Sash window replacement worth it?

ranman1973

Just wondering what sort of energy savings I canexpect. I live in a pretty old house with about a dozen windows on the main floor, all fairly large... 30' x 60'. Single paned, and they leak air in the winter and moisture forms. I live in a moderate climate (Vancouver, Canada). What sort of payback period would I be looking at?

jkgray

The Energy Saving Trust state that "Energy Saving Recommended double glazing can cut heat lost through windows by half, as well as saving you around £135 a year on your heating bills. It can also save you around 720kg of carbon dioxide (CO2) a year." (http://www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Glazing)

In simple terms when I have looked at this before unless you are also replacing your windows for some reason other than just 'money saving' it is not worthwhile as the payback period is too long.

Say your double glazing cost £5000 at £137 per year it would take nearly 40 years to pay back and that is not taking into account any interest that would have been earned on that £5000 or interest paid on the loan.

If the windows do need replacing for some other reason, e.g. unserviceable, or simply you want a warmer house then you may still think it worthwhile.

gmgmgm

Agreed.

Better to do a few things to stop draughts (if that's a problem) than to replace. (Try stuffing clingfilm in the gaps).

Replacing functional windows for energy/money saving is madness.

Suzy_M

If the window frames are suitable it may be possible to replace single panes with double glazed units.

Alternatively there are various secondary glazing systems that can be fitted to the insides - either permanent or just seasonal.

Though agree with gmgmgm draught proofing sash windows makes a heck of a difference.

sashman

jkgray wrote: »

The Energy Saving Trust state that "Energy Saving Recommended double glazing can cut heat lost through windows by half, as well as saving you around £135 a year on your heating bills.

In simple terms when I have looked at this before unless you are also replacing your windows for some reason other than just 'money saving' it is not worthwhile as the payback period is too long.

If the windows do need replacing for some other reason, e.g. unserviceable, or simply you want a warmer house then you may still think it worthwhile.

jkgray, yep based just upon heat savings alone, replacements are hard to justify, but dont ignore the maintenance, painting etc during that period and the carbon involved with the work men doing the work.

EST should use the information provided to them from the BFRC who run the energy scheme for windows, they say old fashioned DG (4.16.4 air units) saves about half the heat lost through single glazing, C rated save threequarters, and A rated saves all of it, A rated MUST be energy neutral or energy positive!!

Effectively this would reduce your figure to only 20 years, but thats still a long time if heat loss is the only consideration.

sashman