Retrotec USACE - Manual (Page 142)

D12 ENERGY & PROCESS ASSESSMENT PROTOCOL
resulting in a signifi cant decrease of the overall window R-value (Figure D17).
When the outside frame gets hot, the heat is transferred to the inside frame
(Figure D18). In humid climates, there is potential for condensation on the ex-
ternal surface when space air-conditioning is used; when outside temperatures
are low, condensation and even frosting can occur on the internal surface.
Figure D18. Infrared thermogram indicating areas with heat losses and air leaks through poorly
sealed single-pane windows.
D.1.4.2 Failure of Window Seals (Waste)
Figure D19. Windows with failed seals
Changes in temperature and air pressure around a window can stress the in-
sulating glass unit’s seals, causing them to fail (Figure D19). Warm and cold
air can then infi ltrate the air space between the sealed layers of glass. Failed
window seals result in fogging, hazing, and moisture between the two panes of
glass and ultimately reduce window insulation value.