Optimization Analysis of the Residential Window-to-Wall Ratio Based on Numerical Calculation of Energy Consumption in the Hot-Summer and Cold-Winter Zone of China
Round 1
Reviewer 1 Report
There is a clear focus on fabric-first energy efficiency solutions and the topic is clear and timely. Although to clarify, there efficiency of the fabric has to be aligned with heat-loss parameters and the simplicity of the form to optimise the surface area for the GIA heated area. Thus, as a minimum, the introductory section requires a mention with regards the potential significance on the overall performance of the building. As a context for this optimisation study, it would be helpful to understand the relative impact in form factors, including the impact of floor to ceiling heights; compared to ration of wall to window.
Sample size seems to be 368 (quite an impressive response rate), although the paper is supported by a very clear and impressive robust methodology, albeit, based mostly upon the occupant’s perception for real buildings.
There is some concern with the focus on typologies, although sound in principle, but seems to have a lot of different variables within each of the modelling. In addition, it is unclear where the WWR has been derived from within this survey? Thus, this does seem to be largely a study looking at modelling hypothetical or typical property typologies. While this isn’t an issue, I would recommend the this is made clear and that the scope of different assumptions around the parameters and geometry of the different typologies.
The modelling of case studies is the most convincing part is the modelling tot the case study units …. Although there seems to be a discrepancy between the GIA sizes of these compared to the average sized units mentioned (para. 2.1.2) ? It would be useful to understand the differences between these sizes and the modelled case studies as it is quite a large discrepancy here.
Within the modelling of the case study units, this is sound evaluation and clear explanation.
It does seem that there is probably too much data behind this work and that it could be more effective as two separate papers, one being a theoretical look at dealing with the modelling of the typologies, and the second being an investigation into the ‘performance gap’ and the differences between modelled and actual results. The later paper would allow more space to address the relationship between the case study typologies and the results from the CRECS perhaps?
Author Response
Dear editor and reviewer,
Thank you very much for your letter and advice on our manuscript. We have resubmited new version of graphs in accordance with recommendations of the technical editor. We have addressed the comments raised by the reviewers, and the amendments are highlighted in red in the revised manuscript. We hope that the revision is acceptable and look forward to hearing from you soon.
Point 1: Is the content succinctly described and contextualized with respect to previous and present theoretical background and empirical research (if applicable) on the topic?
Response 1: We have split introduction into introduction and literature review two chapters. The introduction section of this paper introduces the current research theoretical trends, as well as some problems, and explains the relevance of the research.
In page 3 and page 4, we introduced the WWR research theoretical trends and explains the relevance of the research “In terms of the current state of research, there have been numerous publications and discussions on the impact of WWR on the building energy consumption, and most of them have confirmed that the building energy consumption and WWR are basically in a positive linear relationship, but no discuss of reasonable WWR is made [11-16]. From the perspectives of dynamic simulation and steady-state calculation are the most common methods, but the research conclusions on the reasonable value of WWR are not very consistent. In the Hot-summer and Cold-winter (HSCW) zone of China, for an indication, the former shows a power-of-quadratic correlation between energy consumption and WWR in the south of the residential buildings, while printing a positive linear relationship in the other directions [17]. The latter, a calculation method based on steady state, points out that the consumption of heating has a positive linear relationship with the WWR in all directions [18]. Clearly, the results of these two studies show that the smaller the value of WWR, the more significant the effect on building energy efficiency. The current "Design Standard for Energy Efficiency of Residential Buildings in Hot Summer and Cold Winter Zone" (JGJ134-2010) [19] of China uses dynamic simulation analysis method to study the relationship between the reasonable value of WWR of each orientation and the thermal insulation performance of external windows [20]. It has been noted that the maximum WWR of 0.6 for south-facing can only be set when the heat transfer coefficient of the external windows is reduced to 2.5 W/(m2-°C) [21]. At the same time, for east and west exterior windows, if an exterior shading facility with a solar radiation transmittance of less than 0.25 is used, the WWR can also be increased to 0.6.
