Paula Wahlgren

Overview and Literature Survey of Natural and Forced Convection in Attic Insulation

This article presents an overview and a literature survey of convection in attic insulation. The study focuses on the onset of natural convection in the insulation, but also discusses the influence of forced convection. It covers experimental studies in small-scale measurement apparatus, large-scale laboratory measurements, in situ measurements, as well as numerical and theoretical work on convection in attic insulation. Suggestions for future work are also presented.

Measurements and Simulations of Natural and Forced Convection in Loose-Fill Attic Insulation

The influence of convection on the thermal performance of loose-fill attic insulation has been investigated using measurements and simulations. Thermal resistance measurements have been performed in a large-scale attic test model, with and without attic ventilation, and on loose-fill rock wool and fiberglass insulation. Measurements of natural convection have shown that the critical modified Rayleigh number for attic insulation in a conventional attic floor is approximately 22. The maximum decrease in measured thermal resistance due to natural convection was 25% compared to that obtained at the onset of convection. There was no indication of a decrease in the total thermal resistance of the attic floor due to attic ventilation.