The study by Walter-Terrinoni et al. intends to present a new bottom-up model for HCFC-141b, a chemical used primarily in foam insulation and whose production is currently being phased out. Using this model, global emissions for HCFC-141b are calculated and compared to measurements. For the time period 1990-2017 the authors find a good agreement with the measurements, but after 2017 the model underestimates the emissions. The authors explain this discrepancy between measurements and model by either a growing additional source of emissions that is inconsistent with reported production or a model deficiency that did not exist or was not apparent before 2017. The manuscript is generally well written and deserves to be published, but major revisions are needed before manuscript can be accepted for publication.

General comment:

In the title, abstract and conclusion it is stated that a new model is presented. However, I could either clearly understand how your model works since I could not find a model description in the manuscript or what the new in this model. Thus, the title, abstract and conclusion do not fit to the content presented in the manuscript and need to be adjusted and the method sections needs to be rewritten so that a model description is provided.

Specific comments:

P4, L119ff: The method section is quite lengthy and the emission values used are explained too much in detail. I had the feeling that I rather read here a scientific report for policy makers than a scientific paper.

P6, L155-L157: For this statements a reference is missing. Where is this documented? Or is this a result from your study? Or are you referring here to some figure shown in the manuscript?

P6, L159 and L169: What are non-Article 5 countries and what are non A5 countries. Same holds for A5 countries, which exactly belong to A5? Where does this naming come from?

P6; L162: This statement is not in accordance with Fig. 2. The highest emissions are for both peaks for the yellow stack which is labelled with “others”.

Figure 2: Why have the “other” countries the highest emissions? Shouldn’t that be rather one of the industrial countries?  

P11, L286-290: Where is the model description and what is new? Are the five equations given here describe the model?

P13, L326: Here you refer to the above described model description which I as reader could not find. For me the previous section was a summary of emission assumptions that have been used to run the model, thus rather which input values have been used rather than how the actual calculation has been done.

P14, L340: Reaching the end of the method section still leaves me puzzled with the questions on what is new and how does the model work. For me this did not become clear only which assumptions have been made.

P15, L358: Add which observations have been used.

Figure 5: Looking at this figure I have two questions:  (1) Your model is generally underestimating the measured emissions. Do you have any idea why? Do you have an idea what could be missing in your model or is this due to an inaccuracy or bias from the measurements? (2) Is this a comparison with pure observations or with models that use observations?

P18, L424: Here you partly answer my first question in the previous comment. It seems that you cannot explain this differences, but do you have any idea?

P19, L444: I would rather name this section “Discussion and conclusion”.

P19, L446: Which “10” geographic regions? In which regions you have separated into has nowhere been mentioned.

P19, L446: Also a list of the 11 foam markets should be added somewhere in the manuscript.

P20, L493: A clear statement what the implication of your study are is missing.

Technical corrections:

P11, L267: remove parentheses around the references.

P15, L358: Figure 5 show -> Figure 5 shows

P19, L439: emissions time series -> emission time series

P19, L442: I guess you mean here rather “noting” than “nothing”.

P19, L452:  remove parentheses around the references.

General comments

This manuscript presents a bottom-up model to estimate global emissions and banks of HCFC-141b based on a comprehensive product lifecycle framework. The study incorporates a wide range of sectoral uses and applies Monte Carlo uncertainty analysis to identify key drivers. The methods are generally robust, and comparisons with atmospheric observations show good temporal agreement. The paper provides valuable insights into bank composition and mitigation potential, which are relevant for policymakers.

However, several assumptions—particularly in parameter selection and uncertainty treatment—warrant further justification. Additionally, the structure of the abstract and limited discussion of regional outputs slightly weakens the policy relevance of the results. Clarifications on model improvements and regional trends would enhance the manuscript’s clarity and utility.

Specific comments

• Line128-135: The decision to assume uniform emission and lifecycle parameters across all regions (except Europe) overlooks the availability of region-specific data, such as those for China (Wang et al., 2015). The authors should discuss the implications of this simplification on regional accuracy or perform a sensitivity test incorporating these regional variations.
• Line 132-133: Since regional differences in consumption and market size significantly affect emissions and banks—ultimately influencing global estimates—I recommend that the authors include regional emission results in the main text to better support regional policy development.
• Line 255-257: Given that a change from 75% (referred in the 2019 TEAP report) to 7.5% is quite large, please provide the exact reason for choosing a scaling factor of 10.
• Line 267-270: The Weibull lifetime parameters appear fixed across regions. It would be helpful to discuss whether regional differences in product lifespans were considered.
• Line 303: The statement “…, however, globally, most foams are likely not shredded before being landfilled” lacks sufficient literature support. It is recommended that the authors cite appropriate references to substantiate this claim or otherwise clarify that this assertion is based on limited regional evidence or expert judgment.
• Line 306-310: The assumed 20% emission rate during dismantling is four times higher than the 5% used in TEAP (2019), which may significantly influence emission and bank estimates. The authors should better justify this choice—ideally with empirical data or sensitivity analysis—and clarify its impact on model outputs.
• Line 335-340: The study assumes independence among most input uncertainties, simplifying the modeling framework. However, market share uncertainties are inherently interdependent, as they must sum to 100%. While a scaling method is applied to address this, the manuscript would benefit from a brief quantitative assessment or supporting citation to demonstrate that this approach does not introduce significant bias.
• Line 379: In Figure 6 caption, it may be clearer to describe the top curve as representing the cumulative amount of HCFC-141b that has either been emitted or remains in banks, rather than simply cumulative consumption, to avoid potential confusion.
• Line 505-509: It is suggested that Table A1 in Appendix A be formatted to fit within a single page to enhance readability
• Line 510-514: Please ensure that the title of Table A2 appears on the same page as the table for clarity and consistency.
• It is also suggested that important sensitivity results (e.g., the relative importance of parameters) be visually summarized in a figure for easier interpretation or listed in Appendix A.