b'Before ReplacementFigure 1: Fig 2Most older windowswere installed whenenergy costs were lowerand building codeswere not so stringent.Air could come into thehome and heat couldescape through jointsin the window frameand the roughframingand siding and wall Figure 2:board.Adding to the air leak and heat escape is the lack of insulation in the interior pockets. There are pockets ofAlso leaking air and empty space where the old weights and balances were heat are the joints hidden, and between the tapered sill and the flat roughbetween the sash and sill, and above the window headeras well as the sidethe window frame and jamb cavities.the interlock of the Thermal imagingsash. Even well weath- shows the heat losserstripped windows through the windowwear out eventually. and through the frameFig 1 around the window.After ReplacementFigure 3: Fig 4Modern ReplacementWindows have tightertolerances in theweatherstripping and at the interlocks. This better design and construction cures most of the window caused air and heat transfersbecause the gapsFigure 4:have been closed. Too often the new window is fit to the left-in-place old window frame without insulation in the weight/balancepockets, below the sill and above the header - or in thejamb cavities. This leavessignificant drafts, heat lossand dissatisfaction with theperformance of the newwindows. Thermal imagesshow the cold around thenew window even thoughFig 3 the window itself iswarmer.Window Fitters Guide to Window Installation13 2020 AWDI, LLC Do not reproduce without permission'