Mould growth causes damage and poses high risk to a large number of existing buildings and their users. Air leakage through air cavity of the building walls, such as gaps between walls and some pipes penetrating the walls, produces obvious hygrothermal exchange, altering the temperature and humidity distribution of the walls. It would promote condensation and mould growth. Air cavity are common on the walls of existing buildings. In order to make a quantitative analysis on the mould growth risks due to air leakage through air cavity, an office room in an existing building in Nanjing, China was selected and hygrothermometers were arranged indoor and outdoor for monitoring. The measured results showed the room was in high temperature and relative humidity from June to early September. Two-dimensional hygrothermal simulation was made to investigate the hygrothermal conditions of the walls with air cavity, using the measured data as boundary conditions and validation for the numerical simulation. Mould growth risks under these situations were estimated.
Mold growth poses a high risk to a large number of existing buildings and their users. Air leakage through the air cavities of the building walls, herein gaps between walls and air conditioner pipes penetrating the walls, may increase the risks of interstitial condensation, mold growth and other moisture-related problems. In order to quantify the mold growth risks due to air leakage through air cavity, an office room in a historical masonry building in Nanjing, China, was selected, and its indoor environment has been studied. Fungi colonization can be seen on the surface of air conditioner pipes in the interior side near air cavity of the wall. Hygrothermometers and thermocouples logged interior and exterior temperature and relative humidity from June 2018 to January 2020. The measured data show that in summer the outdoor humidity remained much higher than that of the room, while the temperature near the air cavity stays lower than those of the other parts in the room. Hot and humid outdoor air may condense on the cold wall surface near an air cavity. A two-dimensional hygrothermal simulation was made. Air leakage through the air cavities of walls proved to be a crucial factor for mold growth.Energies 2020, 13, 1177 2 of 20 wall materials is the most important factor triggering the growth of microorganisms. The United States (US) Center for Disease Control stated in its guidance that "elimination of moisture intrusion and leaks and removal of mold" constitutes one of the three crucial interventions for houses implementation [16].Currently, advanced mold prediction models deal with the main influencing factors for mold growth: the surface temperature and relative humidity. Vereecken et al. [17] reviewed the models for mold growth and environmental risk prediction (isopleth systems [18,19], bio-hygrothermal model [20], ESP-r mold prediction model [21,22], VTT model [23]). Abe et al. [24] developed the fungal index to indicate the environmental capacity for mold growth. Hukka et al. [25] proposed a quantitative relationship between mold growth initiation conditions, maximum growth and growth rate. Sedlbauer [26] developed WUFI-Bio software (Klaus Sedlbauer, Department Hygrothermics at the Fraunhofer IBP, Munich, Germany) to assess mold risk by temperature, humidity and substrate in cases of transient conditions.Heat and moisture transfer simulation coupled with suitable temperature and humidity conditions for mold growth can also be used for evaluation [27].Building walls made of porous bricks or stones are easily exposed to outdoor moisture, including wind-driven rain [28] and rising dampness [29]. Additionally, improper energy conservation treatment [30][31][32], including inadequate insulation and unwanted air pathways, may cause thermal bridges and allow the surface temperature to become lower than the dew point of surrounding air, leading to unwanted condensation. Among them, air leakage through an air cavity [33] serves as one of the main moisture-transferring routes, redistributing the temperature and humidit...
Internal insulation serves as a compromise between historical facade conservation and indoor thermal comfort, but one should be aware that it may also result in condensation, mold growth, frost damage, etc. To restrict moisture-related problems, vapor open calcium silicate board (CSB) and wood fiber board (WFB) have been widely applied. The two capillary active materials, however, vary significantly in liquid moisture transport, and have differences in moisture storage and vapor transport as well. It is hence still required to fully investigate the hygrothermal performance of the two capillary active materials as internal insulation. In this paper, the hygrothermal performances of two masonry walls internally insulated by either CSB or WFB are simulated via DELPHIN, with a non-insulated wall as a reference.Peer-review under the responsibility of the organizing committee of the ICMB23.
Mould growth causes damage and poses high risk to a large number of existing buildings and their users. Air leakage through air cavity of the building walls, such as gaps between walls and some pipes penetrating the walls, produces obvious hygrothermal exchange, altering the temperature and humidity distribution of the walls. It would promote condensation and mould growth. Air cavity are common on the walls of existing buildings. In order to make a quantitative analysis on the mould growth risks due to air leakage through air cavity, an office room in an existing building in Nanjing, China was selected and hygrothermometers were arranged indoor and outdoor for monitoring. The measured results showed the room was in high temperature and relative humidity from June to early September. Two-dimensional hygrothermal simulation was made to investigate the hygrothermal conditions of the walls with air cavity, using the measured data as boundary conditions and validation for the numerical simulation. Mould growth risks under these situations were estimated.
Mould growth, caused by favourable hygrothermal environment like high relative humidity, proper temperature and other environmental variables, is one of the most severe hazards to soil ruins in high-humidity regions. Nevertheless, the effects of these variables on mould growth under extremely high humidity conditions remain elusive. In our previous research, samples from Wenzhou Qiaolou soil ruin were used to estimate the effects of two factors, ventilation and lighting modes, in unison. Based on that, a subsequent analysis has been conducted to assess mould growth differences with air relative humidity and lighting modes. We found that the extremely stable high-humidity environment (99.9%) had a significantly inhibitory effect on mould growth of damp surface of soil ruins. This paper also gives suggestions on the management of soil ruin exhibition halls in high-humidity regions.
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