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    Review of 'The moisture distribution in wall-to-floor thermal bridges and its influence on mould growth'

    The moisture distribution in wall-to-floor thermal bridges and its influence on mould growthCrossref
    There is certainly work done by the authors. However, it needs further analysis and discussion.
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    The moisture distribution in wall-to-floor thermal bridges and its influence on mould growth

    Moisture in the building envelopes increase the energy consumption of buildings and induce mould growth, which may be amplified within the area of thermal bridges due to their different hygrothermal properties and complex structures. In this study, we aimed to (1) reveal the moisture distribution in the typical thermal bridges (i.e., wall-to-floor thermal bridge, WFTB) and its surrounding area, and (2) investigate the mould growth in the building envelope that includes both WFTB and the main part of the wall. The transient numerical simulations that lasted for five years were performed to model the moisture distribution. Simulated results indicate that the moisture distribution presents significant seasonal and spatial differences due to the WFTB. The areas where moisture accumulates have a higher risk of mould growth. The thermal insulation layer laid on the exterior surface of WFTB can reduce the overall humidity while uneven moisture distribution, which may promote mould growth and water vapour condensation.

      Review information

      This work has been published open access under Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com.

      Mould growth,Built environment,Coupled heat and moisture transfer,Moisture distribution,Wall-to-floor thermal bridge

      Review text

      Specific comments are below:

      • This document needs proofreading
      • There are a number of sentences where more information is needed  (e.g., line number 16, where was moisture distribution modelled?
      • In line 42, the author referred to condensation for the germination and development of mould, however, mould only develop under high levels of humidity and not condensation.
      • Also, in line 42, the authors indicate that mould could grow inside building envelopes. Please provide a few examples of where inside the envelope, mould could grow.   
      • It is not clear why the software COMSOL was used.
      • More details should be provided regarding the weather climate used in the modelling presented in Figure 2. You refer to a climate zone in China.
      • Fig 2a should be uninsulated, while 2b insulated. Please amend.
      • You also refer in section 2. 3.1 to an existing Atlas; what exactly is this?
      • In section 2.3.2 please provide more information on how data was collected from a residential building in Hangzhou.
      • Figure 3 explains how radiation intensity and moisture load were used in the study.
      • In figure 3, please use lines to express temperature and relative humidity. The use of dots makes it extremely difficult to read and understand the environmental conditions in both graphs.
      • Correct the text in lines 181 and 182; it should read Figure 4a and 4b.
      • Explain what each of the values in Table 3 refers to. But also how they were used to assess the risk of mould growth. Did you consider time in the evaluation?  
      • Please explain the concepts used in the analysis, moisture sink and moisture shadow. This is very unclear in the document.
      • Please add some explanation in Fig 5, so what do the colours represent; red=cold and blue=warm?
      • Are you presenting in Fig 5 the results for the uninsulated or insulated detail?
      • Why is it important to calculate the area for each moisture sink and moisture shadow? Please explain, in more detail, how they were generated and how they can be used.
      • Please enlarge Fig 6. The moisture shadows and most of the information you are trying to describe in the text is unreadable.
      • In line 242, you refer to the germination of mould spores inside the building envelope; are you referring to the space between the insulation and concrete?  
      • Regarding mould assessment, did you use the info in the isopleth to define transient conditions? The isopleths were created based on steady-state conditions.
      • Please better explain figure 7; it is unclear what exactly you are showing and where in the diagram and wall detail you have assessed mould growth. Also still very unclear how the risk of mould growth was calculated. What do the red arrows and red area represent?
      • Mould need time to germinate and grow. So, the conditions of RH and Temperature presented in the isopleths (Fig.4) need to be constantly occurring for the time there indicated for mould to germinate and grow. Under transient conditions, mould will take much longer or don't react to those conditions. Please explain and discuss.
      • Regarding your discussion, please expand the discussion on the urban heat island effect and how the phenomenon found could be affected in winter.
      • Explain further the role of solar radiation and wind-driven rain and their impact on the results obtained. This was not at all assessed in the paper. You need to consider that in practice, external wall insulation won't be just insulation on the external pane of the wall. Other materials will be installed and   
      • Explain in more detail the white dew and cold dew concepts


      2022-03-27 18:59 UTC
      2022-03-27 18:58 UTC

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