Submitted Successfully!
To reward your contribution, here is a gift for you: A free trial for our video production service.
Thank you for your contribution! You can also upload a video entry or images related to this topic.
Version Summary Created by Modification Content Size Created at Operation
1 -- 1508 2022-11-25 08:12:45 |
2 visual heck of data Meta information modification 1508 2022-11-25 08:44:25 | |
3 visual check of data Meta information modification 1508 2022-11-25 08:44:56 | |
4 format correction -13 word(s) 1495 2022-11-28 03:48:41 |

Video Upload Options

Do you have a full video?

Confirm

Are you sure to Delete?
Cite
If you have any further questions, please contact Encyclopedia Editorial Office.
Nath, S.;  Dewsbury, M.;  Künzel, H.;  Watson, P. Mould Growth Analysis. Encyclopedia. Available online: https://encyclopedia.pub/entry/36518 (accessed on 24 June 2024).
Nath S,  Dewsbury M,  Künzel H,  Watson P. Mould Growth Analysis. Encyclopedia. Available at: https://encyclopedia.pub/entry/36518. Accessed June 24, 2024.
Nath, Shruti, Mark Dewsbury, Hartwig Künzel, Phillipa Watson. "Mould Growth Analysis" Encyclopedia, https://encyclopedia.pub/entry/36518 (accessed June 24, 2024).
Nath, S.,  Dewsbury, M.,  Künzel, H., & Watson, P. (2022, November 25). Mould Growth Analysis. In Encyclopedia. https://encyclopedia.pub/entry/36518
Nath, Shruti, et al. "Mould Growth Analysis." Encyclopedia. Web. 25 November, 2022.
Mould Growth Analysis
Edit

The external wall’s moisture accumulation and mould growth were simulated for a period of ten years using the transient hygrothermal simulation tool, WUFI® Pro, and the mould growth model, WUFI® VTT.

energy efficiency condensation hygrothermal mould growth

1. Condensation and Mould Problem in Homes

Due to much cooler winter conditions, other developed nations, including the United States, Canada, Japan, the United Kingdom, and Germany, have established a co-relationship between better envelope design and hygrothermal design since the 1990s, as these countries encountered condensation and mould problems in buildings at earlier times [1][2][3][4][5]. However, many countries in temperate and warmer climates have not needed to consider building envelope related condensation and mould matters until the last decade, when insulation and air-tightness measures have been introduced in response to energy efficiency regulations. Mould growth involves five of the following conditions: infestation, i.e., germination of mould spores; nutrients (mainly cellulose and starch, but also dirt and dust); temperature (in the range of 0–50 °C); moisture (surface relative humidity of above 65%); and oxygen [5][6][7][8][9][10][11]. Figure 1 shows the various conducive conditions for mould growth.
Figure 1. Growth conditions for mould [12][13].
According to the Australian Occupational Health and Safety (OH&S) guidelines (July 2011), the recommended range of interior relative humidity is 30–60% [13]. This range of relative humidity was adopted from the Canadian CSA Standard CAN/CSA Z412-00 (R2005)—"Office Ergonomics” which refers to ASHRAE 55 (2010) [13]. Research conducted by Dewsbury at the University of Tasmania documented a considerable quantity of interior relative humidity values recorded above 95% in subfloor zones and 85% in living room zones, with regular instances of surface and interstitial condensation and mould in Tasmanian homes [14]. The CSIRO’s national Indoor Air Study, which collected data regarding the temperatures within code-compliant housing, also collected relative humidity data [15]. Figure 2 shows the measured indoor relative humidity data that has been collected by the CSIRO. The data shows the indoor relative humidity for one calendar year, from houses in Queensland, South Australia, and Victoria [16]. The data shows that houses from different Australian states, with distinctly different climate zones, in different seasons have recorded interior relative humidity values above 75%, which may be providing conducive environments for mould growth.
Figure 2. Indoor relative humidity in different seasons of Australian states [16].
In Australia’s temperate and cool-temperate climates, the external air temperature is less than 20 °C for between 50 and 92% of the hours in a calendar year. The focus in southern Australia has been to make houses warmer in winter [17]. With these insulated and more airtight new homes, with warmer interior conditions, design and construction professionals, and inhabitants, are reporting increased incidents of condensation and mould during the cooler months (April–October) in all eight Australian legislative jurisdictions [5][18]. This is a significant issue, as moisture and/or mould in the built fabric lead to building degradation and substantive impacts on human health [14][19][20][21].
Whilst this is a present issue for Australia, countries like New Zealand, which is cooler than most of Australia, had their crisis two decades ago [22]. Meanwhile, other warmer and less developed countries will have their own building condensation and mould-related crises in the coming decades. Those cooler countries that have developed standards and guidelines have made changes to insulation and airtightness in their built fabric since the late 20th century for human health reasons and have retrospectively worked towards hygrothermal simulation to solve the problems of condensation and mould in building envelopes and building interiors. Due to Australia’s post-1998 focus on reducing greenhouse gas emissions, the first, and somewhat simplistic, energy-efficient building envelope regulations were not applied in Australia until 2003.
As these insulation requirements have increased, it is only in the last decade that concerns have been raised regarding condensation and mould in new housing. Sadly, many uninsulated older houses also have mould problems, but this is often accepted as ‘normal’. At the 2021 International Conference on Moisture in Buildings, Kuenzel and Dewsbury [23] identified the international need for complex transient hygrothermal simulations to inform building envelope design.

