m Ransley wrote:

Again, YOU made the claims. It's your job to prove them.
And again, where were you when they handed out Logic :-)

Proving "No skylight is good enough to gain heat on an average December day
in Chicago" would seem to require that you have a list of every skylight on
earth, including those yet unbuilt :-)

I've already shown how to build a net heat gainer with multiple layers.

Nick

"I've already shown how to build a net heat gainer with multiple
layers.
Nick "

I don't know what planet you;re living on, but here on earth people in
this newsgroup buy skylights, we don't build them based on hypothetical
ramblings.

... here on earth people in this newsgroup buy skylights, we don't build them
based on hypothetical ramblings.

Some do, some don't, based on 300-year-old high-school physics, eg Newton.

Do you have a list with the physical characteristics of every
commercially-available skylight on earth to prove your claim? :-)

If so, post it.

Nick

Nicks "Net gainer" , every day is a sunny one.

Nicks famous ideas, " Keep basement floor wet for humidity" " Remove
steam radiator air vents for added humidity"

Nicks theory, caulk will solve all lack of humidity issues.

Nicks hero, the hubble telescope engineers, "But the numbers were
right, we just forgot a few equations."

There ya go nicko ol boy misquote me,
Can you prove your " net gain" theory, no you cant, go take your
alzheimers pill, the pink one, or is it the blue one you must ask
yourself.

m Ransley errs again:

Nicks "Net gainer" , every day is a sunny one.

Nope. Average days.

Nick

Dec 28, 3:57 pm show options
Do you have a list with the physical characteristics of every
commercially-available skylight on earth to prove your claim? :-)

Now that's special. We're supposed to track down every skylight spec
to prove the mythical one your rambling about doesn't exist? That's
like me claiming a 3 headed bird species exists and then demanding
anyone challenging the claim inventory every bird in the world to
refute it. Is that how they think at Villanova?

BTW, the only claim I made was that it appears that skylights lose
about 2X more energy than similar vertical windows. I provided a link
to an independent site that appears credible to back up that claim.
And I said that some of that delta is likely made up in winter by
additional heat from the sun. However, the situation quickly reverses
in the summer, last time I checked, so the sun is more likely an
overall negative.

wrote:
... here on earth people in this newsgroup buy skylights, we don't build them
based on hypothetical ramblings.

Some do, some don't, based on 300-year-old high-school physics, eg Newton.

Do you have a list with the physical characteristics of every
commercially-available skylight on earth to prove your claim? :-)

If so, post it.

Nick

Nick

Interesting observation. I feel better about my south facing windows
now.. (here in PA in the winter)

If you add in wind chill factor and radiation cooling losses and the
fact that most skylights or windows are not aligned directly to the
sun, they may end up being a net loss but not a hugh loss.

Nick, you appear to be the ultimate engineer and these other buys are
more practical. Both points of view have value.

Mark

wrote:

Do you have a list with the physical characteristics of every
commercially-available skylight on earth to prove your claim? :-)

m's claim...

...We're supposed to track down every skylight spec to prove the mythical one
your rambling about doesn't exist?

That's what m would need to do to prove his claim :-) As an alternative,
he might disprove it with a little 300-year old high-school physics.

BTW, the only claim I made was that it appears that skylights lose
about 2X more energy than similar vertical windows. I provided a link
to an independent site that appears credible to back up that claim.

Yes indeedy.

And I said that some of that delta is likely made up in winter by
additional heat from the sun.

Try numbers, if you like.

However, the situation quickly reverses in the summer, last time I checked,
so the sun is more likely an overall negative.

As I've described over and over, unwanted summer gain is easily to avoid
with an overhang which also enhances winter gain.

Nick

Mark wrote:

I feel better about my south facing windows now.. (here in PA in the winter)

They can more house heat on an isolated sunspace that gets cold at night.

If you add in wind chill factor and radiation cooling losses and the
fact that most skylights or windows are not aligned directly to the
sun, they may end up being a net loss but not a hugh loss.

Where I live near Phila, 1000 Btu/ft^2 of sun falls on a south wall on a 30 F
average January day, so a square foot of R2 window with 80% solar transmission
will gain 800 Btu and lose 24h(65-30)1ft^2/R2 = 420. On a sunspace, it might
only lose 6h(65-30)1ft^2/R2 = 105.

Nick

Cut the bull **** nick, the missquotes and all, You say Net Gain. And
now you recommend an overhang on peoples roofs to shade summer sun, one
ugly house that would be. You are a hack, I would love to see your work,
but there is none to see.

m Ransley wrote:

now you recommend an overhang on peoples roofs to shade summer sun...

Yup... 2000-year-old physics :-)

Nick

m Ransley wrote:

now you recommend an overhang on peoples roofs to shade summer sun...

Yup... 2000-year-old physics :-)

Well, maybe 2500 years old...

