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EXPRESS FILMS EXPERT QUIZ #1 - OCTOBER 2011


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Back to the Quiz....

LE = VLT divided by SC

LE of 1:00 or higher is considered "Spectrally Selective"

Hello Big Owl !!!!

You got it !!!!! That was the last one !!!!!

I will do a recap later !!!

-Howard

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Any engineer knows his stuff will laugh you out of the building if you try to impress them with IR numbers.

Hi Vq,

This statement tells me that we are fundamentally (99%+) in agreement.

Your posts are chock full of "pearls of wisdom" and I will address them when I can.

-Howard

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as long as we use BTU meters in sales demonstrations, as long as we use IR heatlamps to drive those meters,

Vq,

This is the only part of your post which I do not understand. The BTU meters measure a wide spectral range (250-1350nm apx) which includes UV, Visible and NIR. How does the use of a BTU meter either support or discourage IR data reporting? Note: The IR lamps emit visible light as well.

I am an advocate of using these meters.

-Howard

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As far as justification of pricing goes, one of the most overlooked factors in ROI is the product's ability or even inability to maintain its performance. Most inexpensive window films contain dyes or pigments that lighten up over time and exposure.

Hi Vq,I

I totally agree and we know this to be factually correct from all the QUV testing that EWF does. It is perhaps the best reason why automotive films are not ideal for flat glass applications when energy savings is a primary objective.

That being said, there are less expensive alternatives to Ultra-HIgh-Priced products that would also not suffer from longitudinal performance degradation. One example would be a stable sputtered alloy (like NiChrome) or even a simple vapor deposited aluminum film (like Silver). We have seen those endure 6,000+ hours of QUV testing with no appreciable loss in solar control properties.

This aspect should be factored into any film-vs-film decision. Many people conclude that the slight decrease in performance over time is acceptable and preferable to a high end product with a 400% (up front) higher price tag.

-Howard

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What you see on the NFRC sticker is what you get

Hi Vq,

Not exactly. I refer you to the disclaimers commonly found in data tables:

Bekaert makes no representation or warranty, expressed or implied, including the implied warranties of merchantability or fitness for a particular purpose, that its products will conform to these test data. Bekaert shall not be responsible for variations in quality, composition, appearance, performance, or other feature. . . . ..

Hanita: Performance results are calculated on 3mm glass using NFRC methodology and LBNL Window 5.2 software, and are subject to variations in process conditions within industry standards and are only intended for estimating purposes.

3M (My favorite one) The information provided in this report is believed to be reliable; however, due to the wide variety of intervening factors, 3M does not warrant that the results will necessarily be obtained.

Huper Optik (On their data cards) This data is subject to variations within industry standards.

By the way, has anyone ever seen published guidelines on how much your published data can deviate from your "typical production runs"? Absent proof to the contrary, I say it does not exist.

There is a much better way to go about it.

-Howard

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how can you accurately model them with the same checks and balances that guarantee accuracy?

So glad you asked. We do it the old fashioned way. As the saying goes, the proof of the pudding is in the eating.

We don't expect anyone to take our word for it, nor that of our competitors or even a 3rd party independent organization. We encourage our dealers to mount our films right next to competing films on the customers actual window and then take BTU readings during peak times of the day.

The hand held BTU meters have been accepted for use in the glazing industry for decades. For anyone that believes that they are either not suited or accurate enough for our industryl, I would encourage you to call EDTM at (419)861-1030. I have spoken with them on several occasions and have had all my technical questions answered to my satisfaction.

I concede that the test equipment used by LBNL/NFRC is slightly (yes slightly) more accurate than a hand held meter, but the window film companies themselves do not guarantee that you will get that performance (hence the disclaimers). I say it's much better to take a reading on the customer's actual glass with the actual roll of film you intend to install.

Simpler is so often better. It reminds me of a story:

Many years ago NASA began doing joint space flights with the Russians, in preparation for our working together on the International Space Station. As you might imagine, astronauts do quite a bit of writing in space (logs, notes, journal entries, record keeping). The engineers at NASA developed special pens which would work in a zero gravity environment. After thousands of pages of specifications were written and millions of dollars were spent, zero gravity, leak proof, non toxic, space pens were invented. When we met up with the Russians in space, we showed them our fancy/expensive writing implements and asked them what they were using. Their response was "we use pencils".