2. Impact of Condensation Problems and Mould Growth on Occupant Health

Several international studies have recognized links between condensation, mould, and human health. The most detailed study was done by the World Health Organisation—Europe, which established:
“Sufficient epidemiological evidence is available from studies conducted in different countries and under different climatic conditions to show that the occupants of damp or mouldy buildings, both houses, and public buildings, are at increased risk of respiratory symptoms, respiratory infections and exacerbation of asthma”
[24]
Architectural science research has identified that Australia has twice the asthma rate of other OECD countries [24][25][26][27]. Asthma is a prominent illness in children aged 0–14 years in Australia, accounting for 12.3% of the total asthma burden [28]. There is ample proof from the discipline of medical science that mould spores are associated with several immunology and allergy conditions that may cause lifelong illnesses [29][30][31][32]. Within this context, if the built fabric of new energy-efficient homes is a cause of moisture and mould in new homes, then the design and construction professions need adequate guidance regarding the make-up of envelope systems or methods by which to ascertain whether an envelope system is truly climatically appropriate.
It has been estimated that the proportion of buildings affected by mould is 45% in Europe, 40% in the USA, 30% in Canada, and up to 50% in Australia, emphasising the significance of this problem [33]. Forty percent of respondents to a 2016 Australian national design and construction industry survey identified condensation and mould issues within stand-alone housing and multi-residential buildings constructed between 2006 and 2016 [14]. Since 2016, there have been several reported cases of condensation and mould problems in contemporary homes in different legislative jurisdictions across Australia [14][34][35][36][37][38][39]. However, to date, there has been no comprehensive investigation regarding the results of the national survey or a deep economic analysis regarding the costs associated with building rectification or impacts on human health.
In Australia, while it is acknowledged that housing affects health [40], housing and health are challengingly governed in different portfolios of government. By comparison, the European Union, the United States of America, Canada, the United Kingdom, and New Zealand have accepted the necessity for interrelated regulatory development between public health regulations and inter-related occupant health requirements within their national building regulations. The first inclusion of clauses requiring the minimisation of condensation and mould within the Australian building regulations occurred in 2019, and this has placed “Australia behind the eight ball on healthy housing” [41]. The new regulations only apply to residential buildings. The newly published regulations for 2022, to be enacted in 2023, still only require action in new residential buildings. Whereas the 2019 regulations focused on condensation [42], the 2022 regulations, which were informed by this research, have included references to the Mould Index [6]. It is hoped that non-residential buildings will be included by 2025. Compounding this, many elderly people, people with health problems, and children spend up to 90% of their time indoors [43]. Furthermore, the COVID-19 pandemic, which caused people to spend more time indoors, has created an urgent situation in which housing and health must be considered together more intentionally [44][45].

