Generative Design Methodology and Framework Exploiting Designer-Algorithm Synergies

Round 1

Reviewer 1 Report

The article presents a study that uses generative design. The paper presents a generative approach in general and applies a case study to the process of shading elements design. The topic is current. There are several research on this topic, and software developers are also working in this area. I have some general suggestions for authors.

Section 1 and 2 introduces the topic of generative design, which is widely known to those involved in this area of research. I recommend that the authors explore the topic in more detail and present a complete picture of state of the art to bring out the innovative aspect of the research presented.

The case study presented is not adequately explained, and it is unclear whether it is a real case. There is a lack of a lot of information that would give insight into the development of the case study. For example, here are some of the questions that could be explored further: is the result obtained through an assessment of indoor comfort or only by the amount of incident light? What were the criteria for defining the optimal result? Where is the building located? What are the climate data and orientation?

The innovative part potentially is the scripts made by the authors, so it is recommended to explore this part further.

The paper's objective seems to be a comparison between traditional and generative-supported design, but the discussion is very brief, and no critical analysis of this aspect is conducted.

Author Response

We thank you for the valuable time you took to review our paper and provide valuable comments. It was your valuable and insightful comments that led to possible improvements in the current version. We hope that after careful revision the manuscript will meet your high standards. The authors have carefully reviewed the comments and have done our best to address each of them. We welcome further constructive comments.

Section 1 and 2 introduces the topic of generative design, which is widely known to those involved in this area of research. I recommend that the authors explore the topic in more detail and present a complete picture of state of the art to bring out the innovative aspect of the research presented.

Additional literature has been provided, but our intention is to show the development of the generative design in lines 44 to 75.

The case study presented is not adequately explained, and it is unclear whether it is a real case. There is a lack of a lot of information that would give insight into the development of the case study. For example, here are some of the questions that could be explored further: is the result obtained through an assessment of indoor comfort or only by the amount of incident light? What were the criteria for defining the optimal result? Where is the building located? What are the climate data and orientation?

The case study section has been expanded to include details about the project and climate data (lines 225-231). An additional figure has been added to show the orientation of the building (Figure 5a). The criteria for optimal results are defined in section 3.2.

The innovative part potentially is the scripts made by the authors, so it is recommended to explore this part further.

The case study computational model section was further expanded to show more about the work done and how a fast and simplified analysis was developed for the purpose of evaluating design options.

The paper's objective seems to be a comparison between traditional and generative-supported design, but the discussion is very brief, and no critical analysis of this aspect is conducted.

The discussion section has been completely revised, moving the previous discussion to a case study section and adding a new discussion where we discuss generative design, how it compares to the traditional approach and why it cannot replace the designer in the current state.

Reviewer 2 Report

The topic of the manuscript seems interesting but it seems to miss a lot of basic information that is necessary to understand the given manuscript. I thereby reject the manuscript to be published in the "Buildings". A more detailed comments are given below.

The title is incomprehensible. An efficient solution of what?

When using abbreviations (e.g. CAD, BIM, etc.) for the first time, please provide full words.

Please avoid using subjective terms. For example, what do you mean by powerful and intelligent in the line shown below?

"Computers are becoming more powerful and intelligent."

" Usually, the designer proposes the 31 solution based on his experience, previous projects and creativity under the given condi- 32 tions and objectives, while the computers are to help with presentation, documentation 33 and analysis, but they do not help with the solving process.": I can't clearly agree with the authors. There are many approaches for solving complex problems using computer algorithms. An optimization scheme is an example. The authors are encouraged to describe what the "generative design" is, and how it is different from optimization.

"The aim of this paper is to present a clear framework and process of the generative design and to answer the question of whether it can replace the designer in the design process.: The statement is also subjective and vague. The authors claim that the proposed method is something

The so-called "framework" shown in Figure 3 and 4 are nothing new. It is already used in structural optimization studies conducted by past researchers.

When performing structural optimization using numerical simulation models, it is very important to provide detailed information about the simulation model since the structural analysis results are largely dependent on the model. Rather than providing detailed information about their model, the authors just adopted the existing software (such as Dynamo, and Revit, etc.) without validating their assumption on model parameter is reasonable. Also, the accuracy of the simulation model is not validated against the experimentally tested results.

Author Response

We thank you for the valuable time you took to review our paper and provide valuable comments. It was your valuable and insightful comments that led to possible improvements in the current version. The authors have carefully reviewed the comments and have done our best to address each of them. We hope that after careful revision the manuscript will meet your high standards. The authors welcome further constructive comments.

The title is incomprehensible. An efficient solution of what?

Upon the discussion between the authors, we changed the title to: “Generative design methodology and framework exploiting designer-algorithm synergies”.

When using abbreviations (e.g. CAD, BIM, etc.) for the first time, please provide full words.

Full words and their abbreviation for CAD and BIM are now provided.

Please avoid using subjective terms. For example, what do you mean by powerful and intelligent in the line shown below? "Computers are becoming more powerful and intelligent."

Subjective terms have been rewritten or removed where applicable.

" Usually, the designer proposes the 31 solution based on his experience, previous projects and creativity under the given condi- 32 tions and objectives, while the computers are to help with presentation, documentation 33 and analysis, but they do not help with the solving process.": I can't clearly agree with the authors. There are many approaches for solving complex problems using computer algorithms. An optimization scheme is an example. The authors are encouraged to describe what the "generative design" is, and how it is different from optimization.