Besides, A number of scholars have discussed the relationship between WWR and human thermal comfort [22-30]. By using an office as an experimental space and conducting thermal comfort evaluation statistics for the people, the best value of the WWR is evaluated, which may provide pleasant situations during the longest time of the year [27]. In terms of comfort, however, it should also be noted that the degree of influence of window characteristics in the practical environment also lies in human performance [9]. It can be found that there are more optimization analyses of WWR for residential buildings, but few sub-studies of different building types relatively, and this paper can fill the gap of relevant basic data in this part. Precisely, the existing studies on WWR, energy consumption in residential buildings and human thermal comfort are independent.
Based on this research background, in this study, the author first conducted a questionnaire survey on the building basic information, thermal comfort, thermal demand, and energy consumption status of residents mainly in three areas in HSCW zone of China, which namely Shanghai, Zhejiang province, and Jiangsu province. By collating the data from the questionnaire, the cases were divided into three building types: detached house, multi-story dwelling and high-rise dwelling. Then, one-year indoor thermal conditions experiment and data collection were conducted on typical cases of each building type. In addition, based on the above, a building model under reasonable boundary conditions was established to optimize the analysis of the WWR. In this context, form people's desire for thermal comfort and the status quo of huge energy consumption, it’s critical to consider these three together. This study investigates this topic, exploring whether there is an optimal WWR, which will not only maximizes the energy efficiency of residential buildings, but will also leads to better thermal comfort for the residents. In short, this study gives practical information for architects and the construction industry, as well as a method that can be used to configure an appropriate WWR, providing reference data for the reasonable value of residential buildings. It has important implications for the design of sustainable residential buildings with high energy efficiency and satisfying thermal comfort.”
Point 2: Are the research design, questions, hypotheses and methods clearly stated? （Can be improved）
Response 2: The article research design, questions, hypotheses and methods are revised and further explained in page 1, the abstract part “In this study, the Hot-summer and Cold-winter (HSCW) zone of China was chosen as the experimental setting for the optimization analysis of WWR. And then, in the three main types of residential buildings, including detached houses, multi-story dwellings and high-rise dwellings, a correlation between WWRS and energy consumption in the cooling season, heating season and year-round was built. The comparisons between the WWRS and energy consumption for different types of residential buildings are presented. The design optimization recommendation for WWRS are proposed. It has significant positive meanings for the development of green and sustainably designed residential buildings that offer high levels of thermal comfort and energy efficiency.” Explains the research design and problems with the current study. The methods are shown in page 4 to 13, the “Questionnaire investigation” “Field survey” and “Simulation method” are applied in the article.
Also, innovation and novelty of this paper were shown in the end of the introduction in page 3.
“The innovation and novelty of this paper lies in the logical coherence. The author first conducted a questionnaire survey on basic building information, thermal comfort, thermal demand and energy consumption status of residents, with 368 valid questionnaires, which is the first-hand information of such research in the region. By compiling the data from the questionnaires, the cases were classified into three building types: detached houses, multi-story houses and high-rise houses. Then, indoor thermal conditions data collection was conducted for one year for typical cases of each building type, and based on this, building models with reasonable boundary conditions were established to optimize the analysis of WWR and ensure the accuracy and reasonableness of the data. In this case, it is crucial to consider all three together by forming the current situation of people's desire for thermal comfort and huge energy consumption. This study investigates this topic and explores whether there exists an optimal WWR that not only maximizes the energy efficiency of residential buildings, but also provides better thermal comfort for the residents, which is a very novel idea and attempt. In conclusion, this study provides practical in-formation for architects and the building industry, as well as a method that can be used to configure an appropriate WWR that provides reference data for a reasonable value of residential buildings. This aspect of the study is important for designing sustainable residential buildings with high energy efficiency and satisfactory thermal comfort.”
Point 3: There is a clear focus on fabric-first energy efficiency solutions and the topic is clear and timely. Although to clarify, there efficiency of the fabric has to be aligned with heat-loss parameters and the simplicity of the form to optimize the surface area for the GIA heated area. Thus, as a minimum, the introductory section requires a mention with regards the potential significance on the overall performance of the building. As a context for this optimization study, it would be helpful to understand the relative impact in form factors, including the impact of floor to ceiling heights; compared to ration of wall to window.
Response 3: As a context for this optimization study, the relative impact in form factors, including the impact of floor to ceiling heights; ration of wall to window.
Page 2, in the introduction part was
“Measures to reduce heat emissions from the interior to the exterior of a building play an important role in creating a suitable indoor thermal environment and saving energy. Measures to reduce heat emission from the inside of the building to the outside play an important role in creating a suitable indoor thermal environment and saving energy. The volume factor of the building should be minimized. Volume factor is the ratio of the surface area to the volume of a building. Its magnitude reflects the size of the surface area of the building. From the comparison of surface results, the larger the volume factor, it means that for the same volume of room, the larger the surface area, the more energy loss way of the building; at the same time, the smaller the volume factor, it means the smaller the external window area of the building and the relatively low cost. The height of the building and the height of the floor are also important parameters that directly affect the volume factor and indirectly affect the heat absorption and heat loss of the building. The performance of the exterior envelope also directly affects the heat loss parameter. The exterior walls and the doors and windows on the exterior walls bear the main functions of lighting and ventilation of the building. Choosing a suitable window-to-wall area ratio and adopting windows with small heat transfer coefficient are important ways to improve the thermal insulation performance of exterior windows.”
Point 4: Sample size seems to be 368 (quite an impressive response rate), although the paper is supported by a very clear and impressive robust methodology, albeit, based mostly upon the occupant’s perception for real buildings.
Response 4: In fact, in page 4, “In this study, questionnaires were distributed in the form of paper questionnaires, which were completed from March to June 2018, with a total of 500 distributed and 480 returned, removing invalid questionnaires for a total of 368 usable questionnaires ”. The authors take the real feelings of people as a starting point, combine the objective conditions related to thermal comfort, and reconstruct the scenario by simulation, with a view to achieving a more logical and reasonable purpose, the related contents are shown in page 8 to 13. Start from “2.2. Field survey” to “2.3. Simulation method”.
Point 5: There is some concern with the focus on typologies, although sound in principle, but seems to have a lot of different variables within each of the modelling. In addition, it is unclear where the WWR has been derived from within this survey? Thus, this does seem to be largely a study looking at modelling hypothetical or typical property typologies. While this isn’t an issue, I would recommend the this is made clear and that the scope of different assumptions around the parameters and geometry of the different typologies.
Response 5: First of all, thank you very much for such valuable comments from the reviewers. The article was revised and clarified in accordance with the reviewers' comments. For the classification of building types, we are based on the Chinese civil buildings with different requirements for different heights of residential buildings, such as the fire protection standard "Building Design Fire Code" GB50016(page 4, the 5th line), according to these requirements in accordance with the practice, residential buildings are divided into detached house, multi-story dwelling and high-rise dwelling. The base data of window-to-wall ratio (WWR) comes from summarizing the building base information from 368 survey questionnaires. The reason why there are many different variables in each modeling is that we have to consider various possible scenarios in a realistic situation. However, in the simulation evaluation process we try to set the boundary conditions clearly so that we can be as close to reality as possible while simplifying the complex realistic situation.
The reasons why we chose WWR as the subject of our study are listed below, page 3.
