Eurocode 1-4 – Wind Load Calculation for Facades

Sample Eurocode Wind Load Report

At Beus Facade, we provide facade consultancy and facade engineering services for building owners, contractors, and architects. According to the TS EN 1991-1-4 (Eurocode 1-4) standard, we perform facade wind load calculations or review existing projects to determine pressures based on basic wind speed, terrain roughness, building height, and facade zones (Zone A–D). These studies are used for preliminary assessment of the static resistance of curtain wall and aluminium facade systems and for preparing data before wind tunnel tests.

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Similarly, you can contact us for calculations of anchor, bolt, welded connection or continuous beam and other static analyses.

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Inputs

Project Subject Prepared by Approved by

Direction Coefficient C_dir – Season Coefficient C_season – Basic Wind Speed V_b,0 m/s Orography Coefficient C_o(z) – Turbulence Coefficient K₁ – Terrain Category (z₀) – Height z m Air Density ρ kg/m³ Structure / Panel Width bₚ m Structure / Panel Height hₚ m Apply area effect
(1–10 m²) m²

A (Loaded area) m²

Pressure Coefficient C_pe (ZONE-A, suction) – Pressure Coefficient C_pe (ZONE-D, pressure) –

Enter the basic parameters; ln(z/z₀) must be defined (z > z₀).

According to EN 1991-1-4/December 2007, section 7.2.1:

For 1 m² ≤ A ≤ 10 m² c_pe(A) = c_pe,1 − (c_pe,1 − c_pe,10)·log₁₀A
A < 1 m² → c_pe=c_pe,1
A ≥ 10 m² → c_pe=c_pe,10
c_pe,1 applies to small elements/fixings, c_pe,10 is typical for the global structure.

If wind pressure acts on a very small surface area, local suction/pressure peaks are higher. As the loaded area increases, local fluctuations are averaged out and the effective pressure decreases. cₚₑ,1 → for 1 m² or smaller areas: represents the “most severe” local effect. cₚₑ,10 → for areas of 10 m² or larger: represents the “average” effect.

Design Wind Load Result

V_b (m/s)

–

K_r

–

C_r(z)

–

V_m(z) (m/s)

–

I_v(z)

–

q_p(z) (kN/m²)

–

C_pe(A)

–

C_pe(D)

–

ZONE-A (Suction)

– kN/m²

w_A = q_p · C_pe,A

ZONE-D (Pressure)

– kN/m²

w_D = q_p · C_pe,D

Note: For q_p in kN/m², the conversion 1 kPa = 1 kN/m² is applied.

Program Logic (EN 1991-1-4:2007)

Summary: As the input parameters change, the following steps are calculated in sequence and results are updated instantly.

Inputs

C_dir, C_season (National Annex) – §4.2
v_b,0 Basic wind velocity (NA) – §4.2
C_o(z) Orography factor – §4.3.3
z₀, z Roughness length & height (z > z₀) – §4.3.2
K₁ Turbulence factor (NA) – §4.4
ρ Air density (typ. 1.25 kg/m³) – §4.5
bₚ×hₚ Component/Cladding area $A = b_p \cdot h_p$ – §7.2.1, Fig. 7.2
c_pe,1, c_pe,10 (Zones A–E; NA & Table 7.1)

Wind velocity — profile — turbulence

$$ v_b = C_{dir} \cdot C_{season} \cdot v_{b,0} \quad [\S 4.2] $$ $$ K_r = 0.19 \left(\frac{z_0}{0.05}\right)^{0.07}, \quad C_r(z) = K_r \cdot \ln\!\left(\frac{z}{z_0}\right) \quad [\S 4.3.2] $$ $$ v_m(z) = C_r(z) \cdot C_o(z) \cdot v_b \quad [\S 4.3.2{-}4.3.3] $$ $$ I_v(z) = \frac{K_1}{C_o(z) \cdot \ln\!\left(\tfrac{z}{z_0}\right)} \quad [\S 4.4] $$

Peak velocity pressure

$$ q_p(z) = \bigl(1 + 7 I_v(z)\bigr)\,\tfrac{1}{2}\,\rho\,v_m(z)^2 \quad (1 \text{ kPa} = 1 \text{ kN/m}^2)\; [\S 4.5] $$

Area effect (for components/claddings)

$$ c_{pe}(A) = \begin{cases} c_{pe,1}, & A < 1 \,\text{m}^2 \\ c_{pe,1} - (c_{pe,1} - c_{pe,10}) \cdot \log_{10}(A), & 1 \le A \le 10 \,\text{m}^2 \\ c_{pe,10}, & A > 10 \,\text{m}^2 \end{cases} \quad [\S 7.2.1,\; Fig.\;7.2] $$

Similarly, for Zone D use $c_{pe,1(D)}$ and $c_{pe,10(D)}$.

Surface and net loads

$$ w_A = q_p(z) \cdot c_{pe(A)}, \quad w_D = q_p(z) \cdot c_{pe(D)} $$ $$ w_{net} = q_p(z)\,\bigl(c_{pe} - c_{pi}\bigr) $$

References

EN 1991-1-4:2007, §4.2–§4.5, §7.2.1, Figure 7.2; National Annex (C_dir, C_season, v_b,0, K₁, c_pe values).

Disclaimer: This calculator provides a sample approach for wind load estimation. It is for preliminary information only; final design and application decisions must be checked and approved by qualified engineers in accordance with relevant standards. Beus Facade accepts no liability for applications based on the results of this tool.

For more detailed façade structural calculations and integration of wind tunnel test results, visit our Façade Engineering Calculation Tools page. For standard summaries, see TS 498 – Wind and EN 1991-1-4 Summary.

Need support in practice? Contact us for façade structural calculations, anchor and connection checks.

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