Evaluating Environmental Impact in Foundations and Structures through Disaggregated Models: Towards the Decarbonisation of the Construction Sector
Round 1
Reviewer 1 Report
This is an interesting paper and overall good for what is aiming to achieve. Authors here developed a disaggregated model to evaluate building solutions (CDM-SABSSF). A “non examined variables” namely construction materials transportation, worker commutes, construction process, dust, noise, vibration emissions and load tests were proposed and a model applied to a high impact real case study: the construction works of the dismounted foundations of the Cylindrical and Coronel buildings, over one of the Seville subway tunnels.
The introduction provided good background and motivation for the study. The research gap is briefly described. The methodology is clear and concise. Development of the model is outlined and an application is discussed. The results are presented clearly and analysed appropriately. The presented conclusions adequately tie together the other elements of the paper.
The points to be addressed in order to make this paper publishable for the Sustainability:
- A literature review is good, however, I don’t think the authors in question have cast their net wide enough in surveying the currently available literature on the matter. Not a well-balanced sample: too many from C-level references – too few from A-level journals. Most of references are in Spanish, which could not be checked by an audience of this international journal. References are relatively old. A more complete study of currently available journal articles on the subject would certainly be welcome by the journal.
- As noted, results are presented clearly and discussed in detail, however, they are more indicative rather than representative. The limitations of the study in terms of the generalization of the findings should be added. Contributions to the new body of knowledge from the international perspective should be justified.
- Discussion concerning the potentialities and limitations of this approach should be presented.
Other:
Title is too long. Breeam, Casbee, etc. should be in uppercase BREEAM, CASBEE, etc. Paper would benefit from proofreading.
The paper is publishable, but subject the kind of revisions outlined above. If these were to be made I am sure the paper would make a valuable contribution to the journal.
Author Response
We are grateful for the review, which has been addressed within the boundaries and goals of the paper. Its quality has undoubtedly improved thanks to it. Namely, the title’s length has been reduced, the summary has been reworked, the introduction has been improved with an updated bibliography, in addition to addressing other issues regarding the format.
In every research work, highlighting its potential and its weaknesses is relevant. In this sense, regarding the limitations of the research, it is worth noting that they are closely linked to its level of scale (the execution of foundations and building structures, although they could be adapted, depending on the case, to structures and foundations of civil and/or industrial works), as well as to the starting methodology (the EHE Concrete Instruction), given that the CDM-SABSSF methodology focuses on the variables that are not explicitly considered by the aforementioned.
However, the greatest potential of this research is the evaluation of sustainability of structures and foundations at this level of scale, regardless of other conditioning factors related to the LCA of the building.
It is worth noting that most building projects are not subject to sustainability requirements (LEED type certification, or similar...), however, a large percentage of these projects show relevant modifications at the level of structural and foundation solutions; in many cases for technical and/or economic optimisation of the solutions included in the projects and in others to solve geological or geotechnical index problems that have not been taken into account for different reasons.
In both cases, the methodology proposed by the EHE (Concrete Instruction) in Spain, allows us to evaluate the sustainability levels of the different solutions and the proposed methodology (CDM-SABSSF), to take into account the variables that have not been considered and that in certain situations can be differential when determining a building solution’s contribution to sustainability at that level of scale (phase of execution of structures and foundations in projects without specific requirements of sustainability)
Reviewer 2 Report
_Maybe In the introduction of the paper, it would be useful to better argue how the sustainability of a constructive intervention can change in relation to the analysis indicators or tools used.
It would be useful to integrate the final research data more closely with the principles of the Life Cycle Assessment (Insert more references on LCA).
_Before making conclusions, it would be helpful to indicate a greater number of case studies (or refer to similar studies and/or research that could support the conclusions of this research).
_Update the paper's references with more recent publications on sustainability.
Author Response
We are grateful for the review, which has been addressed within the boundaries and goals of the paper. Its quality has undoubtedly improved thanks to it. Namely, the title’s length has been reduced, the summary has been reworked, the introduction has been improved with an updated bibliography, in addition to addressing other issues regarding the format.
In respect to arguing, in the paper’s introduction, the way in which the sustainability of a building solution can change in relation to the indicators or analysis tools used: this is one of the main goals of the case study analysis. The solution that was actually implemented was indeed the most sustainable one. However, it is easy to deduce that if some conditions had changed, the most sustainable solution could have been a different one. In the case study, the choice was made without taking into account any requirements in relation to sustainability. The fact that the VDT solution proved the most sustainable one is a mere coincidence, as shown in the research.
