A large-scale model of a ventilated attic has been built in a climatic chamber to investigate heat transfer in loose-fill attic insulation, in particular heat transfer by convection and its effect on heat losses through the attic floor. Initial measurements in the attic test model have been made on homogeneous, high-density, mineral wool boards to verify the performance of the attic test model without convection. Thermal resistance measurements on loose-fill insulation show that the measured and calculated thermal resistance of the attic floor is within the margin of error. Both measurements and simulations indicate air movements in the insulation, which are detectable by studying the temperature patterns at the surface of the insulation. However, the air movements are insufficient to cause a decrease in the thermal resistance of the attic floor. Attic ventilation has a minor effect on the measured thermal resistance of the attic floor but does cause a decrease in temperature at the upper surface of the insulation.

Authors: Paula Wahlgren

Citation: Thermal Performance of the Exterior Envelopes of Buildings VIII

Keywords: December, Florida, 2001