Is insulation overrated?
McHephaestus
| Posted in General Questions on
Hi everyone,
I was just wondering if anyone has ever read Insulating Modernism by Kiel Moe. The premise of the book is seemingly, as far as I can tell, a declaration that insulation is not an important aspect of green buildings… Basically the antithesis of everything mainstream building science advocates (to my knowledge at least), but it appears to be gaining traction in some circles, the author was even featured on the Building Science Podcast lately though this book wasn’t the main subject of discussion.
Do the arguments put forward in this book hold water or is it pseudo-science? I’m anxious to hear other opinions!
Thanks,
Carter
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Replies
Carter,
I am not a Building scientist. If he is saying that insulation is subject to diminishing returns and other issues, such as air sealing, are important, I would agree (based on my limited understanding of “green” construction).
Thanks for the response Steve,
I have not yet read the book but it appears tha Moe is arguing that the concept of of insulating a building is fundamentally flawed, for example he actually built a building (called stackhouse) that has walls of solid timber... That's it, no other layers, just wood all the way through, and he argues that this type of an approach is actually more sustainable somehow.
Unfortunately his books are very verbose and conceptually dense but I was hoping someone here would be able to advise if the concepts presented are even worth digging into. It's not the most practical question as there are still codes that need to be met, but if my conception of insulation's role in sustainability is so misled I would like to be set straight!
Carter,
Here is a link to an abstract by Harvard.
http://www.gsd.harvard.edu/2014/09/a-new-view-on-thermodynamics-kiel-moe-publishes-insulating/
I guess I'm getting dumber, or aways was. I can't understand what he is taking about.
Malcolm,
Good to know I'm not the only one!
I don't want to spend too much time deciphering this book if it's just a bunch of academic nonsense born of the "publish or perish" mindset, but if the bold claims about insulation's irrelevancy have any truth to them I would think it's something we should be talking about...
Carter,
I think we should pressure Martin into wading through it.
"Very verbose and conceptually dense," is an understatement.
Full disclosure: I don't own this book.
In addition to reading the abstract that Malcolm Taylor pointed out, interested GBA readers can listen to Kiel Moe in a video posted online. (His talk begins at 11 minutes 45 seconds.)
If you are a practical person -- a builder, say -- Kiel Moe's language, refined in the corridors of Ivy League universities, will quickly drive you nuts. He has fallen down the rabbit hole, and become enamored of a type of discourse that is almost entirely divorced from the everyday world -- a self-referential type of speech aimed only at fellow academics. In the video, for example, he laments the fact that "pre-thermodynamic conceptions of energy dominate our pedagogy."
If you ever wondered how architects managed to graduate from architecture school without understanding the fundamentals of building science -- practical details, like how to avoid condensation in roof assemblies -- Kiel Moe would be Exhibit A.
I'm just guessing, but Kiel Moe appears worried not just about insulation, but also isolation. Insulation is bad, because it isolates. We all know that modernist architects want to dissolve the barrier between the indoors and the outdoors, which is why walls of glass were so prevalent in the 1950s.
Transcribing Moe's words is painful, but as a service to the GBA community, I did a little transcription. Here's what Moe has to say: "The prime condition of this knowledge demands a different model of models. In my view, one deceptively innocent way to begin to see around our current model of models is a seemingly simple question: What causes something to appear the way it does today? The topic of appearance is an important step towards this other model. Appearance refers not only to the visual composition of something, but equally to the physical composition of something as well as its literal becoming and behavior, how something literally comes to appear in this world and act in this world. Buildings, landscapes, and urbanization do not appear out of nowhere, but rather from a very complex type of engenderment. As such, appearance challenges the most basic and obdurate epistemological limits of architecture."
There may be more to what Kiel Moe has to say, but I don't think I'm going to spend $84 to buy the book.
For a builder like me, Kiel Moe borders on self-parody -- the architect as total idiot. Listening to him is fascinating. He hasn't the foggiest idea what he sounds like. It's almost like he has a brain tumor or an unusual neurological condition. When I meet architects like this, I despair for architecture.
Here's some more: "As such, it repays us to consider our models of causation at their deepest ontological levels that otherwise routinize our thoughts and practices. ... Regarding these models of causality and how they structure appearance in architecture, we need reference to a couple of philosophical models that are central to all of our work but typically remain unarticulated in schools of design. For instance, whether, again, in formal, technical, or urban terms, our most recurrent and traditional model of causality in architecture is perniciously hylomorphic. Hylomorphism is a transcendent model of the world, independent of matter and energy. It is model in which human ideas and forms are imposed upon seemingly inert matter and energy. It a teleological model that presumes that the planet exists as the substrate of human action and for the exertion of our will."
Thanks for the detailed response Martin,
I guess Kiel Moe is just too "isolated" in his ivory tower... Oh well.
Carter,
I wish I were the Czar of Architecture. Then I could command my minions! I would sentence Kiel Moe to four years as a laborer on a construction site. Perhaps he could specialize in removing fiberglass batts from damp crawl spaces. After a few years of training, he might be able to learn to install kickout flashing.
Maybe. I'm not sure that he's the best person for detail work. I think his mind would tend to wander.