“However, as a part of high energy consumption, there is still a great gap between China and the other developed countries in the level of energy efficiency of residential buildings. Therefore, to improve effectively the energy consumption of residential buildings and their impact on the climate environment, many scholars have conducted many studies on the energy consumption and thermal performance of the residential building envelope. And these studies confirm that the most direct and effective way to improve the thermal performance of residential buildings is to change the exterior form of the building and optimize the thermal performance of the envelope [7]. But it’s worth noting that this is not a single and easy task, as well-known to all, the composition of the building envelope is complex, including many components, such as walls, windows and doors, etc. The thermal performances of these constituent elements are different and therefore have different effects on on the flow of energy (heat loss, solar gain, etc.) between the interior and exterior, as well as on various aspects of indoor comfort, such as visual shading, acoustic transmission, etc. Additionally, people increasingly tend to prefer residential buildings with large floor-to-ceiling windows in modern life, but floor-to-ceiling windows are detrimental to building energy-saving, as exterior windows contribute to a larger proportion of the energy consumption of maintenance structures. It can be seen that the window-to-wall ratio (WWR), defined as the ratio of the area of the window opening to the area of the wall facade of the room in which the window is located, is an important parameter that affects the thermal performance of the building envelope and the energy consumption of the building. Because the heat transfer factor of the window is greater than that of the wall. With an increase in the area of the windows, the heat transfer from the room to the outside the heat gained by the solar radiation inside is all enhanced. Both of these are unfavorable factors for the cooling load of the building, but doubly so for the heating load. Thus, when the cooling load of the building becomes the main energy consumption, excessively large windows are damaging to energy efficiency. However, for residential buildings with multiple orientations, the extent to which the WWR con-tributes to the energy consumption of a room varies in each direction, as the solar radiation is different in each direction of the building. Therefore, in order to most directly and effectively improve the energy efficiency of residential buildings, it is essential to determine the impact of WWR on the energy consumption in all directions. It has been shown that increasing the value of WWR will not only increase the solar radiation indoors, but also enhance the energy flow and heat exchange between indoors and outdoors. In this way, the increased solar radiation, although beneficial to improve the indoor thermal environment in winter, will lead to an increase in energy use for air conditioning in summer. In addition, while the increased indoor-outdoor heat exchange raises the heat consumption of the room in winter, it facilitates indoor heat dissipation in summer [10]. Several studies have shown that the effects of increased WWR are multifaceted, with benefits and detriments to the indoor thermal environment in winter and summer, respectively. Therefore, a reasonable WWR should be determined in order to jointly improve human thermal comfort and energy efficiency.”
Point 6: The modelling of case studies is the most convincing part is the modelling tot the case study units …. Although there seems to be a discrepancy between the GIA sizes of these compared to the average sized units mentioned (para. 2.1.2)? It would be useful to understand the differences between these sizes and the modelled case studies as it is quite a large discrepancy here.
Response 6: The slight difference between the GIA size and the average size in this article is due to the fact that we have chosen the median of the size ratios and therefore there is a slight difference. The median of the building model was chosen because the mean is used to measure the average level of the data and the median is used to compare the dispersion of the data. Many parameters of many buildings in the selection of the average value, in fact, is a virtual value, and the median can be better in different building types in the residents reflect the current situation and the existing residential exterior envelope, body shape coefficient and window-wall ratio parameters, so we believe that the median is more appropriate.
Point 7: It does seem that there is probably too much data behind this work and that it could be more effective as two separate papers, one being a theoretical look at dealing with the modelling of the typologies, and the second being an investigation into the ‘performance gap’ and the differences between modelled and actual results. The later paper would allow more space to address the relationship between the case study typologies and the results from the CRECS perhaps?
Response 7: We are very grateful to the reviewers for their affirmative and positive comments on the article, which we finally chose to publish as a single article in order to maintain the logic of the article, and would like to thank them for their comments.
The reason is shown in chapter 1, page 3.
