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Comparison of fibrous insulations: cellulose and stone wool in terms of moisture properties resulting from condensation and ice formation
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.ORCID iD: 0000-0003-0615-4505
2010 (English)In: Construction and Building Materials, ISSN 0950-0618, Vol. 24, no 7, 1151-1157 p.Article in journal (Refereed) Published
Abstract [en]

Cellulose fibres are often used as thermal insulation in buildings. The organic nature of cellulose fibres, however, makes the insulation sensitive to high moisture content. This study investigates the moisture performance of cellulose insulation when exposed to a subzero environment. The paper is focused on the condensation and freezing in the material and includes comparison with the authors previous studies on stone-wool insulation. While the used stone-wool samples were water repellent due to resin binders,cellulose is a typical representative for hydrophilic thermal insulation to which anycontact with water condensate can be crucial.

Test specimens of loose-fill cellulose were placed in a special laboratory device providing high moisture load. During a period of 100 hours the specimens were subjected to a continuous load of moisture at atmospheric conditions on one side while the other side of the specimen faced a surrounding temperature of 0, -10 and -20°C and the laboratory tests were repeated three times for each set of the specific thermal conditions(Ti=+20°C, Te=0, -10 and -20°C). The results indicate that there are minor changes inthe water vapour permeability of the specimens. The experimental data from the investigation is compared with a mathematical model that simulates moisture diffusivityof cellulose together with accumulation due to sorption and freezing, using the actual climatic data.

Place, publisher, year, edition, pages
2010. Vol. 24, no 7, 1151-1157 p.
Keyword [en]
Cellulose, Stone wool, Material properties, Frost formation, Condensation, Moisture transport, μ-value, Sorption curves
National Category
Materials Engineering Building Technologies
URN: urn:nbn:se:kth:diva-11681DOI: 10.1016/j.conbuildmat.2009.12.026ISI: 000278039400008ScopusID: 2-s2.0-77950459709OAI: diva2:279249
QC 20100818Available from: 2009-12-02 Created: 2009-12-02 Last updated: 2011-11-06Bibliographically approved
In thesis
1. Condensation and frost formation in fibrous thermal-insulation materials
Open this publication in new window or tab >>Condensation and frost formation in fibrous thermal-insulation materials
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Heavily insulated constructions are at present being used to strike at the vast energy consumption in residential buildings and commercial alike. They introduce a high-thickness layer of thermal insulation in the building envelopes. Such constructions have great moisture capacity and could be at risk due to moisture leakages and other moisture related problems connected to bad design, climate effects, extended construction period to late autumn and winter seasons and mishandle of building materials.

Thermal-insulation materials based on stone wool and cellulose are commonly used in a wide range of applications that harness their high thermal-insulation properties. Both these materials could be fault-prone due to their fibrous structure in case of moisture problems – e.g. built-in moisture, annually repeating condensation and frost formation in the cold climates.

The aim of this research was to observe the stone-wool and cellulose specimens in various temperature fields under extreme moisture load and to explore the issue of moisture transport and real moisture properties of the tested materials when condensation and frost formation occur. A special testing device, Thermobox, was constructed and the fibrous samples were exposed to temperature gradients simulating real conditions. The climate data as well as the moisture-transport data were registered. They were used in calculations of moisture resistance factor, µ, denoting permeability of the tested samples in the defined moist conditions. Following the laboratory measurements, a mathematical simulation was done to compare total moisture accumulation in the specimens with the practical measurements and to be able to simulate these processes in a longer time interval. Besides, a special outdoor experiment concerning the effect of outdoor climate on the stone-wool structure was executed.

Final research findings proved that the phenomenon of frost formation can exist in the fibrous insulation materials. Moisture transport properties of stone wool and cellulose were affected by the extreme water condensation and freezing, but they remained highly permeable. As regards the moisture storage in the samples, this process was continuous during the tested period and it indicated significant growth of the total water accumulation in connection with dry densities of the tested materials. This emphasises the importance of proper handling with the fibrous thermal-insulation materials and keeping them dry.

Place, publisher, year, edition, pages
Stockholm: US-AB, 2009. 43 p.
Trita-BYMA, ISSN 0349-5752 ; 2009:1
Fibrous thermal insulation, Stone wool, Cellulose, MAterial properties, Moisture transport, Condensation, Frost formation, Exterior conditions, Interior conditions
National Category
Civil Engineering Other Materials Engineering
urn:nbn:se:kth:diva-11632 (URN)978-91-7415-468-9 (ISBN)
Public defence
2009-12-11, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Disputationen indragen.Available from: 2009-12-02 Created: 2009-11-26 Last updated: 2012-03-22

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