Steel–Timber Hybrid Buildings: A Comparative Life Cycle Assessment Study of Global Warning Potential Impacts

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper is interesting and well organized and presented. Some minor comments should be addressed.

- The abstract does not present any numerical data. Please revise.

- Please define the abbreviation (GWP) in the abstract section.

- The keywords are already mentioned in the paper title. Please choose another informative keywords.

- In the legend of all figures the number (2) in (CO2)should be set as subscript. Please revise.

- The authors should add a short paragraph on the limitations and should concentrate on the fire performance of the building made with hybrid (timber and steel).   

Author Response

We thank all three reviewers for their useful comments that gave us the opportunity to greatly enhance the quality and readability of our paper. The replies to the specific comments from each reviewer are addressed in the attached PDF.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is a quite thorough and well researched paper.

However, its discussion and presentation could be improved by attention to areas like the following:

·         The paper would benefit from a glossary of terms. While some terms are quite well defined, some terms , such as standards, appear to be referenced only by their numbers or abbreviations. Readers who are not familiar with these are required to consult the definitions of these standards to identify them.

·         While the paper is quite detailed, it can take time to read it.  It may be useful to use more dot points when describing processes and possibly consider condensing some sections.

·         Were tools other than One Click LCA considered for the analysis undertaken in the paper?

Author Response

We thank all three reviewers for their useful comments that gave us the opportunity to greatly enhance the quality and readability of our paper. The replies to the specific comments from each reviewer are addressed in the attached PDF.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Generally, the topic investigated is a very interesting one. Especially, the comparison between Europe and North America stimulates thinking.

From an overall perspective the beginning of the contribution reads a like "pro-timber" discussion. Which, from my point of view is not proved in this clarity by the results.

Furthermore, the comparisons in diagrams are often difficult to read and understand. One of the main reasons is that often refence is made to the scenarios 1 to 8. The reader needs to learn them by hard to be able to later understand the diagrams. I suggest to rearrange the diagrams for easier readability. For instance the diagrams could be structured having all 20-floor scenarios to the left and all 40-florr scenarios to the right.

In the conclusions some new aspects are introduced in the discussion which should be discussed before in the text (e.g. the contributions of De Wolf et al.)

Please also have a look into the attached file, which contains further information.

Line 33:

„this is due to…“ without comma

 

 

Line 68-69

Please comment on the fact that in Europe more or less all timber ist burnt after its use. Re-Use very rarely takes place.

 

 

Table 1:

In other tables you have used "sqm" instead of "mq". Please use units consistently throughout the contribution.

The differences between the given values are rather large. Please add a paragraphhow the mentioned structures differ and where the differences come from. Please further comment on whether the studies were comparative studies and also gave values for steel or RC-structures.

 

 

Line 114-115

Please comment on, why this is better compared to steel. In fact, here advantages for timber are given, but no comparison to other products are made.

 

 

Table 2:

It is not „Stories“ it is either „floors“ or „storeys“

 

 

Figure 3:

The differences in sketches b to d are bearly visible. Please show the differences between the sketches more obvous. Furthermore, I suggest to mention in detail in the caption what the scenarios are showing.

E.g.: (b) Steel bars, wooden plate and concrete... This would increase readability.

 

Table 3:

It is not clear whether the given values are mean values or other values. Where are the values taken from?

 

 

Figure 4 line 527:

the left and right bars are very difficult to distignuish. Pleases make them more distiguishable.

 

furthermore please use very brief descriptions for the scenarios. Naming them 1 to 8 is very difficult to follow.

 

 

Line 560:

It would increase readability if you would mention what is calculated in scenario 6

 

 

Line 579:

You mention „all steel scenarios“ please name them by number as well.

 

 

Figure 6:

It would increase readability, if you would briefly characterize the scenarios here. What is meant by „NA“?

 

Table 7 line „D“:

Please define somewhere precisely, what is included in C and D LCA phases.

 

 

Line 705

please mention here again, what „0/0“ implies

 

 

Line 709:

please be more precise here what is covered by "efficient material use"

 

 

line 721 ff.

The comment you are giving on the contribution by de Wolf et al. is very brief. Are the structures, loading and storey comparable?

 

 

Line 743 ff.

 

Could you give one or two examples what the differences in NA and Europe are?

Comments for author File: Comments.pdf

Author Response

We thank all three reviewers for their useful comments that gave us the opportunity to greatly enhance the quality and readability of our paper. The replies to the specific comments from each reviewer are addressed in the attached PDF.

Author Response File: Author Response.pdf