If your windspeed is indeed m/s then this is not correct. This scale division is for km/h. For m/s the values are:
- platform: template
sensors:
windforce:
friendly_name: Wind force
icon_template: " mdi:weather-windy"
value_template: "{% set wind = states('sensor.windspeed')|float %}
{% set wind_round = wind|round(1) %}
{% if wind <= 0,2 %}Bft: 0, Wind stil, {{wind_round}} m/s
{% elif wind <= 1.5 %}Bft: 1, Zwak: flauwe wind, {{wind_round}} m/s
{% elif wind <= 3.3 %}Bft: 2, Zwak, {{wind_round}} m/s
{% elif wind <= 5.4 %}Bft: 3, Matig: lichte bries, {{wind_round}} m/s
{% elif wind <= 7.9 %}Bft: 4, Matig: flauwe bries, {{wind_round}} m/s
{% elif wind <= 10.7 %}Bft: 5, Vrij krachtig, {{wind_round}} m/s
{% elif wind <= 13.8 %}Bft: 6, Krachtig, {{wind_round}} m/s
{% elif wind <= 17.1 %}Bft: 7, Hard, {{wind_round}} m/s
{% elif wind <= 20.7 %}Bft: 8, Stormachting, {{wind_round}} m/s
{% elif wind <= 24.4 %}Bft: 9, Storm, {{wind_round}} m/s
{% elif wind <= 28.4 %}Bft: 10, Zware storm, {{wind_round}} m/s
{% elif wind <= 32.6 %}Bft: 11, Zeer zware storm, {{wind_round}} m/s
{% else %}Bft: 12, Orkaan, {{wind_round}} m/s
{%- endif %}"
Cool project though!