SIST EN 1991-1-2:2024/oprA1:2026
(Amendment)Eurocode 1 - Actions on structures - Part 1-2: Actions on structures exposed to fire
- Abstract
1.1 Scope of EN 1991 1 2
(1) The methods given in this Eurocode are applicable to buildings and civil engineering works, with a fire load related to the building and its occupancy.
(2) EN 1991 1 2 deals with thermal and mechanical actions on structures exposed to fire. It is intended to be used in conjunction with the fire design Parts of EN 1992 to EN 1996 and EN 1999 which give rules for designing structures for fire resistance.
(3) EN 1991 1 2 contains thermal actions either nominal or physically based. More data and models for physically based thermal actions are given in annexes.
(4) EN 1991 1 2 does not cover the assessment of the damage of a structure after a fire.
(5) EN 1991 1 2 does not cover supplementary requirements concerning, for example:
- the possible installation and maintenance of sprinkler systems;
- conditions on occupancy of building or fire compartment;
- the use of approved insulation and coating materials, including their maintenance.
1.2 Assumptions
(1) In addition to the general assumptions of EN 1990 the following assumptions apply:
- any active and passive fire protection systems taken into account in the design will be adequately maintained;
- the choice of the relevant design fire scenario is made by appropriate qualified and experienced personnel, or is given by the relevant national regulation.
- Status
- Not Published
- Public Enquiry End Date
- 29-Jul-2026
- Technical Committee
- KON - Structures
- Current Stage
- 4020 - Public enquire (PE) (Adopted Project)
- Start Date
- 10-Jun-2026
- Due Date
- 28-Oct-2026
SIST EN 1991-1-2:2024/oprA1:2026 is a Slovenian draft amendment to Eurocode 1, prepared by CEN/TC 250 and published by SIST. It covers thermal and mechanical actions on buildings and civil engineering works exposed to fire, for use by structural designers, fire engineers, and anyone checking fire-resistance design within the Eurocode system.
What does SIST EN 1991-1-2:2024/oprA1:2026 specify?
SIST EN 1991-1-2:2024/oprA1:2026 specifies how to treat fire as an action on structures. The underlying Eurocode part applies to buildings and civil engineering works with fire load related to the building and its occupancy, and it is meant to be used together with the fire design parts of EN 1992 to EN 1996 and EN 1999.
It focuses on thermal actions and mechanical actions for structures exposed to fire. It does not cover assessment of structural damage after a fire, and it leaves out supplementary matters such as sprinkler installation and maintenance, occupancy conditions for a building or fire compartment, and the use and maintenance of approved insulation and coating materials.
The document is arranged as a set of amendments to the whole text and to specific clauses and annexes.
| Annex | What it covers |
|---|---|
| Annex A | Parametric fire curves |
| Annex B | Thermal actions for external members - Simplified calculation method |
| Annex C | Localized fires |
| Annex E | Fire load densities, fire growth rates and rate of heat releases |
| Annex F | Equivalent time of fire exposure |
| Annex H | Thermal actions for structural fire loads of timber structures |
What are the key requirements of SIST EN 1991-1-2:2024/oprA1:2026?
SIST EN 1991-1-2:2024/oprA1:2026 mainly updates the fire-design procedure, the definitions used in fire calculations, and several annex methods. The most important practical effect is that designers must follow the amended wording, references, and calculation inputs when using the 2024 edition.
- Clause 4.4 now separates two design paths. With a nominal fire curve, the temperature analysis is done for a specified period without a cooling phase; with a physically based fire model, the analysis runs for the full fire duration, including cooling. In practice, this changes how long the structure is analysed and which fire scenario is checked.
- Clause 3 updates key symbols and terms. The definition of absorptivity is replaced by thermal effusivity, and W is defined as the width of the wall of the fire compartment, perpendicular to wall 1. This matters because the fire model uses geometry and material response together.
- Clause 3.2.3 redefines Γ and Γ_lim as time factor functions of the opening factor O and thermal effusivity b. That affects parametric fire calculations and the inputs needed for compartment fire modelling.
- Annex A revises the parametric fire curve model, including the use of thermal effusivity for the total enclosure and updated formula references. This is the annex to consult when using parametric temperature-time curves.
- Annex B updates the simplified method for thermal actions on external members and points to EN 1993-1-2:2024 for equivalent rectangles representing flame geometry. In practice, this supports calculations for exposed columns and beams.
- Annex E revises the fire load density data, including the example occupancy table and wording around compartment floor area A_f. This affects how fire load assumptions are selected and documented.
