It seems a little naf to go to the effort of making a passive solar house and not double glaze the windows. However, earth bag building is an inexact art and double glazed windows of custom sizing are prohibitively expensive. A conundrum.
It's always seemed to me that the challenge of double glazing was in the frame - the rest is just two sheets of normal glass, surely? We could debate the merits of low-E coatings and argon filled cavities for days I'm sure, but the basics is two sheets of glass held a little way apart and sealed well. Glass is easy to get hold of in almost whatever size we want (again, we love the tip shop dearly - people throw away the most amazing things), so then it's just a matter of spacing the glass, sealing it in, and ensuring any moisture trapped in the gap is dealt with.
I found several sites describing various methods of DIY double glazing, from the very simple to the more in-depth. Also, a great how-to.
Optimal distances for double glazing for thermal insulation purposes is somewhere in the region of 10-20mm (sound insulation appears to be different again, opinions vary and I haven't yet delved into actual research articles on the matter). The gap needs to be small enough to prevent convection currents from forming in whatever gas exists in the middle. Any number of spacers from bits of wood to strips of plastic seem to be used for achieving this depending on the frame. I particularly liked this suggestion about how to deal with moisture in the gap - sprinkle a little silica gel in between the glass, and let it absorb the moisture over time. None of this high-tech desiccant stuff!
So two layers of glass is do-able. Do we want the windows to open and close, or be fixed? The answer to this is obvious in a more conventional house where one needs the ventilation. Our house, however, will likely have ventilation tubes running underground to cool the air before it gets to the house itself (the ongoing debate about ventilation tubes vs. wind scoop is ongoing and will be posted later). Whilst opening windows are pretty there is a whole lot of extra stuff to do with them - more technical to construct, need fly screens, all that sort of thing. It is very tempting to have a screen door that can be left open at need, ventilate via underground tubes, and do away with opening and closing windows all together.
I foresee considerable research going into this decision.
It's always seemed to me that the challenge of double glazing was in the frame - the rest is just two sheets of normal glass, surely? We could debate the merits of low-E coatings and argon filled cavities for days I'm sure, but the basics is two sheets of glass held a little way apart and sealed well. Glass is easy to get hold of in almost whatever size we want (again, we love the tip shop dearly - people throw away the most amazing things), so then it's just a matter of spacing the glass, sealing it in, and ensuring any moisture trapped in the gap is dealt with.
I found several sites describing various methods of DIY double glazing, from the very simple to the more in-depth. Also, a great how-to.
Optimal distances for double glazing for thermal insulation purposes is somewhere in the region of 10-20mm (sound insulation appears to be different again, opinions vary and I haven't yet delved into actual research articles on the matter). The gap needs to be small enough to prevent convection currents from forming in whatever gas exists in the middle. Any number of spacers from bits of wood to strips of plastic seem to be used for achieving this depending on the frame. I particularly liked this suggestion about how to deal with moisture in the gap - sprinkle a little silica gel in between the glass, and let it absorb the moisture over time. None of this high-tech desiccant stuff!
So two layers of glass is do-able. Do we want the windows to open and close, or be fixed? The answer to this is obvious in a more conventional house where one needs the ventilation. Our house, however, will likely have ventilation tubes running underground to cool the air before it gets to the house itself (the ongoing debate about ventilation tubes vs. wind scoop is ongoing and will be posted later). Whilst opening windows are pretty there is a whole lot of extra stuff to do with them - more technical to construct, need fly screens, all that sort of thing. It is very tempting to have a screen door that can be left open at need, ventilate via underground tubes, and do away with opening and closing windows all together.
I foresee considerable research going into this decision.
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