On Thu, 24 Jul 2014 22:44:47 -0400, rickman wrote:

... It's the power
consumption in watts that's important, not the surface temperature.
(...)

That makes no sense. The window doesn't heat the room because the glass
is at 100°F, it heats the room because it allows radiant heat in.
Comparing the temperature is totally invalid and not useful in any way.

Agreed. I suspect you may have misread what I scribbled. See my
quote above.

True, if you assume uncoated glass. With a Low-E coating, much of the
IR is reflected. I can grind the numbers for how much later if you
want.

I would love to see some numbers.

Sure, but give me a few daze. I'm giving a Linux on Chromebook talk
tomorrow and am totally unprepared (as unusual). I'm also trying to
take next week off so that I can claim that I've actually had a
vacation this year.

I found this old meter in my mess:
http://802.11junk.com/jeffl/crud/IES%20Solar%20Heat%20Meter.jpg
It has a solar cell on the back, with a 1/2" diameter aperture mask.
It's a "Solar Heat" guess meter, measuring BTU/hr-sqft (F), which can
be converted to something more sane like (5.68) watts/meter^2 (C).
There's no far-IR bandpass filter, so I don't think this is going to
be very useful. It's probably made for solar water heaters. Rather
than play with the calcs, I'll take some measurements today. Bug me
if I forget.

Also, this paper might be of some interest:
"Study of titanium nitride for low-e coating application."
http://802.11junk.com/jeffl/crud/Low-E-titanium-nitide-glass.pdf
I use it as a cheat sheet for how low-E glass works.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558