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EXPRESS FILMS EXPERT QUIZ #1 - OCTOBER 2011


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Howard,

I will submit a definition for SHGC not to enter in the quiz but for you and everyone else to reference when I respond to your post.

Solar Heat Gain Coefficient (SHGC)

is the fraction of incident solar radiation that actually passes through that window, including solar energy that is both directly transmitted and that which is absorbed and subsequently released inwardly by re-radiation and conduction.

An easy way to explain SHGC is in terms of a ratio; where 1 is the maximum amount of solar heat gain that can come through a window and 0 is the least amount. An SHGC of 0.40 then means that 40% of the available solar heat is coming through the window. The lower a window's solar heat gain coefficient, the less solar heat it transmits.

There are two types of SHGC measurements:

Center of glass SHGC = This is common to our industry as most "spec cards" and performance data sheet list the "Center of Glass SHGC" for window film on 3mm clear single pane glass without calculating in the whole window system (frame and all).

Whole Window SHGC = This would be the SHGC of the entire window including the frame. The NFRC reports SHGC as a whole window measurement and not center of glass. This is important, because SHGC ratings also include the ability of a window to absorb the heat form the sun and transmit it (conduct it) through the entire window and into the room. Therefore the type of window, as well as the glass, can affect the SHGC rating.

Common SHGC Equations

1 - TSER = SHGC

SHGC = .86*SC

Some Additional SHGC Information

SHGC is also known as the "G Value" which is the coefficient commonly used in Europe. G-values just like SHGC values ranges from 0 to 1, a lower value representing less solar gain.

SHGC is one of three fenestration energy measurements used in Building Information Modeling (BIM). Can you name the other two? Of specific note is the fact that Shading Coefficient (SC) is not used nor is it reported in NFRC performance data. SC is a ratio used to rate the relative effectiveness of a glazing system compared to a "standard window." The glazing industry has moved away from use of the term since a "standard window" is no longer a single pane clear window with double strength glass.

Bonus Question for Your Quiz

Explain what a T-value is and its relevance to fenestration and window film?

I'll respond to your post when I get some spare time, take care. :beer

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Hi Vq,

Not only did you make a superb and educational post on SHGC, you are now the leading contender for the free pack of Olfas.

1-TSER = SHGC

SHGC = .86*SC

These were two of the mathematical relationships I was referring to in the quiz.

Who knows the remainder???

Vq - since we know you have one or two packs of Olfas on hand YOU ARE DISQUALIFIED FROM THIS QUIZ!

-Howard

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Howard,

I understand that you are a long time regular on this board with an investment here so when a new guy like myself raises questions you will reply with a very thorough answer. TG was right. I am familiar with what you speak of and while I appreciate you efforts to educate the community here, I also take it as a direct reply to me that needs a response for a number of reasons namely some strong pointed language at products that I represent.

Since there is so much content in your post, I am going to break it up a bit.

Hi Vq,

As usual, you ask excellent questions. People have come to expect square answers from me, so here you go. Your question is one that I had anticipated.

I respect that as I enjoy spirited discussion of facts but when people converse in print online it is very difficult to understand their intentions so my response is going to be based on what I perceive in your post.

First, let me once again state my position on IR. I do not use it to market myself, I do not think it is necessary, and I would like to see it disappear from all window film marketing. But the reality is this. As long as IR is maketed in Asia, as long as we use BTU meters in sales demonstrations, as long as we use IR heatlamps to drive those meters, as long as films filter the NIR portion of the solar spectrum, and as long as the majority of window films remain without NFRC or similar performance validation, there will always be an IR discussion in marketing. You cannot escape it completley. If you are going to attempt to abolish IR marketing, then you have to get rid of more than just a column on a performance data card.

