Search

When sprayed polyurethane foams are fabricated under field conditions, they usually form a continuous layer that controls the flow of heat, air and moisture through the building component they cover. However, the replacement of blowing agents such as chlorofluorocarbons (CFCs) with partially halogenated hydrochlorofluorocarbons (HCFCs), which have thermal insulating performance inherently lower than that of CFCs, has raised the question of the long-term thermal performance of such foams.

Methodology for the evaluation of long-term thermal performance of cellular plastics is being developed under a collaboration of North American foam industry with the National Research Council of Canada. The mechanism of this collaboration includes a joint research project between the Society of Plastics Industryand the NRC Canada. To evaluate long-term thermal performance (LTTP) of cellular plastics the agingprocess must be accelerated. This can be done either by means of elevated temperature or by the use of thin layers of the foam. The first approach changes the permeability and solubility coefficients of different gases to such a degree that predicting the foam performance under field conditions is difficult.

Traduit de: Construction Canada 35(2) fév 1993, p. 24-27, Reprinted in La performance et la durabilité de l'enveloppe du bâtiment, colloque technique (NRCC-38991F)

Reprinted in Construction Practice: Selected Applications in Construction Technology Section 3 (NRCC- 35475)

Aussi disponible en francais: L'isolant de fibres miné rales requiert une installation soignée

Building Physics '93: 3rd Symposium on Building Physics in the Nordic Countries, September 13, 1993, Copenhagen, Denmark

Few construction materials have undergone more changes than thermal insulation over the last two decades, and few products have been so well adapted to fit market needs. But insulation continues to be selected for its perceived field performance, rather than on the basis of accurate laboratory tests and, in many cases, scientists have yet to develop lab tests to simulate the field.

Reprinted in Construction Practice: Selected Applications in Construction Technology Section 3 (NRCC- 35475)

One of the techniques used to determine aging of gas-filled cellular plastics (GFCP) is to correlate the thermal resistance of thin material layers with that of full thickness boards. Either models of aging or scaling factors may be used for this purpose. This paper discusses the concept of scaling factors relating aging of thin and thick layers of GFCP, and points out their limitations.

Part 1: This paper presents results of a study with the following objectives: 1. Determine the effects of transport and placement conditions on the inital density of the insulation; 2) Establish a standardized method for producing specimens of blown cellulose fiber insulations; 3) Investigate the factors that cause the material to settle after placement; 4) Establish a standardized method to produce settlement in the specimens comparable with those found in field studies. A method recommended for producing settlement in the specimens consists of two procedures, one simulating settlement by impact produced on the standardized containers, and the other causing settlement under climatic cycling of the material. Part 2: The thermal resistance of a number of commercial blown loose-fill cellulose fiber thermal insulations has been measured using the guarded hot plate and heat flow meter methods. An equation describing the variation of thermal resistance with temperature, temperature difference, density, and thickness has been derived from these measurements and, with lesser precision, from the data provided by other investigators. The equation does not include the effects of chemical content, moisture content, chemical composition, or structure of the paper particles. The thermal resistance of a layer of insulation was found not to be directly proportional to thickness. The equation for thermal resistance fits the National Research Council of Canada (NRC) data with a standard deviation of less than 3.5 percent for thickness of 50 to 305 mm., Thermal Transmission Measurements of Insulation : Symposium: 19 September 1977, Philadelphia, PA., USA

To provide combined moisture and thermal protection for basements, high-density glass fiberboard was used on the exterior of two prototype basements. This insulation- drainage layer can easily be adapted to current construction procedures and the cost is not excessively high. Performance of the 140-kg/m[3] (9 lb/ft[3]) glass fiberboard installed vertically below grade was monitored. Early results are encouraging. Favorable moisture distribution and compressive deformation were found. After two years of burial the insulation still maintained a thermal resistivity that ranged from 22.6 to 26.8 m.degrees C/W. It is believed that the concept of an insulation-drainage layer has the potential to keep the basement dry, to provide improved thermal insulation, and to enable better curing of concrete. With refined design details the concept is attractive and worthy of continued study and development. This paper describes methods of installation, monitoring instruments, and some findings obtained from two experimental basements monitored since 1976 by the Division of Building Research/National Research Council of Canada., Symposium on Thermal Insulation Performance: 22 October 1978, Tampa, 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.

Components of the research program jointly sponsored by the Institute for Research in Construction, National Research Council of Canada, and the Polyurethane Division, Society of the Plastics Industry of Canada, are described. The program is designed to improve the means of evaluating and comparing the value-in-use of various residential thermal insulation materials and systems. To assess value-in-use of insulations such as glass fibre, cellulose, and spray- applied products of which sprayed polyurethane foam is one, the performance of the building envelope as a system, in addition to analysing the materials and components, will be considered. Elements of the program will include: -- thermal and energy performance, -- contribution of the insulation to the air and vapour barrier performance of the envelope system,-- interaction with other building components, -- changes in the material performance with time.

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.

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

This paper reviews the technical aspects of one particular insulation sytem concept where a rigid fibrous insulation is placed outside the basement wall and thus contributes to both thermal and moisture control of the building structure. The following properties of mineral fiberboards are discussed: drainage characteristics of the material and water retention after the drainage process, thermal resistance, compressive strength, and elastic and irreversible deformations. All these properties are affected by the aging process of the material. Effects of various aging conditions simulated in the laboratory are compared with deterioration of the material exposed for 5 or 6 years in soils and on an experimental roof deck. Findings of Scandinavian and Canadian research are presented., Symposium on Thermal Insulation Performance: 22 October 1978, Tampa, FL, USA

This report presents a joint project of the Society of the Plastics Industry and the Institute for Research in Construction of the National Research Council of Canada. The objectives of this project were to manufacture two spray polyurethane foams bases on the existing industrial technology but using alternative blowing agents, compare the properties of these foams with those blown with CFC-11 and establish a basis for development of new polyurethane spray foams with alternative blowing agents. The following properties were examined: thermal resistance, dimensional stability, compressive strength, water vapour permeance, blowing agent concentration and effective diffusion characteristics. This study combined advanced industrial and academic research, predicted 25-year thermal performance from 3-4 months testing results and characterized foams with selected thermal, moisture and mechanical properties.