in pursuit of energy efficient minimalism
The 2013 NW Green Home Tour is this weekend from 11 am to 5 pm. Tours are open and don’t cost a thing, so come out and support your local green gurus!
Last year’s tour had some great offerings including an efficient HufHaus featuring CLT panels.
I will be at the Dwell project all day with some PH goodies and lots of info, so feel free to bring your questions! It’ll be a glorious n’ gloomy, cold day – perfect for observing the awesomeness that is Passivhaus!
More details about le Tour here (alas, it’s not really bike-able – but I know you can see a lot of ‘em that way, Jesse). There are also google maps showing locations, which can be accessed from the ecoguild. Eventually, it would be great if these events were turned into an app – with archival info/fotos/contacts stored. That way, when people are walking by in future years, they would be able to learn about the green projects around them…
This week, I got an email from a colleague asking about insulated concrete, and assumed he was asking about AAC – autoclaved aerated concrete. Now AAC is a pretty interesting product, which was apparently invented by a Swedish architect (vinna!!). We’ve looked at AAC to thermally break a stemwall – and something like 50% of construction in Germany consists of AAC – so there are more than a few passivhaeuser incorporating it. Finehomebuilding covered Hebel block (a form of AAC) a few years ago, and the use has slowly risen Stateside as production has increased. AAC block’s thermal performance is something like a 17-fold increase over CMU, but it comes at a premium. However there are tradeoffs – labor can be less since with AAC blocks as they weigh significantly less, and it gets you closer to meeting energy code (CMU ain’t even close).
cohort: ‘Know anything about insulating concrete products?’
me: ‘Doy, I know what AAC is. No, I’ve never used it but we’re always looking for guinea pigs, er I mean clients.’
cohort: ‘NO! not that, I know about AAC. I’m looking for concrete or block that has an insulating aggregate…’
me: ‘You don’t mean to cast concrete w/ perlite in it, do you? LECA, maybe?’
me: ‘Do you know who Patrick Gartmann is?’
For those in the know, Patrick Gartmann is one of the principles of engineering wunderbuero Conzett Bronzini Gartmann. I’ll wait while you google their work, and the phenomenal bridges of Joerg Conzett. If you don’t know, CBG have engineered some of the most incredible buildings in Switzerland. Cream of the crop is an understatement, it is really engineering elevated to fine art.
Back in 2003, Gartmann designed and built his own house as a demonstration project. This is a stunning monolith of beton and that’s it – oh wait, wood (flooring, doors and window frames) and glass. He was able to do this by two means – one, Swiss craftsman generally produce amazing concrete work; and two, expanded clay and expanded glass from Liapor. The expanded clay (blaehton) replaces gravel, and the expanded glass (blaehglas) replaces sand. This results in an architectural feat of Mies’ bienahe nichts‘ that even Mies couldn’t achieve. It seems to induce an almost monastic asceticism – I find incredible peace just LOOKING at this project, I’d imagine even more so living in it. C’est Magnifique!
The magic sauce of Gartmann’s house isn’t really magic at all. It’s clay. Specifically, clay that is fired in a rotary kiln and expands significantly – in much the same way cork insulation expands when heated. This results in a lightweight concrete that has improved thermal resistance, acoustical properties, etc. Universally, it’s better known as LECA (lightweight expanded clay aggregate) and can be added as an aggregate to CIP concrete or block. LECA block is found all over Europe as well, including one of our favorite little infill projects in Sweden, Elding Oscarson’s Landskrona townhouse.
There are other methods of increasing the performance of a concrete wall, but all of them add cost and labor and some can be overly fussy. You could insulate the exterior of the wall (and get to use some of the thermal mass of the exposed concrete – yummy), but then that requires a cladding (stucco, fiber cement board, wood, etc). You could do a double leaf of concrete sandwiching some rigid insulation – but that’s not the easiest thing to accomplish and can entail some tricky structural gymnastics. You could insulate on the interior – but that approach seems a lot like using spray foam to me (e.g. lazy…). There are methods that can compensate for the lower U-value if just using the insulating concrete – most importantly reducing surface area, and that’s in effect what Gartmann did.
Lest you think Gartmann’s house was a one-off, there are other projects utilizing similar concepts (and products!). One is this betonhaus in Berlin-Pankow by bonnen architekten. The ultralight concrete incorporated here is actually lighter than water. You can read more about the house in this DBZ article (German) with snazzy fotos and details. I’m intrigued how it compares, performance-wise, with Haus Gartmann – Berlin is significantly colder with less insolation than Chur.
And limited to single family houses? Definitely not… this stunning mixed-use infill, deftly situated in the heart of the Konstanz altstadt, by Kraus Schoenberg Architekten utilizes this approach in a similar manner. Images and info at Archdaily.
