Wiki: Window insulation

[meow2222]

First draught for comment

NT

Windows are the main areas of heat loss in most houses, and are usually eas= y & cheap to insulate.

=3DDraughtproofing=3D Should be done before any other [[insulation]]. In most cases, cheap, easy = & effective.

Most windows can be draughtproofed using foam tape. Cheap foam doesn't last= well, EPDM does.

=3D=3DMetal windows=3D=3D Old Crittall metal windows usually have far more layers of [[paint]] on tha= n they were designed to work with. A strip and repaint can much improve the= m. If further draughtproofing is needed, one way is to apply [[silicone]] t= o one surface and close the other onto it after applying clingfilm. Silicon= e isn't the most robust stuff though. When set, remove clingfilm with care = and apply clear tape to the face of the silicone to stop it sticking, and t= rim.

=3D=3DSliding sash windows=3D=3D=20 These are best draughtproofed by #remove beading & remove sliding sashes #route a groove around the edge #fit a lightweight flexible [[plastic]] strip in the groove # refit windows

Brushbars can also be used, but make window movement stiff.

=3D=3DLead lights=3D=3D Old lead lights are often very draughty. #Ensure the leadwork is tied to any iron reinforcement bar(s) fitted to pre= vent movement. #Brush the leadwork with linseed putty to fill any gaps between lead and gl= ass #Apply chalk and rub off with cloth

=3DInsulation options=3D All the following reduce window heat loss. If you're determined, the more i= nsulation measures used the better.

=3D=3DDouble glazing=3D=3D Double glazing much reduces heat loss, but its cost generally makes retrofi= tting it not pay back. If you need to replace the window anyway, the extra = cost of dg is worth it.

=3D=3DSecondary glazing=3D=3D Cheaper than double glazing, and easy to fit. Secondary glazing can be done= in

• glass - tough but breakable

• acrylic sheet - long lived, impact resistant. Can scratch though

• plastic film - very cheap, limited life, easily torn

Secondary glazing can be fitted

• onto the opening sashes

• onto the outer window frame

• or spaced away from the frame

Usually its best to fit it to the sashes, as fitting to the outer frame pre= vents easy opening of windows. But in the case of metal windows (Steel and = leaded lights) the heat loss of the frame is so poor that secondary glazing= is best fitted spaced off the window frame. It can be fitted to a new ligh= t timber frame fitted into the wall recess.

Secondary glazing is sometimes fitted without draughtproofing first. When t= his is done it then acts more like draughtproofing, losing much of its insu= lating value.

=3D=3DCurtain=3D=3D Curtains reduce night time heat loss. To maximise effect, close the gaps ro= und the curtains as well as possible to minimise air movement.

• curtain bottom should be close to the cill or floor

• sides can be velcroed to the frame

• curtain top can be pelmetted

=3D=3DCurtain lining=3D=3D Lined curtains can roughly halve the [[heat]] loss of a single glazed windo= w.

=3D=3DCurtain thermal lining=3D=3D A fleecy thermal lining to curtains improves their [[insulation]] further. = If you only want something very temporary, a blanket clothespegged in place= also works.

=3D=3DSecondary film curtain=3D=3D A small lightweight secondary curtain rod is fitted close to the window, an= d a clear plastic fim curtain hung on it. Less effective than secondary gla= zing, but can be added easily to just about any window, and doesn't obstruc= t it. Fit soft thick string along the bottom so it hangs properly.

=3D=3DShutters=3D=3D Shutters provide the ultimate insulation at night, if they're made of thick= [[insulation]] sheet and draughtproofed. Old fashioned [[wood]] shutters a= lso help, but rather less.

=3D=3DTriple glazing=3D=3D When putting in new windows, TG doesn't cost a lot more than DG. The increa= sed weight can be an issue.

=3D=3DTertiary glazing=3D=3D Adding a 3rd layer over double glazing improves things further.

=3DGreenhouses=3D Greenhouses can use 2 more methods:

*Acrylic glazing - warmer than glass *Bubblewrap secondary glazing

=3DInsulation figures=3D R values for windows:

*Single glazing: 0.18 *Double glazing, basic air filled: 0.35 *Double glazing, coated & argon filled: 0.5 *Triple glazing, basic air filled: 0.52=20 *Triple glazing, coated & argon filled:=20

=3D=3DSee also=3D=3D [[Insulation]]

[js.b1]

You may want to add in figures for secondary glazing.

Secondary glazing is far cheaper, so quicker payback, and particularly usef= ul where windows do not need replacing or form part of the character of the= house. It is worth adding that a silica gel bag can be added in the gap wh= ere sealing is imperfect to avoid condensation for a winter, if not an enti= re year, where necessary (100g-250g depending on size).

Where acrylic is used to span multiple panes (eg, 3) it is worth buying 4mm= and not 3mm despite the higher cost to avoid it centre bowing into the roo= m.

[Terry Fields]

I suggest the following:

A small lightweight secondary curtain rod is fitted close to the window, and a clear plastic film curtain, or one made from ordinary cheap curtain lining material , hung on it to give multiple air gaps. Possibly less effective than secondary glazing, but can be added easily to just about any window, and doesn't obstruct it. Fit soft thick string along the bottom so it hangs close to the floor or sill. Easily removed and stored when the cold season is over.

