Double Glazing in Canberra's new homes?

ThisIsAName said :

We are renting in one of the newer houses (2 yrs old) with a high EER, but the heat loss is absolutely shocking. The attic has plenty of insulation

Out of interest, what is your EER and heat loss in general terms? (eg. temperature drop overnight)

On paper, my place has a 5* EER, but I think the heat retention should be better (to my untrained eye). The place can be heated to ~19-20, the heating turned off, and it’ll drop to 10-11 by morning. This is only ~2-4 degrees better than a somewhat refurbished 50 year old (?) place I once rented in the inner north. I can’t find the EER, but it would be <= 3. My current place has R4 ? ceilings, R1.5 walls and single glazed aluminium windows (with pelmeted curtains or insulating blinds).

This story appeared recently on the 7:30 report, which may be relevant:
http://www.abc.net.au/7.30/content/2011/s3200765.htm

I've found gaps in the roof insulation:
* 30-40cm squares cut around the drop lights
* cutouts for fans (though the insulation is snug against at least one of the pipes)
* there is an uninsulated gap under a wooden platform that the central heater is mounted on

It'd be useful to know how much heat is lost there & if something similar to the link above is happening.

——

Gungahlin Al: you recently posted here http://the-riotact.com/8-overnight/51151 that your place only dropped to 16 overnight. What is your place rated at?

Only 5.5. But it runs only 11 degrees off east-west, every living space and bedroom is on the north side, which is pretty much a wall of glass. But there is also a large overhang to prevent midday summer sun getting in them.

The south and west sides have much smaller windows, all shaded with very little direct summer sun hitting them – will be zero when the trees get up a bit higher. No windows on the east end – garage.

It should not drop as far as 16 but I have to get some insulation around a heat transfer kit I put in to suck hot upstairs air and dump it down in the laundry/bathroom area. Just been a bit slack.

Downlights are your killers. Change the halogens for compact flouros (or LEDS if they are affordable yet – haven’t looked for a while), then also get the plastic cowls that fit over the hole. The cowls stop the draft but you can’t put them over halogens because they are too hot – they chew through enormous juice too. Once the cowls are in place you can stuff a bunch more insulation right up the them.

Get DraftStoppas to fit over your exhaust fans too – another gaping hole!
Make sure any flues (like where your kitchen exhaust goes outside) have self-closing flaps on the outside too.

matjones said :

Ceej1973 said :

KB1971 said :

On of the reasons the whole EER system is a crock…..

+1. We have double all round, and to think that one of those dual occupancies in the newer areas with hardly any nth/nth wst windows can have the same energy rating as us. Pfft.

We are renting in one of the newer houses (2 yrs old) with a high EER, but the heat loss is absolutely shocking. The attic has plenty of insulation

Out of interest, what is your EER and heat loss in general terms? (eg. temperature drop overnight)

On paper, my place has a 5* EER, but I think the heat retention should be better (to my untrained eye). The place can be heated to ~19-20, the heating turned off, and it’ll drop to 10-11 by morning. This is only ~2-4 degrees better than a somewhat refurbished 50 year old (?) place I once rented in the inner north. I can’t find the EER, but it would be <= 3. My current place has R4 ? ceilings, R1.5 walls and single glazed aluminium windows (with pelmeted curtains or insulating blinds).

This story appeared recently on the 7:30 report, which may be relevant:
http://www.abc.net.au/7.30/content/2011/s3200765.htm

I've found gaps in the roof insulation:
* 30-40cm squares cut around the drop lights
* cutouts for fans (though the insulation is snug against at least one of the pipes)
* there is an uninsulated gap under a wooden platform that the central heater is mounted on

It'd be useful to know how much heat is lost there & if something similar to the link above is happening.

——

Gungahlin Al: you recently posted here http://the-riotact.com/8-overnight/51151 that your place only dropped to 16 overnight. What is your place rated at?