Unfortunately, the requirement to integrate the data more closely with the principles of the Life Cycle Assessment cannot me met, due to the fact that neither the methodology proposed in the model that we reference in this paper, nor the complementary one proposed in our research are based on LCA.
At this scale, this research is unprecedented in relation to certain variables (noise, dust, vibrations, temporary traffic diversions, load test, ...), so it is not possible to mention a greater number of case studies, as this one is unique. Only a small amount of research has had an impact at this scale, on aspects such as the laying of concrete; but without taking into account, for instance, the transportation of workers to the building site. See [27] r Mel Fraga, J., Del Caño Gochi, A., De la Cruz López, M.P., 2014. Sustainability in the preparation, transport and casting of the concrete in Spain: Analysis of Energy Consumption and CO2 emissions. 18th International Congress on Project Management and Engineering. Alcañiz, 16-18th July 2014.
http://www.aeipro.com/files/congresos/2014alcaniz/CIDIP2014_0508_0520.4196.pdf
Reviewer 3 Report
Title:
Too long. I would shorten it focusing on the main idea.
Abstract:
Please, you should put into context the "Spanish Standard Annex 13".
I recommend you to follow the structure suggested by MDPI:
First, placing the question addressed in a broad context and highlighting the purpose of the study. Then, describing briefly the main methods or treatments applied. Next, summarizing the article's main findings. Finally, indicating the main conclusions or interpretations.
Keywords:
They are not aligned with the abstract. For example, temporary traffic diversions?
Introduction:
This should be improved. It should briefly place the study in a broad context and highlight why it is important, defining the purpose of the work and its significance, reviewing the current state of the research field carefully, citing key publications, highlighting controversial and diverging hypotheses when necessary. At the same time, it should briefly mention the main aim of the work and highlight the principal conclusions.
Although LCA is discussed, nothing about EF. Limitations of tools for the evaluation of materials and building solutions and to certify the global sustainability of the building during its occupation stage are not stressed.
[8] and [9] are not many research studies carried out by the University of Seville. On the other hand, what is new about this study?. Please, introduce the issue step by step.
When authors hold "Time becomes a fundamental factor and it conditions the hypotheses that must be taken into account at this level of scale", Do the refer to delivery? To climate?
When authors hold "project designers must incorporate the goals of sustainable development in their designs focused on soil improvement and construction methods, through the quantitative evaluation of the environmental impact", Why? Who's forcing it?
Please, introduce [10] and [11] into the text. Translate EHE'08 or don't, but don't do it halfway.
Authors must highlight their contributions with reference to IVMSA.
Which particularities, features and special circumstances are taken into account in the Edificio CilĂndrico and the Casa del Coronel buildings?
Is the University of Seville the author of the paper?
A case study is being presented (this should be done in the next section). This should be forced by no previous research on the topic and insufficient empirical observations to turn it into a quantitative study. Simple cases must be straightforward. These ones are chosen because they are unusually revelatory, extremely exemplary, or because they represent unique opportunities for gaining research insights. This must be stressed by the authors.
Materials and Methods:
If the method proposed is complementary to IVMSA, then this one should be better introduced and explained. Due to the regulatory origin of IVMSA, the method proposed by the authors can only be carried out in Spain? It is a strong limitation that must not be forgotten into the conclusions.
Please, improve the Figure 1 so that it can be read more easily. On the other hand, explanation of the Figure 1 (essential in their research) must be improved too.
Values from Table 1 and 2 can vary. How does it affect to the model?
Development of the Disaggregated Model:
As the IVMSA is not properly presented, the different sub-models are proposed, but differences and similarities are not justified.
Some of the simplifications of formulas (2) to (7) should be well argued and referenced:
Are authors sure the Efi is propotional to the weight? When authors hold Wi/LCi are considering that an empy vehicle does not waste. A corrective factor should be introduced. For example, if Ef0i is emission of the empty vehicle and Ef1i of the full vehicle then Efi could be Ef01+(Ef1i-Ef0i)*Wi/LCi
Machinery and workers weight. Then, when authors define the number of trips, the emission of the vehicle depends on this issue.
Applications of the Case Study:
The use of a case study should be better explained and justified.
The sustainable criteria of the solutions are not described. The scope of this study should be better explained.
