CREYAP 2021 - WindEurope Technology Workshop 2021
Resource Assessment & Analysis of Operating Wind Farms 2021
8-10 September • Online


In partnership with:

How does your model perform? Take part in our latest CREYAP and find out!

Since 2011, WindEurope has been a proud supporter of comparison and benchmarking exercises that can help the industry improve its modelling and analysis capabilities.

CREYAP stands for “Comparison of Resource and Energy Yield Assessment Procedures”. Courtesy of Ørsted and DTU, Technical University of Denmark, this fifth edition – the third to focus on offshore wind – aims to investigate new themes which have become relevant in the wind energy sector during the most recent years and which were not included in the previous CREYAPs. The latest CREYAP was run in 2015, and this new CREYAP exercise will allow us to assess how the wind energy sector has developed and understand where wind analysts need to focus to continue developing this area.


The 2021 CREYAP exercise will be based on the operating Walney Extension offshore wind farm, which consists of 40 MHI-Vestas 8.25 MW wind turbines and 47 Siemens Gamesa 7 MW wind turbines. Using the data provided, the participants (organisations/teams) will estimate the net energy yield for the Walney Extension wind farm, accounting for wind speed variations over time and across the site, and for turbine interaction losses.

The exercise is supposed to provide a realistic estimate of the Walney Extension wind farm energy yield. It is intended not only as a comparative exercise, using public information about the wind farm, but also as a benchmark exercise gauging how well the industry can estimate actual offshore wind farm energy yields.

To focus the exercise on the different modelling applied by the different participants, all participants will receive and apply the same wind measurement data from the site, which have been provided by Ørsted and quality assessed and filtered by DTU Wind Energy.


From previous CREYAP exercises for offshore wind farms, the following themes have been identified as important: uncertainty estimation and calculation, turbine interaction modelling, long-term extrapolation methods, systematic operational losses estimation, vertical extrapolation and tall turbines, horizontal extrapolation, stability and challenging climatology, wind conditions and site suitability.

The CREYAP 2021 exercise will include these new themes:

Moreover, the exercise will be similar to previous CREYAP exercises and report on:


3 May 2021Data pack and instructions available for download
28 June 2021Deadline to submit results (send output template back to techworkshops[a]
July-August 2021DTU to:
  • analyze the submitted results
  • prepare feedback and reporting
  • prepare the presentation for the participants
10 September 2021Results presented at the WindEurope Technology Workshop: “Resource Assessment & Analysis of Operating Wind Farms 2021″

Still some questions?

You downloaded the datapack, you read the instructions, and something is still unclear? We are at your disposal to answer any question you may have on the exercise, but BEFORE you email us, please check out our ‘Questions and Answers‘ page, we might already have answered it! 🙂 Otherwise, you can email your questions to techworkshops[a]


Energy yield assessment process

All participants will apply the same input data and follow the main steps in the energy yield assessment process. However, the different participants will apply different modelling and therefore derive different results. This will allow for specific comparisons of the different results and modelling.


DTU Wind Energy will apply the following methodology:


A summary of CREYAP exercises from 2011-15 is given below; these publications have been downloaded more than 6,000 times from at DTU.

References for offshore wind farms are:

References for onshore wind farms are: