Advantages of DG Windows

Glass isn't that good a conductor of heat. Take a 6" by 1/4" bar of glass and put the end in a gas flame you'll be able hold it by the other end more or less for ever. Now try it with a metal bar of same dimensions...

Glass 1 W/mK, Copper 400 W/mK, Ali 250W/mK, Brass 100 W/mk, Iron 80 W/mK (approx).

Reply to
Dave Liquorice
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No. it cant be several hundred watts per square meter in the summer.

The sun doesn't produce that much . At high summer in clear air in a desert, its about 15W/sq meter.

without a lens or curved mirror, you cant increase that.

However on black painted metal, it is enough to fry and egg, for sure.

The answer in the UK is to fit blinds, of course or draw the curtains.

Reply to
The Natural Philosopher

which is why SG windows in wood frames are not as bad as the ecowarriors like to think.

Reply to
The Natural Philosopher

Seems wrong, how much skin area does an average person have? 1 to 2 m^2 would 30W make you feel so hot on a summer day?

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"Average over the entire earth is 164 Watts per square meter over a 24 hour day"

"8 hour summer day, 40 degree latitude 600 Watts per square meter"

Reply to
Andy Burns

Hmm. I see you are more or less right. I wonder where the other figure came from.

Reply to
The Natural Philosopher

checking UK figures, its about a bit less than that..other sources suggest 400W peak on a summer day in UK.

Just when its not needed of course ;-)

Reply to
The Natural Philosopher

15W/sq meter wouldn't compensate for the losses in the pipe work of a solar thermal system and as they *do* work it can't be a correct figure.

AIUI a bright sunny summer day in the UK should be around 750W/m^2. How ever this is overall received radiation not just that direct from the sun so the effective collector area is much larger. Does this account for the discrepancy?

Reply to
Dave Liquorice

That discrepancy is mainly down to a couple of things - the UK isn't at a latitude of 40 deg and the crap weather.

Reply to
Mike

Pity there is no follow up to this project as solar gain was a major contributor to the heat requirements.

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Reply to
Mike

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