Assessing the Feasibility and the Potential of Implementing Solar Water Heaters in Dimbaza, a Township in Eastern Cape, South Africa
Round 1
Reviewer 1 Report
For authors
This investigation presents relevant data for the region under study that should be widely spread around the South of Africa. However, the following concerns need to be addressed:
1. The questionnaire used for data collection is not provided. If the authors do not want to include each question, at least, the authors must synthesize the details, i.e., number of questions, how many sections it is divided (control, liker scale, ranking), and a description of each section, among others.
2. The paragraphs ending with “… (Objective #),” do not help the flow of the reading. Please consider writing it or remove.
3. Text from lines 256 – 287 is just repeated information from lines 181 – 211. It is not necessary to repeat the same text; just called upon the same equations.
4. Text from lines 290 – 306 seems as they should be in the results section.
5. Every number below 10 should be written in words, i.e., one instead of 1, two, three, …
6. What does “high level audits” means?
7. This first paragraph of section 3.4 talks about a study performed in Housing in Brazil [22]. However, in the references section, reference 22 indicates a study performed in South Africa. Was this a mistake? How is this study relevant to energy audits?
8. What do the authors mean when writing “first-degree walk-through”? in line 417.
9. From lines 551 – 562, Why is it important to point out such results from reference [35], instead of discussing them with your results?
10. Table 7 appears to be missing results for costs and energy (see lines 290 – 306).
11. The caption of Table 8 says “… radiation,” while the table presents no radiation data. In contrast, Table 9, does present radiation data.
12. In line 641, the value of 5.02 years appears for the first time in all the manuscript. Since this is the conclusion section, this result must be presented and discussed before.
13. Likewise, the terms “net present value” appears first in the conclusion section. No mention of such a term is found in the methodology or results.
14. The authors should emphasize more in the innovation of the study.
Author Response
see attached PDF file
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Authors,
The aim of your paper is to evaluate the potential benefits and feasibility of installing solar water heaters in Dimbaza (South Africa) and to evaluate the local inhabitants’ awareness of energy consumption-related impacts on climate change. Its main contribution and strength is the analysis of energy sources used in households in Dimbaza as well as the overview of energy consumption and costs in a typical household.
Before reconsidering your manuscript, I would like to recommend you address the following weaknesses of your manuscript:
1) the contribution of your study to scholarship (currently available body of scientific knowledge) is not clearly explained
2) your research objectives are not fully matching with the contents of the paper
3) your results and methods are not presented in a clear way
4) your conclusions are not thoroughly supported by the results.
5) the recent relevant references are missing (please consider analysing them and including the most relevant ones in your discussion), e.g.:
a. Tang, A., Alsultany, F.H., Borisov, V., Mohebihafshejani, A., Goli, A., Mostafaeipour, A., Riahi, R. Technical, environmental and ranking analysis of using solar heating: A case study in South Africa (2022) Sustainable Energy Technologies and Assessments, 52, art. no. 102299, DOI: 10.1016/j.seta.2022.102299
b. Nwodo, J.C., Overen, O.K., Meyer, E.L. Decoupling the monitoring of solar water heaters and their usage profiles (2021) Water (Switzerland), 13 (22), art. no. 3186, DOI: 10.3390/w13223186
c. Mujuru, M., Dube, T., Mabizela, H., Ntuli, N. Evaluating greenhouse gas emission reductions by using solar water heaters: A case of low income households in Ekurhuleni, South Africa (2020) Physics and Chemistry of the Earth, 116, art. no. 102843, DOI: 10.1016/j.pce.2020.102843
d. Naidoo, A. The socio-economic impacts of solar water heaters compared across two communities: A case study of Cato Manor (2020) Renewable and Sustainable Energy Reviews, 119, art. no. 109525, DOI: 10.1016/j.rser.2019.109525
e. Hohne, P.A., Kusakana, K., Numbi, B.P. A review of water heating technologies: An application to the South African context (2019) Energy Reports, 5, pp. 1-19. DOI: 10.1016/j.egyr.2018.10.013
Please find below my specific comments:
1) Line 19: the term ‘electric geysers’ is often used in South Africa and in India, but in my opinion it is not widely used and understood in other countries. Therefore, I suggest replacing this term throughout the whole paper with the term: ‘electric water heater’. According to the Cambridge Dictionary, a geyser is either: (1) a hole in the ground from which hot water and steam come out; or (2) especially in the past, a device that uses gas to provide a house with hot water.
2) Line 20: ‘selected buildings’ – please explain in the Methodology section how the buildings were selected and what is the overall population of buildings in Dimbaza.
3) Line 22: please specify what is the ‘annual ambient temperature’.
