On-Angle Performance Measurements -My Angle

Well I guess it’s about time for me to address the whole “on-angle” Total Solar Energy Rejection measurement. As many of you are aware it is a measurement that is currently marketed by 3M to show the performance of their Prestige Window Film line. The whole premise is that the window film industry has always tested and derived the Total Solar Energy specification at 90° perpendicular to the glass. 3M reasons that the sun does not reside at 90° throughout the day, especially at the hottest part of the day, thus the need to create a film that in their mind performs better “on-angle.” So the need for an “on-angle” measurement arises and subsequently the specification finds its way into their marketing literature.

Despite the fact that the window film industry has never promoted such a measurement and the NFRC does not post angular performance data on the product certification labels, the general public is left to assume that this is a common measurement that sets one product apart from all others. The assumption gets propagated further when window film dealers add inaccurate statements and insert fiction into what is fact. For instance one dealer writes a rebuttal on their website in response to the statement:

3M’s total solar energy on angle spec is not supported by the National Fenestration Rating Counsel

Dealer’s Response: This is true but this is new technology. No other manufacturer (glass or window film) can rate their product this way. The two hundred layers in the new 3M Prestige window films with nano technology make this new on angle specification possible. All window film manufacturers measure the total solar energy rejected at a 90 degree angle to the glass.

Let us separate fact from fiction here…

Fact: The NFRC does not support the Total Solar Energy Rejection On-Angle specification. All manufactures measure the total solar energy rejected at a 90 degree angle to the glass.

Fiction: The statement that this is new technology and that no other manufacturer (glass or window film) can rate their product this way. Also the statement that it is 3M’s multi-layer nano-technology that make this new angular specification possible.

The reality is that any manufacture can easily report their performance ratings this way, if they wanted too. This specification is not made possible by the unique construction of Prestige Window Film’s multi-layer technology nor is the on-angle measurement a new measurement. Lawrence Berkley Laboratories has had software available for many years that gives angular performance data of window coatings and window films on almost any glass type available. This software and the measurements that result from it are recognized by the Department of Energy (DOE). 3M did not invent this measurement and neither did any other window film manufacturer for that matter. So let’s use this LBNL software and run our own test comparing “on-angle” performance data of a few films. This particular test was run on clear single pane glass .120 inch in thickness with some 70% vlt films that have their specifications listed.

Sun’s Angle

SHGC @ 0°

SHGC @ 30°

SHGC @ 60°

SHGC @ 80°

SHGC @ 90°

Prestige 70

0.503

0.499

0.427

0.188

0.00

Vista VS 70

0.476

0.471

0.404

0.178

0.00

V-Kool 70

0.440

0.435

0.373

0.164

0.00

What I’m seeing here is that there is on-angle data available for all 3 brands not just Prestige. The SHGC or Solar Heat Gain Coefficient is the opposite of the Total Solar Energy Rejection measurement. The lower the number, the better the overall performance. So ignore the fact that Prestige 70 gets outperformed on every measurement by the other two films, but rather, focus on the pattern. As the sun’s angle increases, the performance of each film increases as well. So much so that when the sun is directly above the window all of these films perform extremely well; they reject all of the sun’s energy! By the way… clear glass has a 0.00 SHGC at 90° too. Why? Obviously as the sun orientates to a higher angle above the window less energy transmits through the glass.

So this whole idea of a company’s technology making a new measurement possible or window film being designed to be unsurpassed by any other window films in on-angle performance is unfounded and inaccurate. Let’s give the consumer some dignity as well as some accurate and relevant data that will not fool them into believing that one product is something that it is not. Window Film Manufacturers can do this by adopting standardized performance measurements and using well respected third party agencies like the NFRC to verify these measurements. Window Film Dealers can and should educate themselves so that they do not propagate inaccurate and false information to the consumer for if they continue to do so, it will only serve discredit a product that is so badly needed in a time where energy conservation is vital.

-vc

Advertisements

2 Responses to “On-Angle Performance Measurements -My Angle”


  1. 1 Mike Feldman July 27, 2008 at 7:15 am

    Thanks for setting the angles “straight.”

    Credibility is critical in this window film industry. When a well known brand of film and their representatives mislead (either intentionally or through ignorance) competitors and consumers collectively suffer the consequences.

    As a former 3M employee (33 years) and former National Sales Manager of 3M Window Film, my perspective is aligned with your analysis, 100%!

    The market will ultimately dictate success or failure, winners versus losers. Facts (we hope) should always over fiction.

    Mike Feldman

  2. 2 TG July 28, 2008 at 8:44 am

    Very good write up V…very impressed and very informative.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s





%d bloggers like this: