Energy Benchmarking Analysis of Multi-Family Housing Unit in Algiers, Algeria

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

I have thoroughly examined your manuscript on residential energy consumption and find the topic relevant and interesting. However, several revisions are necessary before publication:

1. Figure placement does not follow first textual reference order. For example, Figure 2 (mentioned in line 91) appears two pages later.
2. Data sources in section 3.1.1 require more precise citation (website, address, email). Consider long-term accessibility of these sources for future readers, accounting for potential institutional changes.
3. The selection rationale for Sidi Abdallah settlement lacks sufficient justification. Please explain your selection criteria and whether you considered other settlements comparable to Algir. If not, explain why such comparisons were deemed irrelevant. Additionally, include population figures and relevant thermal characteristics that influence building services design, as these significantly affect energy consumption analysis interpretation.
4. The term ‘universal unit’ in line 166 is ambiguous. The scientific community recognises the SI system and its derivatives. While kilowatt-hour (kWh) is common in residential contexts, the ‘universal’ descriptor is inaccurate (cf. units used in the USA). Units in lines 174-175 contain typographical errors.
5. Equations (1) and (2) should be presented formally, as expected in scientific publications.
6. Figure 4 requires significant quality improvement. However, the information could be summarised in 1-2 lines of text, making the current format redundant.
7. Some labels in Figures 7 and 8 are illegible.
8. The definition of CDD and HDD values, particularly the equations used, is missing. Please justify why these values were determined for an entire country rather than the specific settlement under study. I recommend reviewing relevant publications in the MDPI Buildings journal for methodological guidance.
9. Figure 10 requires additional data points as the curves appear fragmented. This also applies to Figure 11, though to a lesser extent.

Author Response

"Thank you very much for the relevant comments."

"Please see the attachment, which includes the response to all the comments."

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Significant weaknesses of the undertaken research:

The 1.4 million units will be all located in the same climatic zone across Algeria? Because if is not this the case, the particular study undertaken in Algiers cannot be generalized. Both heating/cooling demand in buildings depend significantly on the microclimate of the region where the building is located. Usually in one country are more climatic zones. How many climatic zones there in Algeria and you connect your study in relation with this relevant particularity? This study might be too local and with very limited general applicability.

Table 7. EPIs from 2022 doesn’t seem plausible. How you explain such an uneven value (e.g. 815.79 kWh/m2.year)? Also, the value is not correlated with the measured data for electricity and gas for the year 2022 (the measured consumption data is not three times higher in 2022 compared to the other two years, 2023 and 2024 – see Fig. 5 and Fig. 6, as EPIs are – see Table 7, Fig. 18, Fig.19). There is a reasonable suspicion that the EPI calculations are not correct.

Table 4. What units are you using for natural gas consumption? Usually is measured in m3, which is easily converted to kWh. What unit measure is “therm” or “thermies”? You should provide values converted in SI units.

Minor observations:

The bibliography is not properly written, according to academic standards. For example, who are the authors of references [16-19] and in which journals are published the papers? Please revise all the bibliography accordingly.

Table 2. Please complete the table more consistently. For example, it would be relevant to reveal where are located the buildings considered as case studies. For some you wrote the location, but for the most you don’t. The weights of different consumption vectors are different for significant differences in climate (predominantly electricity for cooling in warm regions and predominantly thermal energy – produced with gas and other fuels, for heating in cold regions).

Figure 8. The legend of the map is not consistent with the colours actually used in the map.

Comments on the Quality of English Language The English could be improved.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Comments 1：(Line 3-5） "This energy consumption refers to a residential building stock of approximately 10 million units." Please clarify whether "10 million units" includes all housing types or only multi-family units. Add a citation for the breakdown (e.g., single-family vs. multi-family).

Comments 2：(Line 20-22） The research question is phrased as exploratory ("What are the main trends..."). Reframe to imply policy impact, e.g., "How can energy benchmarking inform adaptive pricing policies for multi-family housing in Algeria?"

Comments 3：(Line 45-47） The gap about "longitudinal data sets" is well-identified, but the justification for 3-year data is weak. Explicitly state why 3 years (vs. 5+ years) are sufficient to capture trends (e.g., post-occupancy stabilization period).

Comments 4：(Line 52-54）"Combining all available energy sources" is a strength, but the methodology section should preemptively address how electricity/gas interactions are analyzed (e.g., substitution effects).

Comments 5：(Line 80-82）The selection of 295 units from 1,500 lacks justification. Explain sampling criteria (e.g., "fully occupied units with complete 3-year data to ensure consistency").

Comments 6：(Line 110-112） Data cleaning mentions removing outliers but doesn’t define thresholds. Specify outlier criteria (e.g., "values ±3 SD from the mean" or "trimesters with <50% occupancy").

Comments 7：(Line 199-206） The clustering method references Sonalgaz’s pricing groups but doesn’t link clusters to policy implications.

Comments 8：(Line 241-244） Outliers >4000 kWh in T3 are noted but not contextualized. Compare outlier consumption to average household income or appliance ownership (e.g., "Outliers may reflect high-income households using multiple AC units").

Comments 9：(Line 291-294） Natural gas trends suggest "better management" but lack evidence. Hypothesize causes (e.g., "Improved insulation post-2022" or "behavioral shifts due to pricing changes").

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Now, I can accept the article.

Author Response

"We would like to thank the reviewer for the relevant comments, which have all been taken into account in the revised manuscript."

"Please see attachment of the point-by-point response to the reviewer's comments"

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Regarding the cover letter (Comment 3), the therm (symbol, thm) is a non-SI unit of heat energy equal to 100,000 British thermal units (BTU) and is approximately 29.3 kWh, link: https://en.wikipedia.org/wiki/Therm. On the other hand, the thermie (symbol, th) is another non-SI metric unit of heat energy, which is equivalent to 1000 kcal or 1.163 kWh, link: https://en.wikipedia.org/wiki/Thermie.

I assume that you refer to “thermie” and not to “therm”, as measure unit used in Algeria. Please correct accordingly within the work, because is confusing, and is not correct to use both as being the same measurement unit. Also, I would suggest adding a clear reference regarding the measure used by the gas provider (thermie).

Lines 231-232. 1 th = 1000 kcal = 1.163 kWh (not 1163 kWh!!!). Please correct accordingly within the work.

Lines 256 – 258. It is not clear what the global values represent. Please be more specific with the reported energy consumption values. For example, electricity consumption increased from 2150 kWh to 2400 kWh. These are global values per year and per medium size residential unit, e.g. from 2150 kWh/year.unit to 2400 kWh/year.unit, or represent something else?

Figure 7, Figure 8. Please add units on the axis of ordinates.

Author Response

"Thank you for your relevant comments."

"The comments have all been taken into account in the revised version of the article"

"Please see the attachment."

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

Lines 231-232. 1 thermie = 1000 kcal = 1.163 kWh (not 1163 kWh),

                                                  1 Gcal = 1163 kWh, as you wrote.

The authors responded punctually to my previous comments. I have no other comments, other than the minor observation (possibly clerical error) above.

Author Response

"Thank you very much for all your relevant comments."

"Please see the attachment."

Author Response File: Author Response.pdf