Options and some clue on costs to replace single-glazed sashes

[d000hg]

We're strongly considering buying a lovely Victorian house. It has lots of nice period features, one slightly more problematic period feature are the windows. They're either the originals patched over the years, or like-for-like replacements, and are really nice single-glazed sash windows.

The owner tells me their annual gas usage is ~85,000 kWh i.e. about £200 a month... it is a big detached house but... ouch. The EPG gives it a current score of 44 with potential of 78, I don't really know what those mean but my assumption is the windows would be a big factor?

So what are my options? Importantly, this property is NOT LISTED. I'm assuming the best and most expensive option is to have bespoke wooden sash windows with double glazing panes made... I'm guessing this would be VERY pricey? Can anyone offer me some sort of sliding scale of options in terms of cost Vs effectiveness?

In my parents' granite farmhouse, they replaced their rotting windows - lovely big ones - with PVC sash windows since the Cornish weather is not so kind. I have to say they're actually bloody good, you have to check them up close to realise they're not wood. Sadly my parents are dead so I can't ask them about their choices and costs...

Cheers.

 

[endecotp]

Are these single pane per sash, or multiple smaller panes ("Georgian")?

I've been quoted about £1000 per window to replace the six panes per sash with thin double-glazed units (http://www.slimliteglass.co.uk), in the existing wooden sash, with the rebate routered to accommodate the extra depth. That would be much less if they are single pane per sash.

Draught proofing, by routering slots in the woodwork ans fitting seals, will help a lot if there is currently nothing there.

Secondary glazing is another option; I'm considering it for bedroom windows and doing the more conspicuous living room windows the expensive way.

Don't assume that the windows are the first thing to fix until you've properly evaluated everything.

 

[ronniecabers]

be careful with just replacing single glass with sealed units as you will also need to change the weights to get them to work properly . Very line sealed units with Low e glass in don't keep the heat in very efficiently ...you would probably be wasting your money in my opinion. Double glazed units with a ' soft coat ' low e coating and argon gas andd an ' ultraclear ' pane ( Diamant glass or Pilkingtons optiwhite Low iron glass to everyone in the industry ...incredibliy common throughout the industry ).

Secondary Glazing ... some very good companies out there offering Balanced vertical sliders to mimic the look of the originals , so from the outside you wouldn't even know they are there and can come with Pilkington K glass to help keep the heat in..

Upvc sliding sashes ... very thermally efficient these days , we did a house in our village and everyone thought they were wood, but they aren't cheap for a good one ( but can't see you paying a £1000 for a whole replacement window unless they are huge! ) ..but you can get them to be made to pretty much mimic everything you currently have ...deep bottom rails, run through horns etc...

It is personally preference really and the only way forward is to get prices for each...

 

[d000hg]

Thanks for your thoughts. To answer a question, they are large panes - most windows are single pane for the top and bottom, large bay windows are 2x2.

I hadn't realised you could retrofit thin double-glazed panes. If I'm going to do it I don't want to get some half-efficient solution though so I'd have to get some more information on that. Thanks for the point re:weight.
Personally, I think secondary glazing is awful, I'd probably rather save up or replace with a standard double-glazed window if it's not a feature!