EXPRESS FILMS EXPERT QUIZ #1 - OCTOBER 2011

[Guest VOLTRON]

I think you both have the same outlook for the most part when it comes to a large project and that there should be an energy audit and how to do that energy audit. I think Howard is mainly speaking of residential applications and installations where an energy audit is alot more difficult so a good alternative to showing performance with 2 different films is a BTU meter. It seems you both are in agreement of large scale applications and how to properly asses them but with residential applications there are too many variable to perform an accurate energy analysis so an alternative way of showing a customer would be with a BTU comparison. It may not be the most accurate but it is a pretty good test considering the options.

[EWF]

Not so, this re-radiated energy is a much longer wavelength

Agreed. The absorbed energy is re-radiated at longer wavelengths, however the percentage of it which is outside the measurable range of the meter is unknown (it is not 100% at 250nm.) EDTM should know that.

I was not going to open this can of worms with you because the Ceramics are higher absorbers than similar films at the same VLT range. Since a portion of the absorbed energy is re-radiated inward, the more you are absorbing, the more you are re-radiating inward which works against you if your objective is to cool the interior space.

-Howard

[vquestfilms.com]

Not so, this re-radiated energy is a much longer wavelength

Agreed. The absorbed energy is re-radiated at longer wavelengths, however the percentage of it which is outside the measurable range of the meter is unknown (it is not 100% at 250nm.) EDTM should know that.

I was not going to open this can of worms with you because the Ceramics are higher absorbers than similar films at the same VLT range. Since a portion of the absorbed energy is re-radiated inward, the more you are absorbing, the more you are re-radiating inward which works against you if your objective is to cool the interior space.

-Howard

Howard,

I know where you have been headed clear from the beginning of this discussion. Our ceramics are unique, they pose a threat to your sales so you are trying to make this and issue and in doing so you are attempting to re-adjust the definition of SHGC which in itself accounts for absorption and re-radiation of energy. Again, you are trying to measure temperature and comparing it directly to energy transmission. They are two totally different things a each affects a building differently, not equally.

It is not a can of worms, it is fact.

[EWF]

You cannot just ignore energy that exists in the further reaches of the solar spectrum. That would be contrary to yours and my whole belief that selective measurements are an inaccurate way to determine total performance. If it exists, then you have to account for it and there are methods that do account for the spectrum 300-2500nm. It all adds up and makes a difference.

I agree - it would be wrong to ignore it, but I consider to the degree by which it comprises the total volume.

250-2500nm = this complete the range

but within that range:

250-1300 = is where 90% of the "volume" exists

-Howard

[EWF]

I know where you have been headed clear from the beginning of this discussion. Our ceramics are unique, they pose a threat to your sales so you are trying to make this and issue and in doing so you are attempting to re-adjust the definition of SHGC which in itself accounts for absorption and re-radiation of energy. Again, you are trying to measure temperature and comparing it directly to energy transmission. They are two totally different things a each affects a building differently, not equally.

Vq,

I consider SHGC to be the single most important metric. The method for determining SHGC is well defined. I do not have my own interpretation of SHGC and even if I did, it would be worthless.

The hand-held meters (while not perfect) closely correlate with the results obtained thru your method, which I concede to be superior. I contend that a film which does better using a hand held, will in all likelihood also do better with your method. It is neither necessary or practical to do a full scale energy audit on 99.7% of window film applications. This is where my focus is. A dealer goes to a home or small office and demonstrates his/her products with the aid of a hand held meter. I contend that such a practice is, valid, useful, accurate and proper in all respects.

I don't think we lose many sales to Huper Optik. Clients who have their minds on products at that end of the market typically do not consider private labels. On the other hand, many of our dealers do presentations to customers that have obtained proposals from a Huper Dealer. With the aid of a hand-held unit, they are often able to convince the customer that an EWF film can do as good (or better) job at a better price.

-Howard

[vquestfilms.com]

You cannot just ignore energy that exists in the further reaches of the solar spectrum. That would be contrary to yours and my whole belief that selective measurements are an inaccurate way to determine total performance. If it exists, then you have to account for it and there are methods that do account for the spectrum 300-2500nm. It all adds up and makes a difference.

I agree - it would be wrong to ignore it, but I consider to the degree by which it comprises the total volume.