Also, is it really acceptable for someone who states in their profile that they sell double-glazed windows to be starting this topic? And also spreading (apparently) false information in regards to single-glazed windows letting 100% of the heat escape?

Gungahlin Al said :

… If it is 40 outside in summer and 20 inside, single skin glass will do a superb job of conducting that heat straight into your home – irrespective of how well shaded the window is. An improved window – as long as it is shaded – will reduce this transfer.

Hmmm, that might explain why many newer houses also seem to have done away with eaves for shading in summer (because it apparently ‘looks’ nicer), yet they still get a good EER?
What’s up with that? Talk about form over function……

The short answer is that builders want to make a profit, therefore they (shock horror!) spend as little money on a house as they can get away with.

New houses are required to have a 6* EER. How this is achieved is up to the architect / EER assessor. If it is on a good aspect, it will only require single-glazing to get 6*. If not, it will likely require double-glazing, etc.

Gungahlin Al said :

So we had to compromise. At that time the “thermally improved” (read: don’t leak through gaps as much) G James frames and laminated low-e windows cost us $11K more than the standard Stegbar leak-like-a-sieve crap the building offered up.

So it’s not just me. We got cedar Stegbar windows, and right from the very first rain storm, they leaked everywhere. Still do, they are absolutely abysmal. The water in some cases is getting into the frame as well as into the house. The double glazed ones have moisture in between the panes.

They are seriously poor quality windows.

#8 Gungahlin Al – Stunning I would never have believed it if I hadn’t read the links that you provided. I had thought that Strine was one of the leaders in environmental design. I’m now glad that we didn’t use them. Some of their clients must now be very annoyed.

I’m not sure why the 6.5 metre wide rooms are so critical. Presumably taller (or clerestory) but well shaded windows would pump solar radiation into wider rooms. Trombe style walls also bring the thermal mass up to the windows to counteract the effect of placing furniture and floor coverings in the path of sunlight.

I don’t know if things have improved but when we built our house about seven years ago we had a lot of trouble getting suitable windows. We didn’t want timber because of the higher maintenance, we couldn’t get thermally broken frames anywhere and we had trouble finding any frames that held an IGU with spacing greater than 10mm. We settled on uPVC but after they were installed we discovered the units were only 10mm.

We also had trouble glazing. Window manufacturers were pressuring us to tint North facing windows and I think they were also recommending other glazing features on the North that were counterproductive to SHGC (I can’t remember now if it was Argon gas, Low E or something else). Tripple glazing was virtually unheard of, would have been cost prohibitive and I doubt that most frames would have accommodated the thicker units.

Yes we were shopping for our house design about 4 years ago and had exactly the same problems with the local glass people. And our budget was really tight after not having any propoerty right through the property boom period. The build almost broke us. So we had to compromise. At that time the “thermally improved” (read: don’t leak through gaps as much) G James frames and laminated low-e windows cost us $11K more than the standard Stegbar leak-like-a-sieve crap the building offered up. To go DG plus low-e would have been another $10K on top of that. Everyone has to draw their own line somewhere according to their circumstances.

One key downside of single or laminated glass that should be considered is that the thin layer and resulting high tempoerature gradiant across it means you get condensation – a lot of it. A problem that just doesn’t exist with DG. And if your builder uses crappy cheap MDF architraves instead of timber, you just know what that condensation is going to do!

Gungahlin Al said :

Just to make it clear: double glazing stops heat transfer but not light transfer. The sunlight pours through double glazing almost unencumbered, hits everything inside and is remitted into the inside airspace as long-wave infrared light = heat. This is radiant heat. This is why double glazing is no help in summer if it is in direct sunlight. The light comes in, everything gets hot, and the heat can’t get out again. You must shade all windows possible from direct summer sun. The EER rating picks this sort of thing up and penalises the rating heavily.

