The Excel Tool for EN ISO 52016-1: Supporting Transparent Implementation of the EPB Standards

Keywords: EPB standards, EPB calculation methodology, EPBD, thermal comfort

The EPB (Energy Performance of Buildings) standards provide the common methodology for assessing the energy performance of buildings in Europe and are increasingly applied internationally. To support transparent implementation of these standards, the EPB Center made available a series of freely accessible Excel demonstration tools that illustrate the calculation procedures step by step and facilitate software validation, education and standardization.

This article presents the major update of the Excel tool accompanying EN ISO 52016-1, covering hourly and monthly calculations of heating and cooling energy needs and indoor temperatures. Besides explaining the original purpose of the tool, the article highlights recent extensions, including assessment of thermal comfort, ventilative cooling and reference control scenarios for movable solar shading according to EN ISO 52016-3. Finally, it discusses the role of these transparent reference tools in validating software implementations and supporting the future evolution of the EPB standards.

Set of CEN and ISO standards to assess the overall energy performance of buildings (EPB)

The set of CEN and ISO Energy Performance of Buildings (EPB) standards (with its core: the family of EN ISO 52000 standards) provides the common technical framework for assessing the energy performance of buildings in Europe and globally. Since their publication in 2017, following a mandate from the European Commission to CEN [1], these standards have formed an important basis for the implementation of European legislation, including the successive revisions of the Energy Performance of Buildings Directive (EPBD [2]), while also being applicable well beyond Europe.

Demonstration spreadsheet tools

One of the recurring challenges in developing calculation standards is ensuring that the calculation procedures are technically correct, but also that they can be implemented consistently in different software tools. For this reason, the CEN and ISO experts responsible for the development of the set of EPB standards, prepared -in parallel with the standards- a series of demonstration spreadsheets accompanying each EPB (calculation) standard.

To avoid that -after the completion of the mandated work in 2017- this kind of knowledge would get lost or scattered, and to stimulate the further development and exchange of information on the set of EPB standards, and to support a wide implementation, the EPB Center was established as service center for information and technical support on the set of EPB standards.

These spreadsheets have since 2017 been made freely available at the EPB Center website. Under a Service Contract from the European Commission [3] several of these spreadsheet tools were improved, case studies were performed, while webinars were organized and short videos prepared to highlight specific topics [4], [5], [6].

It is important to note that these Excel tools are not intended as commercial software, but as transparent reference calculation tools that allow users, software developers and standardization experts to understand, verify and test -step by step- the calculation procedures. In addition, these Excel tools provide a clear indication which input data are needed and which output data are produced. In that way, the numerous input-output links between the standards (the output of one EPB standard is needed as input for another EB standard) can be checked for consistency. By the way, each EPB standard has a corresponding technical report, containing explanations and justification of the standard. The technical reports also contain example calculations, based on the Excel tools. A major update has now been completed for the demonstration spreadsheet accompanying EN ISO 52016-1 [7], [8], the standard describing the calculation of hourly and monthly sensible and latent energy needs for heating and cooling, internal temperatures and related performance indicators.

A key standard within the EPB family

EN ISO 52016-1 occupies a central position within the EPB set of standards. It provides calculation procedures for determining building energy needs and indoor temperatures using either a monthly or an hourly approach.

Figure 1. How EN ISO 52016-1 fits within the EPB standards.

1) https://epb.center/support/documents/iso-52000-1/

2) https://epb.center/support/documents/iso-52003-1/

3) https://epb.center/support/documents/en-16798-7/

4) https://epb.center/support/documents/en-16798-5-2/

5) https://epb.center/support/documents/en-15316-1/

6) https://epb.center/support/documents/en-15316-4-2/

7) https://epb.center/support/documents/iso-52016-1/

8) https://epb.center/support/documents/iso-52018-1/

9) https://epb.center/support/documents/iso-52010-1/

10) https://epb.center/support/documents/iso-52120-1/

11) https://epb.center/support/documents/en-16798-1/

The monthly method offers a practical solution for regulatory assessments and simplified calculations. The hourly method, however, captures the dynamic behaviour of buildings much more realistically, making it suitable for evaluating thermal comfort, passive cooling strategies, solar shading control and other time-dependent phenomena, such as use patterns and dynamic interactions between the energy needs and indoor temperatures on one hand and technical building systems and their control options on the other.

