14 September 2009

Advice on double glazing ?

| Raf
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Hello Rioters.

We are looking for your advice, good and bad experiences on double glazing of windows.

We have purchased a house backing onto a main road so we are looking to reduce the noise in the bedrooms. We aren’t complaining, it’s not unbearable, the road was obviously here before us and we were aware of the issue before buying, but we are looking to reduce a little bit of noise to make sleeping just a little more restful.

We will be buying heavy drapes, with pelmets etc, but want to know if you have had experience with double glazing – good Canberra companies, not so good companies – and any indication of a price would be a bonus. Most importantly – does double glazing actually work for noise reduction ?

Thank you, any advice much appreciated!

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travissimons1:43 pm 19 Feb 15

Double glazing your windows seems like a good idea. My parents did it to their house and it actually prevented someone from being able to break into their house. It seems to also lower the cost of their heating bill. http://www.envirovision.com.au

Hi gungahlin Al and Canberra Sustainable House. When are your tours, I have heard of your house and how it is cut off from the power grid. I wouldn’t mind to see it :), when do you do guided tours?

Also, while doing some research, I hit a bit of a snag. What exactly is Energy Advantage (EA) glass? I get the feeling its just a low E coating. But I’m noticing that these EA windows are still achieving a relatively high SHGC rating of around 0.5

So, what is EA glass?

If it’s just clear glass with a Low-E coating, how can it achieve a high SHGC rating?

Gungahlin Al5:36 pm 04 Jul 10

I would imagine the two different thicknesses you talk about is because each absorbs sound of different wavelengths. the sound that passes through one thickness would pass through the second sheet if it were the same.

I look forward to triple glazing being available and cost effective.

Canberras.Sustainable.House8:02 am 04 Jul 10

We have a showcase sustainable house in Ainslie and conduct guided tours on a regular basis. Our windows are double glazed throughout and we also added some additional features ensuring they are high performance windows. Such as low E cotaings, gas fills to gap and timber frames. The end result is excellent thermal performance. Combined with passive solar design principles we included, our home does not drop below 18 Deg C in winter and does not exceed 25 Deg C in the hottest summers. The double glazed units are a contributer to this.

High level accoustic insulation requires two ingredients, difference pane thicknesses (eg: 4mm & 6mm, rather than 4mm & 4mm). Ideally the gap should be at least 20mm. Most double glazed units have a 12mm gap or less. Irrespective you can expect a significant reduction in outside noise with double glazed units.

The positive message is that double glazing is becoming less expensive as demand increases. At present double glazing occupies approx 53% of the ACT glazing market. Supply and demand will drive costs down. In the USA double glazing is cheaper than single glazing – a comforting thought.

Gungahlin Al3:22 pm 25 Oct 09

Ha! Didn’t realise this was a resurrected post.

It sounds like there may be a couple of versions of ‘comfort glass’. One of them has a ‘film’ deposited on the inner face. Whatever you do, DO NOT use any metal scraper, blade or other metallic object on the glass. It will cause a dark discolouration which cannot be removed.

Learned the hard way!

Gungahlin Al8:27 am 25 Oct 09

Great thread, and generally the advice given is spot on. Sepi, *plain* DG won’t don’t a heap of good on a west-facing window because it only addresses conducted heat. It does nothing to stop radiant heat.

Some basics will help people understand the differing needs for glazing – advice that is unfortunately lacking among glazing retailers here (or so I found when product sourcing 2 years ago).

There are 3 types of heat transfer:
Radiant is when the light itself hits something and warms it up. The visible light band is absorbed by that thermal body and re-emitted as long-wave or infra-red light, or put simply: heat.
Conducted is where a body is heated on one side and conducts that heat through itself and emits it on the other side.
Convected is where heat is transferred by the air itself being warmed and then moving (usually up). When radiant heat warms things up, then convection moves that warmth around the house – but it is fairly inefficient at warming up thermal bodies – which is why ducted heating doesn’t do much to warm the building fabric (particularly floors) making it quite inefficient.

So to glazing types:

Plain glass does nothing to stop radiant heat – it is clear for the very reason of letting light through. But this means it also lets not just visible light through, but also short-wave (ultraviolet) and IR. So the UV fades all your stuff, the IR conducts through the glass to then heat the air on the inside, and the visible light hits everything inside and is also converted to IR (heat). That’s in summer. In winter, it does a brilliant job at conducting all your heat outside. Single layer plain glass is a bad option for every single window in your house in Canberra (except in your garage).

Double glazing is just two sheets of plain glass, so you can see that it also wouldn’t do anything to stop radiant heat, because the visible light passes right through, and heats up everything it lands on. But there is an air space between the two sheets, and it is this that inhibits the conduction of heat in either direction, depending on the season. The larger the air space, the better it does. You can also get the space filled with Argon gas instead of plain air, and this improves the blocking even more because Argon is an inert gas so conducts heat even less.

Low-E film filters both the UV and IR ends off the spectrum, allowing just the visible light through. This film is usually placed between two sheets of glass in a lamination – no air space. Typical domestic product is called Comfort-Plus by Pilkington and is 6.38mm thick. This does a great job of reducing the heat that radiates into your home in summer or out of it in winter, plus it chops off the UV and protects your furnishings. And being laminated, it also does a good job at sound insulation and is harder to smash through, giving a security benefit. But without the air gap, it does still conduct heat through it. And you do get a fair bit of condensation inside in winter. It is a good product, that probably gets you around 70% of the thermal performance of DG, but with added benefits of UV filter, security and is cheaper.

DG with Low-E adds to the cost, but circumvents the short-falls of plain glass DG. But it costs more.

Of course there’s also the frame. I believe around 30% of heat loss on poor windows can be through the frame – through conducting through the frame itself (aluminium frames) and through poor sealing. Next windy day, go around your house with an incense stick and you’ll be amazed at how much wind is blowing in through your frames (and exhaust fans!) – weep holes in particular. Someone mentioned Atlas being a bit pricey – that would be because they use G James frames, which are “thermally improved”, meaning a lot of attention to sealing them up properly. This is different from “thermal break” frames, where they circumvent aluminium frames’ conduction problems by sandwiching a plastic layer between the inside and outside. I haven’t seen anyone promoting this frame type in Canberra yet. Timber frames don’t have a conduction problem, but can get a lot of gaps and leakage – especially as they age. PVC frames are good both ways, but ones I’ve seen can mark up easily and are then hard to clean. Some of the finishes are ordinary too.

In our own home design, and facing serious budget limits, I recall it being about $11,000 to trade up from the builder’s standard crappy Stegbar frames and single glass to laminated Low-E and better frames through Atlas. To add DG and Low-E was something like another $9000 on top of that. Argon gas another $2000. We went for the low-e laminated solution. Service was woeful at Stegbar, Monaro never got back, then claimed they lost our details. Checked some PVC options, but as said, wasn’t happy with the finish. No-one knew much about their own products, and I ended up talking with a technical adviser through G James Glass in Brisbane. Moen Glass’ online information was among the best I could find.

If you are designing from new, please be careful about your window placement. If you have massive glass expanses facing west (like a new home in Harrison facing west to Flemington Road like a bloody fishbowl), no amount of window improvement is going to stop you from baking inside in summer.

You have to stop summer sun even hitting any glass wherever you can. You still need eaves on the north – at midday the sun is straight over Rockhampton, meaning if you don’t have eaves, you’ll be getting sun in at the worst possible time. Awnings or eaves, plus landscaping are also critical for any windows exposed to the south-west afternoon summer sun. Obviously if windows on the east and west are smaller, they’ll also be easier to shade.

As an aside, when checking out some architects for our design, I went to see Strine. When I asked about double-glazing, she (the architect there) said “We put them on the south windows, but you don’t want them on the north windows because they stop the heat of the sun getting in in winter.” I never went back.

Trade Windows10:08 pm 24 Oct 09

Double glazing is easily the best home improvement you can make from noise and heat loss pollution do it now you will notice the difference how ever make sure the company is reputable and check at least two references

[url=http://www.trade2public.co.uk]Trade Windows[/url]

We double glazed one west facing window and results were a bit disappointing for heat.

If all you want is heat reduction (not noise or cold) then external shutters may be better – or the reflective glass mentioned above, although I’ve not tried that.

Someone told me that even double glazing can’t cope with direct western sun beaming onto the glass.

We only did one window in the room though, (it needed replacing), so not a good representation.