- Annex H updates timber-related fire-load references and the note on National Annex provisions. This matters for timber fire design using the Eurocode timber fire part.
What terms does SIST EN 1991-1-2:2024/oprA1:2026 define?
- Thermal effusivity (b) - the material property used in the amended parametric fire expressions instead of absorptivity.
- Opening factor (O) - a parameter used in compartment-fire modelling to represent the effect of openings on fire development.
- W - the width of the wall of the fire compartment, measured perpendicular to wall 1.
- Γ and Γ_lim - time factor functions used in the parametric fire model and linked to O and b.
- Nominal fire curve - a prescribed fire-temperature curve used for a specified period without cooling.
- Physically based fire model - a fire model that follows the full fire duration, including the cooling phase.
- Fire compartment - the enclosed space used as the basis for fire-load and ventilation-related calculations.
Who uses SIST EN 1991-1-2:2024/oprA1:2026?
SIST EN 1991-1-2:2024/oprA1:2026 is used by structural engineers, fire engineers, and code reviewers who design or check fire resistance for buildings and civil engineering works. It is also relevant to teams working with concrete, steel, composite, masonry, and timber structures under the Eurocode fire-design framework, and to authorities or checking bodies that rely on National Annex choices and defined design fire scenarios.
What changed in SIST EN 1991-1-2:2024/oprA1:2026 from the previous edition?
- References to EN 1990:2023 and EN 1990 are replaced by EN 1990:2023+A1:2026 and EN 1990-1:2023+A1:2026, with corresponding updates in the text.
- The Introduction is updated to point to EN 19100, Eurocode 10 - Design of glass structures, and to note new parts under development for fibre-polymer composite structures and tensioned membrane structures.
- The reference to the Construction Products Regulation (EU) No 305/2011 is replaced by Construction Products Regulation (EU) 2024/3110.
- Clause 4.4 is rewritten to distinguish nominal fire curves from physically based fire models.
- Annexes A, B, C, E, F and H receive technical and editorial updates, including a revised occupancy table in Annex E and updated timber references in Annex H.
Which standards are used with SIST EN 1991-1-2:2024/oprA1:2026?
| Reference | Contribution |
|---|---|
| EN 1990:2023+A1:2026 | Basis of structural and geotechnical design used in the fire-design procedure |
| EN 1990-1:2023+A1:2026 | Updated basis reference used throughout the amendment |
| EN 1990-2 | Cited in a note where additional or amended provisions may be needed |
| EN 1992 to EN 1996 and EN 1999 | Fire design parts used together with this standard for structural fire resistance design |
| EN 1998 (all parts) | Provisions for seismic design and assessment |
| EN 1993-1-2:2024 | Used in Annex B for equivalent flame rectangles around external members |
| EN 1995-1-2:2025, Annex A | Used in Annex H for timber fire-load related reference data |
What does the SIST EN 1991-1-2:2024/oprA1:2026 document contain?
SIST EN 1991-1-2:2024/oprA1:2026 is an amendment document, so it contains modification instructions rather than a full reissue of the standard. It updates the foreword, the Introduction, Clauses 2, 3, 4 and 6, and Annexes A, B, C, E, F and H.
The content includes revised terms and symbols, changed references, updated fire-design procedure wording, and amendments to formulas, figures, and one table. It also identifies where editorial corrections were made.
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Frequently Asked Questions
SIST EN 1991-1-2:2024/oprA1:2026 is a draft published by the Slovenian Institute for Standardization (SIST). Its full title is "Eurocode 1 - Actions on structures - Part 1-2: Actions on structures exposed to fire". This standard covers: 1.1 Scope of EN 1991 1 2 (1) The methods given in this Eurocode are applicable to buildings and civil engineering works, with a fire load related to the building and its occupancy. (2) EN 1991 1 2 deals with thermal and mechanical actions on structures exposed to fire. It is intended to be used in conjunction with the fire design Parts of EN 1992 to EN 1996 and EN 1999 which give rules for designing structures for fire resistance. (3) EN 1991 1 2 contains thermal actions either nominal or physically based. More data and models for physically based thermal actions are given in annexes. (4) EN 1991 1 2 does not cover the assessment of the damage of a structure after a fire. (5) EN 1991 1 2 does not cover supplementary requirements concerning, for example: - the possible installation and maintenance of sprinkler systems; - conditions on occupancy of building or fire compartment; - the use of approved insulation and coating materials, including their maintenance. 1.2 Assumptions (1) In addition to the general assumptions of EN 1990 the following assumptions apply: - any active and passive fire protection systems taken into account in the design will be adequately maintained; - the choice of the relevant design fire scenario is made by appropriate qualified and experienced personnel, or is given by the relevant national regulation.
