The Air Quality Impact Evaluation of Modular Construction Practices in Hong Kong and Singapore

Round 1

Reviewer 1 Report

This study explore the air quality impact evaluation of modular construction practices in Hong Kong and Singapore. The topic is interesting. However, some major comments need to be addressed.

1 what are the real innovation and contribution of this study?

2 the literature review can be enriched by citing more related study?

3 How did the authors select the paired-samples for the DID model？How could the authors ensure the reliability of the data of the sample? I am worried about this.

4 How did the authors compare the results of this study with related studies?

5 why did the authors choose the DID model?

6 The discussions can be enhanced with more in-depth analysis?

Author Response

1.What are the real innovation and contribution of this study?

There have been many evaluations of the sustainability performance of a single construction using modular constructions, but the environmental impacts of implementing modular constructions on a city scale are rarely explored. Few scholars have studied the impact of the application of this technology on the air quality to the small regional scale. Therefore, this study aims to fill this gap by comparing and analysing the modular construction policies in Hong Kong and Singapore and evaluate the impact of the policy on air quality in the two cities.

2.The literature review can be enriched by citing more related study?

Many have evaluated the sustainability of a single construction project using modular construction technology, but the environmental consequences of implementing modular constructions on a city scale are rarely explored. This research attempts to fill the gap in this field.

3.How did the authors select the paired-samples for the DID model？How could the authors ensure the reliability of the data of the sample? I am worried about this.

Singapore and Hong Kong launched the modular construction policy in different years, which give us the possibility to apply DID analysis. Meanwhile, Singapore and Hong Kong are in similar geographic location, with similar size, population, and share similar climate, which also provides the possibility to use DID analysis.  

The empirical data in this work is collected from the official statistics bureau of Singapore and Hong Kong. It is public data and can be accessed anytime.

4.How did the authors compare the results of this study with related studies?

At present, almost no researchers have compared the impact of modular construction policies on these five gas emissions on a city scale.

5.Why did the authors choose the DID model?

(1) Endogenous problems can be avoided to a large extent: Policies are generally exogenous relative to microeconomic entities, so there is no reverse causality problem. In addition, the use of fixed-effect estimates also alleviates the problem of missing variable bias to a certain extent. (2) The traditional method of evaluating policy effects is mainly by setting a dummy variable of whether the policy occurs or not and then performing regression. In contrast, the model setting of the DID is more scientific and can more accurately estimate the policy effect.

6.The discussions can be enhanced with more in-depth analysis?

We have added some in-depth discussion in the manuscript (Chapter 5.1 and 5.2).

Reviewer 2 Report

The topic of the paper is interesting and the paper is very well structured. The novelty of the paper is well stated and the question that authors tried to address in their research has been fully addressed. However, the following are required to be considered by the authors before the paper being accepted. 

• The current conclusions are massive, and it contains lots of unnecessary information. Therefore, authors are firstly required to state the main aim of the current research at the conclusion before listing the main findings. Then the findings should be summarised in and shortened as they are seems to be too much information there.

 

Author Response

We have edited the conclusions part accordingly.

Reviewer 3 Report

Overall, the paper is in a good shape and of very good quality. My only comment on the manuscript is that many of the tables have the same values in all columns, which can be then substituted with a description within the wording or a chart, instead of the table format.

Author Response

We have changed some tables where it applies.