Wind zones map

What are the French wind zones according to Eurocode 1 ?

On the map of the national annex, the French metropolitan area is divided into four wind zones identified from 1 to 4. Amendment A3, published in April 2019, replaces the division by cantons into a division by municipalities.

Zone	1	2	3	4
Fundamental value of the basic wind velocity v_b,0	22m/s	24m/s	26m/s	28m/s

The French overseas departments, overseas territories and overseas collectivities each have a specific basic wind velocity.

Basic wind velocity for overseas departments
Zone	French Guiana	Mayotte Island	Martinique Island	Reunion Island	Guadeloupe Island
Fundamental value of the basic wind velocityv_b,0	17m/s	30m/s	32m/s	34m/s	36m/s

Basic wind velocity for overseas territories and overseas collectivities
Zone	New Caledonia	Wallis and Futuna	Saint Martin	Saint Barths	Saint Pierre and Miquelon
Fundamental value of the basic wind velocity v_b,0	36m/s	41.2m/s	36m/s	36m/s	36m/s

Wind zoning of Metropolitan France (2019-2024)

How to adjust the basic wind velocity for each direction of wind and according to return period in France ?

A variation have to be considered with the probability factor C_prob.

When the wind comes from a direction where the probability of occurrence of strong winds is less, a reduction can be considered with the directional factor C_dir.

You should also take in account the effect of the roughness of the terrain (vegetation / urbanization) and the effect of orography (terrain relief) to accurately determine the peak velocity pressure for each wind direction.

Which are the terrain categories in France ?

0 -

Sea or coastal area exposed to the open sea; lakes and water bodies covered by wind over a distance of at least 5km.

II -

Open field, with or without a few isolated obstacles (trees, buildings, etc.) separated from each other by more than their height x40.

IIIa -

Campaign with hedges; vineyards; grove; sparsely populated.

IIIb -

Urban or industrial areas; dense grove; orchards.

IV -

Urban areas with at least 15%% of the surface is covered with buildings whose average height is greater than 15m; forests.

Particularity concerning New Caledonia

Wind zoning of Metropolitan France (2019-2024) The terrain categories have been transposed to Caledonian landscapes. The reference to terrain category IV is removed and categories 0 to III of standard NF EN 1991-1-4 are illustrated by the photographs below :

0 -

Sea side.

II -

Open field.

IIIa -

Campaign with hedges.

IIIb -

Industrial areas.

Source: RCNC

Example of results given by the software

See the features of Eurocodes Zoning for snow analysis in France

Available in English/French, otherwise «Google Translate»!

B1 - Localization

Coordinates in World Geodetic System 1984 (WGS84) 3.5332°, 45.7153°

Coordinates in French Geodetic System 1993 (Lambert 93) 741482m, 6512993m

Address D 304A, 63120 Sauviat, Auvergne-Rhône-Alpes

B2 - Elevations

Distances / Direction	At the place of construction	500m	1000m
North	436 m	360m	407m
Northeast		405m	465m
East		456m	473m
Southeast		419m	446m
South		449m	476m
Southwest		432m	411m
West		360m	468m
Northwest		403m	452m

B3 - Building

Type of building Design working life category Max height Orientation from North

monumental building

100 years

15.0 m

80°

B4 - Terrain categories

Sectors	1	2	3	4
Categories	IIIa	IV	IV	IV

Radius R of the angular sector 593m

C1 - Snow

NF EN 1991-1-3/NA (may 2007) + A1 (july 2011)

Zone : A2(s_k,0 = 0.45 kN/m²)

Criteria for zoning : PUY-DE-DOME (63)

Characteristic value of snow on the ground at the relevant site : s_k,436 = 0.686 kN/m²

Ground snow load with a return period of 100 years : s_{100 ans} = 0.774 kN/m²

Design value of exceptional snow load on the ground : s_ad = 1.0 kN/m²

C2 - Wind

NF EN 1991-1-4/NA (march 2008) + A1 (july 2011) + A2 (september 2012) + A3 (april 2019)

Zone : 2(v_b,0 = 24.0 m/s)

Criteria for zoning : PUY-DE-DOME (63)

Zone c_dir : 1

Sectors	1	2	3	4
Sector definition	from 35 ° to 125 °	from 125 ° to 215 °	from 215 ° to 305 °	from 305 ° to 35 °
Fundamental value of the basic wind velocity v_b,0	24.0m/s
Shape parameter K	0.2
Exponent n	0.5
Annual probability of exceedence p	0.01
Probability factor c_prob	1.038
Directional factor c_dir	0.7	1.0	1.0	1.0
Basic wind velocity v_b	17.4m/s	24.9m/s	24.9m/s	24.9m/s
Reference roughness length z_0,II	0.05m
Roughness length z₀	0.2m	1.0m	1.0m	1.0m
Terrain factor k_r	0.209	0.234	0.234	0.234
Height above ground z	15.0m
Minimum height z_min	5.0m	15.0m	15.0m	15.0m
Roughness factor c_r(z)	0.904	0.635	0.635	0.635
Orography factor ^* c_o(z)	1.0	1.0	1.0	1.0
Mean wind velocity v_m(z)	15.8m/s	15.8m/s	15.8m/s	15.8m/s
Turbulence factor k_l	0.97	0.854	0.854	0.854
Standard deviation of the turbulence σ_v	3.544m/s	4.989m/s	4.989m/s	4.989m/s
Turbulence intensity I_v(z)	0.225	0.315	0.315	0.315
Air density ρ	1.225kg/m³
Exposure factor c_e(z)	2.102	1.292	1.292	1.292
Peak velocity pressure q_p(z)	392.0N/m²	491.5N/m²	491.5N/m²	491.5N/m²
Peak wind velocity for Serviceability Limit States v_p(z),SLS	91.1km/h	102.0km/h	102.0km/h	102.0km/h
Peak wind velocity for Ultimate Limit States v_p(z),ULS	111.5km/h	124.9km/h	124.9km/h	124.9km/h

* Here, the orography factor is calculated according to Procedure 1, for an orography consisting of obstacles of various heights and shapes. This type of orography is the most frequently encountered.However, if the building is in a case of orography consisting of well individualized obstacle (isolated hills and ridges or cliffs and escarpments) the orography factor must be calculated according to the procedure 2. According to EN 1991-1-4 §4.3.3(1), the calculated orography factor (1.018) is not taken into account because it does not increase wind velocities by more than 5%%.

C3 - Seism

Code of the Environment - Article D563-8-1 (09/01/2015) JORF n°0248 of 24/10/2010 text N°5

Zone : 3(1.1 m/s²)

Criteria for zoning : Sauviat, Puy-de-Dome (63)

A seismic analysis may be required for this building.

Wind zones map - France