Is the same level of contribution to sustainability (Level D) defined at a sufficient level of definition or is there a sufficient gap to call this classification into question? If ICSS gives it, What is new about the paper?
Influence of non examined variables must be conveniently discarded.
Results:
The head of Table 13 must be included.
The interest of the paper lies in the methodology, not into the result of VDT, VAR1-2, HPO. For this reason, the methodology should be better determined step by step. If not, if the interest is in the constructive solution, then a sensitivity analysis is required in order to determine the robustness of the method (modifying section, length, distances, etc. in order to discover which parameters are relevant).
Discussion:
Discussion is not well raised. Authors must discuss the results and how they can be interpreted in perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted.
No references (previous studies from other authors) are included. Advantages of this method over previous ones are not emphasized.
Conclusions:
Interpretations should be generasible. Limitations and future research, included.
Author Response
We are grateful for the review, which has been addressed within the boundaries and goals of the paper. Its quality has undoubtedly improved thanks to it. Namely, the title’s length has been reduced, the summary has been reworked, the introduction has been improved with an updated bibliography, in addition to addressing other issues regarding the format. Furthermore, any comments that were not sufficiently clear or cannot be addressed have been addressed in a substantiated way.
Introduction:
Regarding the fact that the paper doesn’t highlight the limitations of the tools for the evaluation of building materials and solutions and for certifying the overall sustainability of the building during its occupancy stage, it is worth noting that the goal of the tool is not related to the LCA, but to the evaluation of sustainability in this phase (design, execution), for the reasons explained above, especially in constructions with low sustainability requirements (practically most projects for the execution of structures and foundations).
There is no other similar research carried out at the University of Seville, so they cannot be quoted as requested, hence the importance of publishing this unique case.
In relation to the question: "When the authors argue that "time becomes a fundamental factor and this conditions the hypotheses that must be taken into account at this level of scale", do they mean delivery? Or the climate?"
The answer is neither the weather nor the delivery (reception). It refers to the time of execution and implementation that conditions the potential sources of CO2 emissions (dust, noise, vibrations, greater or lesser need for labor and therefore transportation, materials, ... etc.). At this scale, the partial execution time of any technical solution is one of the aspects to be taken into account in decision making process, and the effects on the environmental impact of these are almost never taken into account.
Regarding the question: "When the authors argue that "project designers must incorporate sustainable development goals in their designs focused on construction methods, through quantitative environmental impact assessment," why, and who is forcing it? At this scale, where most of the structures and foundations of buildings in urban environments are designed and executed without any type of sustainability requirement, it is necessary for them to incorporate previous evaluations such as the one included in Instruction EHE-08. The application of these evaluations is not currently mandatory. However, the application of these evaluations is not currently obligatory. In the future and in future revisions of this Instruction, it should incorporate the mandatory nature of the sustainable evaluation of the implemented building solution, incorporating the variables that are currently not taken into account as established in this research, and establish control tools in the case of changes in the solutions planned and evaluated in the project phase.
Regarding the question: "The authors must highlight their contributions with reference to IVMSA.” IVMSA is the basis of the methodology proposed in Annex 13 of the Instruction, which is based on obtaining an ICSS added value that determines the greater or lesser contribution of the structure to sustainability. It is not the purpose of this paper to go into detail on the IVMSA methodology.
Regarding the question: "What particularities, characteristics and special circumstances are taken into account in the Cylindrical Building and the Casa del Coronel buildings? Is the University of Seville the author of the article? "This is a completely pioneering solution due to the difficulty stemmed from the interference with the works execution of the subway line. This action is very representative in two aspects what are not contemplated in the ICSS, such as the temporary traffic diversions (which were carried out in a sustained manner over time, and as shown in the research, may have had special impact for or against the sustainability of the implemented solution) or the load tests to be carried out given the special characteristics of the adopted solutions (bridge-type foundation). The University of Seville was the promoter of the works developed in this paper and the author of said paper participated actively in their execution, as project manager. All this is explained in the content of the document.
A case study is put forward (this should be done in the next section). This should not be forced by any previous research on the subject and insufficient empirical observations to turn it into a quantitative study. Simple cases should be simple. They are chosen because they are unusually revealing, extremely exemplary, or because they represent unique opportunities for research knowledge. This should be stressed by the authors.
