Need more information? (+33) 6 78 57 09 94

Wind zones map – Italy

What are the Italian wind zones according to Eurocode 1 ?

On the map of the national annex, the Italian area is divided by region (and sometimes by province) into nine wind zones identified from 1 to 9. The islands (with the exception of Sicily and Sardinia) and open sea form zone 9.

Zone123456789
Fundamental value of the basic wind velocity vb,025m/s25m/s27m/s28m/s28m/s28m/s28m/s30m/s31m/s
Increased wind velocity above elevation a01000m750m500m500m750m500m1000m1500m500m
Wind zoning of Italy (2010-2024)

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

\[\displaystyle v_{b} = c_{prob} \cdot c_{dir} \cdot v_{b,0}\]
  • A variation have to be considered with the probability factor Cprob.
  • No reduction can be considered with the directionnal factor Cdir=1.0.
  • 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 Italy ?

In Italy, the exposure categories are calculated from :

  • the four roughness classes identified from D to A
  • the distances to the shorelines
  • the elevation of the relevant site

Roughness classes

0 :

Area free of obstacles (open countryside, airports, agricultural areas, pastures, swampy or sandy areas, snowy or icy surfaces, sea, lakes, …)

I :

Areas with widespread obstacles (trees, houses, walls, fences, …); areas with roughness not attributable to classes A, B, D.

II :

Area with low vegetation such as grass and isolated obstacles (trees, buildings) with separations of at least 20 obstacle heights.

IV :

Area in which at least 15% of the surface is covered with buildings and their average height exceeds 15m.

Exposure categories for each wind zones

Zones 1 to 5
Distance to the shorelinefrom  -2 km  to  0 kmfrom  0 km  to  10 kmfrom  10 km  to  40 kmmore than  10 km 
Elevationfrom  0 m  to  500 mfrom  500 m  to  750 mmore than  750 m 
AIVIVVVV
BIIIIIIIVIVIV
C*IIIIIIIVIV
DIIIIIIIIII**
*Category II in zone 1 to 4, category III in zone 5.
**Category III in zone 2 to 5, category IV in zone 1.
Zone 6
Distance to the shorelinefrom  -2 km  to  0 kmfrom  0 km  to  10 kmfrom  10 km  to  40 kmmore than  10 km 
Elevationfrom  0 km  to  500 kmmore than  500 km 
AIIIIVVV
BIIIIIIVIV
CIIIIIIIIIV
DIIIIIIIII
Zones 7 and 8Zone 9
Distance to the shorelinefrom  2 km  to  0.50 kmfrom  -0.5 km  to  0 kmon landDistance to the shorelineat seaon land
AIVAI
BIVBI
CIIICI
DIII*DII
*Category II in zone 8, category III in zone 7.

Example of results given by the software Eurocodes Zoning

B1 – Localization

  • Coordinates in World Geodetic System 1984 (WGS84)  10.5188° , 43.7455°

Address 56011 Calci, Toscana


B2 – Elevations

Coordinates10.5181°, 43.7303°10.5198°, 43.7596°10.5198°, 43.7596°10.5179°, 43.7901°
Elevations60m798m798m109m
Obstacle effective height H 738m689m
Slope actual length Lu / Ld 3261.4m3379.8m
Slope angle Φ 22.6%20.4%
Horizontal distance site/top x1571.5m
Elevation at the place of construction216m

B3 – Building

  • Type of building: monumental building
  • Design working life category: 50 years
  • Max height: 10m
  • Orientation from North: 15°

B4 – Terrain categories

Sectors1234
CategoriesCCBB
Radius R of the angular sector 1000m
Sectors1234
Sector definition from  330 °  to  60 ° from  60 °  to  150 ° from  150 °  to  240 ° from  240 °  to  330 °
Distance to shore > 100 km > 100 km 21.3 km 19.5 km
Exposure categoryIIIIIIIIIIII

C1 – Snow

UNI EN 1991-1-3 Appendice nazionale 24/09/2010

  • Zone : III(sk,0 = 0.6 kN/m²)
  • Criteria for zoning : Pisa, Toscana
  • Characteristic value of snow on the ground at the relevant site : sk,216 = 0.613 kN/m²
  • Ground snow load with a return period of 50 years : s50 ans = 0.613 kN/m²

C2 – Wind

UNI EN 1991-1-3 Appendice nazionale 24/09/2010

  • Zone : 3(vb,0 = 27.0 m/s)
  • Criteria for zoning : Pisa, Toscana
Sectors1234
Sector definition from  330 °  to  60 ° from  60 °  to  150 ° from  150 °  to  240 ° from  240 °  to  330 °
Value of the basic wind velocity from the map  vb,0 27.0m/s
Elevation above which wind velocity increases  vb,0 500m
Fundamental value of the basic wind velocity  vb,0 27.0m/s
Shape parameter  K 0.138
Exponent n1
Annual probability of exceedence p0.02
Probability factor  cprob 1.0
Directional factor  cdir 1.01.01.01.0
Basic wind velocity  vb 27.0m/s27.0m/s27.0m/s27.0m/s
Reference roughness length  z0,II 0.05m
Roughness length  z0 0.1m0.1m0.1m0.1m
Terrain factor  kr 0.20.20.20.2
Height above ground z10.0m
Minimum height  zmin 5.0m5.0m5.0m5.0m
Roughness factor  cr(z) 0.9210.9210.9210.921
Obstacle typeisolated hills
Exposure typedownwindupwind
Factor depending on the type and dimensions of the obstacle  s max 0.4440.00.2820.0
Orography factor  * co(z) 1.1811.01.1281.0
Mean wind velocity  vm(z) 29.4m/s24.9m/s28.0m/s24.9m/s
Turbulence factor  kl 1.01.01.01.0
Standard deviation of the turbulence  σv 5.4m/s5.4m/s5.4m/s5.4m/s
Turbulence intensity  Iv(z) 0.1840.2170.1930.217
Air density  ρ 1.25kg/m3
Exposure factor  ce(z) 2.7062.1382.5322.138
Peak velocity pressure qp(z) 1233.0N/m2974.0N/m21153.8N/m2974.0N/m2
Peak wind velocity for Serviceability Limit States  vp(z),SLS 159.9km/h142.1km/h154.7km/h142.1km/h
Peak wind velocity for Ultimate Limit States  vp(z),ULS 195.8km/h174.1km/h189.4km/h174.1km/h
* The orography factor is calculated for a well individualized obstacle (an emergent zone compared to a general ground without marked relief) 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%.