Ceej1973 said :

DawnDrifter said :

excellent thread
is there any problem with just double glazing one side of the house and leaving the other windows as is(ie just doing west aspect and leaving the rest)

Hmmm. Well now you opening up a can of worms. Yes it does make a difference. Google “Double glazing + energy rating” and a heap of hits will come up.This was the best explanation I could find: http://www.abcb.gov.au/index.cfm?objectid=DA77B42F-9749-AE67-E1E5DB1D9E241C08. If you read into some of the hits, there is a big difference between windows on different sides of the house, which City you are in, etc. There are some readings (from that search option) that describe in great detail the rating levels of windows, insulation, aspect etc, and how this triggers whether your house gets a 2 star or 6 stars. A North facing window will attract more points than a south facing window. Stars are broken down into points. For example, my own house is rated at 5 Stars with 13 sub points, so I am just shy of 6 Stars (although that was prior to internal fitout).

Actually, this is better link:
http://74.125.153.132/search?q=cache:ouFcB_0B3NcJ:www.abcb.gov.au/index.cfm%3Fobjectid%3DDA77B42F-9749-AE67-E1E5DB1D9E241C08+first+rate+energy+rating+canberra&cd=1&hl=en&ct=clnk&gl=au

DawnDrifter said :

excellent thread
is there any problem with just double glazing one side of the house and leaving the other windows as is(ie just doing west aspect and leaving the rest)

Hmmm. Well now you opening up a can of worms. Yes it does make a difference. Google “Double glazing + energy rating” and a heap of hits will come up.This was the best explanation I could find: http://www.abcb.gov.au/index.cfm?objectid=DA77B42F-9749-AE67-E1E5DB1D9E241C08. If you read into some of the hits, there is a big difference between windows on different sides of the house, which City you are in, etc. There are some readings (from that search option) that describe in great detail the rating levels of windows, insulation, aspect etc, and how this triggers whether your house gets a 2 star or 6 stars. A North facing window will attract more points than a south facing window. Stars are broken down into points. For example, my own house is rated at 5 Stars with 13 sub points, so I am just shy of 6 Stars (although that was prior to internal fitout).

excellent thread
is there any problem with just double glazing one side of the house and leaving the other windows as is(ie just doing west aspect and leaving the rest)

Oh and one other reason we got the double glazing was the original 1970s glass in the house. It was thin and rattled whenever we closed a door or the wind was blowing. Not to mention we were worried the floor to ceiling windows would one day see our kids going through them. In that situation we were told the glass would shatter into nice jagged edges also! 1970’s windows are not up to current safety specs apparently.

With the double glazed units the house is just that much more ‘solid’ now and the use of toughened glass in the frames surrounding the entry doors gives us a bit peace of mind also. No one is going to smash them and reach through to let themselves in very quickly!

We just had the window replaced in our bedroom with a new window/door unit with cedar frames and double-glazing. Made by Monaro Windows (Queanbeyan). The difference in both noise and thermal properties was noticeable immediately – the chill you feel standing near an uncurtained window in the evening is there but only barely noticeable, compared to our other windows which are like standing in front of an open fridge!

We have quotes to replace the glass in several other windows with double-glazed units. The installation price includes routering out the timber frames to take the thicker units.

Our house is 1972 and the windows are all 3mm glass.

Thanks for your comments – Aronde, my parents had double glazed done about 5 yrs ago and it was so much cheaper too. I asked all of the window companies who did quotes why it had gotten so much more expensive – answer was same for all. Supply and demand – window manufacturers can basically charge what they want, so they go crazy! Very annoying! I looked into comfort glass as well, it relects light so thats how it works, however dbl glazing is more than double as effective as comfort glass (from the research I did).

Yeah, like Pandy sez. I mentioned the thickness because of sound insulating properties. The Comfort Plus has some sort of reflecting mechanism (I have a feeling it is a tint inside the window, not on the outside) but that it works best for direct sunlight or something like that. What I mean is that the winter sun can still enter the room, but the hot summer sun can’t. You can google E-glass and find out more. Comfort Plus is probably just a brand name.

I replaced all my bedroom windows with double-glazed “spanline” windows. The only unfortunate thing was that the company that Spanline used to use (Homespace) did the work. They separated from Spanline soon after and the “after installation” service was dreadful – sloppy, with scratches on the new windows left by the installers. My advice is that double-glazing works (but is not a miracle solution to noise). Don’t use Homespace if you want good quality service. Good luck.

gun street girl9:59 pm 14 Sep 09

Double glazing worked for us on a busy main road in Sydney.

Comfort plus is E-glass. It has stuff in it and a tint that reflects heat from outside.

Double glazed: +1 for sound and insulation. Recommend whole heartedly

We had the whole house except for a sliding door upgraded to double glazed about 10 years ago. We have timber framed windows. Just Rite home improvements remove the existing glass and install the made to measure double glazed units. Absolutely worthwhile for both heat and noise insulation.

