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Isotopic tracing of moisture in buildings
KTH, Tidigare Institutioner                               , Byggnader och installationer.ORCID-id: 0000-0003-0615-4505
2001 (engelsk)Inngår i: Nordic Journal of Building Physics: Acta Physica Aedificiorum, ISSN 1402-5728, Vol. 2, s. 1-10Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The means of tracing the flows of moisture in a building by using the stable isotopes of oxygen-18 and deuteriumare described. It is shown that knowledge of the effects of the transport mechanisms and reactions on the isotopiccomposition can be used to identify the sources of moisture. This is illustrated by an example from a building inthe southern part of Sweden.

sted, utgiver, år, opplag, sider
2001. Vol. 2, s. 1-10
Emneord [en]
Moisture in buildings, isotopes, transport processes, fractionation, leakage
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-13309OAI: oai:DiVA.org:kth-13309DiVA, id: diva2:323518
Merknad
QC 20100611Tilgjengelig fra: 2010-06-11 Laget: 2010-06-11 Sist oppdatert: 2017-12-12bibliografisk kontrollert
Inngår i avhandling
1. Alternative methods for analysing moisture transport in buildings: Utilisation of tracer gas and natural stable isotopes
Åpne denne publikasjonen i ny fane eller vindu >>Alternative methods for analysing moisture transport in buildings: Utilisation of tracer gas and natural stable isotopes
2003 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

New methods, based on tracer gas measurements and isotopicanalysis can be used to evaluate the moisture properties ofbuilding materials and provide the means for forensic analysisof the origins and history of excessive water in buildings, theimmediate practical consequences of which will be the abilityto improve the moisture performance of constructions.

It is shown, in theory and through measurements how thewater vapour permeability of porous building materials can witha good degree of accuracy be estimated with tracer gasmeasurements that provide an efficient alternative to the cupmethod. Complementary measurements may be carried out in orderto evaluate the contribution of surface diffusion and theeventual enhancing effects of moisture content on the diffusioncoefficient. The Random Hopping Model is used to illustrate howthe surface diffusion coefficient depends on the amountadsorbed and the activation energy of migration that can beevaluated from the sorption isotherms.

It is explained how the abundance ratios of two of the mostordinary isotopes of hydrogen and oxygen in water can be usedto determine its history. These isotopes are stable and givethe water a distinct signature that can be used to reveal itssource as shown in a case study. In a contrary manner themeasured isotopic separation can be used to determine therelevance of different transport processes and reactions. It isof central importance that not only does the magnitude ofisotopic separation for the reactions vary for deuterium andoxygen-18 but even the ratio thereof. One of the challenges hasbeen to construct an experimental method for retrieving samplesof water for comparison.

Furthermore this thesis includes an evaluation of a new typeof a light weight construction with loose-fill cellulose fibre,in which the conventional polyethylene vapour barrier has beenreplaced with polypropylene fabric. With a verified model ithas been investigated how the construction would perform fordifferent internal moisture loads and reference climate fromthe literature. The results suggest that this type ofconstruction is not to be recommended.

KEYWORDS:tracer gas, water vapour permeability,diffusion, surface diffusion, isotopic analysis, deuterium,oxygen-18, fractionation, vapour barrier, transient numericalmodelling of diffusion.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2003. s. xii, 57
Serie
Trita-BYT ; 191
Emneord
tracer gas, water vapour permeability, diffusion, surface diffusion, isotopic analysis, deuterium, oxygen-18, fractionation, vapour barrier, transient numerical modelling of diffusion
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-3509 (URN)
Disputas
2003-05-09, 00:00
Merknad
QC 20100611Tilgjengelig fra: 2003-04-28 Laget: 2003-04-28 Sist oppdatert: 2010-06-11bibliografisk kontrollert

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