standards in particular strongly facilitate the implementation of novel technologies because of the holistic approach and the modular structure.

Read more on the holistic approach and innovation

2019-07-19

A ‘nationally’ calculated energy performance value is the product of:

• the actual building (of course)
• “the EP METER” with which you ‘measure’ your building. This is the calculation method that consists of
  • the national definitions,
  • nationally assumed indoor and outdoor conditions, and –last but not least:
  • the calculation engine.

It’s obvious that you need the same EP METER to compare EP values. National benchmarks (reference values) that are used for information, for (national) comparison, and as basis for EP requirements are determined on the basis of the same national definitions, conditions and calculation engine. So, benchmarks and regulatory values are also EP-METER dependent.

• That different conditions lead to different EP values is obvious.
• Less obvious, but nevertheless very true is that different definitions also lead to different EP values. For example: the definition of useful floor area has a significant effect on the calculated EP.
• Even less obvious, but also very true is that different calculation methods (the engines) also lead to different EP values.

Some examples:
Hourly versus monthly methods (see webinar on this subject).
A monthly method lacks the capability to detect (to name a few):

• undersized systems,
• thermal comfort problems,
• the potential of ventilative cooling,
• the dynamic interaction of heat pump performance with energy needs,
• the surplus of on-site produced electricity
• control strategies potential
• generators interactions with storage.

Details of the method:

• A significant influence may be observed from calculation procedure versus tabulated values for specific elements, e.g.:
  • Thermal bridges,
  • Heating or cooling generators,
  • Heat distribution systems,
  • Heat recovery units,
  • A different method may have incompatible parameters.
    • E.g.: not compatible with the choice between total, non-renewable, renewable primary energy….
    • E.g. not compatible with perimeter choices of the energy performance
• A different method may have a limited range of covered technologies.
  • E.g. not all relevant parameters (input data) included
    (for instance: missing distinction between different types of heat pumps, ventilation systems, etc.)
• The method may embed and hide relevant choices, such as exported energy evaluation

Related FAQs:

• FAQ on the relation between standards and innovation
• FAQ 21090810bis (on the different calculation methods in Europe) [pending]
• FAQ on monthly versus hourly calculation methods

2022-02-07

No. Each EPB standard is unambiguous, however allows specific choices to be made at national/regional level for accommodating differences in climate, building tradition, policy and user behaviour.

Example 1: The energy performance depends much upon the outdoor climate (e.g. temperature and solar radiation). Using different climates leads to different results.

Example 2: Each country/region can choose to include or exclude the lighting outside the building (e.g. for car parks) in the EPB assessment. Obviously this will affect the results.

The National Annexes/National Data Sheets are designed to provide information on the choice in a specific country/region. Note that such differences will also have an effect on the national/regional levels for the minimum EP requirements and EP ratings, which may to some extent compensate the differences in the calculated energy performance.

A more detailed discussion on this subject can be found in e.g. CEN ISO/TR 52003-2.

Read more on page on flexibility/national choice

See also FAQs on “National choices” further on.

2019.07.22

Having explicit and traceable options in a common methodology is a rational way to take into account national or regional differences in climate, legal context, building tradition and building use. The Mandate M/480 from the European Commission to CEN explicitly asked to develop a harmonized but flexible methodology.

Such differences will indeed hinder the international comparability of the EP calculation methodology. So it would be recommended to check which choices appear to be really necessary, in order to gradually decrease the number of choices to a minimum.

Then, in such a common context that allows a few options, you can always switch between one option and the other to compare results with the same methodology.

Related FAQ:

• On the importance of international harmonization of the EP calculation procedures

2022-02-08

As a general rule, CEN and ISO standards as such do not impose any regulation. Laws and regulations may refer to standards, because standards provide harmonized specifications (e.g. terminology, key characteristics) and harmonized methods for tests or calculations.

The EPB standards contain methodologies to assess the EP, and specifications of EP characteristics, including EP indicators, that can used to compare against benchmarks. These benchmarks include overall and partial minimum¹⁾ EP requirements, such as the Renewable Energy Ratio (RER) or the thermal insulation level.

See EN ISO 52003-1, EN ISO 52018-1 (and accompanying technical reports).

2022-02-04

The correct understanding and application of EPB-standards requires extensive informative clarification such as:

• reason for the choices made in selecting methods;
• intended use of the different methods;
• correct evaluation of data input;
• information to those responsible for national implementation.

