Experimental Validation of Water Flow Glazing: Transient Response in Real Test Rooms

Round 1

Reviewer 1 Report

The authors need to make major improvement of the manuscript. The current format is not acceptable in Sustainability.  My suggestions and comments are shown below.

• Abstract: Does not clearly reflect the content of the study, it is necessary to review its structure,the Abstract should include the background, scientific gaps, straightforward objective, methodology, results and future potentials. Please revise the abstract, incorporating these suggestions.

• Introduction: Current peer-reviewed publications related to the topic should be cited, analyzed and criticized: specifically related to WFG and test cell facilities.

Lines 52 to 62 describe general knowledge, which may not be pertinent to this section.

Line 72:“Glass facades characterize the values…. century” do not understand the meaning and the interest of this sentence here.

Line 116-117, “WFG can improve the performance coefficient of cooling systems by increasing the indoor comfort temperature and the inlet temperature of the fluid through the glazing [47].” Increasing? Could you explain this in more depth? Is this due thermal radiation?

Line 123 “provides actual data of the energy absorption by the water and its influence on the room heat gains “.  Is this an objective or a result?

• Materials al methods: Please. Clarify what it is, and a conceptual explanation of what mass flow rate is could be useful.

Please check Figure 3 and figure 2 order to facilitate reading.

Please, in figure 2 specify that with Temperature, you mean θ out in order to facilitate reading.

Line 197: “When the water flow stops, the thermal transmittance depends mainly on the air chamber.” It depends on the glazing, the spacers, the sealing………. not only the chamber.

• The main reservation on this work concerns this section. The size of the test cell is very small. The insulation of the walls is poor. No information is presented on the U of the glazing’s units, with the possibility that the heat flow through the opaque envelope is greater than the heat flow through the glazing, which means variables are not being isolated.

It is necessary to expand the information, justify and validate its application with scientific literature.

Line 238: Which free cooling techniques?

The position of the thermal sensors is not clear, are they inside, a section sketch or a picture will facilitate reading.

What type of temperature sensors are they? Where are the pyranometer and the flow meter placed?

Line 245: In think instead “heat exchanger” you mean “Heat exchange”

• Results: Line 288-291: That is a normal behaviour because there is not enough insulation and the cell is small. I would not say it is a result of this work.

Explain operation hours of the “peltier”, is it a scheduled time or there is a set temperature to start and stop? This should be probably en the section Materials and Methods.

• Discussion: More information about the software used and the simulation assumptions and parameters need to be provided.

Line 395. Above 25ºC in summer is not comfort zone.

• Conclusions: Line 445: “it can be concluded that night cooling strategies increased the system's energy efficiency.” What strategies?

Line 447-450: That’s basic information, it is not a conclusion

Line 451: “temperature curve” which? Refer to the figure

Line 452: sufficient?

Line 453: This effect can increase the “thermal” comfort

Line 454: “The Reference glazing replicated the thermal oscillations of the outside temperature, generating discomfort inside the building and contributing to overheating.” This is not a conclusion

• A proof reading by a native English speaker should be conducted to improve the clarity of the manuscript.

Author Response

Please, see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper presents a prototype that has been monitored during 2 years and serves to validate a predictive model of the performance of the Water Flow Glazing.

The paper is well structured, the methodology is well developed and clear, the analysis of results is extensive and complete; and the conclusions are concise.

To improve the understanding of readers who does not know the climate of Spain, it is recommended that a specific section be included about the climatic conditions of the location of the prototype.

The study has many equations, so it is recommended that a table of symbols be included at the beginning or the end of the paper.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The work shows and explains a simplified approach in assessing the Water Flow Glazing systems. The paper retraces the theoretical approach in assessing the thermal analysis of WFG and it well presents the results in the experimental phase, showing good results in validation.

Nevertheless some changes/integrations should be implemented to improve the article overall quality:

• introduction: please provide some reference about the increasing demand in cooling consumptions as introduced in lines 111-112;
• in section 2.1, insert in the text all the abbreviations (h0, hw, ect.) and their definition in order to have a simplified reading (the image reference cannot be the only reference for the reading). For example, introduce a description for θSTAGNATION (no references exist). Moreover, check all the references in the text about the equations (e.g. line 158).
• in section 2.2: please introduce a table with the overall properties for both glass configurations and explain the selection of reference one; the work compares two different kinds of glass systems and discusses results according to them. Finally, provide a reference for the experimental location (in Spain maybe, in which city?). 
• results - Section 3.1: The caption of Image 10 should be rewritten. Moreover, as in section 2.1, all the acronyms should be discussed in the text (e.g. Tw_up_L, Tw_up_R).
• discussion - Section 4: which simulation tool has been used for simulations?
• Finally, check again the text in order to delete some typing errors. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have made the requested modifications. The size of the test cell, still a concern, has been justified in reference to previous work done at the same university.