Wood Curtain Wall Systems

Before the appearance of this Unicel system, I've been part of projects that married glulams with the "veneer" curtain wall extrusions that can be used with steel or wood backup.  We've used these most recently on our Thaden School project (where the longer the span, the beefier the glulam, but when I was at P+W Canada 2005-2009 we used these at SFU Blusson and Saywell Hall and at UBC CIRS.  I believe that Payette has used this approach on a Penn State project and did nice thermal simulations.

https://www.kawneer.us/products/curtain-wall/custom-curtain-wall-system/

Hey Deb, We're using them on a project -- they're an absolute joy to work with! Came on as a design assist, breezed through shops, waiting for install. We got to visit their manufacturing plant up in Canada. For this project they're sourcing glulam from Nordic Structure. They're a common vendor for Unicel unless you're looking for a non-SPF wood.  They take a lot of care to refinish the glulam, bringing it to interior quality. I'd suspect that's where the LVL difference might play in. They can run the deflection calcs on anything though I'd expect they prefer the glulam they're used to.  For performance, that's a bit of a sales pitch. They (and several other companies) are sourcing a Raico, screw-on glazing pocket. They use all their hardware too and can integrate almost any vent window or door. This system thermally performs well -- where their claim is. And I'd expect the efficiency claim is compared to a thermally improved product (like a kawneer 1600). Unicel seemed to have the most experience with it and a long history of engineering which is why they were selected. 

I've looked at the system, but wasn't able to get it into the project due to cost constraints. I don't have the quantification for that but can add that we did look at embodied carbon and compared to a typical Kawneer thermally broken system, the Unicel wood-backed was a 40% GWP reduction, considering just the framing (no spandrel/glass/insulation) and focusing on A1-A3.

Chris, I'd be curious how you did that calculation. As far as I know, Raico doesn't have an EPD. They've sent me weights of different materials and we've approximated. 

We have used Sierra Pacific Timber Curtain Wall on a couple of projects (glulam). Sierra Pacific Windows - Timber Curtain Wall Styles - Residential, Commercial, Architectural Windows and Doors The middle project on the webpage (View max Plus) is the Price Science Commons library we design. I heard they have a new LVL product on the market but haven't seen it. Heather DeGrella AIA, LEED Fellow, Fitwel Ambassador, LFA | (she / her / hers) Associate Principal | Sustainable Design Director Registered architect in Oregon We're moving to the Central Eastside! Our Lovejoy location closes June 14. As of mid-July, Opsis Architecture will be located at the Custom Blocks - 975 SE Main Street, Portland, OR 97214. Learn more about our move here. [cid:opsis_rgb_blue_1c67de12-b325-4318-95e7-0704d8f48949.png] Architecture, Interiors & Planning 975 SE Main St., Portland, OR 97214 o 503.525.9511 d 503.943.6228 w opsisarch.com

Very good point. Uncel said something was in the works, and I needed to know the answer sooner to try to make a case for it. I treated aluminum and wood as commodities, and did 2-D take-offs of the system and used generic factors for both systems. So grain of salt, but I believe right ROM.....

Awhile back we were talking with Blackcomb Facade (out of BC) at a L+L and they were intrigued about the possibility of salvaged material for the timber back up, or even something fabricated from site-felled lumber should we encounter that situation and could quantify the engineering.
https://www.blackcomb.tech/ But they were open to it and the veneer type curtain wall systems have been around for awhile. Interesting to think about REALLY minimizing the new components to what is necessary. Hopefully can chase this further on a future project!

For wood selection, we defaulted to the spruce, pine, fir (SPF) mix since it'd match the mass timber structure. I'm sure they source from other companies besides Nordic, but that didn't seem like a premium and Nordic is FSC/Legal. The client particularly liked that they harvest their own forest. We briefly looked at oak but that was much more expensive.  Since they do their own finishing, I’m sure they can find a coating to tolerate any humidity issues. They use a Sansin product for clear coating – the same thing Nordic uses. There is an exterior version of this too. Before VE we had exterior wood mullion caps -- they do that out of Alaskan Yellow Cedar normally and that’d tolerate a high humidity interior. Not sure your specific concern with the humidity, but in our initial planning there was lab space adjacent to the timber curtainwall. Our client didn’t like potential of bio-based materials in a lab and Unicel helped develop a “splice” where we’d use steel HSS mullions instead of timber for those spaces. This would be an option if it’s not the whole building. Luckily, our project was reconfigured to avoid that.

We've done several projects with the Kawneer veneer over GLB framing like Z mentioned, where the GLB framing is designed as part of the architecture. If you look at the performance data from Kawneer, this gets a couple of points reduction in U-value from a comparable aluminum tube backed curtainwall. E.g. with the same glass and spacer, the Kawneer veneer with wood backing gets to U-0.31 vs U-0.33 with aluminum. Because it still has aluminum in the "wrong" place - i.e. the thermal barrier. The Unicel/Raico (or Blackcomb/Raico for those in the West) gets better performance than the Kawneer more because of the design and the thermal breaks as opposed to the use of the wood backing. The idea of "72% better" is a stretch, and definitely not all due to swapping out aluminum for wood (i.e. what is a "conventional aluminum curtainwall?") We are using Blackcomb/Raico on a few projects in construction right now. Results forthcoming. Other options for timber-backed curtainwall (varying span and structural capabilities for these systems) * Sierra Pacific (mentioned by Heather) * Solar Innovations * Unilux - we've used their products on about 3 projects and they are good but comes all from Germany (as opposed to just using German engineering) * Schuco (not sure available in US) * I also see that Loewen windows has a timber curtainwall Beware of the presence of NFRC certification on these systems. I think Blackcomb for a long time maintained they didn't need it, but I think I remember hearing they finally agreed to get it for this stuff. It's a code compliance barrier. The domestic systems and Unilux have NFRC certification as far as I know. Jim Jim Hanford, FAIA, LEED AP BD+C, Principal The Miller Hull Partnership, LLP