I think a better reorganisation of what you said is: Radiant energy (short wavelength) from the sun, comes through the window, and heats up the inside of the house.
This heat energy (long wavelength) in the form of hot air and other thermal conduction transfers its energy to places of less energy, at different rates depending on the difference in energy level.
Thermal barriers, such as double glazing are far more effective at slowing the heat transfer from the high concentration to the low concentration. This occurs because the convection currents that are the mechanism by which heat energy is supplied and transfered through the glass surface are prevented from involving a large volume circulating air mass.

Ceej1973 said :

KB1971 said :

On of the reasons the whole EER system is a crock…..

+1. We have double all round, and to think that one of those dual occupancies in the newer areas with hardly any nth/nth wst windows can have the same energy rating as us. Pfft.

We are renting in one of the newer houses (2 yrs old) with a high EER, but the heat loss is absolutely shocking. The attic has plenty of insulation, but the heat loss through the single pane windows & 2 patio doors in the main living area is terrible. The second the heater turns off, you can feel it. I’m highly doubting that there is any kind of insulation in the walls either.

I also feel that ALL new constructions should be required to have solar panels on the roof. It’s a no-brainer really. The only people who would be against this are the energy companies. Last thing they want is all houses producing their own electric, where would they make their profits.

Holden Caulfield said :

EvanJames said :

Holden Caulfield said :

As it happens we will be having double glazed windows, but because we want to, not because we’ve been told to.

Maybe if you hadn’t have, you would have been told to.

Nope, no reference to the type of glazing was made on our plans or building applications.

It was part of the certification process. The certifier had a glazing calculator that the new part of the building had to comply with, and to get the heat transmission target we had to upgrade the glass. The scheme is called WERS — http://www.wers.net/.

KB1971 said :

On of the reasons the whole EER system is a crock…..

+1. We have double all round, and to think that one of those dual occupancies in the newer areas with hardly any nth/nth wst windows can have the same energy rating as us. Pfft.

We all know if you put $50k of PV panels on your roof you won’t pay for electricity any more, so why isn’t everyone doing it?! (stupidity?)

Isn’t it disgusting they allow poor people to have houses built when clearly they can’t afford to ‘Have it all’. I blame under-priced and over-abundant new land…

I hate to be sarcastic, since I understand the benefits of double glazed over single, timber frame over aluminium etc – it’s just that every single aspect of building houses is going up up up and it’s just one more thing to spend another $10k + and I’m wondering how over-priced land encourages spending ever more on the house for essentially comfort features. It is unfortunate.

(I’m indirectly blaming the ACT Labor government btw)

100% of your heat escapes through a single glazed unit.

The who to the what now? What in blazes are you talking about? 100% of your heat? Are you seriously suggesting that every surface in your house other than single-glazed windows is a perfect insulator? And that no air could possibly escape or enter? Geeze – I can’t help but wonder what the hell I’ve been breathing, since the oxygen should have run out ages ago.

Seriously, I know you’re truing to spruik your double glazing business under the guise of concern for the environment, but please: at least try to make your ridiculous claims sound slightly plausible.

I would suggest two things

1. The overall efficiency of your house in winter is driven by the net heat loss through walls, windows, floors and ceiling. The key word is *net* because it means that you can compensate for one area ( single glazed windows) by increasing insulation in another area ( ceiling ).

2. Double glazed windows are a rather costly way to reduce a relatively small amount of heat loss compared to adding more ceiling insulation and/or insulating blinds.

Hence why builders use single glazed but can still get a reasonable EER. There are many things wrong with the EER system, but this is not one of them. It’s an accurate representation of the physics in this case.

bugmenot said :

Builders also do strange things, like double-glaze only the south facing walls instead of all around.

Unfortunately that comes from certain misinformed architects, the likes of Ric Butt in particular who claim that “you don’t want double glazing on the north windows because it would stop the heat of the sun getting in” (direct quote, to me, by one of his architects). No understanding of the physics of light.

