1. Eurocode 1: Actions on structures –
Part 1–2: General actions – Actions on structures exposed to fire
Annex B (informative)
Thermal actions for external members – Simplified calculation method
Part of the One Stop Shop program

2. Introduction This method allows
Determination of maximum compartment temperatures
Determination of size and temperatures of flame from openings
Determination of radiation and convection parameters
This method is only valid for fire loads higher than 200 MJ/m2

3. Ventilation mode Forced draught conditions
If there are windows on opposite sides of the compartment (or air is being fed from another source)
No forced draught conditions
If the windows in one side of the compartment are the only source of fresh air

4. No forced draught The heat release rate is given by
The temperature of the compartment is given by
The flame height is given by

5. D / W ratio When there are windows only in Wall 1
Width of wall perpendicular to Wall 1
When there are windows only in Wall 1
Sum of window widths
Width of Wall 1 (assumed to have greatest window area)
When there are windows only in more than one wall
Sum of window areas on Wall 1
Total area of vertical openings
Length and width of the core
When there is a core in the fire compartment
Length and width of the compartment

6. No forced draught
Flame width
The flame width is taken as equal to the width of the opening from which it is projected
Horizontal cross-section of opening

7. Flame depth The flame depth is 2/3 of the window height
No forced draught
Flame depth
The flame depth is 2/3 of the window height
Vertical cross-section of opening

8. Horizontal flame projection - Wall above window
No forced draught
Horizontal flame projection - Wall above window
In the case of a wall existing above the window
For
And the distance to another window
In all other cases
Vertical cross-section of opening

9. Axial Flame Length - Wall above window
No forced draught
Axial Flame Length - Wall above window
In the case of a wall existing above the window or if as
Vertical cross-section of opening

10. Flame projection and length - NO Wall above window
No forced draught
Flame projection and length - NO Wall above window
In the case of a wall not existing above the window, the horizontal projection of the flame is given by
The flame length along the axis can be given as
Vertical cross-section of opening

11. Flame temperature The flame temperature at the window is given by
No forced draught
Flame temperature
The flame temperature at the window is given by
with
The flame temperature along the axis is given by
with
The emissivity of flames may be taken as
The convective heat transfer coefficient is given by
Flame thickness

12. Forced draught The heat release rate is given by
The temperature of the compartment is given by
The flame height is given by

13. Flame dimensions Horizontal cross-section Vertical cross-section
Forced draught
Flame dimensions
Horizontal cross-section
Vertical cross-section
Flame width
Flame length along axis
Horizontal projection of flame is given by

14. Flame temperature The flame temperature at the window is given by
Forced draught
Flame temperature
The flame temperature at the window is given by
with
The emissivity of flames at the window may be taken as
The flame temperature along the axis is given by
The convective heat transfer coefficient is given by
The emissivity of flames may be taken as
Flame thickness

15. No forced draught
Awnings and Balconies
If located at the top of the window (across whole width with wall above window) and the following adjustments should be made
Flame height should be decreased by
Horizontal projection should be increased by
For NO wall above, or
Flame height should be decreased by
Horizontal projection should be increased by

16. Configuration factors
The overall configuration factor of a member for radiative heat transfer from an opening should be determined from
is the configuration factor of member face i for that opening
is the cross-sectional dimension of member face i
is the protection coefficient of member face i:
protected
unprotected