Investigating the Energy-Saving Effectiveness of Envelope Retrofits and Photovoltaic Systems: A Case Study of a Hotel in Urumqi
Round 1
Reviewer 1 Report
This paper investigates the effectiveness of energy saving retrofit and photovoltaic systems of an old hotel building in Urumqi. This study is certainly worthy of investigation and is well organized. However, it is still space for improving the manuscript by restructuring the manuscript, by refining the major parts of the methods, and by carefully tackling the below observations on the manuscript, presented as major comments.
1. Title of this study “ Research on Energy Saving Retrofit and Sustainable Strategy of 2 Old Buildings in severe cold regions of China：A Case Study 3 of A Hotel in Urumqi” is a little bit vague, please change the title to be more focused, like "Investigating the energy-saving effectiveness of envelope retrofit and photovoltaic systems …: A case of …. "
2. Some recent literature regarding building energy retrofit should be reviewed in the literature review part such as:
10.1016/j.scs.2023.104482
10.1016/j.scs.2023.104602
3. Page 4, Line 142, you mentioned “which is far higher than the limit of 0.3W/m2∙K stipulated in China’s national design standard.” Which national design standard and which year’s standard? Please give an appropriate citation,
4. Page 7, Line 216-219. why did you choose those retrofitting options than the others? Give more explanation about this consideration, don’t abruptly give those options out.
5. Page 9, you mentioned that you will quantify hours of discomfort during the heating season, but how to quantify the discomfort hours, according what standard?
6. In your validation part, you can directly replace the standard weather data by your measured outdoor data. Just compared the indoor simulated and measured data, not need to compared the outdoor simulated and measured data.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper presents an interesting approach regarding potential strategies to implement in old buildings to save energy by heating indoor air. The method is correct when it compares experimental data with computer simulation data. It is well written; however, some points need attention and correction, as listed below.
-In Table 2, extend the line to the outdoor layer. Furthermore, explain that the sequence of the presented layers in the figures is from outdoor to indoor.
-In Figure 6, replace the axis title (Time/Day) with Day/Time. This change applies to the other graphs.
-In lines 196 -198, the authors find that the hotel's temperature is still low in the case of heating in winter. What is the range of temperatures for comfort in winter and summer in China?
-In the simulations, it is assumed that the internal loads were not considered and that the windows and doors were closed. Make that clear.
-In Figure 10, the colors of the lines in the graph are inverted relative to the legends.
-In Figure 11, the caption is inconsistent with the graph. The simulated indoor temperature is the solid line, and the simulated outdoor temperature is the dotted line.
-On line 383, it is verified that the expression "exterior wall" should be "renovation" (overall retrofit).
-On line 396, is Date/Time correct? Verify.
-On line 442, is Time/year correct? Verify.
-On lines 514 - 515, the statement that PV reduces energy consumption is a mistake. PV reduces utility-supplied energy use.
- In references: 12, 23, 33, 36, and 39, use the capitalized letter at the beginning of the first word (author's surname).
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript presents a case study on energy efficient retrofitting in China at a location in a severe-cold climate. In its current state, it cannot be published as a research paper. It is not written in proper technical English, and the structure and especially the content, is quite weak. It is a straightforward case study without novelty.
My comments on the manuscript:
1. The authors claim that there exist a few studies on energy retrofitting in severe-cold climates. Furthermore, these studies are concentrated on only one retrofit measure, and the existing studies seldom consider renewable energy. The novelty of the manuscript is built on these claims. But, there exist many building energy retrofit studies on cold and severe-cold climates. Here I listed some of them, and most of these studies were conducted by Chinese researchers.
https://www.sciencedirect.com/science/article/abs/pii/S0959652622018042
https://www.researchgate.net/publication/343087875_Retrofitting_High-Rise_Residential_Building_in_Cold_and_Severe_Cold_Zones_of_China-A_Deterministic_Decision-Making_Mechanism
https://ideas.repec.org/a/eee/rensus/v180y2023ics1364032123001569.html
https://escholarship.org/content/qt75s5t0xr/qt75s5t0xr_noSplash_5bc8301af13d6d304f551e21150571ac.pdf
https://go.gale.com/ps/i.do?id=GALE%7CA551035524&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=21920567&p=AONE&sw=w&userGroupName=anon%7Eb8cadc90&aty=open+web+entry
2. The introduction is not included a thorough review of the literature to set a basis for the study and to define a gap in the literature. There are a high number of publications that conduct energy retrofitting studies using Building Energy Performance tools and monitoring campaigns in various climatic zones. A strong argument and justification is required. The authors should indicate what is different in their work comparing other studies. Otherwise, it looks like an exercise for developing retrofitting scenarios without novelty.
3. Materials and Methods section does not include a flow diagram of the study; starts directly introducing the case building. Measuring devices and specifications should be given in a table. To be able to validate a model, at least one-year measurements should be taken from the case building. Only four days of measurements (in March) are not reliable for validation. Furthermore, the building is about 5500 m², but the authors take measurements only from one room and expect to represent the whole building. Therefore, the model and the simulation results are not reliable.
What does comfortable/uncomfortable hours? Criteria? The authors should talk about thermal comfort.
4. Results section: The validation does not include statistical analysis (RMSE and MAPE) to be able to justify validation.
The aim of the study is to decrease energy consumption, but no actual energy consumption data for the building is presented. Also, the cost of the retrofit measures is not discussed properly. Investment costs comparing energy consumption reduction should be discussed. PV production is quite low. What is the installation cost? CO2 emissions are only mentioned for PVs, not for the other measures.
5. Language: Poor English with many non-technical words/terms. Such as;
" Indoor temp. is shallow". What does shallow temperature mean?
The buildings from the 70s-80s are classified as historic buildings? The authors confused old buildings-historic buildings.
Indoor temperature problem, low indoor temperature ??? What does "indoor temperature problem"? The authors should talk about thermal comfort or set point temperature instead.
6. Conclusions should be elaborated to draw more general results and should be improved, including future work direction and comparison with the literature.
The limitations of the study should be discussed.
I gave language comments on the first part.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscript has been siginificantly improved. I believe it can be accepted in the present form.