4) Line 97-105: please expand/modify – please explain the importance and relevance of the research topic (impacts and feasibility of SWH installing in Dimbaza) for other locations in South Africa and beyond.
5) Line 107: research objectives are not fully matching with the contents of the paper. Please consider removing the word ‘social’ from the text, or provide additional explanation on this type of benefits in further sections of your manuscript.
6) Fig. 1: please move the red caption ‘DIMBAZA’ so that the map is more legible and explain the bolded red line in the map legend.
7) Line 147: please add the questionnaire template as an annex (supplementary material) to the manuscript.
8) Line 148: please describe the population residing in Ward 36 and what is a ward in the local context.
9) Line 155 and 417: please remove the words “first degree” or justify/explain this term.
10) Line 164: in the studied population the 3.0 kW, 150 L electric water heaters were found most frequently, while the indicated ‘representative household’ uses a 200 L, 4.0 kW device, which your data suggests are the least popular. Please explain how you defined a ‘typical home’ in Dimbaza or change the term ‘typical’.
11) Line 176-177: I suggest removing the phrase “as a true representative of the monthly energy consumption[24]” as it is unclear.
12) Line 177: I suggest removing the word ‘typical’.
13) Lines 190-191: please explain what is the backup element of the solar water heater. Is it an auxiliary electric heater?
14) Line 203: please add data on the conversion factors used (e.g., a table).
15) Lines 293-306: please improve - provide a clear explanation how the awareness was evaluated. Please refer to the annex (supplementary material) with the questionnaire template.
16) Lines 323-324: please verify the values, as they are inconsistent with the ones you mentioned in the abstract.
17) Lines 364-365: please explain what you define as summer and winter period.
18) Line 377: please replace the word ‘energy’ in the figure caption with ‘electricity’.
19) Line 387-389: please explain how the savings between 25-40% were calculated/measured or provide a reference.
20) Line 395: please replace ‘energy savings’ with ‘electricity savings’.
21) Table 2: please modify the column headings and the first column text, so that the presented data is self-explanatory and easy to understand.
22) Line 432: please provide additional details in the sentence ‘Heating one litre of water requires 199.5 kJ of energy [34]’.
23) Line 436-443: please remove these lines, as they repeat the text in lines 345-352.
24) Lines 502-503: please correct, as the values presented are a range, not an average.
25) Table 5: please consider changing the column headings:
a. “No. of males” with “No. of households with males as household heads”;
b. “No. of females” with “No. of households with females as household heads”;
c. “Estimated range of average monthly income” – please specify if the income concerns the overall household or only the household head;
26) Lines 524-525: please explain how the value of 46% (share of electricity consumption for hot water heating in the overall electricity consumption) was calculated/estimated.
27) Table 7: please correct the table title as it does not match with the table contents.
28) Line 575: please specify the year considered.
29) Line 583-585: please provide additional calculations that justify this sentence, considering the theoretical (expected) heat generation from solar energy and the electricity consumption, given the household demand for water heating.
30) Table 8: please specify the year in the table title.
31) Line 635: please explain in the Methodology section how you define the awareness level
32) Line 649-650: please explain why more households are to be included in the survey and audits.
33) Conclusions: please consider explaining the limitations of your research concerning:
a. missing experimental data on SWH performance, especially its assumed electricity consumption. In your research (line 394) you assumed the percentage of savings at the level of 40%. Please explain how this assumption may affect the results of your study.
b. the selection of the household for analysing the impacts of SWH installation.
Author Response
Please find attached PDF file
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors did not provide a specific answer to all 14 queries, making it difficult to check the changes made. Equations are still repeating. There is no need to repeat the entire equation, only to cite the equation and so on. Please address the previous queries to improve the manuscript reading flow and presentation.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
Dear Authors,
Thank you for providing the revised version of your manuscript and addressing some of my remarks. Please find below my further comments and suggestions for improvement. Most of them were included in the previous review round, but were not addressed by you in the revised version.
1) Use of ‘electric geysers’ term – despite your declaration that the term “electric geysers” has been replaced throughout the document, it is still present on lines 19, 91, 234, 303, 366, 444, 498, 542, 613, 673, 723, 727, Table 7 heading, 1032, 1050. Please correct.
2) Line 20: ‘selected buildings’ – please explain in the Methodology section how the 73 buildings were selected from the population of 300 houses in Ward 36.
3) Fig. 1: please move the red caption ‘DIMBAZA’ so that the map is more legible and explain the bolded red line in the map legend.
4) Line 286-287: please correct units of conversion factors (from eq. 3, it appears they should be in kg/kWh, not in kg) and please provide a reference for this data, including a date.