The point of my story being - simpler is often better. Just put all the films on the window and point a BTU meter at them. The film that has the lowest BTU reading is blocking the most heat.

-Howard

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as long as we use BTU meters in sales demonstrations, as long as we use IR heatlamps to drive those meters,

Vq,

This is the only part of your post which I do not understand. The BTU meters measure a wide spectral range (250-1350nm apx) which includes UV, Visible and NIR. How does the use of a BTU meter either support or discourage IR data reporting? Note: The IR lamps emit visible light as well.

I am an advocate of using these meters.

-Howard

Howard,

No, sir.

Please show me a hand held "BTU Meter" that measures from 250-1350nm, I have never seen one that can do that. A beam splitter can measure wide spectral ranges but most affordable ones only go up too 1100nm and as you know, this is not the whole solar spectrum nor is it the whole NIR spectrum.

The most common hand held BTU Meters measure from 900-1100nm. It's all IR right there.

IR lamps do not emit much visible light energy. They radiate over 90% of their energy in IR. As you already know, IR is one of three regions that contributes to total solar energy. So IR lamps are a poor representation of what comes naturally through a window.

My point was and still is, IR will always need to be explained even in heat demonstrations. It is still smoke and mirrors... very similar to IR rejection numbers :twocents

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how can you accurately model them with the same checks and balances that guarantee accuracy?

So glad you asked. We do it the old fashioned way. As the saying goes, the proof of the pudding is in the eating.

We don't expect anyone to take our word for it, nor that of our competitors or even a 3rd party independent organization. We encourage our dealers to mount our films right next to competing films on the customers actual window and then take BTU readings during peak times of the day.

The hand held BTU meters have been accepted for use in the glazing industry for decades. For anyone that believes that they are either not suited or accurate enough for our industryl, I would encourage you to call EDTM at (419)861-1030. I have spoken with them on several occasions and have had all my technical questions answered to my satisfaction.

I concede that the test equipment used by LBNL/NFRC is slightly (yes slightly) more accurate than a hand held meter, but the window film companies themselves do not guarantee that you will get that performance (hence the disclaimers). I say it's much better to take a reading on the customer's actual glass with the actual roll of film you intend to install.

Simpler is so often better. It reminds me of a story:

Many years ago NASA began doing joint space flights with the Russians, in preparation for our working together on the International Space Station. As you might imagine, astronauts do quite a bit of writing in space (logs, notes, journal entries, record keeping). The engineers at NASA developed special pens which would work in a zero gravity environment. After thousands of pages of specifications were written and millions of dollars were spent, zero gravity, leak proof, non toxic, space pens were invented. When we met up with the Russians in space, we showed them our fancy/expensive writing implements and asked them what they were using. Their response was "we use pencils".

The point of my story being - simpler is often better. Just put all the films on the window and point a BTU meter at them. The film that has the lowest BTU reading is blocking the most heat.

-Howard

Howard,

Ok, here is where you are miles apart from the energy community.

The old fashioned way as you put it, using had samples and BTU meters will not get you EPAct credits. The DOE says that you need an approved software simulator such as certain LBNL simulators. You will not get EPAct, PUC rebates, or anything requiring validation with a BTU meter.

I understand your methodology, it works great in a home and I highly recommend installing samples and "feeling the difference." However, business persons, engineers, architects, and the like prefer validation and you cannot provide it with a BTU meter.

I concede that the test equipment used by LBNL/NFRC is slightly (yes slightly) more accurate than a hand held meter, but the window film companies themselves do not guarantee that you will get that performance (hence the disclaimers). I say it's much better to take a reading on the customer's actual glass with the actual roll of film you intend to install.

Howard,

You say LBNL/NFRC procedures are slightly more accurate? Can you show me a link or something? I know some of the scientists over at LBL I would put their software up against a meter any day, and the NFRC feels the same way. It is part of the process for certification.

BIM is not about issuing a guarantee, that would be foolish. It is the most accurate way to project performance and estimated savings. Many respected organizations rely on these tools. If a customer wants assurance that the claims in a model, film spec, HVAC spec, lighting spec, etc are valid, then it would necessitate coming back after a project and doing a retrocomission of the building which is also quite common.

We need to use more than a pencil in this industry, that is what has held us back for decades. :twocents

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