Unfortunately local architect Ric Butt (Strine) also gave the same line to Sanctuary magazine and they printed it http://www.scribd.com/doc/21370093/Sanctuary-magazine-issue-9-The-Millennium-House-Canberra-green-home-profile

I took them to task over it and they conceded that it didn’t sound right at the time but they went with it. As a result, they ran a full feature article about window types next issue, in which they corrected the error http://www.scribd.com/doc/25739197/Sanctuary-magazine-issue-10-Windows-that-work-green-home-feature-article

Just to make it clear: double glazing stops heat transfer but not light transfer. The sunlight pours through double glazing almost unencumbered, hits everything inside and is remitted into the inside airspace as long-wave infrared light = heat. This is radiant heat. This is why double glazing is no help in summer if it is in direct sunlight. The light comes in, everything gets hot, and the heat can’t get out again. You must shade all windows possible from direct summer sun. The EER rating picks this sort of thing up and penalises the rating heavily.

Back to the physics of light/heat. Heat moves from the hotter side (more energy) to the colder side (less energy – where the air molecules can move around with more elbow room and less bouncing into each other if you like). This is mostly by conductivity. If you have single skin glass the heat loss in winter is phenomenal. This is another reason why Ric Butt’s advice is so critically wrong. If it is 40 outside in summer and 20 inside, single skin glass will do a superb job of conducting that heat straight into your home – irrespective of how well shaded the window is. An improved window – as long as it is shaded – will reduce this transfer.

So what happens in some of Ric Butt’s designs is the people have their blinds all draw all day through summer living in darkness to try to compensate for the error. And they don’t get anywhere near the benefit they should from the winter solar access.

Laminated low-e is better than single skin. Double glazing is better again. DG with low-e better still. That plus with argon gas filling better still. And framing with a thermal break will also reduce some 25% heat loss that ordinary aluminium framing has. That’s either wooden frame, two-piece aluminium with a plastic bit sandwiched between, or PVC. It comes down to how much you can afford. Put money into better windows before many other essentials that can come afterwards.

Doesn’t make sense here either. We are doing substantial renovations, requiring a DA (owner builder), but nowhere does it stipulate double glazing is to be used.

We also have put in double glazed windows, but they weren’t even on the submission for the DA. Perhaps it’s a builder/contractor trying to get one past you.

However, to the main concern of why builders are allowed to single-glaze… It purely comes down to builders not being physicists and having the wool pulled over their eyes by vendors and lousy EER schemes. The vendors want to sell low-E glass and films (and claim they will do the same job as double-glazing) because it’s easy. To *properly* do double-glazing takes a bit of smarts as to the application. The EER scheme doesn’t help as they can make up points with more ceiling insulation etc.

I’ve had a long-standing argument with a builder-friend as to why double-glazing works (and why low-E isn’t). You just can’t win an argument with logic when the person didn’t use logic to get themselves into that opinion in the first place.

Builders also do strange things, like double-glaze only the south facing walls instead of all around.

EvanJames said :

Holden Caulfield said :

As it happens we will be having double glazed windows, but because we want to, not because we’ve been told to.

Maybe if you hadn’t have, you would have been told to.

Nope, no reference to the type of glazing was made on our plans or building applications.

Holden Caulfield said :

As it happens we will be having double glazed windows, but because we want to, not because we’ve been told to.

Maybe if you hadn’t have, you would have been told to.

mikal said :

I recently did an extension, and was required by the government to put in not only double glazing, but special low-e glass as well…

Huh?

We’re part-way through some renos/extensions and will be replacing all of our windows. ACTPLA has not stipulated any requirements as to what type of glazing we use. As it happens we will be having double glazed windows, but because we want to, not because we’ve been told to.

I recently did an extension, and was required by the government to put in not only double glazing, but special low-e glass as well. Additionally, R4 for ceilings and R2 for walls are now minimum standards. So, I’m not sure what you’re talking about? Surely new buildings have to comply with the same standards (or better) than extensions?

On of the reasons the whole EER system is a crock…..

“100% of your heat escapes through a single glazed unit”.

Only if some idiot has left the single glazed unit open.