“The author first conducted a questionnaire survey on basic building information, thermal comfort, thermal demand and energy consumption status of residents, with 368 valid questionnaires, which is the first-hand information of such research in the region. By compiling the data from the questionnaires, the cases were classified into three building types: detached houses, multi-story houses and high-rise houses. Then, indoor thermal conditions data collection was conducted for one year for typical cases of each building type, and based on this, building models with reasonable boundary conditions were established to optimize the analysis of WWR and ensure the accuracy and reasonableness of the data. In this case, it is crucial to consider all three together by forming the current situation of people's desire for thermal comfort and huge energy consumption. This study investigates this topic and explores whether there exists an optimal WWR that not only maximizes the energy efficiency of residential buildings, but also provides better thermal comfort for the residents, which is a very novel idea and attempt. In conclusion, this study provides practical information for architects and the building industry, as well as a method that can be used to configure an appropriate WWR that provides reference data for a reasonable value of residential buildings. This aspect of the study is important for designing sustainable residential buildings with high energy efficiency and satisfactory thermal comfort.”
Finally, on behalf of all the authors, I would like to thank the reviewers again for reading and wish you everything goes well. We hope that the revision is acceptable and look forward to hearing from you soon.
With best wishes
Haiqiang Liu etc.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The subject and main idea are interesting and promising, but the paper needs an extensive editing of English language, alongside with the fixing of some other minor errors. I have several suggestions, which I hope will be helpful:
- Please check and fix several errors regarding the English language. I spotted several in some paragraphs, but there are more than that: Page 2: “Under the current circumstances (…) residential buildings”, Page 2: “many scholars have done many studies”, Page 3: “From the perspectives of dynamic simulation (…) relationship in the other directions”, Page 4: “Then, one-year indoor thermal conditions experiment (…) comfort for the residents”, Page 4: “It has important implications for (…) thermal comfort”
- Do not put a capital letter after a coma, e.g. in page 2 “In addition, People increasingly (…)”, in page 3 “Besides, A number of scholars have (…)”, in page 10 “According to the results of the questionnaire Investigation, three (…)”, etc.
- The degree Celsius symbol (°C) doesn’t appear correctly in page 11.
- In both the graph captions (a) and (b) of figure 15, you write “Monthly heating/cooling loads of detached house”. Shouldn’t one of them be “Monthly heating/cooling loads of multi-story dwelling”?
- In page 2, in paragraphs “In addition, People increasingly tend to prefer residential buildings with large floor-to-ceiling (…)the impact of WWR on the energy consumption in all directions”, you use a non-scientific phrasing. Please use a more scientific approach, suitable for a research publication.
- Please discuss and clearly present the novelty of your work in the end of the introduction.
- Please split introduction and literature review into two chapters.
- In order to make the conclusion section clearer, authors are highly encouraged to include the point-by-point findings of this article. The current conclusion is written very wide and it is not easy to maintain the key findings.
Author Response
Dear editor and reviewer,
Thank you very much for your letter and advice on our manuscript. We have resubmited new version of graphs in accordance with recommendations of the technical editor. We have addressed the comments raised by the reviewers, and the amendments are highlighted in red in the revised manuscript. We hope that the revision is acceptable and look forward to hearing from you soon.
Point 1: Please check and fix several errors regarding the English language. I spotted several in some paragraphs, but there are more than that: Page 2: “Under the current circumstances (…) residential buildings”, Page 2: “many scholars have done many studies”, Page 3: “From the perspectives of dynamic simulation (…) relationship in the other directions”, Page 3: “Then, one-year indoor thermal conditions experiment (…) comfort for the residents”, Page 4: “It has important implications for (…) thermal comfort”.
Response 1: The article was revised and clarified in accordance with the reviewers' comments.
Page 2: “Under the current circumstances (…) residential buildings” has been modified to “Under these circumstances, people's indoor environment does not give them a comfortable thermal comfort condition. It follows that people's growing demand for thermal comfort is one of the core contributors to the increasing energy use of residential buildings”.
Page 2: “many scholars have done many studies”. “Done” has been revised to “conducted”.
Page 3: “From the perspectives of dynamic simulation (…) relationship in the other directions” has been changed to “From the perspectives of dynamic simulation and steady-state calculation are the most common methods, but the research conclusions on the reasonable value of WWR are inconsistent. In the Hot-summer and Cold-winter (HSCW) zone of China, for an indication, the former shows a power-of-quadratic correlation between energy consumption and WWR in the south of residential buildings, while printing a positive linear relationship in the other directions”.