Your comments regarding MFG's that have withdrawn versus those that are "holdouts" kind of tells me that you have two specific brands in your cross-hairs here. I cannot speak for one but I will address the other since you have excluded your brand and a few others from IR marketing even though you all are currently reporting it. The reason I say so is you are either reporting IR and thus marketing it, or you are not. Allow me to illustrate:

You will note in my post that I mentioned the manufacturers that have removed the IR Data: Llumar, Vista, Panorama, Solar-Gard, Madico, Hanita. Several others (including EWF) are in various stages of withdrawing or "deemphasizing" it. By way of example, Sun-Tek only publishes IR data on 4 of the 25 films listed in their data tables. Another example is Johnson, who only publishes it on just 3 of 32.

Here you use the term "deemphasizing" which is puzzling to me because the word "de-emphasize" does not mean that you have ceased, but rather, it means that you are still carrying on. So logically, you cannot include yourself or anyone else that is in the state of "de-emphasizing" as a company that has ceased and desisted from IR marketing. Intentions are well and good but how many times have companies stated in the past that they would have NFRC certified products and to date nothing has happened? I applaud the intentions but the facts are what they are.

Unlike global brands, you as the owner of your company have the power to control the marketing of your private label. I will be one of the first to congratulate you when you revise your performance data in November. :beer

Something to keep in mind is I do not have control over what HOI in Singapore chooses to do internationally. They will base their marketing on the demands of the massive East Asian market where IR is king. This marketing bleeds over into the US because Huper Optik is a global brand. I'm not sure why you see Huper as being one of the larger violators of IR reporting when you yourself are still currently engaged in it? To the contrary, I see Huper in the US being marketed in a completely opposite fashion. We have NFRC certified films, we report SHGC numbers, we are involved heavily in energy modeling of our films. None of this involves IR, I will go on to explain why in a further post.

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Let me go one step further.

If you read the IWFA letter I referenced, it outlines the fact that IR is confusing/misleading and that SC/SHGC exists as a much more accurate & comprehensive measure of solar performance (their exact words). Let me provide more insight and detail into why this is so.

“IR Rejection” like all other “rejection” measurements are taken from the outside surface and measure the energy coming off the glazing and toward the meter. Unless the client told you that they want a film that will heat the air outside their building, rejection data by itself, while not entirely useless, is not where you want to focus. What matters is what is going on inside, not outside.

“Rejection” is made up of 2 components. The first is the energy that is directly reflected away. The second component is the energy that is absorbed by the glazing and re-radiated outward. Rejection tells you nothing about the energy which is absorbed by the glazing and reradiated inward. This is why SC/SHGC exists. It takes into account the energy that is directly transmitted PLUS the amount that is absorbed by the glazing and radiated inward. Because Ceramics absorb more than other films (at similar VLTs) this increased absorption also increases the amount that is reradiated inward (decreasing overall performance) . That’s why you need to focus on SC/SHGC.

You see the rather strong language (confusing and misleading) used in the IWFA’s memorandum on this subject. Do clients really care how much you are heating the air outside their building? Of course not. They care how much they are being “shaded” from the solar energy, which includes the energy absorbed by the glass and radiated inward. Only the SC/SHGC tells you that.

Howard

Please refer to the definition of SHGC I submitted.

I agree with your reasoning above. However, I get confused when the IWFA or anyone for that matter tries to reason on why we should not have an "IR rejection" measurement but then goes on to accept a "Total Solar Energy Rejection" (TSER) measurement when the whole issue of reporting "energy rejected" is not the accepted method in other professional industries. I see a double standard here... When doing energy models for buildings there is no input field for TSER even though they say it is the the opposite of SHGC. Even though TSER is a total performance measurement, it is window film industry term just like IR rejection. How do we look going into the engineering industry, the glass industry, and so forth throwing around these terms?