If the informative content is mixed with the normative content, the standards may become confusing and heavy to read. Therefore, a clear separation between normative and informative content is recommended whenever possible.
Consequently, as a rule, only normative content is in the EPB standard. Informative content is given in an accompanying Technical Report, with the exception of short Notes and Examples.

This significantly reduces the length of the EPB standards and strengthens their focus, thus facilitating the adoption (including translation) in national/regional regulations.

It also makes it easier to check if the EPB standards is unambiguous and software proof.

2022-02-04

The most time-consuming task when preparing a calculation for an energy performance certificate or compliance check, is describing the building with all it’s details.

So, if the same calculation procedure can be used also for design calculations it makes life much easier. Moreover, you ensure that you use compatible definitions and assumptions. For exactly this reason it was decided in 2015 to merge the calculation of the energy cooling load (which was originally intended to be developed as a separate EPB standard under CEN Technical Committee (TC) 156, Ventilation and Cooling) into EN ISO 52016-1 (Calculation of energy needs for heating and cooling and indoor temperatures).

In EN ISO 52016-1 the hourly calculation of the internal temperature, the energy need for heating and cooling and the calculation of the design heating and cooling load all use the same hourly internal temperature calculation. Although aim and outcome of these calculations are different, the calculation methods are identical and use the same inputs, where this makes sense.
Specific assumptions of the calculations may differ, such as the conditions of use and climatic data (design conditions) and (depending on the situation) the thermal zoning of the building.

In EN ISO 52016-1, a distinction is made between a basic cooling/heating load calculation and a system specific cooling/heating load calculation.
For the basic cooling/heating load and energy need calculation, a continuous operation and no power restrictions for the cooling/heating system is assumed, and the emission is assumed to occur purely convective.
For the system specific cooling/heating load and energy need calculation, a limited operation time may be assumed, the available power of the system may be limited, the recoverable losses may be further specified and a convective fraction according to the system intended to be installed can be used.
However, it is very important to note that design is much more than only system sizing.

Other FAQs related to design:

• 19052802
• 21090869
• 21090873
• 21090878

2022-02-04

The responsible ISO and CEN technical committees (TCs) have working groups (WGs) where the technical experts are cooperating to prepare new standards or revise existing standards. The technical experts are nominated by the National Standards Bodies (NSBs), the CEN/ISO members.

The background of these experts is very diverse: designers, industry, practitioners (dealing with system or building design), also researchers and members of the academic community and representatives from policy makers and regulators. So quite diverse groups that prepared the documents.

Each standard is published as draft for a public consultation period of a few months, during which period all stakeholders can give comments. Dedicated national mirror groups, organised by the NSB, collect and discuss the comments at national level and submit the result as national comments to the ISO or CEN committee.

The WG discusses all comments and prepares a final proposal.
Finally, the national mirror groups vote whether they accept or reject the final proposal.

If you count, for instance for Europe alone, for all EPB standards (covering five CEN Technical Committees), all experts including the experts in the national mirror groups, it is estimated that probably 500 persons or more around Europe reviewed the set of EPB standards that was published in 2017, gave their feedback and actively contributed to the production.

Related FAQs:

• FAQ 21090805 #faq-16176 on which stakeholders were involved <this FAQ>
• FAQ 21090835 on what services the EPB Center could provide
• FAQ 19052807 #faq-15603 on how and where to provide feed back on the EPB standards

2022-02-04

First of all, (EN) ISO 52000-1, the overarching EPB standard, introduces the term “building portfolio”: a set of buildings and common technical building systems whose energy performance is determined taking into account their mutual interactions. An example of common technical systems is an energy generation system (PV panels, wind turbine, cogeneration unit, boiler, etc.) serving the building portfolio. So the interaction of a group of ‘nearby’ buildings is covered in the set of EPB standards.

Apart from that, the current EPB standards do not cover explicitly how to deal with a group of buildings. However, the interaction with the external world, such as electricity grid interaction (delivered and exported energy) should provide the information needed to assess a group of building i.e. a local network, See short video: on how to deal with exported energy to the grid.

Also in the current discussion, in Europe, of the Smart Readiness Indicator (SRI) it will be an issue that is expected to be addressed, in the coming months and years. Although this further depends on the acceptance of the SRI as a tool to show the potential level of interactivity between ‘your’ specific building and the energy grid. A bidirectional EV charging unit could be part of this local grid approach. The ongoing (2021) revision process of the EPBD may influence this process.

