Characterising Embodied Energy in Construction Activities Using Energy Inventory Life Cycle Assessment Method

Round 1

Reviewer 1 Report

The paper presents a measure of the energy consumption associated with transportation and on site construction activities (phases A4 and A5 according to en 15978). LCA studies usually neglect this phase, and only provide a proportion relative to the other phases as pointed out by the authors.

some aspects of the English language need to be revised, for instance line 28 uses “construction projects” and “building projects” as a literal translation from Portuguese, while one would normally use the words “construction industry” and “ buildings”. Also on line 381-382 are strange should “fences” be replaced with envelope? Should “internal seals” pe sobs titled with “internal finishes”? What does “project’s walls” on line 545 means. Does it stand for system boundaries?

the use of the comma “,” and dot “.” for the identification of thousands and decimals is often confused, such as at lines 209 and 210; 394; 472; 486

lines 140-151 can be omitted as the same info is presented also in table 2.

the results of the formula (5) at line 215 is not clear: where does the numbers 0,2; 0,06 and 0,7 come from?

the result of line 394, though explained in the following table 4 is not well demonstrated and it needs explanation

lines 405-407 seem to be in contradiction with lines 409-411 and lines 414–416

Table 5 is unnecessary, as that level of detail is not used for the calculation of the transportation energy for laborers, while only the total man-hours are relevant.

Author Response

The paper presents a measure of the energy consumption associated with transportation and on site construction activities (phases A4 and A5 according to en 15978). LCA studies usually neglect this phase, and only provide a proportion relative to the other phases as pointed out by the authors.

Response: Thanks for your time in reviewing our manuscript. The comments are valuable and we have tried our best to answer them. 

some aspects of the English language need to be revised, for instance line 28 uses “construction projects” and “building projects” as a literal translation from Portuguese, while one would normally use the words “construction industry” and “buildings”. Also on line 381-382 are strange should “fences” be replaced with envelope? Should “internal seals” pe sobs titled with “internal finishes”? What does “project’s walls” on line 545 means. Does it stand for system boundaries?

Response: Thank you for this comment and sorry for the misunderstandings. We have checked this issue in the updated manuscript.

the use of the comma “,” and dot “.” for the identification of thousands and decimals is often confused, such as at lines 209 and 210; 394; 472; 486

Response: Thanks for this comment. We have checked this for the whole manuscript

lines 140-151 can be omitted as the same info is presented also in table 2.

Response: Thanks for this comment. We have corrected in the updated manuscript based on the suggestion of the reviewer.

the results of the formula (5) at line 215 is not clear: where does the numbers 0,2; 0,06 and 0,7 come from?

Response: Thanks for your comment. The author would like to apologize for this mistake. We have corrected the updated manuscript as follows:

“At this level of the analysis, an occupancy rate is indicated based on the location of the projects as follows: 0.2 is applied for car transport, 0.06 is applied for motorcycle transport, and 0.74 is applied for public transport. The weighted average consumption parameter is defined according to Equation (5), which shows that the mean consumption parameter defined is 0.575 MJ/km.

                          (5)”

the result of line 394, though explained in the following table 4 is not well demonstrated and it needs explanation.

Response: Thanks for your comment. We have demonstrated and explained the results in the updated manuscript as follows:

“From Figure 4, it is apparent that the mass of the building; components such as structure, fences (envelope), glass, and walls and floor coverings, can highly predict the total energy consumption associated with transport of the material. A relationship exists between the materials of the building mass and the resulting energy consumption associated with the material transportation can be notified. For example, Figure 4 illustrates that approximately 5% of the energy spent on the transportation of materials is associated with the wall coverings. This issue can be justified due to the use of heavy and non-local coatings such as granite Besides, the super structure and infrastructure components less than 50% of the energy spent on the transportation of materials.”

 

lines 405-407 seem to be in contradiction with lines 409-411 and lines 414–416

Response: Thanks for this comment. We have corrected in the updated manuscript in accordance with the previous comment.

Table 5 is unnecessary, as that level of detail is not used for the calculation of the transportation energy for laborers, while only the total man-hours are relevant.

Response: Thanks for this comment. We agree with the author that the information presented in this table is not used for the calculation of the transportation energy of laborers, however, this Table presents the composition of man-hours per activity developed, which has been conducted according to the worksheet presented in the supplementary file. Hence, the authors think that such a table could resume some parts of the supplementary file and facilitate the understanding of issues for the readers.

Reviewer 2 Report

The paper proposes an inventory method integrated within a Life Cycle Analysis (LCA) framework: the aim is  to characterize the energy consumption in the building phase of construction projects early in the design process. The proposed approach relies on Data Quality Indicators (DQI) and a Pedigree Matrix to quantify the building's Direct Component of Initial Incorporated Energy (DCIIE). 

The paper methodology is clearly described and the aims of the work is well presented.