[meow2222]

eful where windows do not need replacing or form part of the character of t= he house. It is worth adding that a silica gel bag can be added in the gap = where sealing is imperfect to avoid condensation for a winter, if not an en= tire year, where necessary (100g-250g depending on size).

mm and not 3mm despite the higher cost to avoid it centre bowing into the r= oom.

Cheers, all added

NT

[meow2222]

Second draught...

NT

Windows are the main areas of heat loss in most houses, and are usually eas= y & cheap to insulate.

=3DDraughtproofing=3D Should be done before any other [[insulation]]. In most cases, cheap, easy = & effective.

Most windows can be draughtproofed using foam tape. Cheap foam doesn't last= well, EPDM does.

=3D=3DMetal windows=3D=3D Old Crittall metal windows usually have far more layers of [[paint]] on tha= n they were designed to work with. A strip and repaint can much improve the= m. If further draughtproofing is needed, one way is to apply [[silicone]] t= o one surface and close the other onto it after applying clingfilm. Silicon= e isn't the most robust stuff though. When set, remove clingfilm with care = and apply clear tape to the face of the silicone to stop it sticking, and t= rim.

=3D=3DSliding sash windows=3D=3D=20 These are best draughtproofed by #remove beading & remove sliding sashes #route a groove around the edge #fit a lightweight flexible [[plastic]] strip in the groove # refit windows

Brushbars can also be used, but make window movement stiff.

=3D=3DLead lights=3D=3D Old lead lights are often very draughty. #Ensure the leadwork is tied to any iron reinforcement bar(s) fitted to pre= vent movement. #Brush the leadwork with linseed putty to fill any gaps between lead and gl= ass #Apply chalk and rub off with cloth

=3DInsulation options=3D All the following reduce window heat loss. If you're determined, the more i= nsulation measures used the better.

=3D=3DDouble glazing=3D=3D Double glazing much reduces heat loss, but its cost generally makes retrofi= tting it not pay back. If you need to replace the window anyway, the extra = cost of dg is worth it.

=3D=3DSecondary glazing=3D=3D Cheaper than double glazing, and easy to fit. Low cost means better payback= than double glazing. Secondary glazing is generally well suited to use whe= re existing windows form an important part of the building's character.

Secondary glazing can be done in

• glass - tough but breakable

• acrylic sheet - quite long lived, impact resistant. Can scratch though

• plastic film - very cheap, limited life, easily torn

Secondary glazing can be fitted

• onto the opening sashes

• onto the outer window frame

• or spaced away from the frame

Usually its best to fit it to the sashes, as fitting to the outer frame pre= vents easy opening of windows. But in the case of metal windows (Steel and = leaded lights) the heat loss of the frame is so poor that secondary glazing= is best fitted spaced off the window frame. It can be fitted to a new ligh= t timber frame fitted into the wall recess.

Secondary glazing is sometimes fitted without draughtproofing first. When t= his is done it then acts more like draughtproofing, losing much of its insu= lating value.

Insulation figures for secondary glazing are much the same as for basic air= gapped double glazing. But the airgap varies in size, varying insulation l= evel some. Imperfect sealing can affect figures a bit too.

Secondary glazing sometimes forms condensation, which can lead to wood rot.= If this occurs, just wipe it off. To avoid condensation for a winter, or a= n entire year, you can add a 100g-250g bag of silica gel where necessary.

Where acrylic is used to span multiple panes (eg, 3) its worth buying 4mm a= nd not 3mm despite the higher cost to avoid it centre bowing into the room.

If secondary glazing that's not easily removed is used, its worth cleaning = everything inaccessible thoroughly before fitting.

=3D=3DCurtain=3D=3D Curtains reduce night time heat loss. To maximise effect, close the gaps ro= und the curtains as well as possible to minimise air movement.

• curtain bottom should be close to the cill or floor

• sides can be velcroed to the frame

• curtain top can be pelmetted

=3D=3DCurtain lining=3D=3D Lined curtains can roughly halve the [[heat]] loss of a single glazed windo= w.

=3D=3DCurtain thermal lining=3D=3D A fleecy thermal lining to curtains improves their [[insulation]] further. = If you only want something very temporary, a blanket clothespegged in place= also works.

=3D=3DSecondary film curtain=3D=3D A small lightweight secondary curtain rod is fitted close to the window, an= d a clear plastic fim curtain hung on it. Less effective than secondary gla= zing, but can be added easily to just about any window, and doesn't obstruc= t it. Fit soft thick string along the bottom so it hangs properly.

=3D=3DSecondary curtain=3D=3D The same as the above can be done with a curtain lining. It hangs better an= d is more robust, but of course it only insulates at night.

=3D=3DShutters=3D=3D Shutters provide the ultimate insulation at night, if they're made of thick= [[insulation]] sheet and draughtproofed. Old fashioned [[wood]] shutters a= lso help, but rather less.

=3D=3DTriple glazing=3D=3D When putting in new windows, TG doesn't cost a lot more than DG. The increa= sed weight can be an issue.

=3D=3DTertiary glazing=3D=3D Adding a 3rd layer over double glazing improves things further.

=3DGreenhouses=3D Greenhouses can use 2 more methods:

*Acrylic glazing - warmer than glass *Bubblewrap secondary glazing

=3DInsulation figures=3D R values for windows:

*Single glazing: 0.18 *Double glazing, basic air filled: 0.35 *Double glazing, coated & argon filled: 0.5 *Triple glazing, basic air filled: 0.52=20 *Triple glazing, coated & argon filled:=20

=3D=3DSee also=3D=3D [[Insulation]]