Increasing levels of insulation do have diminishing returns, but they also have diminishing cost (or at least can, if you choose wisely). For example, dense packed cellulose has a low material cost, and the incremental increase in time to blow in 32" vs 20" in your attic is not a whole heck of a lot. We have an R120 roof, R60 floor and R50 walls, and I am glad of it. Very nice feeling to spend all day in the house without the heating coming on, despite being -10C outside.
Just read the quotes from this Moe guy. Funny stuff. I think the invocation of Poe's Law might be appropriate here.
Trevor,
If I understand correctly, Poe's Law refers to the difficulty of determining whether a statement on the Internet is a sincere statement or a parody.
It's possible, of course, that Kiel Moe has posted a parody lecture -- that theory is about as likely as my brain tumor theory.
But if it's a parody, he pulled it off without winking.
This author has mastered the art of long-winded obfuscation. I keep wanting to yell at him: get to the point! I gave up before finding the point. I am guessing it is the "dissolving the barrier between the indoors and the outdoors" point of view Martin mentioned. It seems like maybe the author wants people to change their expectations of comfort and embrace the natural variations of the weather outside? That seems unrealistic...
It's an even more impressive gag when you consider how many books he's written in this style!
There's a video on YouTube called "Kiel Moe, The Building Lecture Series" (the spam filter won't let me link) that I found to be a far more palatable explanation of his thesis. I guess it all boils down to embodied energy, which is probably fair, though I'm not sure if the indoor environmental quality of these boxes can live up to his claims. He says he doesn't need a heating system for the uninsulated Stackhouse even with several feet of snow outside, I suspect a night after a few consecutive cloudy days would lay that claim to rest.
Probably the most disconcerting thing I found about architecture school, was the disconnect between what architects claimed about their buildings, and the buildings themselves. Look at any current periodic and see if you can find one that doesn't claim to be sustainable or green - no matter what the building looks like or what features it includes. Architects as a group are wonderful bullshitters. Some people find that endearing. i find it a bit annoying.
Back to the original proposition, that insulation is overrated, there's this Georgia-based brick mason who has been arguing the point for years. He's also been building, specializing in "mass wall" construction that he says is far more sustainable than the methods discussed on this site. He's worked with some techies at Clemson University in a study that he says "revealed significantly better performance than standard energy modeling provides, and we attribute this to an R-biased industry." Ouch! Are we an R-biased industry? What does that even mean? (I haven't seen this study published.)
Clay Chapman writes at http://www.hopeforarchitecture.com.
I grew up in CZ 6; I once wrote to him and asked what possible relevance his concept of uninsulated structural brick (with fireplaces, usually) would have for us northern folk. He's since moved to Oklahoma, where the winters might be a little chillier than southern Georgia, so maybe he's working on that.
Martin, I think the key point is not his true intent, but that you can't tell. If someone made a parody, it would be no more ridiculous than the genuine article.
Leaving aside for now the intended message of Kiel Moe, I'll address the question, "Is insulation overrated?" A few points:
1. The effects of increased insulation are a matter of physics, not opinion. We know the effects of increasing insulation levels from (for example) R-5 to R-10, or from R-10 to R-20. Opinions are irrelevant to energy flux measurements and fuel bills.
2. The question is somewhat complicated by builders' historic ignorance on the importance of air sealing. A leaky house with an R-40 envelope can perform worse than a tight house with an R-20 envelope. In other words, insulation matters, but air sealing matters more.
3. The latest wrinkle in the equation concerns our current climate change crisis, and the "front loading" problem of CO2 releases associated with very thick insulation. (For more on this topic, see Carbon Emissions By the Construction Industry.) Very thick layers of insulation may be cost-effective for homeowners with a long view -- for example, homeowners who don't mind waiting 30 or 40 years for payback on their insulation investment. But the planet may not have the luxury of such a long wait. If the CO2 releases associated with manufacturing thick insulation are all released this year, these CO2 releases contribute now to rapid changes in our climate -- and lower levels of CO2 releases (for thinner insulation) would be doing the planet a favor.
I've known some excellent tradespeople who aren't as highly skilled with words as they are with their hands. So rather than only judging Kiel Moe on his words, perhaps we should consider his work. Martin in particular might have comments on Moe's roof design . This is at 9000 feet in Colorado. The picture right after the one linked shows what the room under that roof is like inside.
I would love to see what the interior looks like today! Maybe it has survived an entire decade without moisture-related problems. But I doubt it.
Late to the thread, as usual. A few scattered thoughts.
Elites around the world, if they’re obliged to interact with the rest of us at all, build walls of words, the more impregnable the better. You come to them, they don’t come to you, and it’s on their terms. Architecture design faculty have no restraint on their sayso over young students, there is no baseline for any appeal. So naturally, Richard Meier has his way for decades until he gets nailed like he did yesterday. There is an incredibly poignant essay by Laura Willenbrock in the 80s (can’t find it on the web) about being a young female in this environment. I’ve been invited into this design criticism world. No thanks.
Moe’s undergrad was at the University of Cincinnati, flakier than most undergraduate programs, along with Rice and Cornell, at least in the previous decades. I’d have guessed Moe came from Cincinnati from his imprecise, impressionistic, expansionist way of speaking. Watch Cincinnati turn around with their new Architectural Engineering program.