3. Key Focus Study Area

The research discussed forms part of broader research activities that are exploring the hygrothermal considerations that need to be considered for the pathway to net zero housing in Australia. Researchers discussed the hygrothermal and mould growth computer simulation methods that were developed and applied, which are innovative within the Australian context [46][47]. Reserchers established and informed hygrothermal analysis methods for residential wall systems within warm temperate, temperate, and cool temperate climates in Australia.
From 2008 to 2016, the University of Tasmania architectural science researchers liaised with the Tasmanian State government, the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO), the Australian Building Codes Board (ABCB), and industry-based collaborators regarding the urgent need to develop hygrothermal (condensation and mould) related guidance and regulation for the design and construction professions. Since 2014, the non-transient calculation methods have been used in Australia and have identified significant knowledge, practice, and regulatory gaps [5][14][18][48]. Non-regulatory adoption of transient hygrothermal simulation software was introduced in 2017. Specifically, this article discusses the detailed hygrothermal and mould growth computer-based simulation to explore moisture accumulation and mould growth risks associated with a clay masonry veneer low-rise residential external wall system. The analysis of the wall system explores the implications of insulation and air-tightness requirements expected for a 7-star regulatory compliant wall system in 2022. Researches required the assessment of hygrothermal calculation methods, their inputs and outputs, and how the method and simulation results could inform building regulatory development. Due to the correlation between mould and several human health impacts and the regulatory lever regarding healthy building interiors, researchers included methods of mould growth simulation. The hygrothermal and mould growth simulation results of a typical clay masonry veneer wall system in a cool temperate climate have been published earlier [46][47]. This article focuses on the results from the timber-framed clay masonry veneer wall system, simulated within the Cfb Köppen-Geiger classified oceanic temperate climate of Melbourne, Australia. The timber-framed clay masonry veneer wall system represents approximately 50% of new stand-alone low-rise residential buildings in Australia. The results of the other residential wall systems in different selected Australian climates will be reported in future articles.

