Optimal Decision-Making of Renewable Energy Systems in Buildings in the Early Design Stage
Round 1
Reviewer 1 Report
The authors aims to suggest a simplified design method for renewable energy system in building at the early design stage. The topic is useful and practical for the architects and engineers. The manuscript is organized well, but should be revised before publication.
Line 27 the Department of Energy -> the U.S. Department of Energy.
Line 192 Line 211 What is the conversion coefficient by region? Why is it needed? The authors should be added more information on the conversion coefficient for the readers who are not familiar with the Korean situation.
Line 229 In addition to the input-output flow chart, the diagram of overall framework or function configuration of the design tool as well as the user interface will be helpful.
Author Response
We are immensely thankful to the reviewers for your extensive review of our manuscript. You have raised important issues, and your comments is very helpful for improving the manuscript. We agree with your comments, and we have revised our manuscript accordingly.
We have incorporated all the suggestions of the reviewers and clarified the text where required. We are confident that the manuscript has now improved significantly. We have responded to each of the comments in detail, and have included the revisions with their corresponding line numbers in the revised manuscript.
We hope that the reviewer will find our responses satisfactory, and we shall finalize the revised version of the manuscript after including any further suggestions that the reviewer might have.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The overall strategy, while simple and showing some merit does not appear to factor in time of energy usage with generation, variability and intermittency considerations.
Multiple adhoc combinations of renewables are unlikely to be used in practice as maintenance costs are obviously going to be affected, building aesthetics are also a likely challenge.
A proper case study should consider seasonal aspects(including climate change anomolies) and show how the load and renewable sources match adequately overall, e.g. under some conditions flat plate collectors may be unable to provide any input where evacuated tube styles are still operating efficiently, this is not considered in any detail.
Costings should be whole of life cycle not merely installation, other factors such as impact from other building may also significantly impact the BIPV figures stated.
Author Response
We are immensely thankful to the reviewers for your extensive review of our manuscript. You have raised important issues, and your comments is very helpful for improving the manuscript. We agree with your comments, and we have revised our manuscript accordingly.
We have incorporated all the suggestions of the reviewers and clarified the text where required. We are confident that the manuscript has now improved significantly. We have responded to each of the comments in detail, and have included the revisions with their corresponding line numbers in the revised manuscript.
We hope that the reviewer will find our responses satisfactory, and we shall finalize the revised version of the manuscript after including any further suggestions that the reviewer might have.
Author Response File: Author Response.docx
Reviewer 3 Report
This work suggested a simple design method for renewable energy system (RES) during the early building design stage. Authors examined the amount of energy generation and installation cost ratio of each RES. I think, these results can provide timely helpful information to make the politic decision on the choice of RES systems. The provided detail data are well analyzed and interpreted briefly. The paper is written very well. Therefore, I would recommend this paper for publication in Sustainability in its present form.
Author Response
We are immensely thankful to the reviewers for your extensive review of our manuscript. Your comments is very helpful for improving the manuscript, and we agree with your comments. We hope that the reviewer will find our responses satisfactory.
Round 2
Reviewer 2 Report
"To consider the overall cost associated with the RES, the life cycle cost (LCC) is a more appropriate index than the installation cost; however, more importantly, the design alternative should meet the requirements of the related law. Therefore, this study primarily considered two indexes, the amount of energy generation and total installation cost, to obtain the optimal design alternatives."
You indicate that the law needs to be met, by this I assume you are referring to the mandatory energy requirements and I have no issue with your approach on this aspect. However it makes no economic or aesthetic sense in having 3 varieties of solar thermal panel of similar efficiency in one installation, as the required spares and maintenance are much higher over the life of the asset. Project Installation cost would inherently be increased as multiple designs would be needed with added procurement, delivery, commissioning, certification etc.
As mentioned previously, your coefficient does little to cater for dynamic conditions (daily and seasonal) and your examples cited seem to be within 5% anyway. How does this overly simplistic approach cater for greater seasonal differences when a flat plate may be ineffective, or is this model only intended for equatorial regions.
Author Response
We greatly appreciate the reviewer’s valuable advice at improving the overall quality of our manuscript.
We have carefully modified the revised manuscript and highlighted all revisions in red.
We hope that the reviewer finds our responses to be satisfactory.
We will finalize the revised version of the manuscript after including any further suggestions from reviewers.
Author Response File: Author Response.docx