Moe teaches at Harvard GSD. So does Robert Silman. Silman’s Philosophy of Technology course makes the other bs just fade away into insignificance. Being the Building Science teacher at a School of Architecture is like being Rodney Dangerfield. You respond by excelling at science (Silman) or disfiguring the science (Moe), or complaining about no respect. Bad building science teaching in architecture schools should not be seen as their problem alone. It’s on us.
Here’s another link between modernist corporatist glass culture and anti-insulation—internal gains. A colleague just told me the balance point for the Sears Tower was 20 degrees F. Perhaps. All this changes with improved lighting.
A question about Stackhouse. The waste stack?
Response to Charlie Sullivan (Comment #20),
It would be interesting to know how Moe flashed those solid-timber parapets. Presumably, the parapets were entirely protected by metal flashing -- but you never know.
When the slope of a sled roof conveys water to a vertical wall, you had better know your flashing. All depends on the scupper. It's a big scupper -- but still.
Bill,
Thanks for your comments. It's rather discouraging to learn that Harvard hires professors with (as you put it) an "imprecise, impressionistic, expansionist way of speaking." Tuition-paying students deserve better.
All subcultures privatize language and invent slang. Young people do it, some minority groups do it, sports enthusiast do it. The intent is always to create a closer group and exclude outsiders. That can be a positive thing, but never in an academic environment. I suffered through French Structuralism and Phenomenology being applied to architecture while I was in school. That approach has mercifully sunk, largely without a trace. Thinking about architecture is vitally important. Doing so in a way that excludes people from participating in the discussion is just a way of guaranteeing your position won't be challenged.
Malcolm,
Jargon and slang can be precise, witty, and cogent. Just because a subculture uses jargon or slang, doesn't mean sloppy thinking or bad writing are required.
Kiel Moe doesn't just have a jargon problem. He has a thinking problem. He lacks clarity, which is a sure sign that he doesn't really know what he's trying to say. To an editor -- anyone trying to untangle his words in an attempt to extract meaning -- his thinking problem is evident.
Hello, Bill Rose
I heard you at the 2007 2nd Annual Passive House Conference, you are still making good sense. Would you please expound on "balance point". This can be your friend or your enemy (from a energy use standpoint).
Another example of imprecise, barely-referential, hopscotch language is marketing. Or flirting. Their effectiveness is measured--well, you know how. Martin, I was thinking of having to be a peer-reviewer for Moe's work. You're right that an editor's job would be more excruciating.
Doug: "Balance point"? In this context I mean it to be the outdoor temperature at which heating needs to kick in, given the heat generation within the building. From comfortable ambient conditions to the "balance point", the building is trying to discharge waste heat, and insulation retards that.
So as Charlie alluded to a few posts ago, is there a building science position behind all Kiel Moe's rhetoric? Is it as simple as he believes high-mass trumps insulation? The discussion would have been a lot more fruitful if it had been put that way.
Martin hit the nail on the head earlier when he indicated the language Kiel is using is self-referential and aimed at other academics. Kiel Moe is a post-modernist by his philosophy, and his language reflects that used by other post-modernists. In my job I’ve had to learn to read and interpret such usages, but it’s never easy.
However, there can be some thoughts of value buried in the discussion. In this case, Kiel is partially using insulation as a metaphor for how over the 20th century we’ve traditionally isolated aspects of building systems. We have separate building codes for structure, plumbing, electrical, HVAC, energy efficiency, etc. We have separate trades specializing in each of these areas, and when building often subcontract these roles out. Building science and architecture programs also teach them as separate subjects in separate classes. This approach reinforces keeping each system separate in the design process… but builders need to recognize the interconnections, and ideally, architects, builders, and trades should cross-train so they at least understand the basics of other people’s role and critical importance thereof (i.e. no plumbers butchering joists, understanding the critical nature and effective practices of air-sealing penetrations, designing the home layout to minimize plumbing runs, roofers and siders working together to correctly flash connections).
The second argument Kiel is making is that our conception of insulation encouraged by the R-value model is limited. Martin outlines one major issue there in his article In Cold Climates, R-5 Beats R-6, mainly that R-value is not a constant, but varies according to delta T across the material, and how this varies depends on the material. Another issue is the simple one-value model encourages us to look past issues of assembly details and installation details in getting good value from our insulation materials. We’re getting there, but many code-minimum builders still assume shoving an R-24 batt into a wall cavity will yield and R-24 assembly.
But at the heart of his design philosophy, Kiel Moe is drawing upon a post-modern systems perspective that builds upon complexity theory. The basic idea here is that order emerges from complex systems. A good example is a hydronic heating system – when a well-designed system is running, the various components move towards thermal equilibrium (where the amount of heat added to the environment matches the amount lost through the walls). Considering a building’s systems in this light does have some promise – but it’s extremely hard to predict where that balance will be in the design phase. A key example is the plethora of passive solar designs from the 60’s and 70’s that consistently over- or under-performed expectations.
We’re getting closer to this point, with technologies like variable-speed and variable-capacity heat pumps and ventilation systems, drain water heat recovery, etc. But the old, well-established approaches have the benefit of lower costs, working in varied locations, and not experimenting with resident’s comfort. I say let Kiel and his disciples blaze a trail through this new territory, and incorporate what useful techniques they uncover, but recognize the bulk of their approach is experimental and probably not suitable for most of us.