Nick

http://www.californiasolarcenter.org...y_passive.html

During the fifth century BC., the Greeks faced severe fuel shortages.
Fortunately, an alternative source of energy was available - the sun.
Archaeological evidence shows that a standard house plan evolved during the
fifth century so that every house, whether rural or urban, could make
maximum use of the sun's warm rays during winter. Those living in ancient
Greece confirm what archaeologists have found. Aristotle noted, builders
made sure to shelter the north side of the house to keep out the cold winter
winds. And Socrates, who lived in a solar-heated house, observed, "In houses
that look toward the south, the sun penetrates the portico in winter" which
keeps the house heated in winter. The great playwright Aeschylus went so far
as to assert that only primitives and barbarians "lacked knowledge of houses
turned to face the winter sun, dwelling beneath the ground like swarming
ants in sunless caves."

Cross section of a Roman heliocaminus. The term means "sun furnace." The
Romans used the term to describe their south-facing rooms. They became much
hotter in winter than similarly oriented Greek homes because the Romans
covered their window spaces with mica or glass while the Greeks did not.
Clear materials like mica or glass act as solar heat traps: they readily
admit sunlight into a room but hold in the heat that accumulates inside. So
the temperature inside a glazed window would rise well above what was
possible in a Greek solar oriented home, making the heliocaminus truly a
"sun furnace" when compared to its Greek counterpart.

Fuel consumption in ancient Rome was even more profligate than in Classical
Greece. In architecture, the Romans remedied the problem in the same fashion
as did the Greeks. Vitruvius, the preeminent Roman architectural writer of
the 1st century BC., advised builders in the Italian peninsula, "Buildings
should be thoroughly shut in rather than exposed toward the north, and the
main portion should face the warmer south side." Varro, a contemporary of
Vitruvius, verified that most houses of at least the Roman upper class
followed Vitruvius' advice, stating, "What men of our day aim at is to have
their winter rooms face the falling sun [southwest]." The Romans improved on
Greek solar architecture by covering south-facing windows with clear
materials such as mica or glass...

Settlers in New England considered the climate when they built their homes.
They often chose "saltbox" houses that faced toward the winter sun and away
from the cold winds of winter. These structures had two south-facing
windowed stories in front where most of the rooms were placed and only one
story at the rear of the building. The long roof sloped steeply down from
the high front to the lower back side, providing protection from the winter
winds. Many saltbox houses had a lattice overhang protruding from the south
facade above the doors and windows. Deciduous vines growing over the
overhang afford shade in summer but dropped their leaves in winter, allowing
sunlight to pass through and penetrate the house...

George Fred Keck, a Chicago architect... began designing homes in the
Chicago area according solar building principles - expansive south facing
glass to trap the winter sun, long overhangs to shade the house in summer,
minimal east-west exposure to prevent overheating in summer and fall, and
the placement of secondary rooms, garages, and storage corridors on the
north side to help insulate the living quarters from the cold north winds.
Keck had a knack for publicity and called the houses he designed "solar
homes." By the mid-forties Keck's work caught the attention of the national
media. House Beautiful, Reader's Digest and Ladies Home Journal featured his
work. Fuel rationing during the war inclined the American public toward
valuing the energy saving features of solar homes. When war ended, the
building market exploded. With the wartime-conservation ethic still imbued
in most people's minds, many manufacturers in the prefabricated home
industry adopted solar design features for leverage in this highly
competitive market.

Overhangs on roofs added for skylights, an ugly thought.

NeedleNose,

Here is an interesting article you would want to read about the leak:

http://www.askthebuilder.com/559_Sky...ht_Leaks.shtml

Regarding your statement about " I can
tell you they are NOT good or even fair insulators at that age.
Perhaps the inert gas escapes in the first 10 years.",

let me ask you this.....have you done any type of assessment regarding
the skylight's insulation (or lack thereof)? As in, temperature
calculations / infra-red imaging (photograph)?

TIA.


NeedleNose wrote:
I also have 10-15 year old velux skylights, motorized venting type.
They are absolutely freezing and one also is begining to leak. I can
tell you they are NOT good or even fair insulators at that age.
Perhaps the inert gas escapes in the first 10 years.
One inexpensive option is to go to Kmart, buy very heavy drape fabric,
and attach it (you can use tape on the upper end) to the inner screen.
This will provide at least some buffer between the room and the cold
skylight.
Another more attractive option is to buy cellular shades, cheaper over
the web, and install them against the glass, or preferably, just below
the glass. They offer / promise 6 R-value or so.
Another option I have not explored is whether the exterior glass hood
on those skylights can be replaced without changing out the portion
installed on the roof. By doing this you might be able to renew the
insulation value of the glass, which I am sure is lost by now.