References

  1. 5250:2002, B; Code of Practice for Control of Condensation in Buildings. British Standards Institution: London, UK, 2002.
  2. Hamdan, M.A. Layered wall design to prevent moisture condensation on its inside surface. Energy Convers. Manag. 2002, 43, 1821–1828.
  3. Karagiozis, A.; Salonvaara, M. Hygrothermal system-performance of a whole building. Build. Environ. 2001, 36, 779–787.
  4. Salonvaara, M.; Ojanen, T.; Kokko, E.; Karagiozis, A. Drying capabilities of wood frame walls with wood siding. In Proceedings of the 7th Thermal Performances of the Exterior Envelopes of Buildings Conference, Thermal VII, Clearwater Beach, United States, 6–10 December 1998.
  5. Dewsbury, M.; Law, T.; Potgieter, J.; Fitz-Gerald, D.; McComish, B.; Chandler, T.; Soudan, A. Scoping Study of Condensation in Residential Buildings-Final Report; Department of Industry Innovation and Science: Tasmania, Australia, 2016.
  6. Viitanen, H.; Krus, M.; Ojanen, T.; Eitner, V.; Zirkelbach, D. Mold risk classification based on comparative evaluation of two established growth models. In Proceedings of the 6th International Building Physics Conference, IBPC 2015, Torino, Italy, 14–17 June 2015; pp. 1425–1430.
  7. Nath, S.; Dewsbury, M.; Orr, K. Is new housing a health hazard? In Proceedings of the Engaging Architectural Science: Meeting the Challenges of Higher Density, 52nd International Conference of the Architectural Science Association 2018, RMIT University, Melbourne, Australia, 28 November–1 December 2018; pp. 71–78.
  8. Clarke, J.A.; Johnstone, C.M.; Kelly, N.J.; McLean, R.C.; Rowan, N.J.; Smith, J.E. A technique for the prediction of the conditions leading to mould growth in buildings. Build. Environ. 1999, 34, 515–521.
  9. Straus, D.C.; Cooley, J.D.; Wong, W.C.; Jumper, C.A. Studies on the role of fungi in sick building syndrome. Arch. Environ. Health: Int. J. 2003, 58, 475–478.
  10. Tsongas, G.A.; Riordan, F. Minimum conditions for visible mold growth. ASHRAE 2016, 58, 32.
  11. Lie, S.K.; Vestøl, G.I.; Høibø, O.; Gobakken, L.R. Surface mould growth on wooden claddings–effects of transient wetting, relative humidity, temperature and material properties. Wood Mater. Sci. Eng. 2018, 14, 129–141.
  12. Kowalski, W. Aerobiological Engineering Handbook: Airborne Disease and Control Technologies; McGraw Hill Professional: New York, NY, USA, 2005.
  13. Law, T. Comfort energetics: Thermal comfort under energy constraints. In The Future of Thermal Comfort in an Energy-Constrained World; Springer: Berlin/Heidelberg, Germany, 2013; pp. 83–115.
  14. Dewsbury, M.; Law, T. Recent increases in the occurrence of condensation and mould within new Tasmanian housing. In Proceedings of the 50th International Conference of the Architectural Science Association University of Adelaide, Adelaide, Australia, 7–9 December 2016; pp. 715–724.
  15. Cheng, M.; Galbally, I.; Gillett, R.; Keywood, M.; Lawson, S.; Molloy, S.; Powell, J. Indoor Air Project Part 1: Main Report—Indoor Air in Typical Australian Dwellings; CSIRO and the Bureau of Meteorology: Victoria, Australia, 2010.
  16. Ambrose, M. Interior Recorded Relative Humidity of Australian States; Nath, S., Ed.; CSIRO: Canberra, Australia, 2020.
  17. Hampton, A. Thermal mass and insulation for temperate climates. Environ. Des. Guide 2010, 1–11.
  18. Dewsbury, M. Condensation in Tasmanian homes-an update from UTAS. In Connections; Consumer, Building and Occupational Services, Department of Justice: Tasmania, Australia, 2018.
  19. Paevere, P.; Nguyen, M.; Syme, M.; Leicester, K.H. Nailplate backout—Is it a problem in plated timber trusses. In Proceedings of the 10th World Conference on Timber Engineering WCTE2008, Miyazaki, Japan, 2–5 June 2008.
  20. Täubel, M.; Hyvärinen, A. Occurrence of mycotoxins in indoor environments. In Environmental Mycology in Public Health; Elsevier: Amsterdam, The Netherlands, 2016; pp. 299–323.
  21. Cederlund, O.; Josefsson, F. An Evaluation of Two Well Insulated Roof Structures. Master’s Thesis, Lund University, Lund, Sweden, 2015. Available online: https://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=7456132&fileOId=7456139 (accessed on 21 September 2022).
  22. Dyer, P. Something rotten in the state…. In ArchitectureNow; AGM A Division of BCI Central: Auckland, New Zealand, 2021; Available online: https://architecturenow.co.nz/articles/something-rotten-in-the-state/ (accessed on 21 September 2022).
  23. Künzel, H.; Dewsbury, M. Moisture control design has to respond to all relevant hygrothermal loads. In UCL Open: Environment Preprint; UCL Press: London, UK.
  24. WHO. WHO Guidelines for Indoor Air Quality: Dampness and Mould; WHO Regional Office for Europe: Copenhagen, Denmark, 2009.
