Transformative Potential of Vertical Farming—An Urban Planning Investigation Using Multi-Level Perspective

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript analyses vertical farming for food production in urban areas as an opportunity for sustainable development. The topic is appropriate for publication in Sustainability.

The introduction is comprehensive and the methodology is clearly described. There should be some further details regarding the different types of vertical farming: indoor/outdoor, sunlight/artificial light etc. Some important aspects like seasonality, management of organic waste (crop residues), pest management are overlooked. Further issues, like the use of municipal wastewater for food farming are highly debatable. The very limited types of crops that are suitable for vertical farming are only mentioned briefly once, although this might represent a major constraint. Clearly, the topic is approached at a theoretical level, and some practical aspects are missed.

The authors are considering vertical farming as a sustainable option for food production in urban environment. In my opinion, certain aspects regarding vertical farming should be clarified:

- Indoor vertical farming in hydroponic systems with controlled environment and artificial light are appropriate for food production and could become sustainable, e.g. by using renewable energy.

- Outdoor vertical farming presents important challenges like logistics/ accessibility, light, water, nutrients and pest control. (On a personal note, I have tried this and it turned into a pool of mosquitoes and other pests + next to zero yields). Moreover in terms of urban planning, although it might have a pleasing aspect during the growing seasons, it could become an aesthetic problem during the cold season. It could be appropriate for rooftops, less for building walls.

- Municipal wastewater contains, apart from valuable nutrients, a plethora of pathogens, drugs, pharmaceuticals, hormones, microplastics, cosmetic products residues, detergents etc. which make it inappropriate for use in food production. There could be some some opportunity in growing an intermediate crop to recover nutrients, but logistical constraints apply.

- Alternative non-food crops could be considered for building walls to achieve climate goals, but even in this case all management aspects should be considered, including pest control. Vertical gardens are complex ecosystems that attract a wide range of living organisms.

My recommendation is to include the above aspects in the discussion.

Below are some specific comments:

286. "On the other hand, this means saving money since capacities in

287. 300  wastewater treatment plants or long-term environmental costs can be avoided by

288. 301  discharging wastewater into rivers or groundwater"

289. Please revise this paragraph as it appears to be against regulations.

Figure 3 replace "bottum" with "bottom" 

442. "Not only from a corporate perspective, it would also continue to

443. 458  being important for promoting acceptance research on circular food systems, which, e.g.,

444. 459  reduces the reluctance to use raw materials from human waste as fertilizer [74]."

As discussed above, human waste fertilizer comes as a package deal in municipal wastewater, so this should be formulated more carefully.

466. "Integrating vertical

467. 479  farming as a biorefinery into a holistic sustainable urban material cycle also makes an

468. 480  important contribution to biological waste recycling and resilient urban ecology to

469. 481  mitigate climate change [61]."

470. I agree, but not for food production. This should be specified.

592. "Other resource savings, such as the low use of water and

593. 594  the extensive avoidance of pesticides and fertilizers, are also key ecological benefits that

594. 595  extend beyond urban areas."

595. The assumption that urban vertical farming would not require pest control and fertilizers should be revised.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. Transformative potential of vertical farming - An urban planning investigation using multi-level perspective” was investigated in this study.

With this paper, the authors place the innovation of vertical agriculture in the context of urban planning in relation to the comprehensive background of climate change. To be able to assess the transformational potential of vertical farming, the authors first:

a) clarified the extent to which vertical farming can be classified as a niche innovation from a multi-level perspective, as well as its advantages and disadvantages for urban planning. Furthermore:

b) clarify under what conditions vertical agriculture can be established as a niche innovation in the urban planning regime.

Finally:

c) address the question of which recommendations for action should be implemented in urban planning to promote vertical agriculture.

The main questions and objectives of this research are very well described and defined in the submitted manuscript. It would be necessary for the authors to highlight more clearly what is new in their research.

It is not clearly pointed out what is new in their study.

2. The topic in this study is original, relevant and specific in this field of research.

However, the authors should highlight this in more detail, in the manuscript itself: originality, relevance, specificity, novelty..., of their research topics in this area.

I note once again, there is a detailed description, but you just need to clearly highlight the key points.

3. The manuscript is interesting and deals with a current and innovative topic in the sustainable, urban and rural development, etc.
However, he would have a suggestion to improve the manuscript in the Introduction so that it contains more data on similar research, which would further emphasize the importance of the topic of this manuscript in relation to similar previously published materials.

4. The methodology in this manuscript is very interesting and adequately described and presented. The method of data collection chosen in experimental work can always be a subject of discussion. In this case, I believe that the collection methods of data, which the authors selected and described, was adequate. However, everything seems to apply only to Germany. If it is possible for the authors to point out how their research could be applied outside of Germany, more broadly, around the world. This is important for the readers of journal such as „Sustainability”.

5. The results are adequately presented in Chapter 3. A discussion of the results is good and is given in Chapter 4. Тhere is a chapter on conclusions, 5. Conclusions, it is included after extensive discussion. The present conclusion is comprehensive and lengthy. But what is said is relevant. However, it could be improved when all the improvements according to the previous points 1-4 are followed in order.

6. The listed references are appropriate. Considering the above, it may be necessary for the authors to improve and supplement them.

Although I am not an expert in English, I think the English in this manuscript can be improved.

Considering the above, this is a request for „Мajor revisions”.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have made a significant effort and have now greatly improved the submitted manuscript.