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Rabert

I'm planning on creating a city for around tenthousand people. The GVCS will most likely be a crucial part of realizing that project. However, I'm missing a central part of construction in the GVCS: sheet glass for windows. I not only need that for the initial construction, but also to be able to replace the inevitably broken windows on a daily rate. Did I just miss that, has that been overlooked, or was it decided that this is not important enough for a Global Village Construction Set?

Matt_Maier

There's tons of stuff left out of the GVCS. For example, it doesn't have a way to make rubber. Also, for some reason, as it was originally conceived it has an oven but not a grain mill. Meh, it's been discussed before. Here's a page I made listing out some suggestions for major changes
http://opensourceecology.org/wiki/GVCS_Changes

I suggest that you hold of on making any plans that depend on the complete GVCS, let alone a fully functional evolution of the GVCS. If you absolutely have to start working before it's done, then think of it as a bunch of tools that are cheaper than their commercial equivalents. You'll still be buying most of your stuff from the existing global market, but there will be a few things you can do better with parts of the GVCS.

Rabert

Thank you Matt, I understand. I'm following a pragmatic path and just try to build a village with the GVCS. It is easy to identify what part of construction work is not supported by the GVCS so far. I'm wondering, on what grounds it was decided to not include for instance windows to the set. Probably the GVCS is not meant to actually assist the complete construction of a village, but only parts thereof?

I can live with some things not provided by GVCS-tools. I need to buy them or find other ways myself to make them. It looks like the GVCS does have a maturity curve which is only in its beginnings right now. But at least, it's a start! :-)

kriswood

I was curious so I looked up how windows are made. I don't see how this could possibly be done without a modern industrial infrastructure. Every single component except the machinery and the recycled materials would have to come from outside the community.

http://en.m.wikipedia.org/wiki/Float_glass

It might be easier and perhaps counterintuitively more sustainable to make plastics from plant based materials.

Ackhuman

PLA can be made transparent, though it probably won't look as good and won't be as strong as polycarbonate or CR-39.

Danial

Here is a fairly low tech glass making operation. In the video they are making opalescent glass, although it could make clear glass just as easily. The downsides are that it is not as strong as plate glass and the process is not as automated as a float glass facility.

Video

Rabert

I have seen this video earlier, it's very impressive. There is mentioned, that glass was invented and made 4,000 years ago already. So in principle, there must be some very low tech methods to make glass, even more low tech then shown in that video. But I'm not out for low tech, I'm out for efficiency with easily handable tech. I think what is shown in the video could be a viable method to make glass replacements. However, it would be probably more efficient to buy ready-made windows for the initial construction of a city or a village, where several thousand windows could be needed.

On the other hand, maybe a 20th century glass making machine could be bought on the used market, or based on such somewhat older technology, the GVCS could be in fact extended and include glass-making in future.

Danial

Glass is a fundamental building block of modern civilization and should be included in the GVCS at some point. Maybe somewhere along the line the float glass manufacturing process could become reduced in scale to produce glass for a small city or town.

Looking at modern window making, especially in thermal pane windows the glass is only the first step, I wonder how complicated it is to make double or triple glazed argon filled windows?

Matt_Maier

http://en.wikipedia.org/wiki/Float_glass

If you're not too concerned with perfection you could use the old process of blowing a giant glass cylinder and then cutting it and flattening it into a sheet of glass. There are a lot of people who still do blown glass, so some of them should know how to do this or should be willing to learn. It wouldn't require much infrastructure.

4ndy

Ackhuman: plain PLA is very transparent, but while having good optical properties, its thermal properties would be worth discussing. Its glass transition temperature is around 55-65C and its melting temperature is between 150-170C depending upon chain length, so during a major fire emergency in a building you can count on PLA windows being very tough to break, and once fire gets anywhere near them they would turn into a hot, sticky, flammable puddle while allowing fresh air to flood in through a hole that they were just covering.
Whether such problems can be obviated by installing fire-fighting structures, such as sprinkler systems, and using strictly low-flammability materials in fittings would need to be considered for a given building spec.

If someone can discover a safely biodegradable thermoplastic with much higher Tg and Tm than PLA, humanity would be sorted for renewable materials, but for now PLA and PCL are limited to things like consumer electronics and push-bike accessories, since their low heat resistance is too risky for many structural applications (you can't even hold a hot drink in a PLA cup).

Edit: I see it hasn't even been mentioned yet, but uPVC is easily moulded into window panes, and although no renewable method of producing it exists as far as I know, it can be recycled.

Rabert

With peak-oil already visible on the horizon, we should not invest in any technology which depends on the availability of cheap mineral oil.

FrankTree

How about glass bottle windows ? They have

a long tradition in germany. also windshields from cars or airplanes are usually not recycled.

Rabert

Actually, living in Germany for all my life, I have never seen a house with glass bottle windows.

I think the easiest solution would be the blowing of glass cylinders and flatten them out into planes. We need to look back to how windows were made in the first half of this century and what machinery they used, maybe we can replicate such technology. We may need to get back to using putty. If we could produce windows with insulation glass and argon without sophisticated machinery, I don't know, and I'm doubtful. I'll ask an uncle of mine, who was a carpenter and worked in a window factory for some years, what he thinks.

For me, window making as such is not that much the problem, if we accept sub-standard technology, but producing plane glass for the windows in large amounts is.

The recycling of glass used in cars, trains, planes, ships, etc is a good idea, but might be problematic in transporting it and conversing it into something what can actually be used in buildings, especially when you have to obey some building codes.

FrankTree

ha i guess you havent been much in southern germany then, we have those quite often on old buildings.

at least theres tons of scrap windows to get for free in germany.

Rabert

That's right, I'm a Northerner. Lived a few years in Bavaria and Baden, though, and never have seen those. But probably simply because I didn't look for that. Overall, that's a good idea, and much better than no glass at all.

Interestingly, recycling and scrap glass is a major part in glass making. There is no glass factory or blowery right now which does not use scrap glass as a major ingredient for its glass recipes.

Using recycled building parts for building new houses is something to look into for sure. Not only windows or doors, but also bricks, pipes, cables, tiles or whatever. Just a few days ago a large building was collapsed in my neighbourhood, and everything was just dumped.

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