We have rephrased the above sentence to reflect that there are, of course, different methods and to make clear of our intention to compare a traditional solution-oriented approach with a generative problem-oriented approach.

We have also rewritten section 4. Discussion where we discuss generative design, its overlaps with optimisation and the differences between the two. If interested, we also recommend reading the work of Frazer and Janssen (https://doi.org/10.1023/A:1013618703385).

"The aim of this paper is to present a clear framework and process of the generative design and to answer the question of whether it can replace the designer in the design process.: The statement is also subjective and vague. The authors claim that the proposed method is something

We have revised the aims of the paper. Our intention was to extend previous work on generative design and provide a general methodology relevant to the current use of computational and BIM models.

The so-called "framework" shown in Figure 3 and 4 are nothing new. It is already used in structural optimization studies conducted by past researchers.

We recognise in the discussion that there is overlap between generative design and optimisation, and it is therefore to be expected that some of the processes will share common points with structural optimisation. In our figures we tried to provide a more general picture relevant to general design problems, whereas in structural optimisation they show the details and workflows that are specific to that subfield and may not be understandable to readers who wish to apply them to general design problems.

Reviewer 3 Report

This paper presents the framework and methodology of generative design and compares this new approach with respect to traditional design methods, thanks to the presentation of a case study.

Overall, the paper is well structured and written. The following suggestions are made to improve the quality of the paper:

·       Abstract (line 20): it should be specified that presented results are for one specific case study

·       Introduction (line 29); please detail what CAD and BIM stand for.

·       Introduction: it should be anticipated that a specific case study will be presented. This would also smooth the strong affirmation made in lines 90-91: “to answer the question of whether it can replace the designer in the design process.”

·       In section 2, before presenting two specific types of algorithms, it would be useful to have an overview of the types of algorithms that have been used so far in building design, based on the review of section 1. Are these two the only ones? Please justify.

·       Section 2.3.1 is too generic. For instance, the difference between parametric geometry model and finite element model could be given. Besides, in Figure 4 (lines 216-218), BIM models seem an important part of the generative design process. Is it mandatory to have a BIM model? What is its role? These could be further explained in section 2.3.1, as so far BIM models are not mentioned there.

·       Section 2.4: please consider renaming this subsection “Design Methodology”. The reader could get confused otherwise and think that this section refers to the methodology of the research work of the paper or the methodology for the specific case study.

·       Line 284 would instead of will.

·       4.Discussion (line 366): this section only discusses the results of the case study, not the overall results of the paper. As a discussion section is too limited. There could be two alternatives to solve this: section 4 could also try to answer to the question “whether generative design can replace the designer in the design process”. To do so, the outcome of the other cited research works in this regard could be mentioned to have a final answer about it. The second alternative would be to have just a discussion section inside the case study (3.4 Discussion).

Author Response

We thank you for the valuable time you took to review our paper and provide valuable comments. It was your valuable and insightful comments that led to possible improvements in the current version. The authors have carefully reviewed the comments and have done our best to address each of them. We hope that after careful revision the manuscript will meet your high standards. The authors welcome further constructive comments.

• Abstract (line 20): it should be specified that presented results are for one specific case study

Abstract has been revised and it was clarified to show that the presented results are for the specific case study.

• Introduction (line 29); please detail what CAD and BIM stand for.

Full words and their abbreviation for CAD and BIM are now provided.

• Introduction: it should be anticipated that a specific case study will be presented. This would also smooth the strong affirmation made in lines 90-91: “to answer the question of whether it can replace the designer in the design process.”

We have added clarification that a specific case study will be presented.

• In section 2, before presenting two specific types of algorithms, it would be useful to have an overview of the types of algorithms that have been used so far in building design, based on the review of section 1. Are these two the only ones? Please justify.

Section 2 has been restructured, where the section 2.3.2 now contains an overview of common optimisation algorithms for building design, followed by the explanation of evolutionary algorithms. Of course, more algorithms are used for these purposes, but this has already been presented in more detail by Singh and Gu (https://doi.org/10.1016/j.destud.2011.06.001). With our summary we intend to show popular algorithms that may be useful for the reader to know which are they and where to find their examples.

• Section 2.3.1 is too generic. For instance, the difference between parametric geometry model and finite element model could be given. Besides, in Figure 4 (lines 216-218), BIM models seem an important part of the generative design process. Is it mandatory to have a BIM model? What is its role? These could be further explained in section 2.3.1, as so far BIM models are not mentioned there.

Section 2.3.1 Computational Model has been revised to explain in more detail how we see computational models in generative design. We also mentioned the use of BIM models, which can serve as a starting point on which a computational model is built and integrated.

• Section 2.4: please consider renaming this subsection “Design Methodology”. The reader could get confused otherwise and think that this section refers to the methodology of the research work of the paper or the methodology for the specific case study.

Section 2.4 was changed to “Design Methodology”

• Line 284 would instead of will.

Changed from will to would (now in line 304)

• 4.Discussion (line 366): this section only discusses the results of the case study, not the overall results of the paper. As a discussion section is too limited. There could be two alternatives to solve this: section 4 could also try to answer to the question “whether generative design can replace the designer in the design process”. To do so, the outcome of the other cited research works in this regard could be mentioned to have a final answer about it. The second alternative would be to have just a discussion section inside the case study (3.4 Discussion).

The discussion section has been completely revised, moving the previous discussion to a case study section and presenting a new discussion where we discuss generative design, how it compares to the traditional approach and why it cannot replace the designer in the current state.

Round 2

Reviewer 2 Report

The authors answered all the comments given by the reviewer.