This insanely wonderful school outside of Zuerich by Christian Kerez utilizes it as well, along w/ 3-pane windows, for a stunning effect. Energy efficient to boot (Minergie), the energy consumption of Schulhaus Leutschenbach is apparently 31 kWh/m²a (9.8kBTU/ft²a). More fotos here, and info here (pdf, German)
It should be pointed out that while this insulation is better than a plain concrete wall, there are few locations where an R-10 wall could meet Passivhaus (Honolulu? San Diego?). So if going that route, additional insulation would be required. It definitely reduces thermal bridging at assembly junctions (especially foundation). Deconstruction/demolition also could become easier – less stuff, less adhesives. I think all of these projects are pretty amazing in their own right. As modernists, the raw expression of materials is fundamental, to be able to reveal concrete rather than bury it under insulation is awesome.
Youtube clip of Gartmann’s house
- Gartmann’s BETONSUISSE slides from 3rd Swiss Concrete Forum (pdf, German)
- Patrick Filipaj’s book on insulated concrete, Architektonisches Potenzial von Dämmbeton
- baunetz interview with Kraus Schoenberg Architekten (German)
- Nissen & Wentzlaff Dämmbeton house in Basel
- expanded shale clay and slate institute booklet from 60s-ish… (pdf)
- TECHNOlith – Austrian company incorporating foamglas granulate into CIP concrete for low-energy buildings
- Misapor – Swiss company incorporating foamglas granulate into concrete
Last week, woodworks hosted the first North American CLT symposium here in Seattle. This was an energetic event with decent attendance given it’s relative unfamiliarity to the North American market. It started off with a social evening – which ended up being the only chance I really had to talk to vendors. In many ways, the CLT community feels like the early days of the North American Passivhaus community (but with effective leadership) – lots of enthusiasm and interest but still light on application and experience. But that seems to be quickly changing – and I’d actually say it seems there is more experience at this point, comparatively – especially in Cascadia, owing to our timber-heritage and a number of European wood specialists transplanting here. The (subterranean) venue was better than I thought it would be – with break out rooms and a central hall with desks and outlets (no round tables!) but it was also another conference where the lack of wifi seemed to be a detriment.
As to be expected, there was a mix of eye candy, technical info and a major focus on BIM/FIM (fabrication information model). This last bit loomed large. Quite large. I know there has been a lot of interest in CLT/massivholz-type construction on our blog, it is routinely the most read article, so what follows is a recap of the symposium with some of my takeaways. Many of the presentations have been or will be uploaded on the Symposium website (yes!!). Most importantly, the US CLT handbook can be downloaded for free (or purchased here).
The night started off with KLH‘s Wolfgang Weirer giving an overview of CLT and a brief history of tall wood structures (which paired nicely with the CLT presentation at the Wood Solutions Fair the same day). In essence, systems like brettstapel had been in use (very sim. to NW floor decking in old timber buildings), but these were susceptible to shrinkage and warping. CLT’s dimensional stability solved those problems. By 2012, KLH was producing over 100,000m³ of CLT, exporting nearly 70% of that outside of Austria. Ninety-five percent of global CLT production still comes from the AT/DE/CH region.
The second presentation was Lend Lease’s Daryl Patterson on the 23 apartment, 10-story (9-story CLT over 1 story concrete podium) Forte in Melbourne – presently the tallest CLT building in the world (32.17m). The project was undertaken as a ‘proof of concept’ – as well as preparation for a carbon economy. The site soils posed some challenges – switching to CLT reduced the number of piles needed, as well as concrete column thickness on the ground floor retail. The presentation was pretty flawless and despite claiming he’s not a salesman, Daryl put out the best sales pitch for CLT I’ve ever heard. It took 6 workers (crane, super, 2 laborers, 2 apprentices) ten weeks to erect 785 panels. There was not a single injury on the job. Daryl stated it was the cleanest and quietest job site he’d ever been on. The elevator shaft was also CLT, and it was so precise the elevator crew didn’t have to plumb any rails. The utilization of CLT resulted in an approx. 1,400 ton reduction in CO2 over concrete or steel. Time lapse video here.
The next morning commenced with Erol Karacabeyli’s presentation on tall wood structures and how CLT was moving through the codification process. Erol discussed the progression of timber construction – from 9-story heavy timber structures built here in the NW over 100 years ago, through light frame construction, to CLT and future wood concepts such as the CREE LCT One tower (more photos) and Michael Green Architecture’s open-sourced Tall Wood system (pdf, large). Presently, wood construction is generally limited to 5 wood framed floors over a 2 story concrete podium, or post and beam – but this leaves wood construction at a disadvantage on mid-rise sites in cities like Seattle, where additional height that could be captured with other construction types (e.g., concrete) isn’t yet permitted. CLT should be looked at as an addition to the ‘wood toolbox’ (e.g. LSLs, LVLs, glulams).
