Test cell evaluation of supply air windows to characterise their optimum performance and its ...


Supply air windows provide fresh air in buildings whilst minimising heat loss. Fresh air is drawn into the window at the bottom, and having been pre-heated by heat exchange and by solar radiation, it enters the room at the top of the window. A PASSYS test cell was used to evaluate a model for the prediction of supply window performance, and to optimise window design. The window consisted of a sealed double glazed unit with a 12 mm gap and a single outer pane of 4 mm float glass. The gap between the outer pane and the sealed unit was varied between 10 and 30 mm, and low emissivity ( low-E ) coatings were applied to different glass surfaces. The windows were fitted in the south-facing wall of the test cell, and temperatures were measured using an array of thermocouples. The effective thermal transmittance ( Ue-value ) and ventilation preheating decreased with increasing levels of ventilation. The window Ue-value was halved when the low-E coating was applied to the outer surface of the double glazed unit. Modelling of the window using thermal and mass flow network software ( ESP-r ) gave good agreement with the experimental data. 11 refs.

Primary author(s): McEvoy M E; Southall R G;Baker P H

Source: Energy Build.

             Vol.35, No.10, 2003, p.1009-1020




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