• Uncategorized 23.02.2011

    If you haven’t participated in a local chapter of the Construction Specifications Institute (CSI), you might want to consider it. I went to Seattle’s chapter meeting last week and was impressed with the marketing opportunities and the attendees’ efforts to learn the ins/outs of all sorts of products. Participants were obviously architectural spec writers, general contractors preparing estimates and other manufacturers. Although the speakers were local to Seattle, they provided some interesting takeaways that may be applicable to other code re-writes going on elsewhere.

    Among the presenters was a testing company representative talking about getting products rated in the CMA/NFRC process and a Seattle code official speaking about energy changes in the code related to cladding. A beef I’ve expressed previously about the NFRC process is that there’s no way (presently) to include insulation or opaque spandrels, either for granite or metal panels, within a site-built installation (which the CMA is meant to cover). According to both the code official and the testing lab representative, these are considered the same as other opaque construction (i.e. masonry), and are NOT considered fenestration. Even if they’re on the same unitized panel, it’s not fenestration, and therefore does not require NFRC certification. NFRC may eventually include the ability to add them in the wall rating, but the code official’s statement, “if you can’t see through it, it’s not fenestration,” gives us in the curtainwall world a way around spandrel construction and how to get the NFRC rating (or not). The see-through area only needs the rating.

    Seattle is requiring a pre-bid NFRC certification of the cladding when submitting plans for permitting, which must state that the windows specified meet the energy performance requirements of the code. The U-values are being lowered (better energy performance) to about 0.3 to 0.38 (don’t quote me on this) – about a 25% improvement over current code.  (Editorial note: I have no idea if other jurisdictions are following suit or have other/different requirements to show the fenestration complies with code.)

    Seattle will accept simulations of new construction based on past certifications in lieu of the NFRC bid doc. They will accept a simulation of actual/planned construction to base the sizing of the mechanical systems, but only if the cladding design incorporates a certified product. The benefit:  the mechanical system size can be lowered based on the real world, not some artificial number based on an 80” x 80” test window. The downside: the simulation cannot be used to show code compliance of the glazing itself. That must be shown per the NFRC bid document based on the standard window size used to certify the product within the NFRC protocol.

    If a product isn’t certified, there are code-allowable U-values for fenestration that are nearly twice those of the NFRC certified products. If the fenestration is better than that, obviously that’s ok, but the tradeoff is the HVAC systems have to be sized to meet the higher U-values by code, which in effect wastes a bunch of the owner’s money. If the simulation of a curtainwall is say, at 0.31 U-value, but the code requires using 0.48 U-value to size the mechanical system, the mechanical system is going to be oversized. And so the architects are NOT going to be crazy about specifying anything but NFRC window and curtainwall certified products.

    This is where the manufacturers in the room – both on the framing and glazing side of the house – took issue, as the NFRC database is not fully complete with manufacturers’ spacer and framing product details. The consensus in the room among the manufacturers (and I’ve heard this same thing from others) was that it might take another 3-5 years before the NFRC database is complete enough to allow the desired certification.

    If I understand this correctly, when an architect wants to specify X company’s frame, Y company’s spacer and Z company’s glass, and any one of those products is NOT in the NFRC database, they have to find a replacement. And that combination is what gets specified. If your company’s product isn’t in the database, you may have problems qualifying for the job, let alone winning the job through the bid process.  Furthermore, if during the bid the products change, the architect and GC are going to have to make sure the new selection meets/exceeds the permitted performance. Otherwise, certificates of occupancy may be withheld, since the cladding does not comply with the permit. Not a situation any of us would like to find ourselves in at or near the completion of a project.

    There’s also a requirement for whole building air infiltration that doesn’t include the windows. You know that air test that requires the curtainwall or windows to show air infiltration at 0.06cfm per a 6.24 psf pressure differential? They’re going to apply that to all the masonry, stud, stucco and all the other opaque construction. I want to be there when the stucco guys realize what this means to them. The testing guys are trying to figure out how to even conduct these tests. For the window and cladding, it may mean seeing more mockups with surrounding construction, especially to test the non-curtainwall/window wall construction, as well as the joints between them. And watch what happens when the curtainwalls or windows pass (the plastic over the fenestration) and test the non-fenestration areas! Won’t THAT be fun? Some of the medicine that glazing has been taking now applied to the other trades. ’Bout time.

    The testing agency guy said computer simulation software that models the thermal performance (U-value, SHGC, VT, etc.) of walls is getting much better, and is showing about 98% accuracy as compared to thermal testing. But if there’s a difference of the U-Value of 0.01 in the two, he considers that a failure. For reference, that’s an equivalent to an R-1 difference. You wouldn’t think that would be significant, but I guess over the life of a building, it could be. Just in case this thought might have occurred to you: the thermal testing done at full scale performance mockups is meant to show air/water penetration performance after testing cycles, not compliance with NFRC 100 testing.

    Triple glazing is coming. The testing guy has seen windows with U-values that are 1/3 of City of Seattle requirements. The triple-paned construction consists of low-E coatings on at least two surfaces. One example was a wall with a U-value of 0.10 with low-E on the #2and #6 surfaces.  That’s certainly an intriguing possibility.

    Low-E coatings on the interior surface of the glass make it less likely to experience condensation since the glass temperature isn’t lowered to a point where condensation forms on it. Are you ready for triple glazing?

    As to the unitized wall/seismic discussion, there wasn’t a whole lot there that was new, for me at least. What was surprising was the reaction of the architects in the room who hadn’t detailed or dealt with this type of glazing before. Concepts that I thought were second nature were brand spanking new to some of them, which they didn’t realize were even possible. For example:  unitized walls that don’t fall to pieces during typical rack testing, or glass that doesn’t break when the inter-story jacking of the mockup chamber steel moves the units. I guess it’s one of those things that unless you have seen it firsthand, you have a hard time grasping it.

    In summary:  the light at the end of the tunnel might not be an oncoming train as it relates to the NFRC certification. But it might take 3-4 years before “all aboard” can be heard. Except the train has already left the station in some areas, such as California, Washington and Nevada, where codes require it.

    What wasn’t addressed is who pays for the ticket: are the owners out there willing to pay for this? And how much is it going to add to the next biggest cost: time constraints to get materials tested, especially custom curtainwalls? The world of designing new/different/cheap aluminum extrusions for that one-off custom look may not be able to withstand the testing time constraint as compared to a “standard” system that’s already in the can at NFRC. So the tradeoff may be it won’t take as much fuel to run the train, requiring less energy for our buildings. Who was it said to hang on, we may be in for quite a bumpy ride? That may be applicable, too.

    Posted by Blogger @ 9:45 am

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