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Specimens of glass fiber, phenolic foam, and extruded polystyrene foam insulation with moisture contents ranging up to about 25 percent by volume were mounted in the roof of an experimental building. The interior of the building was maintained at about 21 degrees C and normal weather conditions prevailed outside. Thermocouples were located at the upper and lower surface of each insulation specimen and at the quarter points of some specimens. A calibrated heat flow meter was used to measure heat flow through each specimen continuously for a period ranging from about 7 1/2 to 18 months for wet specimens and somewhat less for some of the dry ones. Heat flow rates were plotted against temperature difference using daily arithmetic averages in most cases; two-week averages were used in a few cases. For open-cell and fibrous insulations of 20 percent moisture content, heat flow rates exceeded rates for dry insulation by a factor of two or more. The data points were scattered. Inspection suggested that this was partly owing to moisture distribution, which affected the rate of heat flow at a given temperature difference. Measurements at the quarter points provided information about temperature gradients along the path of heat flow, and hence about moisture distribution in the insulation. These results suggested that moisture migrated to the upper layers in the wintertime, leaving the lower layers nearly dry. Ratios of heat flow in wet and dry specimens were in fairly good agreement with those obtained by other investigators., Proceedings of the Conference on Thermal Insulation, Materials and Systems for Energy Conservation in the 80's: 08 December 1981, Clearwater Beach, FL, USA

This paper is concerned with the thermal performance of blown Mineral Fibre Insulation (MFI), and more specifically with the question of how to ensure that the purchaser receives the amount of thermal resistance contracted for. It is shown that, owing to the variability of the material and installation techniques, two requirements must simultaneously be fulfilled at the time of installation: ( i) minimum installed thickness; and (ii) minimum mass per unit area. This Note deals with the determination of these minimum values, and the sample preparation and laboratory testing of the thermal resistance of MFI.

With the growing emphasis on energy conservation, various codes and building authorities have raised the requirements for the thermal resistance of building envelopes. Although these requirements are related to a nominal level of performance, very little is said about the difference between material performance in-situ and estimates established by laboratory measurements. This review discusses how to develop appropriate test methods for evaluating the performance of thermal insulation under service conditions.

As in horizontal applications, the thickness and safety aspects of cellulose fibre insulation (CFI) also apply to wall applications. In the latter case, however, failure to allow for settlement will not decrease thickness but will leave uninsulated gaps at the tops of the stud spaces. As it is impossible to see the CFI flowing into the spaces, a good installation depends on proper machine adjustment and installation technique. This paper reports on the findings of a study conducted to determine the effects of application technique on installation quality.

Users of cellulose fibre insulation (CFI) have two basic concerns: whether the insulation will provide the desired thermal resistance over the life of the building, and whether its use will constitute a health hazard or contribute to the deterioration of the building. Thermal resistance is primarily a function of thickness. CFI, however, is prone to settlement so the thickness will depend on the initial or blown density and the settled or design density. This note examines the precision of various methods used to determine design density. This is important in order to assist the contractor in determining the amount of CFI required for an installation and to ensure that the long term R-value of the CFI is as required.

Experimental flat roof systems were studied at an outdoor test facility. Heat flow rates and temperatures were measured with heat flow meters and thermocouples, and the values were recorded on magnetic tape at fixed intervals. The results were averaged over 24-h periods. Thermal resistances of systems and individual components were found using average net heat flow rates and temperature differences. Two analytical methods were used. In the first, the ratio of heat flow to temperature difference was calculated. This method was unreliable at low heat rates due to a bias in the results. In the second method, the slope of heat flow versus temperature difference was used as the basis for calculation. Thermal resistances of several pieces of insulation found by this method were compared with results obtained using laboratory equipment. The differences ranged from about 0.5 to 5 percent., Symposium on Thermal Insulation Performance: 22 October 1978, Tampa, FL, USA

During the service life of gas-filled cellular plastics ( GFCP), air diffuses into the foam cells and the gaseous blowing agent diffuses out, each at a rate that depends on the type of polymer and temperature. This process, which reduces the effectiveness of insulation, is known as aging. This paper presents a model for calculating the thermal resistance of the GFCP slab as a function of time. It incorporates the effect of phase changes (condensation and evaporation) in the gaseous blowing agent and the use of material characteristics (diffusion coefficient) varying in the cross-section of the GFCP slab. The results are compared with measurements., Also published in Improved Thermal Insulation : Problems and Perspectives