Specifically, during the development of the standard (2012-2017), considerable attention was given to making the hourly method practical. This fits well with the general condition to avoid the need for input data that are hard to obtain or to verify.

In particular, to keep the threshold for hourly calculations as low as possible, the intention was that users would not need to provide more input data than for the monthly calculation. Through carefully selected simplifications—while allowing national annexes to override these assumptions where appropriate—the hourly procedure remained accessible without compromising its main advantages. The two main ‘default’ simplifications are:

·         No need to specify construction details: only the thermal transmittance (U-value) and a rough classification of the construction with respect to mass and distribution of the mass over the depth of the construction.

·         No need for exact geometrical details, such as the position of a window in a wall. The geometric input data are restricted to size, orientation & tilt angle.

Why demonstration spreadsheets?

Implementing standards directly in software is not always straightforward. Standards necessarily describe calculation procedures in normative language rather than software code. Different programmers may therefore interpret certain equations or calculation sequences differently.

The demonstration spreadsheets address this challenge by providing a fully transparent implementation of the calculation procedures. Every equation can be inspected, every intermediate result can be followed, and every assumption is visible.

These spreadsheets therefore serve several purposes, beyond the initial testing and demonstration of the calculation procedures:

·         validating commercial or national software implementations;

·         supporting education and training;

·         assisting experts involved in national implementation of EPB standards;

·         facilitating maintenance and future revisions of the standards themselves.

Unlike proprietary software, an Excel implementation makes every calculation step directly accessible. This transparency has proven invaluable both during standard development and during practical implementation.

The complete collection of available demonstration spreadsheets is maintained by the EPB Center and is freely accessible to the international building performance community.

It is important to understand that these spreadsheet tools are, as a rule, describing the calculation procedures of an individual EPB standard. Nevertheless, on an ad hoc basis case studies have been performed to demonstrate dynamic (hourly) interactions, such as between ventilation systems and energy needs and between energy need and heat pumps [5]. However, executing two or more Excel tools with hourly exchange of data (sometimes even in an iterative process) between the tools, over a time sequence of a full year is not realistic.

Evolution of the EN ISO 52016-1 spreadsheet

The original version of the spreadsheet was developed during preparation of EN ISO 52016-1 between approximately 2012 and 2017.

Its initial objectives were relatively modest:

·         verifying that the equations described in the standard were internally consistent;

·         checking both the monthly and hourly calculation procedures;

·         demonstrating that the hourly method could operate with essentially the same user input as the monthly method.

As practical experience accumulated, however, the spreadsheet gradually evolved beyond these original objectives.

Rather than serving only as a validation tool, it increasingly became a platform for demonstrating the additional possibilities offered by hourly calculations.

The latest version [9] illustrates several developments.

Assessment of thermal comfort

Because indoor temperatures are calculated hour by hour, the spreadsheet can directly evaluate thermal comfort indicators instead of only annual energy use.

This enables assessment of overheating risks and allows adaptive comfort criteria to be incorporated where appropriate. For example, the criteria developed in the EU ALDREN project [10] and now being integrated in the standard that is intended to succeed EN 16798-1 [11].

Figure 2. Example of thermal comfort criteria (from ALDREN) that can be tested and evaluated in the Excel tool.

Such analyses have become increasingly relevant as buildings are expected to remain comfortable under warmer climatic conditions while minimizing cooling energy demand.

Integration of ventilative cooling

The hourly framework also allows the effects of ventilative cooling to be represented.

