Energy and Economic Life Cycle Assessment of Cool Roofs Applied to the Refurbishment of Social Housing in Southern Spain
Round 1
Reviewer 1 Report
Comments on Dominguez-Delgado et al. “Energy and economic Life Cycle Assessment of cool roofs applied to the retrofitting of social housing in Southern Spain”
I am thankful for the chance to read your paper, which deals with a very interesting application of the LCA methodology to the building sector located in areas with high cooling demands. It appears to be well carried out. In general, the paper is clear but sections could be rearranged in order to match their purpose. Results appear to have been properly obtained and figures and tables are in general well presented.
In the following I am providing more detailed suggestions which I hope can support you to improve the paper, reporting them not in order of importance but of appearance.
In the “Introduction” section the authors introduce a presentation of the current state of the research putting the problem into context. I would like to find that the authors identify the precise gap in the current state of knowledge that is being addressed by their research.
On the other hand, in order to give our readers a sense of continuity, we encourage you to identify “Sustainability” publications of similar research in your papers. Please, do a literature check of the papers published in “Sustainability” about social housing retrofitting, for example, in recent years and relate the content of relevant papers to the results and findings presented in your publication.
In its actual form, the sections of the manuscript are Abstract, Keywords, 1. Introduction, 2. Methodology to estimate the roof energy performance, 3. Case buildings, 4. Numerical resolution, 5. Energy analysis, 6. Life cycle analysis, 7. Results 4. Discussion, 5. Conclusions.
However, the “Results” section is only focused on the LCC analysis, and energy simulation results are included in Section 5.
It will benefit the paper if the authors take into account the structure recommended by the Sustainability MDPI Journal's Template. According to the Template, it is recommended that a research paper contains the following sections with some adequate subsections in order to separate energy and cost analysis: Abstract, Keywords, 1. Introduction, 2. Materials and Methods, 3. Results, 4. Discussion, 5. Conclusions (not mandatory), 6. Patents (not mandatory), Supplementary Materials (not mandatory), Author Contributions, Funding, Acknowledgments, Conflicts of Interest, Appendices, and References.
Following the former structure, I am going to start with the energy analysis.
The dynamic energy model proposed in Section 4 is not complex but it adjusts well the observed behavior. As the aim of this paper is not the model itself but the comparative analysis of the thermal behavior of roofs with or without coating, errors are compensated and the model can be considered reasonable. However, a couple of details must be taken into account. First, it is not clear what n means in equations (2) and (3) and the same letter has been chosen for the opaque sky cover or for years. Second, in equation (4), radiative flux for the external surface directly depends on the horizontal solar radiation, and no slope for the roof is considered. This is only for the case under study because roofs are flat type (line 162) but I consider that it would be better to write the general expression and later explain the simplification for this case.
Table 1 must include the data source.
Some clarification regarding the choice for the set-point temperatures (line 211) is welcomed: ¿Comfort temperatures according to x?
With respect to Sections 6 and 7, more conciseness in particular in Section 6 could help the clarity of the paper. First, the heading of this section must include the word “costs”. Second, Tables 5 to 16 are hard to follow. In fact, in the Discussion section, Table 12 is cited as a sort of summary of results but I was not able to find. I suppose that there is a mistake. In fact, section 6 would improve if results presented in subsections 7.1 to 7.8 were tabulated and summarized in one table similar to Table 2. If authors want to keep Tables 5 to 16, maybe an Appendix could be adequate.
It is shown that there are no significant differences in total loads regarding the maintenance regime, however, it seems logical that the punctual improvement that is obtained after washing in terms of energy cost will reflect differently in the LCC if maintenance is quinquennial or decennial. Some analysis must be included.
From my knowledge, electricity cost in Table 3 is very high especially in the case of social housing where households are usually beneficiary of the “Bono Social”. Are the authors able to justify this data?
The question posed in lines 659-661 is very obvious. Regarding life cycle cost analysis, a sensitivity analysis would improve the discussion. Another possibility could be evaluating scenarios with specific values for i and d.
