As reviewer of the Manuscript wes-2026-38 entitled " Lifetime reassessment of offshore wind turbines considering different operating conditions using Kriging meta-models", I have thoroughly reviewed the manuscript, and I would recommend in accept the manuscript based on my review.

1. In the abstract, lifetime reassessment is performed using three different models. It is worth adding in the abstract itself, the quantitative comparison among the three different methods.
2. In the abstract, the author can add their insights on high level takeaways and choices among three different methods.
3. In the literature review, there are significant number of references are mentioned in the manuscript, but there is no clear description on the gap in the existing literature and how it is addressing in the current manuscript. It is value added to clearly bring this into the manuscript.
4. I would suggest adding table of comparison with pro’s and con’s among three different methods to easily understand from the manuscript.
5. There is typo error in 1^st paragraph of conclusions ….which served as a reference soluation and a lifetime calculation
6. General comment: whether the proposed simulation methods are also applicable for onshore wind turbines? Any justifications/comments on the validity might be worth to add as important note in the manuscript.

I hope my critique helps the authors to improve their work and find useful in this review. Best of luck in developing this study further. Thank you!

This paper investigates the use of Kriging/Gaussian-process meta-models for offshore wind turbine lifetime reassessment, considering both normal operation and idling conditions. The authors compare three approaches: a full aeroelastic simulation-based reference calculation, a reduced load-case approach based on IEC 61400-3, and a Kriging meta-model-based approach. The study uses the NREL 5 MW reference turbine on the OC3 monopile, environmental distributions based on FINO 3, and evaluates lifetime damage equivalent loads at the monopile and blade root.

Overall, the paper is well structured, clearly written, and logically developed. The choice of surrogate model is technically sound and supported by established literature. This work represents a valuable contribution to the wind energy community. However, several methodological clarifications and additional validation details are needed before publication. I therefore recommend publication after the authors address the following comments.

Specific Comments

1. In Section 2.3, the authors use a Monte Carlo step-by-step sizing approach to determine where the lifetime DEL converges, thereby avoiding the need to run the full set of 1,314,900 simulations. However, the manuscript does not clearly define the criterion used to determine convergence. What criterion was used to decide that the lifetime DEL had converged? This should be clearly defined.

2. In Lines 324–330,:  I believe the inclusion of idling conditions is one of the key selling points of this paper. Therefore, a deviation of this magnitude should not be dismissed without further explanation. At the very least, some reasoning or investigation should be provided. For example, if idling conditions were excluded, would the deviation remain similarly large? This issue is particularly important if the proposed method is intended to be applied to cases where idling loads are more influential.

3. In Section 3.3, the authors note that using the mean Kriging prediction is not conservative and then state that using the 65th percentile for normal operation and the 70th percentile for idling leads to conservative lifetime DEL estimates. This is an interesting and useful correction, but the choice of these percentiles appears empirical and case-specific. The manuscript should explain how these percentiles were selected and discuss whether they are expected to generalize to other turbines or sites.

1. Line 83 contains a typo: “The paper ist structured as follows.” This should be corrected to “The paper is structured as follows.”
2. Line 158 contains a double period: “...for the in-plane and out-of-plane bending moments.. For idling...”.
3. In Table 2, the range of TpTp​ is listed as “0.25–30.25 m.” This should likely be in seconds rather than meters.