5) Line 387-389: please provide a reference for the value of 40% of electricity savings thanks to SWH.
6) Line 559: please replace ‘energy savings’ with ‘electricity savings’ in the sentence “The annual energy savings due to the potential implementation of the SWH will be 2690.4 kWh”, as the energy demand will not be affected by the analysed investment type, but only the electricity demand from the national power grid.
7) Table 2: please modify the column headings and the text in the first column, so that the presented data is self-explanatory and easy to understand.
8) Line 498-505: please remove these lines, as they repeat the text in lines 614-620. The sentences starting with "Francioli (2018) ... " are still duplicated in the revised manuscript.
9) Lines 729-730: please indicate in the text that the value of 46% (share of electricity consumption for hot water heating in the overall electricity consumption) was calculated or measured by you, but assumed by you based on the available literature. Please also provide literature references on which your assumption was based.
10) lines 966-976: the newly added 4 references are not referred to in the article text. Please explain in the manuscript what insights from these studies are relevant for your paper, how their findings are similar/contradict/support your results.
11) Line 811-813: please provide additional calculations that justify this sentence, considering the theoretical (expected) heat generation from solar energy and the electricity consumption, given the household demand for water heating.
12) Line 895-896: please include in the manuscript your explanation why more households are to be included in the survey and audits (as you explained in the letter: “To get the fair representation of the entire population. Also, to cover wide range of the entire location”).
13) Conclusions: please include in the conclusion section of your manuscript a paragraph explaining the limitations of your research concerning:
a. missing experimental data on SWH performance, especially its assumed electricity consumption. In your research (line 394) you assumed the percentage of savings at the level of 40%. Please explain how this assumption may affect the results of your study.
b. the selection of the household for analysing the impacts of SWH installation.
14) line 1039-1040: “The questionnaire structured to produce information on patterns of energy consumption was designed to be administered to low-income households with SWH in the area“. Please remove the words in bold. As you stated in your repsonse to my review, Dimbaza does not have Solar Water Heater rolled out yet.
15) line 1014: please add annex title
16) line 1029: please remove student number and cell number
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
Thank you for addressing my comments.
Author Response
Thank you for providing the speedy comments and feedback from our revised submitted manuscript and we are delighted.
Reviewer 2 Report
Dear Authors,
Thank you for providing the next version of your manuscript. Please find below my further comments and suggestions for improvement.
1. Line 124: please include an opening sentence before the bullet point list.
2. Lines 418-420: Please rephrase this sentence “The average monthly electricity savings by retrofitting an electric water heater with a flat plate SWH harboring auxiliary water heater was between 25 – 50 % [41]”, considering the following remarks:
a. It should provide an explanation how you calculated the range (25-50%), as this range is not explicitly stated in the paper you cited. It is important to clarify this point, as this value is the main justification for the crucial assumption in your study.
b. Please include a note on the geographical area (Brazil) and climatic conditions from which this data origins, as the reader deserves being informed on these aspects to properly understand your paper.
3. Lines 422-426: “Therefore, the average annual electricity consumed by the electric water heater for the purpose of sanitary water heating was 6726.00 kWh as shown in Table 2. The average electricity savings by replacing the electric water heater with a SWH, having an auxiliary electric heater was considered as 46 % [41]” – please clarify, as the value of 46%, which is the critical assumption of your study, is not explicitly stated in the paper you cited.
4. Table 2: please replace the words “baseline”, “assessment” and “impact” with more specific explanation. If that is the case, you could use the following phrases “electric water heater (baseline)”, “solar water heater with an auxiliary electric heater (assessed scenario)”, “avoided emissions/energy/material consumption due to changing the water heating supply (difference between the baseline and the assessed scenario)”.
5. Table 2: Please update the table title: add information on the timeframe of benefits – “over one year”, if that’s the case.
6. Table 2: Please provide units in heading of each column. The headings in the first and second rows of the table are still confusing. Readers should not guess what you mean by, e.g., “1.34L”. Please provide clear names of each column and units, e.g. “Electricity consumption [kWh]”, “CO2 emissions [kg]”, etc. The values in the second row are confusing.
7. Sections 6 and 7: these sections should be merged with section 5. Please ensure consistency between sections, e.g. add a sentence before the paragraph on limitations: "The findings of this study have to be seen in light of some limitations." – or a similar sentence. Please also provide a similar introduction sentence before the last paragraph with your recommendations.
8. Lines 204-206, 245-247, 350-353, 447-448, 608-610: please consider removing these lines. They do not contain grammatical subjects and do not improve the clarity of the study.
Author Response
All responses have been attached in the file.
Author Response File: Author Response.pdf