1.1 Scope of EN 1991 1 2 (1) The methods given in this Eurocode are applicable to buildings and civil engineering works, with a fire load related to the building and its occupancy. (2) EN 1991 1 2 deals with thermal and mechanical actions on structures exposed to fire. It is intended to be used in conjunction with the fire design Parts of EN 1992 to EN 1996 and EN 1999 which give rules for designing structures for fire resistance. (3) EN 1991 1 2 contains thermal actions either nominal or physically based. More data and models for physically based thermal actions are given in annexes. (4) EN 1991 1 2 does not cover the assessment of the damage of a structure after a fire. (5) EN 1991 1 2 does not cover supplementary requirements concerning, for example: - the possible installation and maintenance of sprinkler systems; - conditions on occupancy of building or fire compartment; - the use of approved insulation and coating materials, including their maintenance. 1.2 Assumptions (1) In addition to the general assumptions of EN 1990 the following assumptions apply: - any active and passive fire protection systems taken into account in the design will be adequately maintained; - the choice of the relevant design fire scenario is made by appropriate qualified and experienced personnel, or is given by the relevant national regulation.
SIST EN 1991-1-2:2024/oprA1:2026 is classified under the following ICS (International Classification for Standards) categories: 13.220.50 - Fire-resistance of building materials and elements; 91.010.30 - Technical aspects. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 1991-1-2:2024/oprA1:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2026
Evrokod 1 - Vplivi na konstrukcije - 1-2. del: Vplivi na konstrukcije pri požaru
Eurocode 1 - Actions on structures - Part 1-2: Actions on structures exposed to fire
Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-2: Allgemeine Einwirkungen -
Brandeinwirkungen auf Tragwerke
Eurocode 1 - Actions sur les structures - Partie 1-2 : Actions sur les structures exposées
au feu
Ta slovenski standard je istoveten z: EN 1991-1-2:2024/prA1
ICS:
13.220.50 Požarna odpornost Fire-resistance of building
gradbenih materialov in materials and elements
elementov
91.010.30 Tehnični vidiki Technical aspects
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
EN 1991-1-2:2024
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
June 2026
ICS 13.220.50; 91.010.30
English Version
Eurocode 1 - Actions on structures - Part 1-2: Actions on
structures exposed to fire
Eurocode 1 - Actions sur les structures - Partie 1-2 : Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-2:
Actions sur les structures exposées au feu Allgemeine Einwirkungen - Brandeinwirkungen auf
Tragwerke
This draft amendment is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 250.
This draft amendment A1, if approved, will modify the European Standard EN 1991-1-2:2024. If this draft becomes an
amendment, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
inclusion of this amendment into the relevant national standard without any alteration.
This draft amendment was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1991-1-2:2024/prA1:2026 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
1 Modifications throughout the whole document . 4
2 Modifications to the Introduction . 4
3 Modification to Clause 2, “Normative references” . 4
4 Modifications to Clause 3, “Terms, definitions and symbols” . 4
5 Modifications to Clause 4, “Structural fire design procedure” . 5
6 Modification to Clause 6, “Mechanical actions for structural analysis” . 5
7 Modification to Annex A, “Parametric fire curves” . 5
8 Modifications to Annex B, “Thermal actions for external members — Simplified calculation
method” . 6
9 Modification to Annex C, “Localized fires” . 6
10 Modifications to Annex E, “Fire load densities, fire growth rates and rate of heat releases”
............................................................................................................................................................................... 7
11 Modification to Annex F, “Equivalent time of fire exposure” . 7
12 Modification to Annex H, “Thermal actions for structural fire loads of timber structures” 7
European foreword
This document (EN 1991-1-2:2024/prA1:2026) has been prepared by Technical Committee CEN/TC 250
“Structural Eurocodes”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document will amend EN 1991-1-2:2024.
NOTE Some modifications are purely editorial corrections to improve the quality of the document and these
will not be tagged in the consolidated publication, as noted after the modification.
The first generation of EN Eurocodes was published between 2002 and 2007. This document forms part
of the second generation of the Eurocodes, which have been prepared under Mandate M/515 issued to
CEN by the European Commission and the European Free Trade Association.
The Eurocodes have been drafted to be used in conjunction with relevant execution, material, product
and test standards, and to identify requirements for execution, materials, products and testing that are
relied upon by the Eurocodes.
The Eurocodes recognize the responsibility of each Member State and have safeguarded their right to
determine values related to regulatory safety matters at national level through the use of National
Annexes.
1 Modifications throughout the whol
...