My father was visiting and had his normal room. Commented the next morning how it was much busier than normal the night before … no busier, he had simply slept with the window slightly open.

Another on the noise front, one of my boys plays the drums … the neighbours never complain.

rosebud said :

For western facing windows, consider Comfort Plus as an alternative to double glazing. It is thicker than normal glass (not as thick as double I believe)

But double glazing isn’t thick glass – it’s two thin layers of glass, and an air pocket in between provides the insulation properties. “Thicker than normal glass” won’t provide protection from heat …. perhaps the Comfort Plus has reflective properties?

For western facing windows, consider Comfort Plus as an alternative to double glazing. It is thicker than normal glass (not as thick as double I believe) but importantly, it repels the hot western sun. We got it for our front door so that we could have glass in the door to lighten up the dark entrance. And now, behind the front door is cooler than anywhere else. Our house faces East West too.

We used Double Glazing Conversions back in 2007. Great job! Not sure what the inflation rate is like in the glass industry but prhhcd we got 57 windows for $14k! ie the whole house and some of them were weird shapes that went from floor to very high ceilings! Very good noise reduction plus has been great in winter keeping the heat in. They basically ripped out all the old thin glass from the 1970s and replaced them with made to measure double glazed units. Some window frames were too thin for the double glazed units so got something called ‘Comfort glass’ (I think). Two bits of glass laminated together with some special coating from memory.

Gee I’m glad you guys all said that! I’m about to get mine installed $7600 for 2 windows and a door! Through window options – came to me recommended!
I am doing it predominantly for noise and heat insulation. I live in a west facing house on a main road (shoot the architect – please!).
Good luck Raf!

Got double glazing installed all round in our new home (not wet areas). Noise levels are way less than anything we have experienced elsewhere, we really notice the diff when in neighbours homes (as well as the temperatures). We also have cedar instead of metal, which makes that added difference. As for temperatures, in summer, it rarely gets over 28 degrees in when its been 38 out, and winter never gets below 14 when we wake up (ducted heating only used between 7-11pm). Insulating under the floor boards also made the difference. As for cooling, we avoided the AC issue, by placing the windows so that we can cross ventilate. Be warned, if you go with cedar double glazing, there is the annual oiling of frames, and the flyscreens in cedar frames can become quite flimsy! Cant recall who the builder used. pretty sure they are Stegbar tho, cause they were in Qbyn.

Raf, had double glaze installed about six weeks ago. For the money I think the benefit is in temperature control. Hard for me to comment on noise reduction because living alongside Cotter Road the traffic is just starting to pick up with the warmer weather and I have nothing to compare it with although during the mountain bikes last week I did notice a big difference between inside and outside from the PA system background noise. Mine are magnetic fitted on the inside (have heard of this type being fitted externally and going missing). I you go for this type I urge you to have proper handles fitted to the frames so they can be removed easily. I ended up with suction caps next to useless.

I know people who are very happy with Magnatite – this is like heavy plastic in a frame that fits tight to he inside of your current windowframe, leaving the existing window.

It prevents a lot of noise, but is not cheap either.

Consider your cooling options though. No point getting double glazed windows if you have to leave them open during the heat and noise of the summernats season because you’ve got evaporative cooling.

Holden Caulfield12:12 pm 14 Sep 09

I have a mate who ordered some double glazed windows through Stegbar. He fitted them DIY and was very impressed with their quality. End result looks tops too and he is more than happy with the outcome.

+2 on the extra noise protection from The cat, although, the windows should be a big help at any rate.

The cat did it11:28 am 14 Sep 09

AA man is correct. Double glazing gave us a significant all-round improvement in thermal comfort and noise control. Any local government with guts would have mandated it years ago, as they did in the UK. Blame building industry lobbying for the fact that it wasn’t installed when your house was originally constructed … If it had been mandated, production volumes would have significantly increased, and economies of scale would have lowered prices.

If it’s noise that’s your main concern though, check the rest of the building as well- you don’t want to spend big on windows only to find you’ve got significant noise intrusion through walls and roof cavity. There are probably noise experts who can advise what your options are for damping noise entering through these routes.

Affirmative Action Man10:38 am 14 Sep 09

We have replaced single glazed with double glazed & there is a major decrease in noise and far better insulation.

Atlas are ok but expensive – Stegbar are cheaper. Expect to pay abt $2000 + for 3 standard windows in aluminium extra if you want them installed.

You can also get cancelled orders or used units at recycled building materials places

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