But, one thing is clear- Velux is not that great of a skylight. My
wood is rotting from all the condensation, and the thermal value is
clearly lost, and I have a leak. With a similar leak on my Andersen
skylight, the rep gladly replaced the light under warranty, despite the
fact that it was 15 years old, and I was not the original buyer. Wow-
talk about standing behind a product. The issue was the seal of the
glass- "we had trouble with the seal on that skylight" he said. Wonder
if I have the same problemwith my Velux.








wrote:
z wrote:

wrote:
m Ransley wrote:

If it could automaticly close with a foam insulating plug when shaded
it could be a net gain.

That's better, but any skylight is a net gain if more solar energy enters
during a day than heat energy leaves during a day, which can happen with
several layers of glazing. For instance, 3 layers of R1 glazing with 90%
solar transmission would gain 0.9x0.9x0.9x460 = 335 Btu/ft^2 and lose
24h(65-26.7)1ft^2/R3 = 306, for a net gain of 29 Btu/ft^2 on an average
December day in Chicago.

By contrast, insulation just loses heat. An R100 ceiling would just lose
24h(65-26.7)1ft^2/R100 = 9 Btu/ft^2.

Would you rather gain 29 or lose 9 Btu of heat per day in December?

Daylight is also nice...

Might I point out that they call it a "greenhouse effect", after the
greenhouses, where glass panes contribute to the retention of solar
heat making the interior warmer than the exterior.

Sure. Glass is a high pass filter, passing high frequency solar energy with
wavelengths shorter than 3 microns and blocking low frequency heat energy,
eg 10 micron heat from an 80 F black body.

Provided of course they face south.

That's better, with 740 vs 460 Btu/day of sun on an average December day
in Chicago. The calc above was for a horizontal surface. A south window can
provide more light than a skylight, esp if it's near a reflective ceiling
with a lightshelf below the window.

Which in summer will make them heat up the interior more than you want.

South walls get less sun than horizontal surfaces in summertime, and
shading them from higher summer sun is easy with overhangs.

Nick

Here is an excerpt from an article:

"Skylights can provide significant passive heating during cold weather.
This advantage is offset by conductive heat loss at night. In all but
the coldest climates, there is a net heat gain if the skylights are
located so that they collect the maximum amount of sunlight. On the
other hand, skylights that face away from the sun may suffer a net heat
loss even in relatively mild climates."

In the burbs of Chicago, there is hardly any sun in the winter months.
It is beyond me to think that skylights will result in a net gain in
such a situation. Besides, NONE of my skylights face south.

Golly! I never thought my original post would set so many brains
ticking.
All have been excellent posts and thanks to each and everyone who
replied.

This is what I pose to you all now:
Equations or not, logic or not, denial or not, common sense or not -
wouldn't it be easier to find out about heat loss or gain through
skylights by doing an infrared image / taking an infra-red picture?

Thoughts?

TIA

The lines I quoted from an article above are from this link:

http://oikos.com/library/eem/skylights/savings.html

wrote:

This is what I pose to you all now:
Equations or not, logic or not, denial or not, common sense or not -
wouldn't it be easier to find out about heat loss or gain through
skylights by doing an infrared image / taking an infra-red picture?

Thoughts?

Thermometers are cheaper. If you want to be fancy, use a recording one.


--
dadiOH
____________________________

dadiOH's dandies v3.06...
....a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

This is what I pose to you all now:
Equations or not, logic or not, denial or not, common sense or not -
wouldn't it be easier to find out about heat loss or gain through
skylights by doing an infrared image / taking an infra-red picture?

Thoughts?


If you actually care, then the sensible thing to do would be to
equip the damn skylights with insulated covers that you close
at night, or which close themselves.

All Nick is saying is that a south facing window with an R factor of 2
or more, gains more BTU during thef day from the sun then it looses
at night , i.e. there is a net heat gain over 24 hours.

Seems hard to beleive at first but when you look at the numbers it
appears to be true.

I pointed out that he did not include radiation losses and wind chill,
but I think these factors are small and do not change the overall
result that much.

If you disagree with the conclusion, please find the flaw in the
analysis.

Mark

Can you please tell me what type of a thermometer I would use? Is there
one specifically for this purpose?

TIA

dadiOH wrote:
wrote:

This is what I pose to you all now:
Equations or not, logic or not, denial or not, common sense or not -
wouldn't it be easier to find out about heat loss or gain through
skylights by doing an infrared image / taking an infra-red picture?

Thoughts?

Thermometers are cheaper. If you want to be fancy, use a recording one.


--
dadiOH
____________________________

dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

"Mark" wrote in message
oups.com...


All Nick is saying is that a south facing window with an R factor of 2
or more, gains more BTU during thef day from the sun then it looses
at night , i.e. there is a net heat gain over 24 hours.

Seems hard to beleive at first but when you look at the numbers it
appears to be true.

I pointed out that he did not include radiation losses and wind chill,
but I think these factors are small and do not change the overall
result that much.

If you disagree with the conclusion, please find the flaw in the
analysis.

Mark


Did you figure in your envelope?
Think you might find your T value to be higher.