250-2500nm = this complete the range

but within that range:

250-1300 = is where 90% of the "volume" exists

-Howard

Technically...

250-280 is UVC that doesn't even make it through the atmosphere.

280-300 is the part of the UVB that gets filtered by atmosphere as well.

Accurately...

You either consider the rest up too 2500 or you ignore it. Films filter differing amounts of energy at different wavelengths through out the whole spectrum. You cannot accurately compare one to the next by ignoring the last 1200nm of the solar spectrum. It may be convenient but it is not accurate.

Case in point... if you measure up to the limit of your BTU meter which is only measuring up too 1100nm, you are going to get beat by films like Prestige just about every time even though your film may have a better SHGC. The IR absorbring multi-density films knock out a huge amount of IR between 900-1000nm. The rest of the spectrum counts no matter how much energy exists there, you cannot ignore it.

[vquestfilms.com]

I know where you have been headed clear from the beginning of this discussion. Our ceramics are unique, they pose a threat to your sales so you are trying to make this and issue and in doing so you are attempting to re-adjust the definition of SHGC which in itself accounts for absorption and re-radiation of energy. Again, you are trying to measure temperature and comparing it directly to energy transmission. They are two totally different things a each affects a building differently, not equally.

Vq,

I consider SHGC to be the single most important metric. The method for determining SHGC is well defined. I do not have my own interpretation of SHGC and even if I did, it would be worthless.

The hand-held meters (while not perfect) closely correlate with the results obtained thru your method, which I concede to be superior. I contend that a film which does better using a hand held, will in all likelihood also do better with your method. It is neither necessary or practical to do a full scale energy audit on 99.7% of window film applications. This is where my focus is. A dealer goes to a home or small office and demonstrates his/her products with the aid of a hand held meter. I contend that such a practice is, valid, useful, accurate and proper in all respects.

I don't think we lose many sales to Huper Optik. Clients who have their minds on products at that end of the market typically do not consider private labels. On the other hand, many of our dealers do presentations to customers that have obtained proposals from a Huper Dealer. With the aid of a hand-held unit, they are often able to convince the customer that an EWF film can do as good (or better) job at a better price.

-Howard

So then based on your comment you would agree that a NFRC reported .37 SHGC ceramic has the same energy solar energy transmittance as a more reflective film that is also .37 SHGC no matter what the difference in SA is between the two?

[EWF]

The rest of the spectrum counts no matter how much energy exists there, you cannot ignore it.

Herewith lies the crux of our disagreement.

Once you get above 1100-1200 there are large section of the spectrum (apx 1275-1400) and (apx 1800-1950) where spectral irradiance is ZERO due to water absorption bands. What difference does it make how well a film performs in that range if there is ZERO (yes ZERO) spectral irradiance in the first place?

From 2,000 - 2,500, spectral irradiance levels are so low that it's (for all practical purposes) inconsequential.

-Howard

[vquestfilms.com]

The rest of the spectrum counts no matter how much energy exists there, you cannot ignore it.

Herewith lies the crux of our disagreement.

Once you get above 1100-1200 there are large section of the spectrum (apx 1275-1400) and (apx 1800-1950) where spectral irradiance is ZERO due to water absorption bands. What difference does it make how well a film performs in that range if there is ZERO (yes ZERO) spectral irradiance in the first place?

From 2,000 - 2,500, spectral irradiance levels are so low that it's (for all practical purposes) inconsequential.

-Howard

Does the NFRC ignore the 1200-2500nm range?

[EWF]

So then based on your comment you would agree that a NFRC reported .37 SHGC ceramic has the same energy solar energy transmittance as a more reflective film that is also .37 SHGC no matter what the difference in SA is between the two?

No. The Ceramic would have an advantage which would be picked up by your method and would not be apparent if you relied upon a hand-held meter. That was an excellent example you provided. Thank you.

Still, due to the fact that a proportionately small volume of the energy is present at the spectral range where the Ceramic does better, the cost differential might lead the client to strongly consider the product which is very close in performance, but not nearly as expensive.

You used a narrow example but made good point. In most cases, clients are not choosing between 2 films with identical SHGCs. It is a more common scenario where a client is presented with a (very rough example) a Ceramic with an SHGC of say 0.59 and a perfectly compatible Nichrome with an SHGC of 0.50 at a fraction of the cost.

-Howard

edit= grammar