Green Building Bible, Fourth Edition |
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These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment. PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book. |
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Posted By: fostertomLike poythene then - not rocket science. Like polythene, all depends on the joint-taping.
Posted By: Ed DaviesWith small cells, can we ignore convection completely (though, perhaps, include conduction through the air or other gas)?Yep
Posted By: Ed DaviesDon't need to worry about the speed of lightMy little joke!
Posted By: Ed Davies1) In the steady state, what proportion of the heat flow is due to conduction in the walls and what to radiation across the voids?Good
Posted By: Ed Davies2) If there's a heat pulse, how much are these proportions skewed by the delay to conduction as a result of heating up the walls?Not exactly. Not the proportion, more like what is the absolute total of the radiant component that is transmitted and received, during the time it takes before the conductive component(s) even reach the other side - and is that absolute total enough to have reduced the temp differential to zero, or almost to zero, all by itself without contribution from the conductive waste-of-time.
Posted By: djhIs the labelling of the photo correct? It's just that 2 & 4 look like foil to me, rather than 1 & 4. I presume 'Very this foil' is very thin foil?
Posted By: BeauThere is a line of stitching every 650mm across the rollIs that '650' correct? Not how I remember it - I seem to have thrown my samples of such things away. Anyway, it's 650 or whatever c/cs in both directions isn't it - a square grid?
Posted By: fostertomPosted By: BeauThere is a line of stitching every 650mm across the rollIs that '650' correct? Not how I remember it - I seem to have thrown my samples of such things away. Anyway, it's 650 or whatever c/cs in both directions isn't it - a square grid?
Posted By: Beau2 Very thin foil
Posted By: fostertomOK stitching is just one direction - it really stitching @ 650c/cs, or 65c/cs or what?
Could you somehow clamp a small square of it, which you mouth would fully cover, with line of stitching across middle of it? Then when you suck, with your mouth covering all the holes on the face you can see, the air can only have come right through from the other face of the composite, not come in sideways.
All in the interest of Science!
Posted By: Ed DaviesFWIW (ie, not much), if it's actually stitching rows and columns on 65 mm centres then I make the area equivalent to a hole 42 mm in diameter:
>>> from math import pi, sqrt
>>> r = 0.75e-3/2
>>> holeArea = pi * r**2
>>> holeArea
4.4178646691106465e-07
>>> colsPerMetre = 1000/65
>>> rowsColsPerSqMetre = colsPerMetre * 2
>>> holeCount = 100 * rowsColsPerSqMetre
>>> totalArea = holeArea * holeCount
>>> equivRadius = sqrt(totalArea/pi)
>>> equivRadius * 2
0.041602514716892185
Still be interesting to know how this stuff sucks.
Posted By: fostertomLess 2 x threads = 0.004mm2at least I did, just so some bugger wouldn't say Aha, but ....
Posted By: mike7Blimey, Ed! And to seventeen significant figures too!Well, yeah, could've added an extra line to round the result which nobody else (except maybe Steamy) would have understood so thought it better to leave it out and round it myself.
Posted By: bot de pailletheir product certificate claims 100 percent air barrierOf course - nothing special - like polythene - all depends on the jointing/detailing/tape, installation care and durability of same - that's where it falls down.
Posted By: bot de pailleI dont see how the thread is going to only take up one tenth of the hole area, I would calculate that the thread wil probably block at least 60 percent of the potential air leak.Nah
Posted By: bot de pailleI dont see how the thread is going to only take up one tenth of the hole area, I would calculate that the thread wil probably block at least 60 percent of the potential air leak.
Posted By: BeauOK now for the suck test.
Not sure weather I have just done this just for your amusement or a genuine scientific experiment but I can say it is NOT airtight but taping the edges made big difference to speed of my possible suffocation. Interestingly I could not noticeably blow through it.
Posted By: SteamyTeaPosted By: BeauOK now for the suck test.
Not sure weather I have just done this just for your amusement or a genuine scientific experiment but I can say it is NOT airtight but taping the edges made big difference to speed of my possible suffocation. Interestingly I could not noticeably blow through it.
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