Single glazed - keep it original. Won't change the look of the period windows at all.

Hello Emmeline,

I rather favour single glazed too especially for a period home like the above in Princelet St. I love this and the others! Win me the lotto!! : ) )

I agree that it is important to conserve and respect historic buildings. However, we should not lazily accept that energy conservation can automatically be dumped because a building is listed as being of historical value. New materials and technologies can offer the best of both worlds. Vacuum glazing can offer the advantage of double glazing without the thickness of conventional double glazed units. More information here:

http://www.lowenergyhouse.com/vacuum-glazing.html

Hello Southpoint,

Yes a good point -I think that goes without saying as we all need to consider this impact and others... I think the topic is very much toward aesthetics in this case and people often throw that aside if allowed and put in something ghastly that may conserve energy- but windows aren't the only place where heat is lost from the home.

If listed then often there isn't much to say or do other than permitted - from my point i'd want to consider all options whilst retaining the aesthetic feel especially in a period or listed building. :))

I agree that both aeshetics and performance both need to be considered. If it is not possible to double glaze then interior shutters and heavy lined curtains can reduce heat loss. Uncontrolled draughts are a major source of heat loss and usually easy and cheap to tackle. I lived in a house with single glazed sash windows and the condensation on the inside used to drive me mad!

Double glazed casement and sash windows look fine on a period property. We have single on most of our windows and the house is very cold. I would always choose double glazing if I had to replace an old single glazed window (unless there was something very specific about the design that prevented me). A much worse crime in my book is replacing old materials (metal, wood) with PVC...

I've installed aluminium secondary glazing on top of original wood framed windows in my 1927 house on an enormously busy, fast road. The effect on noise is minimal; on heat and draughts it's been great. Ultimately, I'll have to repair/replace the original windows (sticking with wood, of course - I agree with russja64 about UPVC) and use double glazed glass in the frames - which I wish I had done at the start. I'll end up with triple glazed in two rooms - those facing the nightmare road. Secondary glazing is not attractive - I was able to colour match it with my chosen paint colour but it is still ugly. And it means three glass surfaces to clean!

Thanks, Southpoint; interesting method. Does it help with noise reduction, too?

Hi Joanne. I do not think it would be as effective as special acoustic double glazing or standard double glazing but better than single glazing.

Hi Southpoint. Thanks for responding and so swiftly. I'm glad to have that information - special acoustic double glazing is probably what I'll have to have. Thanks again.

Hi Joanne. Definitely get some specialist advice from a glass manufacturer who will match a specification to the noise problem you want to solve. Also remember that you need to think of other ways noise could be getting into the building. For example there would be no point in having special double glazing in a window with a standard trickle ventilator as the sound would bypass the glazing, or using it in a poorly sealed window. These are the two big glass manufacturers. I am afraid they are enormous websites.

http://www.saint-gobain.co.uk/

http://www.pilkington.com/en-GB/uk

My house has probably the worst of all case scenarios - It's a Georgian house with single glazed 1960s wood framed windows to the front and Crittal windows to the rear. To add insult to injury the house is listed (with these windows) so I would have to apply for permission to replace them and get approval for replica sash windows to match the other houses on the street! All of which is time consuming and the windows would cost a fortune, especially if I wanted anything other than standard single glazed units. The only good thing I can say is that the front windows are surprisingly draft free (although not great at noise reduction). The same can't be said of the crittal windows at the back which are like refrigeration units. Thankfully the house is easy to heat and retains the warmth well despite the windows, in fact this winter has been so mild some days we have just lit the log burning stove in the lounge and not bothered with the central heating at all!

Hello Gerry,

Oh yes that's quite a difficult situation. If the house is a grade 2 it may be easier to do something about it. I'm thinking it could be as hard to imagine a grade 1 with those windows although strange to think it happened at all without an uproar! Why not approach a conservationist? They may be able to help you apply for permission to restore what has clearly gone awry with the several styles of window and an apparent lapse, could be those works were done before the build was listed.. Some research could tell you.. It's not unusual though for listed builds to have undergone some less than sympathetic transformations.

I love Crittal but in a 30's build or something that would suit, unless they look like Georgian style sash. Maybe worth some research as you could perhaps see if you can apply for a grant if you can't afford all the replacements.. Just a thought here as you would need to see what is possible.. .. :))

Thanks, Southpoint, for more information. I think you are right ... part of my current problem could well be because the original windows, outside the secondary glazing, are poorly sealed - a couple are slightly bowed and I can see daylight between the edges and filth certainly comes in gradually. I didn't think that a small a gap could make such a difference but with your better knowledge, I understand now that that must be a significant contributory factor. I'll tackle the windows one room at a time, starting with the most badly affected one. Thanks again for the excellent advice. Jo

Good luck with the project Joanna. There are companies like Ventrolla who can repair sash windows. Might be worth giving one of them a call.

http://www.ventrolla.co.uk/

Thanks, Southpoint. I don't have sash windows - casement - and I think I have a supplier who can do repairs though I'm not sure how much is possible with repair; I suspect some will need to be made from scratch. But thanks for the recommendation.