In this paper, the case study was selected because it represents a unique opportunity to obtain research knowledge and to serve as an example for other similar cases that may arise in the future when faced with a similar real case that may take place. In relation to the above, the selected case has allowed us to highlight and put into context the sustainability impact that the variables included in the proposed methodology (CDM-SABSSF) may have.
Materials and methods:
The goal of this paper is not to go into detail about the IVMSA methodology on which the ICSS (value added) is based. And the fact that it is included in the Spanish Instruction does not prevent it from being applied as a method for the sustainable evaluation of structures and foundations in other countries. In fact, the methodology proposed in this paper (CDM-SABSSF) complements the decision making process derived from obtaining the ICSS, and can be applied in any structural area (national and international).
It is not clear what exact changes does Fig.1 need in order to be improved. With regard to the tables, it is clear that they can vary, and in each specific case, the values corresponding to the supply (supplier company, country, ...etc.) must be adopted. In our case, the research presented indicates the origin of the data used (ENDESA, 2007).
Development of the Disaggregated Model:
As mentioned above, IVMSA is the basis of the ICSS (value added), and this paper does not aim to go deeper into the sub-models associated with it. This paper focuses on the sub-models of the variables that are not taken into account in obtaining the ICSS. These are disaggregated models (the results are quantifiable in terms of CO2 emissions, unlike the ICSS which gives us a level of contribution of the structure or foundation to sustainability, A, B, C, D or E)
The model assumes only fully loaded vehicles and applies the emission factor in this situation. The fuel consumption varies according to the load, but according to the representativeness of the expected results, no correction factor has been taken into account, since it is also very complicated and practically impossible to know the fraction of the load of the trucks in relation to the maximum load a priori, therefore making any correction introduced to be not representative either.
Applications of the Case Study:
As explained above, in this case, when the proposed methodology is applied to the real case study, the most sustainable solution is the one established by ICSS. But this is a mere coincidence. In fact, in the sub-model with the greatest limitations, the same result is obtained by taking into account the real dates on which the works were carried out. If they had taken place on other (warmer) dates, the results would have been significantly different, taking into account the proportionality with the execution time of each of the solutions analysed. On the other hand, the load test was necessary in all the solutions analysed, but it would not have been necessary in a solution in situ that had not been tested, so that in quantitative terms we have obtained an order of magnitude of its representativeness in the decision-making process.
Results:
Indeed, the significance of the research lies in the order of quantitative magnitude of the variables not contemplated in ICSS, not in the result of VDT, VAR1, VAR2 and HPO, for this reason an analysis of the representativeness of the results obtained was performed. However, the results, according to the hypotheses raised, are ones published. The discussion of results should emphasise the methodology on the one hand (already described) and in the order of magnitude of the modelled aspects.
Conclusions:
In relation to the sensitivity of the variables taken into account in the proposed methodology, it is worth highlighting:
- The most notable impact pertains to the influence that the generation of dust and noise can have in urban environments, and that in the case of the study it does not have relative influence as the execution periods of the different alternatives are carried out outside the sensitivity period (according to the actual execution period of the works). This aspect is by far the most qualitatively relevant (potential for CO2 emissions), and when it comes to the execution of building works in sensitive periods (hot weather) it can be decisive in relation to the decision making process. However, this sub-model is the one with the most limitations, according to the initial hypotheses put forward and the characterisation of the areas of influence, so this must be taken into account when extrapolating and adapting the methodology to other situations, geographical areas and countries.
- On the other hand, it is clear that the execution period is of vital importance in the case of temporary traffic diversions (in favour and against the sustainability of the solution) and yet its applicability is immediate and can be extrapolated to any situation based on the appropriate characterisation of the traffic affected.
- The construction process, and namely the transportation of materials and installation, depends mainly on the technical building solution put into place, and the proposed methodology allows a quantification of the emissions generated to be obtained from a disaggregated model, so that its adaptation and applicability to other cases is immediate if the solutions are suitably characterised. These aspects are the most influential in the design and execution process and are the ones that are easiest for the agents involved to obtain reliable data.
- Finally, the transportation of workers and the execution of the load test are easily applicable to any situation, but the absolute results show a smaller overall impact in the contribution to the sustainability of the analysed building solutions.
Round 2
Reviewer 1 Report
I am satisfied with the efforts made by the authors to improve the quality of the article. The changes made have improved the article, so I have no further suggestions. I believe that the work has an interesting original contribution to this literature, and my recommendation is Accept the article.
Reviewer 3 Report
Good job!
