A Review of Ventilation and Environmental Control of Underground Spaces

Round 1

Reviewer 1 Report

This paper has reviewed the ventilation and environmental control of underground spaces. Generally, the work is well written. However, a major revision is still required to give a clear overview of the environmental control of underground spaces.

 

1. The title is a little confusing. Ventilation is one of the environmental control strategies. Besides, the current paper does not focus on environmental control, as 2.1 Moisture transfer and 2.2 Heat transfer are about the mechanism of the underground environment, and 2.4 Smoke Control and exhaust involves the fire safety of underground spaces.

 

2. The authors are encouraged to reorganize the structure. As also stated in Question 1, 2.2 Heat transfer is not the ‘unsolved problem’. The section title ‘Unsolved Problems in Underground Spaces’ is not appropriate to cover the text.

 

3. Section 1.2, proposing some solutions is one of the aims. However, I could not find sufficient discussions on the solutions.

 

4. Conclusions are quite simple, more academic input is expected.

 

5. Line 242, ‘insufficient combustion’ should be ‘incomplete combustion’.

Author Response

See attached document.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper undertakes a literature review on ventilation aspects, including the comfort of people in underground spaces. It is very interesting and takes up important issues related to life in the modern world.

The paper is theoretical. The authors cited 91 literature items in order to prepare it.

The article lacks a broad analysis by the authors and own interpretation of the issues raised, also in terms of the future. I suggest creating an additional point in the paper: Own analysis. Conclusions of the paper should also be extended to include this aspect.

Please check the paper in terms of language.

Author Response

See attached the responses, thanks.

Author Response File: Author Response.docx

Reviewer 3 Report

Authors presented the studies on “Ventilation and Environmental   Control of under Ground Spaces”. The theme of the paper is good which is very important in Covid-19 scenario. But, this paper need extensive modification in term of quantitative results.  My comments are given below which helps to improve this manuscript.

• There are many grammatical and typo errors which need to be improved. Some are given below;

1. In Abstract ‘Concrete problems include excessive humidity, heat transfer specialty, excessive CO caused by blockage in long distance traffic tunnels, difficulty in smoke exhaust and evacuation during fire, harmful microorganisms, radioactivity pollutants, psychological problems, and so on.’ Improve this sentence.
2. Line 26-29, “Underground spaces are increasingly being used,….”. Correct this sentances.

• Line 31-32, “Underground space development is becoming increasingly important as cities become more densely populated.” Incorrect sentence.

1. Line 116-118, “From the perspective of moisture insulation, applying straw board as the interior material in this type of underground civil air defence work without occupants can mitigate daily and monthly humidity variations, to achieve a good humidity environment”. Improve this sentence.
2. Line 222-224, “Construction ventilation, used for comprehensive control of underground space construction environments, has a direct impact on body health and construction efficiency of tunnel construction workers.” What does mean by construction ventilation.
3. Line 250-251, “Fire-induced smoke is the main reason of huge casualties and property loss when fire happens in underground spaces.” Correct this sentence.

• Line 472-473, ’” Their barrier efficiency is affected by their structural parameters, installation location and airflow angle as well as size of chamber door.” What does mean by barrier efficiency.

There are many more grammatical errors which need to be improved.

• Ventilation is very important in underground spaces and it is extremely important in Covid-19 scenario. Authors need to elaborate.
• Authors explained natural and mechanical ventilation. But there are number of ventilation strategies e.g. displacement ventilation, mixed ventilation and so on which need to be included.
• This paper looks like a basic paper. More studied need to be included on ventilation strategies. Different models on ventilation should be included.
• Authors need to include quantitative results in the form of tables or graphs.
• Some qualitative recommendation should be given based on the results comparisons.
• Case studies should be included with the results.
• The conclusion is very basic which should include interpretation of the past studies.

Comments for author File: Comments.docx

Author Response

See attached the file, thank you.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Paper is corrected as desired. I recommend to accept it

Author Response

1. Mollier diagram is no longer used by the scientific community dealing with building physics. Please use the psychrometric chart by ASHRAE and revise Figure 1 consequently.

Reply: Thank you for your advice. We have changed Figure 1 to psychrometric chart by ASHRAE.

 

2. Surface condensation can also occur in case of raising damp phenomena. Please revise the manuscript and provide some references (e.g., https://doi.org/10.1016/j.culher.2018.04.001)

Reply: Thank you. We have added content about raising dampness in the manuscript, see added text below:

In the case of rising damp phenomena, surface condensation can also occur. Rising damp can increase indoor high humidity and materials deterioration, especially for porous materials [14,15]. The presence of moisture in the material pores, coupled with other environmental factors, may lead to biological erosion, salt crystallization, chemical erosion, clay-containing stone expansion, freezing damage, etc., and ultimately lead to mate-rial loss and even structural problems [15]. A large amount of literature research is devoted to studying the mechanism of underground capillary water rise [14,16]. Ground and concrete are generally porous mediums affected by moisture to some degree [17]. Therefore, using these materials in underground spaces may have negative consequences. Emery et al. showed that it was very inappropriate to cover the masonry surface with ordinary waterproof materials (such as impermeable gypsum, asphalt), because this would make the rise of moisture more serious [18].

 

3. The discussion about comfort models is too generic and does not seem specific for underground spaces. Moreover, the authors seem to forget that the Fanger model works only in mechanically conditioned buildings, whereas adaptive models are suitable in NV buildings under specific conditions (e.g., the possibility to open windows and adjust clothing). These issues must be specifically stated and contextualized to the topic of the manuscript (underground spaces).

Reply: Thank you. The purpose of discussing thermal comfort model is to show that current research is mainly focused on above ground space. However, the research related to underground space is less compatible with each other, and further research is needed. We have added the scope of model use in the manuscript.

 

4. The reference section is poor concerning international standards devoted to Indoor Environmental Quality. This is an important issue for a review paper. The authors are invited to discuss this topic especially if current standards cannot be “adopted as they are” to underground spaces which exhibit several peculiarities.

Reply: Thank you for your advice. We have discussed this issue in the manuscript, see added text below:

• In Europe, related agreements stipulate that subway air-conditioning filters should be replaced regularly every month [43]. However, Moreno et al. found that filters could maintain air quality for at least three months, and if pathogens can also be maintained within the standard range during this period, then the current agreement needs to be changed. They also pointed out that the WHO should give an additional and equally important attention to improveunderground air quality [43]. " Construction specifications on underground excavation engineering of hydraulic structures" stipulates that the minimum air velocity used when calculating the ventilation of large underground spaces is 0.15 m/s [44]. Li et al. found that the air velocity could control the dust level, provide the required oxygen concentration and control the temperature within an acceptable range, but it was not enough to reduce the CO concentration below the acceptable safety limit [45].
• In order to characterize the thermal comfort of transition areas such as the platform level and hall level of subway stations, the relative warmth index (RWI) and heat deficit rate (HDR) proposed by the Transportation Air Conditioning Committee of American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) are introduced [109,110]. HDR means that human body is in a cold environment, and the mean skin temperature is the heat loss rate at the lower limit of the comfortable skin temperature (about 30.6⁓35°C), that is, the negative human body heat storage rate [110]. Table 4 shows the corresponding relationship between the RWI value and the ASHRAE thermal sensation scale [109,111].