EXPRESS FILMS EXPERT QUIZ #1 - OCTOBER 2011

[vquestfilms.com]

Can it measure the full solar spectrum? No

It measures 93%+ of the energy at those wavelengths that penetrate the earths atmosphere and reach the earth's surface. There is radiation above 1300nm but it is a small factor and much of it is blocked by atmospheric moisture.

No, you are missing a couple of important factors.

1. You are still not measuring the entire solar spectrum up too 2500nm. By measuring 300-1100nm you are only covering about 50% no matter what the intensity is.
   
2. And of that 50% that you are measuring, the crystalline silicone cell in your meter can only measure up too about .09 W/m2/nm which leaves the rest of the energy >.09 to 1.4 W/m2/nm as unmeasurable. So you are missing a good chunk of energy in the 400-750nm range.
   

Your method is selective and limited... still not very accurate.

[EWF]

Hey TT

Nothing like a lively tech thread. It's probably a cure for insomnia for most readers.

-Howard

[vquestfilms.com]

Can it measure the full solar spectrum? No

Can it determine the SHGC of the window with film applied? No

Can you use the BTU reading and convert it into SHGC? No

Can you take that BTU reading and use it in LBNL software to do an energy analysis? No

Can you use this meter to determine whether you qualify for EPAct or PUC rebates? No

BTW: A non contact thermometer can also be used to compare Film-A to Film-B by measuring the temperature change of a nearby substrate behind two different films.

-Howard

It is not going to help you figure out your kWh/hr savings.

Temperature and energy are two different things. Remember, you start this discussion talking about the importance of SHGC and SC over IR. Those two important measurement deal with energy and not heat.

[vquestfilms.com]

Are we absolutely certain that LBNL is considering 250-2500nm anyway?? I am not sure we have even established that. The reason I ask is that I have searched around with laboratory equipment manufacturers and nobody had a model that went anywhere near that high anyway. LBNL does not make their own gear. They buy it on the lab supply market and as far as I can tell, there are no units (I could find) that go that high.

Does anyone have the email address for a contact person over there? I would be glad to correspond directly with them and find out. Please email me his/her email address.

If LNBL stops at 1300, that would put an entirely different spin on this discussion. I really would like to find out.

Thanks,

Howard

Yes we are absolutely certain. LBNL has software that does a point by point energy transmission measurement of the entire solar spectrum. It is really cool!

[EWF]

You are still not measuring the entire solar spectrum up too 2500nm.

Vq,

Are you 100% sure LBNL goes that high? I for one do not know and am seeking a definitive answer. I did check with several of the largest lab equipment manufacturers and none of their units went that high.

If you have the email address for a contact person there, I will inquire and let you know what I learn.

-Howard

[vquestfilms.com]

You are still not measuring the entire solar spectrum up too 2500nm.

Vq,

Are you 100% sure LBNL goes that high? I for one do not know and am seeking a definitive answer. I did check with several of the largest lab equipment manufacturers and none of their units went that high.

If you have the email address for a contact person there, I will inquire and let you know what I learn.

-Howard

I will fire up the software and confirm. -BRB

[EWF]

Your method is selective and limited... still not very accurate.

Vq,

Not so - because any inherent inaccuracies in the meter would apply equally to all the films you were testing, providing no particular advantage to any one film.

This is what I mean:

You want to purchase the fastest car on the market

You choose ignore the speedometers in the cars and use a radar gun instead.

Your radar gun is out of calibration. It is off by 4mph. A car going 100mph meters at 104mph. (The meter reads 4 mph too high).

You take consecutive readings:

Car A is actually going 80 mph, but meters 84 mph

Car B is actually going 90 mph, but meters 94 mph

Your radar gun is off, but you can still conclude (with accuracy) that Car B is 10mph faster than Car A. Even with an imprecise measuring tool, accurate comparative conclusions can be drawn.

I hope I did a good job of explaining this concept.

I acknowledge the meter is of limited use if you are doing a full scale energy audit and simulation. But it's use as a Film vs. Film evaluation tool is both reasonable and accurate based upon the radar gun example I have set forth.

-Howard

[EWF]

The crystalline silicone cell in your meter can only measure up too about .09 W/m2/nm which leaves the rest of the energy >.09 to 1.4 W/m2/nm as unmeasurable. So you are missing a good chunk of energy in the 400-750nm range.500nm.

If such a known vulnerability existed, how difficult would it be for EDTM to adjust the meter's firmware to account for this? Probably not hard at all. When I spoke with them, they explained that they checked their hand held's performance against larger bench top units and that they were very, very close (considering the price differential).

I guess I am going to have to call them again.

-Howard

[EWF]

Vq,

Thanks for checking into that. I am rather impressed that you actually have that software at your fingertips.

I am not able to post anything further today. I will catch you tomorrow.

I enjoyed our debate. I learned much from it thanks to you and I look forward to meeting you at SEMA.

-Howrad

[vquestfilms.com]

The crystalline silicone cell in your meter can only measure up too about .09 W/m2/nm which leaves the rest of the energy >.09 to 1.4 W/m2/nm as unmeasurable. So you are missing a good chunk of energy in the 400-750nm range.500nm.

If such a known vulnerability existed, how difficult would it be for EDTM to adjust the meter's firmware to account for this? Probably not hard at all. When I spoke with them, they explained that they checked their hand held's performance against larger bench top units and that they were very, very close (considering the price differential).

I guess I am going to have to call them again.

-Howard

They will tell you that the cell has its limits. EDTM can get more sensitive cells but then the price of the unit will go up considerably.