Sorry for the length of this message, but it is an issue that I have some concern about.
I have done a fair amount of digging around on this question. I have some concerns, but they are not the big brother type of concerns expressed above. Since my firm specifies huge numbers of residential window products, I have grown quite accustomed to the use of NFRC to specify thermal performance, and favor its use. Yes, NFRC was funded by the DOE - big deal. (Jus cause it the guv-mint, dun mean it bad.) The program has made purchasing energy efficient windows better for millions of Americans. The market for residential windows in the US is about 65 million units per year, (dwarfing the commercial window market) so you can see its benefit.
For those who are not familiar with how it works, the Solar Heat Gain Coefficient and the U-factor can be simulated using software developed by the Lawrence Berkeley Labs in California. Boiled down to its essence, the software has a library of components, glass, frames, spacers etc. that are entered into the simulation software to determine the SHGC and U-factor. Software allows a frame shape to be simulated for heat flow. The results are validated by a physical test, but the process is set up so that every possible configuration of components does not have to be physically tested by a manufacturer. This saves money, obviously, because the simulation is quick and simple to run. The software is free, and anyone can download and use it.
The second piece is probably more controversial, and that is certification. The program is set up for manufacturers to put temporary and permanent labels on products which certify their performance. This permits code authorities to easily verify that the product meets the energy code for the jurisdiction. In fact, some codes do specifically require NFRC certification (California among them). Others only call for certification, but as a practical matter, only NFRC is set up to do this. The certifications are done by third party laboratories licensed by NFRC to do the tests and simulations.
Now we go on the commercial side. NFRC is proposing that a version this standard be adopted for the commercial side. I support this entirely, at least in some form. My concern is the truly bizarre (from a designers perspective, at least) part of this: a proposal, not yet adopted, that would make the designer of record responsible for certifying the product! How a designer could do this not knowing exactly which manufacturer will be used, what spacer the manufacturer will use, etc., etc. is goofy at best. There is no way that the designer can be in the position of making these determinations or decisions. The designer doesnt get paid for this either.
Some of the possibly legitimate concerns of manufacturers, I think, is that there are far more variables in the commercial world than residential, and having to pre-certify many products could be expensive. (Remembering, however, that running the simulation on a variation of a product, say, changing the spacer, would NOT be very expensive.) I am not convinced this is such a big expense for a manufacturer, but that is a topic for legitimate disagreement.
I think that the designers obligation, as it currently exists, should be to determine the required thermal performance of the windows and confirm with manufacturers under consideration that they can meet it. These manufacturers can run the simulation software in-house to test various assumptions. Many will do this for you already. I do not think labeling is much of on issue in the commercial world of controlled construction. My view is that a certification as part of the submittal process should be sufficient. After all, the code officials rely on the designer for much more during construction of commercial products, and this could be one (Remembering that nothing equivalent exists in the world of residential construction.)
I had a few conversations with NFRC staff about this issue, and shockingly I was told there were no architects involved in the development of this now standard. Bipin Shah of the NFRC came to a meeting of the Boston Society of Architects Building Enclosure Council (which I missed) to explain these efforts. Apparently, he never finished his presentation because of the controversy around making designers responsible for certifying the performance of products. The good result is that the NFRC will be getting someone from the DC BEC to attend their meetings. I have not heard of any follow up.
If you care about this, call the NFRC at 301-589-1776 and ask for more information. Jim Benney (ext 202) is the executive director, and Bipin Shah (ext. 205) is program manager developing this new standard.