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Condensation risk: comparison of steady-state and transient methods

Mumovic, D; Ridley, I; Oreszczyn, T; Davies, M; (2006) Condensation risk: comparison of steady-state and transient methods. BUILD SERV ENG RES T , 27 (3) 219 - 233. 10.1191/0143624406bse163oa. Green open access

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Abstract

Accurate assessment of both surface and interstitial condensation risk is important not only to reduce the damaging effect of moisture within the structure of buildings, but also to provide a healthy environment free from mould growth. The current British Standard (BS EN ISO 13788: 2002) contains an assessment procedure based on the assumption of a steady-state heat flow through the building envelope, neglecting the transient nature of the problem. This paper compares and evaluates numerical results of the condensation risk calculation under both steady-state and transient conditions using the existing numerical codes. Significant differences are apparent between the predictions of the simple (steady-state) and complex (transient) methods for all construction details modelled.Practical application: The current British Standard (BS EN ISO 13788: 2002) gives calculation methods for determining the internal surface temperature of a building component or building element below which mould growth is likely, given the internal temperature and relative humidity-the method can also be used to assess the risk of other surface condensation problems. The calculation methods in the Standard are steady-state. The paper concludes that for cases where the steady-state method predicts that surface RH values will remain below the key value of 80%, a transient method can predict surface RH values to be above 80% for several hours. The practical implications of this work then are that transient calculation methods may be necessary under certain circumstances. This is particularly relevant given that the issue of a time period of a few hours is now more pertinent as it relates to a new transient performance standard in the new draft Approved Document F (Building Regulations-England and Wales).

Type: Article
Title: Condensation risk: comparison of steady-state and transient methods
Open access status: An open access version is available from UCL Discovery
DOI: 10.1191/0143624406bse163oa
Publisher version: http://dx.doi.org/10.1191/0143624406bse163oa
Additional information: © The Chartered Institution of Building Services Engineers 2006. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 3.0 License (http://www.creativecommons.org/licenses/by-nc/3.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page(http://www.uk.sagepub.com/aboutus/openaccess.htm).
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment > Bartlett School Env, Energy and Resources
URI: https://discovery.ucl.ac.uk/id/eprint/149446
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