AJ INTERIOR STYLING

Hi, thanks for your advice :) It's quite complicated because I believe that this and the house next door were originally one and divided in the 60's. The online listing details (it's Grade 2) obviously date from after this. It does mention the front windows but the listing is very brief so it does bear some research, I suspect the house has a bit of a chequered history! The Crittal windows were fitted when the kitchen and bathroom extension was added, presumably as part of the renovations following the division. I am sure that the 'developer' was on a budget and that the conservation authorities were not involved! I'm betting the original windows were rotten and they went for the cheapest option. You definitely wouldn't love the Crittal windows, even the 'panes' are actually just nasty metal strips gummed to the glass :(

It's quite a common problem that the authorities include whatever features existed at the time of the listing and, however inappropriate they may be, it becomes set in stone.

That isn't to say I wouldn't get permission to change them bearing in mind they are rather unsympathetic but I'd still have to jump through all the usual hoops. Unfortunately I understand they are reluctant to award any grants locally regardless of merit. To be fair some people had been taking advantage of the system for years (and this is hardly a deprived area) with the result that applying is now about as easy as extracting hen's teeth :D

I'm planning to move this year so, as I've resolved lots of the other problems I inherited, I'm inclined to pass this one on to the next owner.... ;)

Hello Gerry,

Yes I certainly see your point and most welcome re ideas. I have one more idea, if you plan to move it could be worth seeing how you could set the plan in motion as this could indeed be passed on to the buyer but you as vendor could make a profit by offering the house with planning already sought. How far you choose to go is of course entirely your choice and I understand that with yours and your neighbours being the same, it would of course have to be a joint effort so to speak. It could add some value though as part of any sale and obviously for the neighbour too.. Whatever you choose hope you find a wonderful new place.. :))

The most important point is to choose replacements that enhance the architectural integrity of your home - your home will look better and be worth more. If the house originally had Crittalls, you should replace them with modern conservation Crittalls. If the original windows were timber, use timber. Today's timber windows last twice as long as PVC-u, are greener and offer better long-term value for money. Double-glazing is a huge advantage over single glazing. Authentic period timber windows are readily available double-glazed with A energy-ratings. Triple-glazing is also available, but, unless your home is exceptionally well insulated, I wouldn't choose them - apart from the cost, they reduce the amount of 'free' heat you get from solar gain.

Makeover - replacing PVC-u windows · More Info

AJ Yes that had crossed my mind - I will get advice from the agents when I get it valued as to whether it would be worthwhile. The house next door was recently bought by a buy-to-let landlord who, judging by the number of times her tenants have had to call in various trades to sort out problems since she 'renovated' it, is carrying on the tradition of investing as little in the property as she can get away with. It would still be possible to replace our windows though as we appear quite separate now (our exterior has been rendered, theirs is still in the original brick for example) and we would at least be in keeping with all the other houses in the street!

Wood Window Alliance Whilst I might have some choice re the rear windows, I would not be allowed to replace the front ones with anything other than Georgian style wooden sash windows (PVC-u windows would NOT be permitted). Not only is the house listed but this is a conservation area and the street is Georgian. Even given the choice I most definitely would not put in Crittal windows, which are totally out of context, and I'm sure were put in because they were cheap at the time. That's not to say I dislike them, in the right setting, and I am aware that the modern versions are much improved re cold and drafts :)

Of course single glazed looks more "authentic" but this is also about comfort and running costs. It is not a museum, it is a home and as such needs to be liveable in comfort. Multiglazing options are coming available that are not ugly, so why not go for energy efficiency?

Triple glazing gives better insulation - greater sustainability and lower energy costs.

Single! Have finally won the battle with my husband to replace them though, so here I come triple!

I am yet to be convinced that triple glazing fits a City market place. I'm not sure it justifies the extra cost. Happy to be proved wrong. Having said that nothing beats seeing whatever products you go with in the flesh so to speak... always good to have a comparison and understand the pros and cons. All your products are on display at our showroom in Balham and we are open Easter weekend.. a shameless plug for...

Triple glazing is now very much a standard, and the price has dropped considerably. No reason not to use triple glazing in new build projects.

Double Glazed are more suitable for these windows

It is important to understand the thermal performance of the entire building. It is generally not good practice to have the insulating properties of the windows higher than the walls. Many people install double glazing on houses with uninsulated walls and then get mould growth due to condensation in the corners of rooms etc. So check out whether the U value of the wall is less than the double glazing and then act accordingly.

double glazing is more than adequate in the Irish climate. Also, when you choose triple glaze bear in mind that the window becomes very thick and cuts down on what is referred to as VLT or visible light transmission which is in fact natural ambient light.