Page 3: “Then, one-year indoor thermal conditions experiment (…) comfort for the residents” has been revised to “Then, indoor thermal conditions experiments and data collection were carried out for one year for typical cases of each building type, and based on the above, building models with reasonable boundary conditions were developed to optimize the analysis of WWR. In this case, it is crucial to consider all three together by forming the current situation of people's desire for thermal comfort and huge energy consumption. This study investigates this topic and explores whether there exists an optimal WWR that not only maximizes the energy efficiency of residential buildings but also provides better thermal comfort to the inhabitants”.
Page 4: “It has important implications for (…) thermal comfort” has been changed to “Precisely, the existing studies on WWR, energy consumption in residential buildings and human thermal comfort are independent”.
Point 2: Do not put a capital letter after a coma, e.g. in page 2 “In addition, People increasingly (…)”, in page 3 “Besides, A number of scholars have (…)”, in page 10 “According to the results of the questionnaire Investigation, three (…)”, etc.
The degree Celsius symbol (°C) doesn’t appear correctly in page 11.
In both the graph captions (a) and (b) of figure 15, you write “Monthly heating/cooling loads of detached house”. Shouldn’t one of them be “Monthly heating/cooling loads of multi-story dwelling”?
Response 2:
Page 2: “In addition, People increasingly (…)” has been revised to “Additionally, people increasingly (…)”.
Page 3: “Besides, A number of scholars have (…)” has been revised to “a number of scholars have (…)”.
Page 10: “According to the results of the questionnaire Investigation, three (…)” has been revised to “According to the results of the questionnaire investigation, three (…)”.
“The degree Celsius symbol (°C) doesn’t appear correctly in page 11” has been corrected.
Page 16: In both the graph captions (a) and (b) of figure 15, you write “Monthly heating/cooling loads of detached house”. Shouldn’t one of them be “Monthly heating/cooling loads of multi-story dwelling”?
The graph captions (b) has been revised to “(b) Monthly heating/cooling loads of multi-story dwelling”.
Point 3: In page 2, in paragraphs “In addition, People increasingly tend to prefer residential buildings with large floor-to-ceiling (…)the impact of WWR on the energy consumption in all directions”, you use a non-scientific phrasing. Please use a more scientific approach, suitable for a research publication.
Response 3:
Page 2: “In addition, People increasingly tend to prefer residential buildings with large floor-to-ceiling (…)the impact of WWR on the energy consumption in all directions” has been changed to “Additionally, people increasingly tend to prefer residential buildings with large floor-to-ceiling windows in modern life, but floor-to-ceiling windows are detrimental to building energy-saving, as exterior windows contribute to a larger proportion of the energy consumption of maintenance structures. It can be seen that the window-to-wall ratio (WWR), defined as the ratio of the area of the window opening to the area of the wall façade of the room in which the window is located, is an important parameter that affects the thermal performance of the building envelope and the energy consumption of the building”.
Point 4: Please discuss and clearly present the novelty of your work in the end of the introduction.
Response 4: The introduction section of this paper introduces the current research theoretical trends, as well as some problems, and explains the relevance of the research to this research. And also presented the novelty of our work in the end of the introduction.
“The innovation and novelty of this paper lies in the logical coherence. The author first conducted a questionnaire survey on basic building information, thermal comfort, thermal demand and energy consumption status of residents, with 368 valid questionnaires, which is the first-hand information of such research in the region. By compiling the data from the questionnaires, the cases were classified into three building types: detached houses, multi-story houses and high-rise houses. Then, indoor thermal conditions data collection was conducted for one year for typical cases of each building type, and based on this, building models with reasonable boundary conditions were established to optimize the analysis of WWR and ensure the accuracy and reasonableness of the data. In this case, it is crucial to consider all three together by forming the current situation of people's desire for thermal comfort and huge energy consumption. This study investigates this topic and explores whether there exists an optimal WWR that not only maximizes the energy efficiency of residential buildings, but also provides better thermal comfort for the residents, which is a very novel idea and attempt. In conclusion, this study provides practical information for architects and the building industry, as well as a method that can be used to configure an appropriate WWR that provides reference data for a reasonable value of residential buildings. This aspect of the study is important for designing sustainable residential buildings with high energy efficiency and satisfactory thermal comfort.”
