Substrate Barrier Effects on Total Heat Transfer for a R-30 Fibrous Insulation Batt

Abstract

By implementing various substrate barriers to a R-30 fiberglass insulation batt, this research shows the overall changes in the substrate heat flux. Independently, a plastic vapor barrier, and both a perforated and nonperforated radiant barrier are analyzed in this study. Conduction, radiation heat transfer, and moisture (mass) transport are considered to be the main contributors to heat transport within attic fiberglass insulation. A transient, one-dimensional, computational thermal model has been developed to simultaneously model all three of these heat transport mechanisms, which allows the total heat flux at the attic insulation substrate to be predicted. This numerical model has the capabilities to determine the effect on each of the three modes of heat transfer once a substrate barrier has been added. Summertime experimental data were collected at an occupied North Mississippi residence for cases with and without a vapor barrier at the substrate for R-30 fiberglass insulation. Within this investigation, experimental and predicted total heat transfer results are compared and analyzed. Profiles such as temperature-time histories, vapor H 2 O concentrations, and individual modes of heat transfer plots are presented to support the experimentally determined overall effects on the heat transfer at the substrate once a substrate barrier has been implemented.

Radiative Properties of High and Low Density Fiberglass Insulation in the 4-38.5 km Wavelength Region

“…Radiative properties of low density fiberglass using q hd data for isotropic scattering. [14,15] which have yielded very good agreement between the measured heat fluxes and the heat fluxes predicted employing the gray properties presented here.…”

“…The gray isotropic ( ¼ 3.73 cm À1 ) obtained from the dh data and ( ¼ 3.92 cm À1 ) obtained from the hd data were in excellent agreement with the average (gray) isotropic obtained by Yeh [1,2] ( ¼ 3.72 cm À1 for a 10.9 kg/m 3 commercial fiberglass). The Planck mean radiative properties have been tabulated in Table 7 for the temperature range of 100-500 K. The Planck mean P has a maximum at about 200 K; the Planck mean P at 300 K (for the isotropic hd case) of [14,15] which have yielded very good agreement between the measured heat fluxes and the heat fluxes predicted employing the gray properties presented here.…”

Phenolic Binder Content Impact on Total Heat Transfer for Fibrous Insulation Batts

“…The approach taken here has been to use the computational tool developed in [1][2][3]5,6]. However, a different thermal boundary condition is employed at the top of the batt to allow the top temperature of the batt to be calculated as a function of the binder adsorption/desorption.…”

Thermal performance of an insulated roof with reflective insulation: Field tests under hot climatic conditions

“…Research usually provides results of laboratory tests, field tests and mathematical models in order to establish the general thermal performance of reflective materials, even compared to traditional insulation (Harris et al, 1996), or the effect of different parameters (physical, geometrical and climatic parameters) and of dust or humidity settling on their effectiveness (Riskowski et al, 1991). The performance of RI materials is generally evaluated as the reduction in the incoming heat flux compared to a reference roof with traditional insulation (‘performance indicator’).…”