SITE COMPLIANCE calculates the main checks required in site suitability assessments according to the IEC61400-1 standard, ed. 4 (2019), ed. 3 (2010) or ed. 2 (1999). For each main check the module evaluates if a wind turbine class (e.g. IIA) is suitable for the actual site and layout conditions.

SITE COMPLIANCE helps identify critical risks in a wind farm project and guide the design of suitable layouts. SITE COMPLIANCE includes easy export of results to fulfil input required by wind turbine manufacturers.

Easy IEC calculations

The module calculates the main checks at hub height of each wind turbine position as required in IEC 61400-1:

  • Terrain complexity
  • Extreme wind
  • Effective turbulence
  • Wind distribution
  • Wind shear
  • Flow inclination
  • Air density
  • Extreme turbulence (ed. 4 only)

Several calculation methods are possible for each main check. Results of multiple methods for a check are easily compared to help choose the most appropriate method and test how results depend on model setup and choice of data.

The module also includes calculation of the supplementary checks:

  • Seismic hazard
  • Annual lightning rate
  • Hours outside normal and extreme temperature ranges


A full assessment of the IEC checks may be performed with site measurements and a WAsP license. SITE COMPLIANCE also includes a seamless and user-friendly integration of the flow models WAsP Engineering and WAsP-CFD as well as pre-run flow results from any CFD model via the Flowres format enabling additional calculation options for several of the main checks. The flow models define the flow field (i.e. variation) of wind speed, turbulence and flow inclination utilized in calculation of the main checks. IEC design classes (e.g. IIIA or IIB) may be individually set for each wind turbine in a layout and a flexible user-input is offered for customized ‘Class S’ models. The module is user-friendly yet allowing elaborate calculation alternatives for advanced users to compare, test and validate results and their sensitivity to key assumptions.

When one or more of the main IEC checks are exceeded the IEC61400-1 standard requires a load calculation to assess the chosen turbine models ‘structural integrity’ for the site and layout. This requires an assessment that on-site loads do not exceed design loads for all turbine components at all turbine positions. The LOAD RESPONSE module (see separate module description) implements this requirement via an advanced response surface methodology based on large amounts of pre-run load assessments to allow very fast and accurate load assessments. The resulting loads are presented as ‘load indices’, i.e. actual loads normalized to design loads, for each main component.


Input Data

SITE COMPLIANCE is a versatile module and may be used with quite different input data. A typical user has one or more on-site masts (Meteo Objects) and a WAsP license. This is enough to perform all IEC main checks. If the user also has a WAsP Engineering  (WEng) license or are using pre-run flow results from any CFD model via the Flowres format, extra calculation options are available.

A full site compliance evaluation may also be performed when no site mast is available. In this case a WAsP license, a calibrated wind statistic (in a Site Data Object) and a WEng license are required to calculate the main checks. All main checks may also be completed with only a representative site mast (Meteo Object) and no flow models. This setup is mainly relevant for small sites in very simple terrain or offshore.

Flexible and easy to use

The main purpose of the module is to offer users a tool, which makes it easy and fast to calculate all the main checks in a consistent and IEC compliant way. Yet the module still allows easy change of important model assumptions to analyse their effect on the results. This is ensured by letting the user define all the input data: site masts, WTGs and results of flow models prior to calculating the checks.


The main report page of SITE COMPLIANCE summarizes the outcome of the main checks for the park, clearly highlighting critical risks, i.e. checks where the chosen turbine model does not comply with the conditions on the site. The report summarizes all the main assumptions in the calculations and presents the results turbine for turbine.