2022-02-07

Why is the calculation of the overall energy performance of a building split into separate EPB standards and not combined into an all-in-one standard (at least all EPB standards that are part of the overall EP calculation)?

In general, the ISO and CEN standards making process is handled by various technical committees or TCs as they are called. The TCs are the key bodies that drive the standardization and comprise experts from the national committees. Each committee is responsible for a specific work area. This ensures a transparent and fair process, having the right experts involved in the development and review of each standard and the right links to the experts in so called national mirror committees. Having said that, joint working groups can be formed between committees in case of standardization work of joint interest.

For the set of EPB standards, the expertise on the overall energy performance is divided in CEN over 5 TCs (building and building components, heating &DHW, ventilation & cooling, BAC and lighting) and also in ISO different TCs are involved.

To coordinate the work aiming at a consistent overall energy performance calculation, a coordinating TC was formed in CEN (CEN/TC 371) and in ISO a coordinating joint working group (ISO/TC 163/WG 4, joint with TC 205) and joint advisory group (ISO/TC 205/AG1, joint with TC 163) were established. In turn, there is close collaboration (including task distributions) between ISO and CEN.

From the start of this coordination work the aim was to go for a modular approach: a matrix in which each element covers a specific part of. the overall energy performance assessment (not only calculation, but also measured EP, inspection, economic evaluation and related aspects).

Ideally, each module is one EPB standard, but for practical and historical reasons this is not always the case. Each of these standards is subject to specific technical and editorial rules provided in the overarching EPB standard, (EN) ISO 52000-1 and in complementary quality documents, to ensure overall consistency.

The modular approach ensures that each country can follow a step-by-step procedure to implement the overall EPB assessment procedures (successively replacing national procedures by the procedures in the set of EPB standards).

Moreover, in the modular approach the need for updating a specific element in the calculation (for example on ventilation systems, heat pump system or thermal transmittance of windows) can be addressed by the specific experts and interested parties in the specific technical committee and result in a proposal for revision of that standard and publication. In case of an all-in-one EPB standard a revision of one chapter would implicate that the whole all-in-one document would need to be revised (and purchased…).

Besides, many users are interested in only a specific aspect of the overall energy performance assessment. For them it would become very costly if they would need to buy “all-in-one”.

Of course, it is essential that the whole set of EPB standards, in particular to calculate the overall energy performance of a building, is consistent and complete. This is, however, not different from an all-in-one document to assess the overall energy performance of buildings, that would still be the combined result of contributions from many experts.

2022-02-07

Yes, each EPB standard has a list of all input and output data. Also, in each of the spreadsheets that are available <link> you can find the list of input parameters for the associated EPB standard.

The challenge, however, is to see through these “blunt” lists of input data. You could easily say that the Pareto principle applies here:
typically 20% of the data is needed in conventional cases, and
typically 80% of the data that you find in the list of input data for the standard are used only for special cases.

That also makes it a little bit less trivial to just make a complete list of all the input data. You should actually try to make a distinction between which data are needed for conventional cases and which for special or alternative cases.

For instance: different input datasets for different type of heat generator, or for a different type of ground floor: suspended floor, floor flat on the ground, a floor above a heated or unheated basement, .. .

A first help in that sense is the classification of input data in the standard and in the spreadsheets.

Product qualitative data typically describe the typology of products involved (e.g. air to water or air to air heat pump, condensing versus non-condensing boiler). This choice influences which quantitative data are then required (see next point).

Product quantitative data are physical quantities qualifying the specific product. Those few who qualify the “size” of the product identify the product (e.g. nominal power of a boiler) shall be input by the user. The remaining data should be found in a catalogue or data–base or conventional values may be assumed, depending on the product qualitative data.

Operating conditions data may be initial information such as outdoor climate and indoor operating conditions: when you are doing a standard calculation, e.g. to check compliance or for an energy performance certificate these are typically pre-set national or regional ‘standard’ data; only for special applications, such as design or an energy audit, you may wish to use all the potentialities of the standard and decide to use tailored values for these.

Finally. many input data for a specific EPB standard are data that are produced as output from another EPB standard in the chain, such as energy flows and system operating temperatures. So when you do an overall EP assessment, these too do not count as input data required from the building.

2022-02-07