Point 5: In order to make the conclusion section clearer, authors are highly encouraged to include the point-by-point findings of this article. The current conclusion is written very wide and it is not easy to maintain the key findings.
Response 5: We have revised the conclusions of the article according to the point-to-point findings as suggested by the reviewers, and we thank the reviewers for their valuable comments.
“This paper provides a comprehensive overview of energy consumption in the residential sector in China based on a detailed dataset of 368 surveyed households from the 2018 China Residential Energy Consumption Survey (CRECS) [54].
First, the questionnaire survey shows that detached house, multi-story dwelling and high-rise dwelling are the three most common types of houses in HSCW zone of China, and that high-rise dwelling is the newest and detached house is the oldest. About 50.00% of the respondents were high-rise residences, 33.33% were multi-story residences, and only 16.67% were detached residences. The age of construction and floor area varied significantly by building type. High-rise dwelling uses the largest window sizes, while multi-story buildings use the smallest window sizes for historical reasons. The total energy consumption of high-rise dwelling is the highest of the three residential building types, while detached house has high total energy consumption, but the lowest annual energy consumption per unit area due to their large size. Residents living in high-rise buildings have the highest human comfort requirements of the three building types. The thermal satisfaction of high-rise residences is better than the other two building types. Meanwhile, the energy consumption generated is related to the type of dwelling: in the south direction, for example, the energy consumption per unit area of the three building types shows a growing trend as the WWR increases.
Second, based on the questionnaire survey, Shanghai, a city located in the middle of the three regions was selected, as the experimental area to represent the HSCW zone in China and selected three residences based on the questionnaire results, combined with the year of construction, the average window area and other characteristics as the experimental subjects. The experiment is an investigation of the current situation of the three dwellings under natural conditions, and the results show that: for example, in the south direction, the PMV of the three building types shows a large difference, with the thermal comfort of high-rise dwelling being better and that of detached houses being the worst. Alternatively, the heating load of each building type is greater than the cooling load in a year, but the energy consumption per unit area of the detached house is the largest, followed by multi-story dwelling, and the smallest for high-rise dwelling. Overall, this part provides the current data basis for the next optimization simulation and analysis of the WWR.
Third, most importantly in this paper, the impact of WWR on indoor heating and cooling energy demand is experimented and then analyzed through hourly-based dynamic simulations, which are of interest to regions in the HSCW region of China, such as the reference location Shanghai. So, at the beginning of these specific experiments, different building types, such as detached house, multi-story dwelling and high-rise dwelling, different envelope and window characteristics were considered as independent variables, including insulation levels, orientation, shading and control of natural ventilation. The results of simulations performed at a constant occupancy rate indicate that an optimal WWR value that balances the three aforementioned energy uses results in the least amount of energy required per year.
Overall, for the comprehensive energy consumption of the detached house, the smaller WWR results in lower energy consumption per unit area. For multi-story dwelling and high-rise dwelling, when WWR value is between 0.4–0.5, a balance be-tween the WWR and energy consumption is achieved. For north-facing rooms, because the direct solar radiation cannot be obtained, increasing the window area makes the increase in the amount of solar scattered radiation limited. However, for high-rise dwelling, the increase in the north-facing WWR has little effect on the increase in heating load in winter. The detached house and multi-story dwelling have increased significantly. It can be seen that the WWR of the north rooms should be reduced as much as possible.”
Finally, on behalf of all the authors, I would like to thank the reviewers again for reading and wish you everything goes well. We hope that the revision is acceptable and look forward to hearing from you soon.
With best wishes
Haiqiang Liu etc.
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