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EWF’s next published update is set to occur on or before 11/7/2011 and all (100%) of the IR data is being removed. In doing so, we will be neither the first nor probably the last to do so. Like the others, we felt it was necessary to include IR data, so we would not be summarily disqualified from bidding on some significant projects. At this point in time, however, the tables have turned dramatically. Thanks in large part to the IWFA and the AIMCAL Window Film Committee, knowledgeable installers, consumers and specification writers are finally dismissing IR Data (in the USA) on an increasing basis. 

The time has come and EWF can remove the IR data with less concern over disqualification. If and when it does come up, we can explain the omission by presenting the letter from the IWFA/AIMCAL Window Film Committee. You raise the issue of NFRC Guidelines. I call your attention to the fact that the NFRC does not now nor did they ever publish IR performance data. That should give you some idea as to their assessment of its usefulness.

Howard,

Granted, I have not been working in the window film industry as long as you have but I do have a lot of experience in window film bids, energy modeling (BIM), glass modeling, and the building envelope. My experience with IR numbers disqualifying other films from bids on significant projects only happens when 3M Prestige has been spec'd on a project. Other than that specific circumstance, I have never seen another scenario that would necessitate including IR performance data as you mentioned. 3M Prestige is what, 5 years old? So maybe in the last 5 out of 21 years I have on occasion had to address IR in significant projects. This was never really an issue back in the 90's even when Solis was being marked as an IR film.

The reality is that if you are doing an energy model on a building then the IR spec becomes irrelevant and easily dismissed. Any engineer knows his stuff will laugh you out of the building if you try to impress them with IR numbers. BIM software has no input field for IR so there has never been a need for me to market it. I'm not knocking what you said but I find it very unlikely that a significant project would disqualify your product for not listing IR.



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The problem for the “holdouts” is that when evaluated in terms of SC/SHGC the premium selling prices for these films are not justified. Applying the SC/SHGC metric (as suggested by the IWFA/AIMCAL Window Film Committee) and in light of the NFRC’s complete omission of IR Data, the perceived “performance edge” suggested by the IR Rejection leads people to spend more and get less.

Please refer to the SHGC definition once again and you will see that the measurement includes "solar energy that is both directly transmitted and that which is absorbed and subsequently released inwardly by re-radiation and conduction." What you see on the NFRC sticker is what you get even with a ceramic film. There is no room to inflate numbers, that is why the NFRC is a third party verification for the protection of the consumer.

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. When subjected to accelerated testing some films increase in VLT which means that the film is now allowing more enrgy to transmit through the glass. IR absorbing dyes found in some film technologies wear out in time and thus the total performance of the film decreases. So my response to your claim that "premium selling prices are not justified" is this; 'How can you justify performance degradation of cheaply made films that lose their filtering capabilities over time?'

And I'd would like to respond also that one of those "holdouts" that you refer too are partly responsible for maintaining and even improving window film market value and dealer's profit margin in our industry. There are still so many dealers that are selling flat glass films at 1990's pricing, pulling the market down. I see complaints about it all over these boards. Personally, I think the fact that a few companies made some moves in the opposite direction deserves a bit of respect from other suppliers. :twocents

Howard, I appreciate your points on the importance of total performance measurements versus regional measurements, and I couldn't agree more that SHGC, along with Tvis and U-factor are three of the most important measurements in modeling. Which brings up more questions...

I ask with all due respect here. You mention NFRC and IWFA quite a bit and I have a lot of appreciation for both organizations. That said, how does your company do energy models for significant projects? Can you accurately model your films on all of the different glass types available in the IGDB? Your films are not NFRC certified and I know why, it is pretty much out of your control. But more importantly, you do not have films in the International Glazing Database, so how can you accurately model them with the same checks and balances that guarantee accuracy?

My point to your comment about justification is simply. How can we begin to justify value if we cannot model a given window film on any given piece of glass to determine its projected affect on a building's performance? Not all buildings have 3mm clear single pane you know...

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Guest tinthoss

Very informative and educational post(s) vquest with points well made. I like you sticking to the facts and not just another smoke and mirror routine to hype your company. Keep up the good posts :thumb

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