Only minor remarks should be considered:

page 7, line 194: "Km" --> "km" (and the same in all others "Km")

line 195: "c₀ : Represents the inactivity coefficient": more details should be done (i.e. which values for c₀?). The same, please for line 202 (page 7).

The same coefficient is proposed at page 9, line 265 as "c₀: Represents the inactivity coefficient of loss" whose value is proposed in the paper, but: what is the difference with the previous c₀?

Page 11, line 338-343: the authors say: "The DQI used are those proposed by the Pedigree Matrix, adopted by Weidema and Wesnaes [18] as an important tool to assess the data quality in LCA based on several indicators ( i.e., reliability, completeness, temporal correlation, geographic correlation, and technological correspondence of data).  However, it is critical to carry out verified and validated data of the construction system to improve the quality of the data, itself, and to promote the application of the two conditions (i) and (ii) defined above to set up the DQI."

Defined above? where?

Page 17, line 486 and 487: "KWh" --> "kWh"

Page 18, table 8: power in "HP" , please use SI units also 

Author Response

The paper proposes an inventory method integrated within a Life Cycle Analysis (LCA) framework: the aim is  to characterize the energy consumption in the building phase of construction projects early in the design process. The proposed approach relies on Data Quality Indicators (DQI) and a Pedigree Matrix to quantify the building's Direct Component of Initial Incorporated Energy (DCIIE). 

The paper methodology is clearly described and the aims of the work is well presented.

Only minor remarks should be considered:

Response: Thanks for your time in reviewing our manuscript. The comments are valuable and we have tried our best to answer them. 

page 7, line 194: "Km" --> "km" (and the same in all others "Km")

Response: Thanks. Checked for the whole manuscript

line 195: "c₀ : Represents the inactivity coefficient": more details should be done (i.e. which values for c₀?). The same, please for line 202 (page 7).

Response: Thank you for the comment, the inactivity coefficient refers to the energy expenditure while not producing work, meaning not rendering output to the system.

The same coefficient is proposed at page 9, line 265 as "c₀: Represents the inactivity coefficient of loss" whose value is proposed in the paper, but: what is the difference with the previous c₀?

Response: Values are obtained from the same source as indicated in the paper and the difference here is in the application as here at this point it is used for the transportation of construction and demolition waste. We are very thankful as we fixed this mistranslation in the paper.

Page 11, line 338-343: the authors say: "The DQI used are those proposed by the Pedigree Matrix, adopted by Weidema and Wesnaes [18] as an important tool to assess the data quality in LCA based on several indicators ( i.e., reliability, completeness, temporal correlation, geographic correlation, and technological correspondence of data).  However, it is critical to carry out verified and validated data of the construction system to improve the quality of the data, itself, and to promote the application of the two conditions (i) and (ii) defined above to set up the DQI."

Defined above? where?

Response: Sorry for the writing mistake. The sentence has been corrected as follows:

“The DQI used are those proposed by the Pedigree Matrix, adopted by Weidema and Wesnaes [18] as an important tool to assess the data quality in LCA based on several indicators ( i.e., reliability, completeness, temporal correlation, geographic correlation, and technological correspondence of data).  However, it is critical to carry out verified and validated data of the construction system to improve the quality of the data, itself, and to promote the application of the two conditions; C1 and C2 that are defined to set up the DQI.”

Page 17, line 486 and 487: "KWh" --> "kWh"

Response: Thanks. Checked for the whole manuscript

Page 18, table 8: power in "HP" , please use SI units also 

Response: Thank you. We included Watts alongside with HP.

Reviewer 3 Report

Comments

In this paper, the authors claim to provide an inventory method to reduce the energy consumption in the built environment. The methodology considered LCA for the building assessment in the design process. Apparently, DQI and DCIIE are utilized. Overall, the writing style is not up to the mark, the reviewer also is concerned about the contribution of the paper, and findings are inappropriately presented in the abstract. The paper has to go through significant modifications prior to publication. Following are the concerns before possible publication.

1. Please state the novelty of this paper in answer to the comments? Do we have existing studies on exactly similar topic? What’s the specific contribution relevant to existing similar studies? Please provide some references related to similar existing studies and then the authors could state the contribution clearly in the manuscript.

 

2.      This paper needs considerable improvements from the perspective of academic writings and has many grammatical errors as well. Also, the literature review part is very short.

3.      Please provide more detailed related to the BIM model? how it is built?

4.      I presume the models and equations utilized are kind of simple. There exists more advanced models that could be utilized for better assessments. Why the authors utilized these simplified models?

5.      Also, the reviewer is concerned about the data utilized? Please elaborate more on this aspect?

6.      So the super structure and infrastructure has the highest mass and energy consumption? But it is not clear what infrastructure mean? Aren’t other components also part of infrastructure?

7.      There has been significant amount of work done in this area. Hence, currently, the reviewer did not find any significant contribution. Please expand on this aspect.