  25. Dewsbury, M.; Nath, S.; Olaoye, T.S.; Künzel, H. Condensation and mould in Australian homes. In Proceedings of the 1st International Conference on Moisture in Buildings (ICMB21), London, UK, 28–29 June 2021.
  26. Nath, S.; Dewsbury, M.; Douwes, J. Has a singular focus of building regulations created unhealthy homes? Archit. Sci. Rev. 2019, 387–401.
  27. Nath, S.; Dewsbury, M. Is regulation making homes unhealthy? In Proceedings of the AIRAH Building Physics Forum Conference, Wollongong, Australia, 22–23 November 2018.
  28. Knibbs, L.D.; Woldeyohannes, S.; Marks, G.B.; Cowie, C.T. Damp housing, gas stoves, and the burden of childhood asthma in Australia. Med. J. Aust. 2018, 208, 299–302.
  29. Juel Holst, G.; Pørneki, A.; Lindgreen, J.; Thuesen, B.; Bønløkke, J.; Hyvärinen, A.; Elholm, G.; Østergaard, K.; Loft, S.; Brooks, C. Household dampness and microbial exposure related to allergy and respiratory health in Danish adults. Eur. Clin. Respir. J. 2020, 7, 1706235.
  30. Mendell, M.J.; Kumagai, K. Observation-based metrics for residential dampness and mold with dose–response relationships to health: A review. Indoor Air 2017, 27, 506–517.
  31. Thacher, J.D.; Gruzieva, O.; Pershagen, G.; Melén, E.; Lorentzen, J.C.; Kull, I.; Bergström, A. Mold and dampness exposure and allergic outcomes from birth to adolescence: Data from the BAMSE cohort. Allergy 2017, 72, 967–974.
  32. Brambilla, A.; Gasparri, E. Hygrothermal behaviour of emerging timber-based envelope technologies in Australia: A preliminary investigation on condensation and mould growth risk. J. Clean. Prod. 2020, 276, 124129.
  33. Brambilla, A.; Sangiorgio, A. Mould growth in energy efficient buildings: Causes, health implications and strategies to mitigate the risk. Renew. Sustain. Energy Rev. 2020, 132, 110093.
  34. Holmes, A. Masonic Care residents given days to vacate homes in Newstead over mould fears. The Examiner, 12 September 2019.
  35. Moodie, C. Mould in rental homes under the spotlight as family claims health problems from mouldy house. ABC News, 20 February 2021.
  36. Moodie, C.; Shine, R. Mould in newly built Perth home blamed for family’s rashes, joint pain and headaches. ABC News, 25 November 2020.
  37. Brown, A.; Atkin, L. Mould in Melissa’s home was so bad she slept in her car. The Canberra Times, 9 December 2018.
  38. Farnsworth, S. Doctor had to plead for boy with lung problems to be moved out of mouldy rental house. ABC News, 18 December 2017.
  39. Asher, N.; Altree-Williams, A. Mould woes add strain for Melbourne renters during coronavirus stage 4 lockdown. ABC News, 30 August 2020.
  40. Baker, E.; Lester, L.H.; Bentley, R.; Beer, A. Poor housing quality: Prevalence and health effects. J. Prev. Interv. Community 2016, 44, 219–232.
  41. Bentley, R.; Baker, E. Mould and Damp Health Costs Are about 3 Times Those of Sugary Drinks. We Need a Healthy Housing Agenda. Available online: https://www.thefifthestate.com.au/urbanism/hazmat/mould-and-damp-health-costs-are-about-3-times-those-of-sugary-drinks-we-need-a-healthy-housing-agenda/ (accessed on 27 October 2020).
  42. ABCB. National Construction Code: Volume 2; The Australian Building Codes Board: Canberra, Australia, 2019; Volume 2.
  43. Cincinelli, A.; Martellini, T. Indoor air quality and health. Int. J. Environ. Res. Public Health 2017, 14, 1286.
  44. Lades, L.K.; Laffan, K.; Daly, M.; Delaney, L. Daily emotional well-being during the COVID-19 pandemic. Br. J. Health Psychol. 2020, 25, 902–911.
  45. Zachary, Z.; Brianna, F.; Brianna, L.; Garrett, P.; Jade, W.; Alyssa, D.; Mikayla, K. Self-quarantine and weight gain related risk factors during the COVID-19 pandemic. Obes. Res. Clin. Pract. 2020, 14, 210–216.
  46. Nath, S.; Dewsbury, M. The use of an innovative hygrothermal simulation method to develop built fabric recommendations for southern Australia. In Proceedings of the 53rd International Conference of the Architectural Science Association (ANZAScA)IIT Roorkee, Roorkee, India, 28–30 November 2019; pp. 1–10.
  47. Nath, S.; Dewsbury, M.; Watson, P.; Lovell, H.C.; Künzel, H.M. A bio-hygrothermal mould growth analysis of typical Australian residential wall systems. In Proceedings of the 54th International Conference of the Architectural Science Association (ANZAScA), Auckland, New Zealand, 26–27 November 2020; pp. 1–11.
  48. Dewsbury, M.; Soudan, A.; Su, F.; Geard, D.; Cooper, A.; Law, T. Condensation Risk Mitigation for Tasmanian Housing; UTAS: Tasmania, Australia, 2018.
More
Information
Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to https://encyclopedia.pub/register : , , ,
View Times: 749
Revisions: 4 times (View History)
Update Date: 28 Nov 2022
1000/1000
Video Production Service