Using control criteria developed within the ventilation standardization community, natural or mechanical ventilation strategies can be evaluated consistently within the EN ISO 52016-1 calculation framework. This work is closely connected with ongoing development of technical guidance on ventilative cooling (FprCEN/TS 18335:2026, Annex H [12]).

Reference control scenarios for movable solar shading

Another important extension concerns movable solar shading devices.

The recently published EN ISO 52016-3:2024, including Amendment 1:2025[13], [14], [15]) introduces detailed reference control scenarios for various types of movable solar shading provisions. These cover manual, motorized and automated control options (in line with EN ISO 52120-1 [16]), for residential buildings and offices, taking into account the type and position of the blind, screen, shutter or adaptive glazing, as well as e.g. heating or cooling mode, solar irradiance, occupancy and daylight, but also occupant behaviour, based on recent findings in practice. These control strategies can now be incorporated and demonstrated directly within the spreadsheet.

This enables users to investigate how realistic shading control influences both cooling demand and indoor comfort while maintaining full consistency with the EPB calculation methodology.

Figure 3. Illustration that also complex control scenarios for movable solar shading provisions can be investigated as an integrated element in the hourly calculation procedures.

Supporting software validation

The spreadsheet has also proven valuable in research and European collaborative projects.

Within the EU LIFE project OpenBEP4EU [17], for example, the spreadsheet has been used as one of the reference tools for validating more advanced multi-zone calculation implementations. In order to minimize the risk of differences in the input data, the Excel tool was significantly upgraded with a separate input data sheet with the detailed properties of each layer of each construction as separate input. As explained above: when EN ISO 52016-1 was written (2012-2017), it was important to avoid that extra input data were needed compared to the monthly calculation method. This new version of the spreadsheet is ready to test the impact of a more detailed set of input data.

Such validation exercises help ensure that software tools developed by different organizations produce consistent results that are fully in line with the standard, while -at the same time-, it helps to investigate possible improvements in the standard.

Looking ahead

The continuing development of the demonstration spreadsheet reflects a broader evolution of the EPB standards themselves. Increasingly, software tools are emerging that aim to be in line with the set of EPB standards. While software houses are exploring how they can deploy their existing building simulation tools to become compatible with the EPB standards. A transparent reference implementation (such as the Excel spreadsheets) become an important benchmark for validating software tools.

On the other hand, the spreadsheet tools are poorly suited for testing dynamic links (interactions) between the various calculation modules. It could be envisaged that, complementary to the spreadsheets, open source Python calculation modules and workflow orchestration tools will become available that will enable validation at a higher, more integrated level. Since Python is a relatively easy and widely used programming language, it can be used to support education, research and future standardization. It will also trigger interest from industry and science to explore the advantages of the systemic approach as adopted in the set of EPB standards, in particular regarding the dynamic ([sub]-hourly) interaction between technical building systems (heating, cooling, ventilation, ..), controls and the building energy needs.

A comprehensive programme is currently being prepared, based on a CEN ISO Roadmap [18], to upgrade the complete EPB standards package in response to new policy requirements (EPBD-2024), technological developments and practical implementation experience.

One of the objectives is the development of a harmonized repository of input data for EPB calculations. A common data structure would improve consistency with and between different software tools and reduce duplication of effort during national implementation.

These developments support the longer-term ambition of making the complete EPB standards family fully software-ready while preserving transparency, traceability and international consistency.

An open resource for the building performance community

The updated EN ISO 52016-1 demonstration spreadsheet illustrates how a tool originally developed for checking equations has evolved into a practical reference tool supporting education, software validation, industry, research and future standardization.

Its availability through the EPB Center reflects the broader philosophy that transparent calculation methods strengthen confidence in building energy assessments and facilitate consistent implementation across countries. Openly available reference tools will remain an essential bridge between normative standards and practical software applications.