I currently have single-glazed as the house was remodeled in 1901 & is within a conservation area.

Hi yes you may have issue with the Planning Authorities installing double glazed products into a Conservation Area. In terms of a replacement product, they may require you to consider a Heritage slimline double glazed product for aesthetics. You wouldn't want to install them and then have them condemned! If you are not allowed double glazing then have you considered Granada's secondary glazing units - in this regard the Balanced Vertical slider (BVS) or tilt in BVS http://www.gsecg.com/granada-secondary-glazing-for-sash-windows-specialist-applications-residential

A typical UK dwelling might have 5-10 air changes per hour. That's 5-10 times per hour that the air in the house needs to be heated up to a comfortable temperature. The first thing that needs to be done is reduce this infiltration rate. Halve that and you halve the space heating bill. So sealing around the windows and doors is a much more cost effective, CO2 reducing, first measure. Only when you've reduced the draughts as much as you can does the double/triple glazed question come in to effect, and then it's a question of what's cost-effective with your particular dwelling.

What about single glazed steel windows? The building in question is stateside and we need to address energy efficiency but without removing/replacing historic windows. I know the addition of interior storms will help but at the cost of aesthetics. I look forward to hearing feedback on this dilemma.

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Jailhouse conversion · More Info

Extremes of hot humid summers and cold wet winters.

Infiltration first, what can you do to seal the windows against draughts? The BRE Robust Details would have mastic seals to the window frames inside and out. Can you fit seals to the rebates on the sashes?

Condensation is likely to be a problem in cold wet Winters if the space inside is heated. Nippon Glass do an evacuated double glazing, (designed to use in traditional Japanese architecture), that has a very narrow air gap of 4mm with panes of glass held apart by small graphite rods on a 100mm grid. You're still likely to get condensation on the frames however. The rust problem could be reduced by renovating the windows, (remove, grit blast, hot dip galvanise, powder coat), glaze, and fit back in.

Can you compensate for the poor window performance by improving a thermal element elsewhere or by making the heating system more energy efficient?

We are a fan of triple glazed granting our location on the North coast! Both thermal and acoustic advantages

Thank you MAS Architectural Design. In more off-the-beaten-track locations away from big city resources (location is in wilds of southern Arkansas) these preservation projects are even more of a challenge due to the (non) availability of pro trades to hire (with respect to steel window refurbishment) and our own limited resources $$. Removing the windows is not an option however, so any work will need to be with them remaining in place. So grit blasting and painting will have to suffice. Perhaps we will need to weigh the option of storms regardless? I will def investigate the Nippon glass glazing. Thanks again.

There is no simple answer on the type of the glazing system: it all depends on the type and age of the building you are working on.

Has anyone had problems with condensation on the external panes of triple or double glazing?

If there is water running down the inside of the external pane then its more than likely the unit seal has failed in some way (perhaps thats obvious!) and you need a replacement double glazed unit......

chanti1, my grandparents used to have massive condensation problems with their double glazing as it was added as an afterthought, it had about a 4 inch gap and was not sealed so they would have to keep cloths in the gap to mop it all up. In my parents house there were a couple of windows prone to this problem between the panes - caused when the seal on the double glazed units failed. Because you can't get to it the result is eventually mould. The units had to be changed which to my mind seems drastic and wasteful. There should be a way of removing, cleaning and resealing units on site.

Of course condensation happens with single glazing all the time.

Where I live now we get condensation on the outside of the window at night. Air conditioning indoors and extreme humidity outside with night time temperatures still in the high twenties centigrade does that.

Thanks for your replies. We are about to have an aluminium bifold door fitted and windows replaced at the back of the house. We had planned to go for triple glazing until I read that the more thermally efficient the glass is, there is an increased risk of external condensation. I realise this depends on certain conditions outside and you can't really tell if it is going to happen until the units are fitted.

I have read that some people have regretted changing their windows because of this, especially when it takes several hours to clear in the mornings and they can't see out of their windows. We may go for double glazed units now. It won't eliminate the risk but may decrease it. We live in the UK.

Slimline double glazed units which can be reduced down to 12mm thickness compared to the standard 24mm, and infilled with Krypton Gas, a heavier gas than the standard Argon will increase the energy efficiency and be more in keeping with the original sash windows. Please enquire for further details. Your Timber Windows team

I would go with A rated double glazed.

I agree, 'A' rated double glazed is the best option.

The best option is to fit 7 mm vacuum double glazing into existing frames (VIG glass has the same thermal efficiency as triple glazing) the window will look original but will have all the benefits of modern glazing.

Here is the thermal test of triple glazing, single glazing, double glazing and 7mm vacuum double glazing:

The difference between new and original window with VIG glass