8.      Figures should be enriched and reference style should be rechecked again.

Comments for author File: Comments.pdf

Author Response

In this paper, the authors claim to provide an inventory method to reduce the energy consumption in the built environment. The methodology considered LCA for the building assessment in the design process. Apparently, DQI and DCIIE are utilized. Overall, the writing style is not up to the mark, the reviewer also is concerned about the contribution of the paper, and findings are inappropriately presented in the abstract. The paper has to go through significant modifications prior to publication. Following are the concerns before possible publication.

Response: Thanks for your time in reviewing our manuscript. The comments are valuable and we have tried our best to answer them. 

1. Please state the novelty of this paper in answer to the comments? Do we have existing studies on exactly similar topic? What’s the specific contribution relevant to existing similar studies? Please provide some references related to similar existing studies and then the authors could state the contribution clearly in the manuscript.

Response: Thanks for such a valuable comment, which helped us define the contribution of the study. We have answered this comment in the updated manuscript in accordance with the subsection (2.1. Reliability of LA) as follows:

“2.1 Reliability of LCA

It is important to note that the reliability of the LCA method depends mainly on the quality of the inventory of the database adopted. As a result, it is essential to assess the quality of the data in the inventory process, a step which is emphasized in this study, to ensure that LCA outputs are well interpreted and communicated [18]. Singh et al [19] quantified the embodied energy and carbon footprint of pervious concrete pavements. The authors applied a comparative LCA to deduce the benefits of pervious concrete pavement over Portland cement concrete pavement for different mixing procedures. Guidetti e Ferrara [20] proposed a comprehensive approach to evaluate the consumption of embodied energy based on retroactive and prospective perspectives in terms of life-cycle energy analysis of an existing building. Chen and Lee [21] provided an effective way to identify good quality data through the definition of reference rules using DQI and pedigree matrix. Zhang et al [22] used DQI and pedigree matrix to assess the level of uncertainty in the LCA of building CO₂ emissions. Yu et al [23] proposed a methodology to build a probability density function for energy intensity coefficient of pavement materials using three weighted methods, namely  DQI, coefficient of variation and analytical hierarchy process. Furthermore, Wang and Chen [24] presented a hybrid stochastic method to develop the uncertainty estimate in LCA with data limitations, using DQI and pedigree matrix. The authors declared that such a study could be used as a valuable tool to evaluate deterministic results of whole-building embodied energy when uncertain information is present. Yu et al [25] estimated the uncertainty analysis of energy consumption and CO2 emission of asphalt pavement maintenance, using DQI and model parameters . Compared to the existing studies, the novelty of this work lies in proposing an accessible approach to assess the embodied energy levels concerning the total energy life cycle in a building, while ensuring valid results when uncertain pdata are present. This will be done via integrating LCA withDQI and the Pedigree Matrix. Data on the following set of activities are collected and validated to evaluate the embodied energy during construction phases in buildings: i) transportation of materials from the manufacturer to the construction site; ii) the transportation of laborers; iii) construction activities taking place on the construction site; and iv) the transportation of waste, as summarised in Figure 1.

Figure 1. Main components of embodied energy in construction activities

As seen by the reviewed literature, there is an obvious lack of a systematic procedure that evaluates the energy performance in the construction industry with reliance on the inventory method for LCA, taking into consideration the production activities and uncertain data during the construction phase of buildings.”

2. This paper needs considerable improvements from the perspective of academic writings and has many grammatical errors as well. Also, the literature review part is very short.

Response: Thanks for this comment. We have done our best to improve the academic writings and correct the grammatical error in the updated manuscript. The literature review has been updated and developed. 

3. Please provide more detailed related to the BIM model? how it is built?

Response: We are sorry for such a technical error. The BIM model is proposed to extract quantities of materials for each project component only. Hence, All BIM related information has been deleted in the whole manuscript. 

4. I presume the models and equations utilized are kind of simple. There exists more advanced models that could be utilized for better assessments. Why the authors utilized these simplified models?

Response: Thanks for this comment. We have justified this point in the updated manuscript based on the improved literature review and scientific contribution of the study

5. Also, the reviewer is concerned about the data utilized? Please elaborate more on this aspect?

Response: Thanks for this comment. We have fully reported this point in the updated manuscript.

6. So the super structure and infrastructure has the highest mass and energy consumption? But it is not clear what infrastructure mean? Aren’t other components also part of infrastructure?

Response: Thanks for your comment. The author apologize for this technical writing issue. In the updated manuscript, the word “infrastructure” has been replaced by “foundation” where it is necessary.

7. There has been significant amount of work done in this area. Hence, currently, the reviewer did not find any significant contribution. Please expand on this aspect.

Response: Thanks for your comment. We have answered it together with the first comment.

8. Figures should be enriched and reference style should be rechecked again.

Response: Thanks for your valuable comment. We have addressed this issue in the updated manuscript.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors have successfully answered the concerns of the reviewer. Hence I recommend this manuscript to be published.