Finally, the paper will benefit if the authors make a step further, beyond their analysis and provide insight at the end of the "Discussion" section regarding what they consider to be, based on the obtained results, the most important steps that all the involved parties (tenants, social services, municipality, etc.) should take in order to benefit from the results of the research conducted within the manuscript.
Adding a list of acronyms should be also considered. In addition, the first time that an acronym is used, the full name should be written previous to the acronym in brackets. For instance, SEER an SCOP are not defined shortly after equation 7 but later. What does EPW (line 195) mean?
Check the text. For instance, in lines 568 and 570 the emissivity 0.1 is mentioned for two cases.
Also, the report contains some mistakes in English: “thermal emissivity” better than “thermic emissivity”; “most of the time” better than “most of time”; in line 229 “heat” of “thermal energy” better than “heat energy”; in line 280 “on the other hand” and not “in the other hand”, to name just a few.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
This is an interesting paper with a very direct application of the research undertaken, not only in this specific area of Spain, but also in other countries with similar climate and building types. However, there are some point that the authors need to make clearer in the paper:
- The results of the simulations should ideally have to be contrasted with the ground truth of direct surveys/fieldwork in order to validate the results. The paper relies on existing literature for this issues. The paper needs to further discuss why this was not found necessary in the study.
- The specific effect of the buildings surroundings should also be briefly discussed
- Extensive data is provided in tables 5-20. This should be reduced to the key relevant results, making all the data available for other researched in open source.
- The words 'retrofitting' and 'refurbishment' are used in the title and text but they have different meaning. I suggest that the most appropriate term to use in this case is 'refurbishment'
Author Response
Please see the attachment.
Reviewer 3 Report
The paper is well written from the methodological point of view. There is one general methodology section (section 2) and then the methodology is also described in section 6 - "Life cycle analysis". Although the scientific soundness of the paper is good, the tables 5-20 should be inserted as the annexes to the paper.
The paper contains some language mistakes, for example:
- line 38: there is "wich", there should be "which";
- line 643: " carry out the LCA analysis, a wide variety ...".
Author Response
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Author Response File: Author Response.docx
Reviewer 4 Report
This interesting paper, clearly written and precise in its argument, aims at performing an energy analysis and conducting a Life Cycle Assessment (LCA) of the cool roofs in a broad framework taking into account the effect on the LCA results of the real weather of Seville. Some amendments are required:
I analyze the single sections:
Abstract: It has inappropriate structure. I suggest to answer the following aspects: - general context - novelty of the work - methodology used - main results. For research articles, abstracts should give a pertinent overview of the work.
Introduction: The introduction should briefly place the study in a wide context and emphasize why it is relevant carrying out the analysis. It is quite unusual to find such weak reference to the literature even in the introduction. This section should define the purpose of the work and its significance. In this perspective, this section is too succinct and fails to effectively point out the existence of a gap in literature. I would suggest the authors to frame the issue also in light of sustainability concept. A relevant issue to consider is for sure sustainability in energy transition:
Some literature to look at, but not limited to:
https://www.sciencedirect.com/science/article/pii/S0040162519308509?via%3Dihub
https://www.sciencedirect.com/science/article/pii/S1364032119300292
https://www.sciencedirect.com/science/article/pii/S2214629617302797
http://www.aimspress.com/article/10.3934/energy.2018.4.645
https://www.sciencedirect.com/science/article/pii/S2214629617303031
Materials and methods: I found this section very important for the readability of the paper. However, several challenges need to be addressed. First, there is no a clear point in arguing that Seville case be a worthy effort area to study itself but it is not clear how generalizable the study might be. Moreover, the research methodology seems underdeveloped. Research method should be described in detail for paper selection. It is important for the replicability of the work.
Conclusions should discuss practical and policy implications looking at literature. Which is the role of social aspects? Taking into account the social nature of the buildings methodological implication could concern the extension of LCA as S-LCA. Please see: (https://onlinelibrary.wiley.com/doi/full/10.1002/csr.1791)
Please provide information on limit of your work and future line of research.
I hope these comments might help in improving the paper and encourage the authors to move forward.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 4 Report
All comments have been adequately addressed.
Author Response
Thank you very much for your positive evaluation of our paper.
Moderate changes have been made in the English used in the text of the paper.
