Abstract
Glass fiber insulation specimens 60 mm thick, with moisture contents ranging up to 15% by volume, were placed on the roof of the Outdoor Test Building of the In stitute for Research in Construction, National Research Council of Canada in Saska toon, Saskatchewan The specimens were sealed in polyethylene to prevent the loss of moisture.
Temperatures were measured at the top and bottom surfaces of each specimen and at the quarter points inside some of them. Heat fluxes were measured with calibrated heat flux transducers. Measurements were recorded every 20 minutes at all seasons of the year.
Thermal conductances were calculated using transfer functions. The results showed an increase in thermal conductance when the weather was warm enough to produce daily reversals in temperature gradient across the wet specimens. This was attributed to latent heat transfer produced by evaporation of water at the warmer side of the insulation and its condensation at the cooler side.
In winter, the moisture was deposited in the upper, colder part of the insulation. It was apparently distributed through the upper part of the insulation and not depos ited as a solid layer at the top surface, since its effect on thermal conductance, indi cated by the interior temperature gradient, extended well down in the insulation.
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