CLT has resulted in a bit of a paradigm shift – and the only question is how high can we go with wood… 9-story CLT projects have been achieved – and through hybrid systems (e.g. that of the Tall Wood collab between Green and Equilibrium’s Erik Karsh – up to 30 stories may be possible. Lest that seems too tall for wood… A 100m CLT wind turbine tower was recently installed near Hanover (video).
BJ Yeh of APA then came on and talked about industry and manufacturing issues. He didn’t talk too much about the actual product (pretty much everyone was up to date on CLT) but did talk specifics regarding limitations (~20” thick), glues (PUR), and manufacturing (hydraulic press, typically). With regards to codes, an ANSI standard was adopted in 2012 (more info here). CLT has been approved by the IBC structural committee for adoption into the 2015 IBC (CLT 2303.1.4 – wooooot!).
There are several budding North American CLT manufacturers – and they should be brought on board early to optimize systems and costs. Those manufacturers are Smartlam (MT), Structurlam (BC), Nordic Engineered Wood (QC), and CST Innovations (BC). There is another Montana facility in planning, and ruminations of others as well. So the industry innovation underway seems to be driving some serious successes on both the manufacturing and design side.
Next up was Christian Dagenais, a fire engineer with FP Innovations, who was one of the authors of the Fire chapter of the handbook. Christian mentioned that in the EU, CLT is understood to have, ‘excellent fire performance due to massive cross sections’ similar to heavy timber. Burn tests and mechanical-based calcs were undertaken to determine the Fire Resistance ratings according to ASTM E119. In terms of behavior – the CLT burns hottest in the early stages – the wood reacts and chars, however this isn’t really a problem – this protects the inner assembly from the effects of heat/flame. The charring depth is fairly linear, and so when sizing members for fire resistance – this char depth is added to the thickness of the member (slab, wall). Eight full scale burn tests were performed, that looked at 3-, 5-, and 7-ply wall/floor panels loaded during the duration of the burn – this resulting in a massive report (pdf, tres large). There were some small delaminations where chunks of wood fell off panels, but overall the tests seemed to show fairly excellent performance. Additionally, the incorporation of type ‘X’ GWB adds another 30 minutes of Fire Resistance. The panels have extremely low thermal conductivity, With one test showing a 16F temperature rise on the non-burned side of a panel. Interestingly, Christian stated that when the furnace was turned off, the panels were self-extinguishing.
Michelle Kam-Biron then presented an overview of fire protection design of CLT, and where CLT fits into the building code. This was a very technical presentation, and was an excellent info dump. The slides are probably much better than my notes, but the takeaway for me was that CLT if classified as Type III or IV construction and paired with sprinklers, area modifications or firewalls – can be quite comparable (or even larger) than non-combustible construction (outside of Type I) for the same occupancy. The specific examples she gave were for an unprotected group B occupancy where Type IIB allows 3 stories/23,000sf; IIIB 3 stories, 19,000sf; IV 5 stories and 36,000sf. If accepted as type IV, and paired with sprinklers, area modifications – you’re looking at up to 6 stories/85’ height limit with up to 405,000sf max area. Thus, large buildings are quite feasible. With regards to where CLT is in the present iteration of the IBC (2009) Michelle believes under most occupancies, with support of ASTM E119, Type III (with FRT-wood at exterior walls), Type IV, Type V possible – in addition to the ‘Alternate Means and Methods’ – which it seems has already been utilized on a few buildings incorporating CLT. Additionally, as CLT has been adopted into the 2015 IBC, progressive jurisdictions may be open to allowing use.
At this point, the group was split into two tracks – the ‘design/contractor’ track, and the engineering track. Unfortunately for my bum (and note taking ability), the engineers got the comfy seats with desk space/outlets in the larger auditorium… I’ll upload the summary of these presentations next Monday.
As promised in our passivhaus v. pv post, here are a few PV installs that we don’t find overly offensive. Unsurprisingly, many of these meet Passivhaus – and no, that’s not a selection bias, these are just the solar panel applications we dig the most… Apparently, we really prefer when PV modules perform multiple functions and intentionality, planning and minimalist details /profiles are laid on thick!
So enjoy the pics, and feel free to add any extras in the comments.
Rolf Disch | solarsiedlung in Vauban. passivhaus + PV.
hermann kaufmann | gemeindezentrum ludesch (AT, foto: Bruno Klomfar). passivhaus + PV.
ETH/bearth + deplaze | neue monte rosa huette (CH). passivhaus + PV(!)
TU Darmstadt | 2007 winning solar decathlon entry. passivhaus + PV…
Beat Kaempfen | Sunny Watts (CH). Multifamily done right! Unfortunately, this Minergie-P-Eco project is on few (if any) radars in the US… It should be everywhere (so study up, kids!). Prefab’d, local materials and Passivhaus + PV. Beautiful…
brooks + scarpa | solar umbrella (LA)
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