Acknowledgement:

Many of these spreadsheets have been developed parallel to the preparation of the set of EPB standards under the M/480 mandate from the European Commission (2012 - 2017).

The EPB spreadsheets produced or upgraded during 2018 - 2021 have been prepared under a service contract from the European Commission [3].

Specific improvements or additions have been made to relevant spreadsheets within the framework of other international projects, such as the EU LIFE project OpenBEP4EU [17].

References

[1]     Mandate M/480: Mandate to CEN, CENELEC and ETSI for the elaboration and adoption of standards for a methodology calculating the integrated energy performance of buildings and promoting the energy efficiency of buildings, in accordance with the terms set in the recast of the Directive on the energy performance of buildings (2010/31/EU), December 14, 2010

[2]     EPBD:2024, Directive of the European Parliament and of the Council of 24 April 2024 )on the energy performance of buildings (recast) https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=OJ:L_202401275

[3]     EC Service Contract ENER/C3/2017-437/SI2-785.185, Support the dissemination and roll-out of the set of Energy Performance of Buildings standards developed under EC Mandate M/480 (2018-2021)

[4]     Spreadsheets on EPB standards publicly available at the EPB Center website https://epb.center/support/documents/

[5]     Case studies on EPB standards publicly available at the EPB Center website https://epb.center/support/case-studies/

[6]     Short videos on EPB standards publicly available at the EPB Center website https://epb.center/support/short-videos/

[7]     EN ISO 52016 1:2017, Energy performance of buildings - Energy needs for heating and cooling, internal temperatures and sensible and latent heat loads - Part 1: Calculation procedures *)

[8]     CEN ISO/TR 52016 2:2017, Energy performance of buildings - Energy needs for heating and cooling, internal temperatures and sensible and latent heat loads — Part 2: Explanation and justification of ISO 52016-1 and ISO 52017-1 *)

[9]     Spreadsheet on EN ISO 52016-1, publicly available at the EPB Center website https://epb.center/support/documents/demo-en-iso-52016-1/

[10]   EU Horizon 2020 project ALDREN https://aldren.eu/https://www.youtube.com/watch?v=hKb7kMNzFgA

[11]   EN 16798-1:2019, Energy performance of buildings — Ventilation of buildings — Part 1: Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics (Module M1–6) *)

[12]   FprCEN/TS 18335:2026, Ventilation for buildings - Ventilative cooling systems – Design (under preparation)

[13]   EN ISO/ISO 52016 3:2023, Energy performance of buildings - Energy needs for heating and cooling, internal temperatures and sensible and latent heat loads - Part 3: Calculation procedures regarding adaptive building envelope elements Incl. Amendment 1:2025, Reference control scenarios for adaptive building envelope elements with dynamic solar shading or chromogenic glazing *)

[14]   CEN ISO/TR 52016-4:2024, Energy performance of buildings — Energy needs for heating and cooling, internal temperatures and sensible and latent heat loads — Part 4: Explanation and justification for ISO 52016-3 *)

[15]   REHVA Journal, Vol. 59, Issue 3, June 2022, Dick van Dijk, A new draft standard with calculation procedures regarding adaptive building envelope elements: prEN ISO/DIS 52016-3

[16]   EN ISO 52120-1:2021, Energy performance of buildings — Contribution of building automation and controls and building management — Part 1: General framework and procedures *)

[17]   EU LIFE project OpenBEP4EU (2024-2027) https://www.openbep4.eu/

[18]   ISO and CEN Roadmap for the set of EPB standards with regard to the key global challenges, February 24, 2024 https://epb.center/media/filer_public/30/4e/304e16d7-c4c0-4639-83f6-dd902d596511/roadmap_for_upgrading_set_of_iso-cen_epb-standards_v_2024-02-24.pdf

*): Summary information on each of these EPB standards and technical reports, including links to spreadsheets, short videos and case studies, can be found at https://epb.center/support/documents/