5 Responses to “Does Chicago Code Require Low-E Glass?”

1. 

   Marc Lafrance November 4th, 2009 at 8:44 am

   To whom it may concern,

   Very poor quality answer. Not to explain the benefit of low e glass
   for both SHGC and U values is not providing appropriate information.

   Warm Regards
   Marc LaFrance
   US DOE Window R&D Manager

2. 

   Mark Meshulam November 5th, 2009 at 9:01 am

   Hi Marc,
   Would you like to contribute the additional ideas.
   Your contribution would be very welcome.
   Best regards,

   Mark Meshulam
   Executive VP
   Builders Architectural

3. 

   Marc Lafrance November 7th, 2009 at 9:00 am

   We have a low e success story fact sheet that you can reference. I was
   just shocked that an article about low e in Chicago did not address U
   value improvement.

   Here is the fact sheet:
   U.S. Department of Energy Low-E Success Story

   Marc

4. 

   Julie Ruth April 7th, 2010 at 7:18 pm

   When the members of AAMA and I developed the table that was eventually approved and adopted as Table 502.3 of the 2006 IECC, which the 2009 Chicago Energy Conservation Code is based upon, our intent was to require low-e coating on all fenestration WHEN prescriptive based design was used. We basically said “Let’s figure out what the U-factor would be if you took the glass package needed to achieve the residential value (0.35 – which is basically double pane low-e with inert gas fill) and put in into different framing systems.

   Charlie Curcija, who has been a tremendous resource for our industry, did the modeling work for us. The result was that U-values of 0.45 could be achieved with some thermally broken curtainwall systems, while placing that same package in a operable commercial window framing system resulted in 0.55, and entrance doors, which are sometimes required to have a 10 or 12 inch high bottom plate due to ADA, would only go to 0.80.

   Other parties felt low-e should always be required for residential – hence the 0.40 performance cap on residential fenestration when performance based design is used.

   There is no such cap for commercial fenestration when performance based design is used. Theoretically uncoated glazing could be used in commercial buildings under the Chicago Energy Conservation Code if performance based design is used, but if that is done, the increased heat loss and gain would have to be made up in some other aspect of the building design.

   I hope I have not put you to sleep with this explanation.

   Julie Ruth, P.E.
   JRuth Code Consulting

5. 

   Mark Meshulam April 8th, 2010 at 8:25 am

   Hi Julie,

   Thanks for that explanation. It is good to dialog with someone actually involved in the creation of codes.

   I don’t see a disagreement between your comments and those of Randy and Patrick in this article. Did I miss something?

   It appears that the numbers your team has derived are in synch with current industry capabilities. What about the future? Are there plans to tighten the requirements along the lines of what the Federal Government is targeting: .30U and .30 SHGC?

   Further, it seems that air infiltration, despite being a major contributor to heat loss, is the poor ignored cousin in all of these conversations. When is the code-producing industry going to take this on?

   And finally, I am wide awake when discussing this subject. It’s the readers that concern me. Wake up guys, We’re done now!

   Thanks again,
   Mark