Nathan,
Thanks for your very helpful summary.
I'm not going to comment on post-modern philosophy. And I have my hands full answering ordinary "insulation as a building material" questions without considering "insulation as metaphor."
I began watching the video that Martin referenced in Comment 7. It's difficult because he simply reads and makes no eye contact. Then I got to minute 18:00. He is explaining what a hylomorphic ontology is and it's a reference or an image or an understanding that comes solely from human will, not prompted by exigencies of nature. So he shows an image of a cloud. And the cloud somewhat resembles a lamb. So in order to make his point he writes at the bottom of the slide "cela ne veut pas un agneau."
Martin speaks French quite well and so do I. This is lousy French, which literally translates as "that one there does not want a lamb", and there's a grammatical error where if you're trying to say "don't want a lamb" it's "ne veut pas d'agneau." What he's no doubt alluding to is Magritte's painting of a pipe, and written below is "Ceci n'est pas une pipe"--"This (one here) is not a pipe" with no grammatical errors. Magritte's painting makes the ontology point perfectly well.
Well, I decided to continue watching the lecture. Silly me. I've heard dozens of lectures like this one, leaving the audience stunned by having learned zilch. The speaker seemed as pained as me, so it's not masturbatory as I initially thought, just dreadful for all participants, an outworn liturgy imposed on architecture acolytes in place of actually learning something. I found out what the essence of thermodynamics and it's--mixing. So his mastery of thermodynamics is worse than his French. I heard him spit words like neoliberal and calvinist at those who favor energy efficiency and energy conservation. I have no need for this crap.
The laws of physics are self-enforcing, no matter how many layers of BS people try to wrap it in.
Mathematics is a better design language for this stuff than butchered French or semiotic semaphore. That's why engineers are generally better at nailing the functional stuff than architects (though there are masters of both.)
I feel the need to apologize for tying this conversation to this particularly incendiary author rather than just enquiring about the downfalls of insulated assemblies compared to a mass wall approach as Malcolm said (comment 29). Thankfully there were a few interesting points made in that vein, particularly Andy's link to Hope for Architecture (comment 17), Martin's explanation of the "front loading" problem (comment 19), and the concepts of balance point/thermal equilibrium (Comments 28 & 30).
Thanks for the thought provoking responses everyone and I'm sorry for inflicting Kiel Moe's writing on all of you!
The insulation vs. thermal mass debate has been covered at length here at GBA. See Martin's article, All About Thermal Mass: https://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-thermal-mass
It's been a while since I read it, but my takeaway was that thermal mass mostly makes sense in (relatively rare) hot climates where you have a hot day and a cold night. You can harvest the heat from the day during the night, and vice versa. In a climate where it's just consistently cold, it doesn't do you much good, because the heat just flows continuously from the inside to the outside. The fact that the heat takes N hours to make it from one side to the other doesn't help you -- it's still flowing away at the same rate it would without the mass, and it's not coming back.
Thanks, Nick, for a very clear and concise summary. Quite refreshing given the context.
Carter,
No need to apologize. Sometimes these rabbit holes yield very interesting discussions.
[Photo of Kiel Moe]
[Caption: Ceci n'est pas un professeur.]
Thanks, Bill. I appreciated your conclusion that "his mastery of thermodynamics is worse than his French."
Dana,
Thanks for your summary. I must agree that, in the timeless struggle between architects and engineers, it's necessary to put up another chalk mark on the engineers' side of the ledger.
I apologize to all (including Prof. Moe) for having made this personal.
When I was in arch school, many years back, postmodernism was a style masquerading as a philosophy. "Signs" were uprooted and replaced in odd configurations, like the Chippendale top of Philip Johnson's AT&T building. I appreciate commenter 30 Nathan Bean's effort to find a pony in this pile. I suppose that all the effort to get me thinking postmodern-ly has been for naught.
What are the fruits of postmodern thought? Postmodern science showing us parts of the world heretofore unseen? Postmodern law nuancing guilt and innocence? Is the state of political affairs in the world postmodern, and does this excuse and explain its incoherence? Is there such a thing as postmodern humor? I followed structuralist thinking (Levi-Strauss) that there are inherent categories of the mind, into post-structuralism (Derrida) where the text supplants the structure, and that didn't really go anywhere for me. I guess I missed the postmodern train. Where do you go to catch that train and take a little ride?
To me, any discussion that tempts Bill Rose to post here is a useful one.
Minor followup point: In French the term "isolation" is used for our English isolation as well as for insulation, though it is often qualified as "isolation thermique".
Bill,
Interested GBA readers (especially Canadian builders and architects who occasionally work in Québec and need to brush up on their French technical vocabulary) will find the following CMHC document quite useful: Glossiare des Termes d'Habitation.
I'm all for opening a window when the weather's nice. But we don't need to write a book about it.
I think those of us who are lucky enough to live in benign climates where the weather is our friend for much of the year could often take more advantage of it. American homes of 100 years ago often had large porches on the ground floor and "sleeping porches" on the upper floor. That's a kind of pleasure in daily living that we could use more of. But having looked at photos of Moe's designs and finding them to be rather dumb boxes cut off from their surroundings I doubt his brand of modernism is how we're going to get there.
All, I'll concede that Moe's writing style is irritating. However, I don't think we should permit ourselves to be distracted by this, he has a lot to say about building physics, and our pat assumptions about it. Recommend reading this older project proposal, written in pretty plain language (I assume he had to write more efficiently since this was an application for grant $$$):
https://www.brikbase.org/sites/default/files/2011%20Upjohn%20report_MOE.pdf
Moe is not a modernist (he's built a building almost completely enclosed in heavy timber for crissakes). Moe is not a postmodernist (he's not concerned about semiotics and symbols, his writing and research and built projects examine performance mostly).
His argument in the insulation book is that the refrigeration industry and the air conditioning industry have rigged the game thru marketing and reductive standards such as ASHRAE. Look at Europe where there's no ASHRAE: we get office buildings like the ones by Baumslauger Eberle that maintain comfortable conditions completely passively, with no mechanical heating, cooling, and ventilation, in cold climate like Austria (https://www.baumschlager-eberle.com/en/work/projects/projekte-details/2226-emmenweid/). Or another small office bldg in Switzerland by Seiler Linhart that uses thick timber walls, with zero insulation and zero petrochemical membranes. (http://www.seilerlinhart.ch/projekte/burohaus-kung-alpnach/)
Moe's research examines qualities of natural building materials that are not well quantified by steady state modelling tools used in the industry like THERM. for instance, he examines the combination mass effects, diffusivity, effusivity, vapor diffusion of wood, and their impact on occupant comfort, independent of dry bulb temperatures. Some of these lessons are similar to what we know about the benefits of thermally active surfaces such as radiant slabs and ceilings.
Moe also has a raft of research into the embodied energy of building materials, much of which is overlooked even in industry lifecycle assessments. Won't go into that here, but worth noting.
Again, the prose is unfortunate, but the content is incredibly fascinating and holds a lot of promise for the evolution of bldg materials, methods, and standards. Even if you don't agree with all of his conclusions, it is worthy of consideration.
(@MartinHolladay)
I couple of discrepancies leap out at me:
"in cold climate like Austria (https://www.baumschlager-eberle.com/en/work/projects/projekte-details/2226-emmenweid/)."
That link is to a building in Switzerland, not Austria. It's not particularly cold, either. It has similar average lows and highs as Nashville, TN, which is on the warm edge of zone 4. It does indeed say that it maintains 22-26C without any heating, cooling or mechanical ventilation (not sure what temperature regulation has to do with ventilation...I notice they make no mention of air quality). Is there any evidence of this other than one line on one website, a website by the company responsible for the building and has a motivation to make themselves look good?
Note that this building also reportedly has "double-skinned walls almost 80cm thick" (32 inches thick). That is the antithesis of what Moe is preaching, so why exactly is this example being connected to him?
"Or another small office bldg in Switzerland by Seiler Linhart that uses thick timber walls, with zero insulation and zero petrochemical membranes."
Thick timber is not "zero insulation". Zero insulation would be a metal wall. A 12" thick timber wall (the minimum of what would qualify as "thick" in my mind), would have a whole assembly r-value of R16. The link provided is literally just a photograph, so we don't know how thick the walls really are, or anything else about this building.
Sorry, this is the one in Austria:
https://www.baumschlager-eberle.com/en/work/projects/projekte-details/2226-lustenau/
The one in Switzerland is in a climate more like Connecticut.
Ventilation is achieved in these building through BAS actuated vents (automated windows). I guess technically this is mechanical ventilation, but the point is it uses no reheat, and requires no tempering or heat exchange. Excessive cooling is prevented through trickle ventilation--opening the vents just a crack. You can read more here: https://www.detail.de/en/de_en/article/house-without-heating-office-building-in-austria-16667/
I'm not arguing that Baumslager Eberle's buildings are in complete alignment with what Moe advocates. If you read my comments more carefully you will note that I cited these buildings as being possible in absence of industry-influenced code standards like those that comprise ASHRAE.
I obvious know that timber is not zero insulation. By insulation I mean commercially manufactured insulation products. Timber is R=1/in. Thus, a 12" wall would = R12. Below the IECC 2018 prescriptive code requirements for commercial buildings in most US jurisdictions.
Listen, you can poke holes around the margins. Come back to me when you've read the grant proposal that I posted, its not that long, just 14 pages with pictures.
This thread is titled "is insulation overrated", so I don't think pointing out your examples are insulated, and in one case insanely super-insulated, is "around the margins".
Softwood timber is R 1.4 per inch, according to the US department of Energy. Some sources say as low as R1.25. It will vary a bit by species. And as I already said, we don't know how thick the "thick timber walls" are. They could be 24", making the walls around R32.
I'm sorry, I'm not reading your 14-page proposal. I just don't care that much.
Huh. if you actually don't care ... why reply twice? Why waste the effort? I care, that why I'm spending this time.
I didn't title this thread. Referring back to the title in reference to a specific point that I've made is a red herring. I am insulation agnostic; there's many wall assemblies that can do many things. A super-insulated wall and an under-insulated timber wall may achieve a level of human comfort through different means: the first through management of dry bulb temperature, the second by taking advantage of the effusivity of wood. For instance, the walls of Moe's timber building in Colorado are mere 5" thick. https://www.acsa-arch.org/proceedings/Annual%20Meeting%20Proceedings/ACSA.AM.98/ACSA.AM.98.108.pdf
anyhow, don't waste your time with more sniping without actually grappling with the topics. Managing the sniping is becoming a waste of my time as well.
I guess it was inevitable to move from triple wyth bricks as the panacea of efficiency and comfort to a mass timber.
This has been a while since the discussion came up, unfortunately the laws of physics have not changed in that time. In cold climate, low R value high specific heat capacity walls simply don't work.
These assemblies are great in mild climate with large diurnal temperature swings though.
Tom,
Why don't uninsulated log cabins (which sound like they fall into the correct category?) fair so well in the north east? Or perhaps the question is rather, why do these thin walled wood building work in your mind? If effusivity has something to do with it, can you expound on that concept? Do you mean diffusivity? And again, what is the mechanism that maintains comfort on cloudy, extended cold north east winters?
I am genuinely curious and not sniping.
Tyler,
Thanks for your thoughtful response. In the proposal linked above, Moe stresses both diffusivity (rate of heat conduction) and effusivity (thermal inertia or responsiveness). Diffusivity is key to understanding thermal mass effects as you likely know, and effusivity has to do with heat transfer between your body, its air films, and adjacent surfaces and air films. I don't have a lot of experience with these phenomena personally, or with measuring them, which is why I am curious about them. With respect to timber particularly, effusivity has much to do with the entrainment of air and water in its cellular structure.
I also don't have any direct experience with log cabins in the northeast, sadly. When I think of log cabins, I imagine structures with fenestration that are inadequate for passive solar gains, and perhaps not sufficiently air tight. Maybe these are charicatured assumptions, I'm not sure; I guess we'd need to control for these. Do you have any anecdotal experience with heat flux in log cabins during a cold winter? thermal effusivity in particular is a qualitative variable that I don't have a great grasp of.
You have a point that Moe's house in Colorado can expect more consistent solar gains both internally and externally than one in New Hampshire.
By the way, one interesting strategy of the Swiss timber walled building linked above that I did not mention: they used poorer grade / rough sawn lumber for the interior plies of the dowelled massive walls as a way of entraining air, to further slow conduction. This relates to some heat flux research that Moe cites in his book in insulation by a norwegian engineer, can't recall the name, who conducted a series of experiments: tracking temperatures in a large series of small enclosures that incorporated various quantities of wood, brick, air space, etc. see attached. would love to revisit the results (i dont own a copy of the book), and would be interested in a contemporary version of this experiment to really get to the bottom of which wall assemblies are the best.
Response to #64: for the last 20 years I have helped maintain my mom's vacation rental in western Maine, a manufactured log home with walls of 6" pine. It has large south-facing glass doors. It is never comfortable inside; it's always too hot or too cold. Use all of the fancy words you want; log homes and passive solar are not a recipe for success in the northeast US.
Reply to Tom #64
Yes, like Michael, I do have first hand experience with log cabins being uncomfortable. It is true that they are often poorly air sealed, but that isn't their only downfall.
Diffusivity and effusively are composite properties that are concerned with the qualities of density, conductivity and specific heat capacity. (note, the product of density and specific heat capacity can be combined into the term 'volumetric heat capacity'). Diffusivity being decreased with increasing volumetric heat capacity, and effusivity being increased. Increasing conductivity will increase both.
I'm still unclear what effect of effusivity we are looking for (in wood?), but in any case, it seems that it is the heat capacity that is performing the 'magic' here (magic relative to R-value speak), yet the 'magic' is only of interest when we are dealing with a *varying* thermal environment. In steady state conditions, we are pretty much just concerned with conductivity.
See this study for example: https://www.fkit.unizg.hr/_download/repository/H1_IMPACT_OF_THERMAL_DIFFUSIVITY_AND_EFFUSIVITY_____VAZNO____.pdf
It is fascinating, but they are dealing with a "varying thermal environment."
Thus, heat capacity properties becomes more relevant the more 'varied' the thermal environment is.
Even a dreary northeast winter is going to experience some solar gains on the roof/siding and through windows, but it's not a terribly reliable heat source. We would need to store that solar energy in a more useful way (like electrically) to effectively and reliably utilize the solar gain. The thermal environment can be too 'unvaried.'
Thermal diffusivity may yield greater benefit in cooling months, especially on something that receives direct solar irradiance like the roof. The thermal environment is more varied.
The neat thing is that there are insulations coming out of Maine soon (and have been in Europe for a long time) made from wood fiber, with good thermal resistance AND high thermal diffusivity. Which in my opinion, as stated above, may not be that important in many situations, but if one believes that these properties of wood are important, then why not use such an insulation that has low conductivity and low diffusivity vs solid wood with poorer performance on both accounts?
TomBeresford,
All the office buildings I worked on in cold climates were still cooling dominated, even in winter. Their mechanical systems were geared to exhausting heat. How does this building differ, except that it has super-insulated walls?
>"All the office buildings I worked on in cold climates were still cooling dominated, even in winter."
Bill seems to be suggesting something similar above (in 2018) with the 20F balance point. I'm guessing this is common knowledge, but new to me. What allows this to be?
Is it the solar gain? The high loads of occupants and electronics compared to exterior surface area?
Clearly for some reason, these buildings are different beasts than residential.
European office buildings far more shallow floor plates (8m max from envelope to core) probably has something to do with it. Internal heat gains to envelope gains totally different balance. In any event, higher internal gains would only help in the case of the Austrian and Swiss climates. Also a good argument against over designing mechanical equip in northern climes here in the us.
maine_tyler,
"The high loads of occupants and electronics compared to exterior surface area?"
Yes, that's most of it.
I just googled the Sears Tower and found that it uses 85 million kWh of electricity a year for 5 million square feet. That's 17 kWh per square foot. If you figure it's occupied 2500 hours a year that's just under 7 W per square foot continuous, which is about 24 BTU/hr per square foot. I could see that keeping it warm at 20F.
DC,
I've read that the conversion of large office buildings to LED lighting can have large knock-on effects for the mechanical systems, once that excess heat from the lighting disappears.
Reply to Malcolm's post #70:
There are buildings here that used to have "luminuous ceilings", and when those were either shut down for energy savings, or converted away from incandescent (usually halogen architectural fixtures) to flourescent or LED, the resulting loss of heat did make an impact in the winter that had to be compensated for by the mechanical plant's heating function.
Typical large buildings have a lot of electrical loads that are always running, such as circulation pumps for the mechanical systems (which can easily be 20-30+ HP motors, and there are usually more than one), and transformer losses, all of that heat goes into the building. You also have heat from lighting. Most of the buildings here were converted to T8 flourescent decades ago, and the conversion from those to LEDs is not as significant as from T12, or incandescent, to LED, so I don't have much experience there.
Remember also that a typical commerical building only has one ground floor and one roof, regardless of how many stories there are. That means a typical floor only really has a perimeter of exterior walls, any losses through the ceiling just help keep the floor above warm, except for the very top floor. It's very different from a typical residential structure, which will tend to have a much higher ratio of exterior surface area to interior square footage compared to a typical multistory commercial building.
Most of the landlords around here charge $1/sqft/yr for electricity for their tenants (which avoids the need to seperately meter the tenants), and that seems to work out pretty close to the electrical load presented by the tenant's electronics, so that would be around 0.7-1kwh per square foot per month, approximately.
Bill
"Most of the landlords around here charge $1/sqft/yr for electricity for their tenants (which avoids the need to seperately meter the tenants), and that seems to work out pretty close to the electrical load presented by the tenant's electronics, so that would be around 0.7-1kwh per square foot per month, approximately."
Very close to the 17kWh/year I calculated for the Sears Tower.
Akos, suggest reading the linked proposal above before making definitive statements. You're not contending with the information. Also, while alpine Colorado does have large diurnal temperature swings, sub-alpine Switzerland does not.
I did.
One could even calculate how much extra it takes to heat that studio VS 2x6 stick build. I don't care enough to do it but my guess would be on the order of 2x.
There are also some unfair comparisons to standard stick build. You can insulate just as well with cellulose to reduce the carbon footprint.
I'm also curious on how magically the energy footprint of a 6x8 timber beam is way less than that of a 2x lumber.
"Some of these lessons are similar to what we know about the benefits of thermally active surfaces such as radiant slabs and ceilings."
We have long, long fights -- er, discussions -- on these very pages about what we in fact know about those things.
This is exactly my point: currently tools don't measure or simulate radiant effects on human comfort very accurately, if at all. One useful thing to come out of such discussions / fights could be better methods to understand these qualitative effects. But not from me, I'm just a dumb architect, ha.
Tom,
"currently tools don't measure or simulate radiant effects on human comfort very accurately"
That argument has been made repeatedly by every proponent of thermal mass (sorry DC) buildings from log houses to earth-ships, and it always seems to boil down to I don't care what the physics shows, they feel more comfortable to me.
I guess the point is just because we haven’t quantified it yet, doesn’t mean we should never quantify it. This could be something real simple folks, like Payettes winter comfort tool:
https://www.payette.com/glazing-and-winter-comfort-tool/
The Passive House standard says that people can feel a difference in radiant temperatures when a surface is about 6-7°F different than nearby surfaces. I'm not sure how they derived that value but I imagine there was at least some science involved, and in any case, few people would argue that a Passive House is not thermally comfortable. While I don't believe that having every space within a house is necessarily healthy or comfortable, it makes logical sense to me that the primary indicator of radiant comfort would be the temperature differential between the surface and your skin. In fact, as long as the air is still, what other properties could possibly be involved?
I think a lot of that is radiant effects are fairly minimal compared to overall thermal issues in the space. Walk past a window in the winter and night, it will feel a bit colder than the rest of the wall. That's minor compared to the entire room being 5-10* colder than you want it though.
I also see from some of these posts that the goal seems to be "avoiding petrochemical" insulating materials. As I've pointed out before though, plastic materials do not have to be made from oil -- other things can be used as a feedstock too. Polyethylene can also be made from corn. It's just a chemical process, where the carbon chains original doesn't matter too much in the final materal.
The other issue is a big thermal mass worth of timber is using a lot more wood than a typical stick framed house. So you're consuming more wood, more trees, than if you built a stick framed house. You're trading the use of a lot more wood for using less insulation, which to me seems like a relatively poor trade in terms of green-ness. That's on top of the other issues that have been brought up regarding thermal performance, and keep in mind that a lot of Europe is a milder average climate compared to much of Northern North America, so things that work there won't necassarily work here.
All of these physical processes regarding thermal transfer, heat flow, etc., are actually pretty well understood, and there is no magic involved. Spacecraft have used radiant systems for cooling for a long time (probably since the first spacecraft that needed cooling was sent up), so it's not like engineers don't understand radiant effects sufficiently well to design with them. The issue is that radiant effects are not the dominant effects in terms of building comfort.
Bill
Diminishing returns, Yes, but overrated? No, I don't agree.
[This is a response to Tyler #72]
I read the Vazno article and I found it interesting, but not for the reasons the author probably intended. When we talk about heat capacity effects in buildings we (or I, anyway) usually just assume that the heat flows freely, it's simpler that way. And since I'm usually arguing that the effect is much smaller than other people might think it is, the free-flow model puts an upper limit on how much the effect could possibly be; if internal resistance within the material is significant it limits the effect further.
For example, concrete and rockwool have almost exactly the same specific heat, a pound of concrete holds the same amount of heat as a pound of rockwool. However, concrete has an R-value of 0.1 per inch and rockwool is about 4, or about 40 times as much. At the same time rockwool has a density of about 0.02 g/cc and concrete is about 100 times as great. So if you were to make two one foot squares and put a pound of concrete in one and a pound of rockwool in the other, the concrete would be about 0.08 inches thick and have an r-value of 0.008, and the rockwool would be about 8 inches thick and have an r-value of about r-32. For the concrete it may be a reasonable simplification to assume that heat flows freely in and out of it, but for the rockwool it clearly isn't.
What Vazno tries to do is to model the effect of internal resistance. He uses a computer model where he divides the piece up into lots of thin slices, treats each slice as if it's linear, and then models the entire behavior. This is a legitimate way of calculating, but it shows that the calculations are not simple. And as expected what he shows is that, yes, if material has thermal resistance heat flows less freely in and out of it.
I would argue that there is still a major simplification in his model, which is that the surface of the material is assumed to be at room temperature. If you look at the design of heating systems the assumption is always that the heating surface will be above the room temperature. The exact interface between surface and air is not well understood, when designing systems people use simplifying rules of thumb. The ones I am most familiar with are that for surfaces heated from below the heat flow is 2.0BTU/square foot/degree F of difference, and for surfaces heated from above the heat flow is 0.71 BTU/square foot/degree F. I got these formulas from John Siegenthaler's book, I don't know how they were derived but I suspect simply from empirical measurement. Note that these formulas say nothing about what the material is made of.
I would argue that the surface/air interface places another limit on the flow of heat between the interior of the building and its components. The heat flow is going to be the lesser of what the internal resistance of the material will allow and what the surface interface of the material will allow. This could be modeled similarly to what Vazno did with just the internal resistance, although I'm not sure what the instructional value would be. (Although my intuition is you would find for most building materials that the surface effect is greater than the internal resistance effect).
This brings us to where I feel the paper falls apart. Vazno begins the paper by defining "diffusivity" and "effusivity." This is done entirely by assertion, there is no derivation. He includes formulas, and while the units look pretty janky to my eye, the real test is in their predictive power: there is none. When it's time to do the actual calculations, the value of "diffusivity" and "effusivity" never gets used. Yes, clearly the heat flow through an object is a function of its physical properties -- size, mass, thermal conductance -- but there is no evidence presented that the calculated values for "diffusivity" and "effusivity" hold any relevance to that calculation. In fact, what his use of a simulation model shows is that a simple linear formula -- such as those presented -- isn't adequate to describe the behavior.
Some of the things you're talking about are used in heatsink design. Wakefield Engineering used to have a good document that explained some of this stuff, along with calculations to help with thermal design. Unfortunately, a quick Google search didn't help me find that document so that I could link to it here.
Fluid dynamics gets complex, and I don't think a simple linear model is sufficient to predict outcomes with any reasonable level of accuracy. I do remember one thing from my differential equations class way back in college too: when you add a term for the viscosity of a fluid, the differential equations become unsolveable. That surely helps to explain some of the complexity involved here.
I have seen before when people try to overly simplify complex models when trying to "prove" something they wish was true. Things don't usually work out well.
Bill
DC, (#75)
Hopefully it was clear that my reason for posting that was to illustrate how these properties regarding thermal capacity are being modeled in *varying thermal conditions* because that is when they are most relevant. In steady state conditions, they become pretty irrelevant.
That was really my only point, but now that you've dove into it...
>"if material has thermal resistance heat flows less freely in and out of it."
It seems like you are referring to the effusivity? Conduction is part of that, but not the ONLY factor. Case in point being the asphalt and gypsum, which have the same effusivity but different conductivities.
>"This is done entirely by assertion, there is no derivation. He includes formulas, and while the units look pretty janky to my eye, the real test is in their predictive power: there is none."
and
"When it's time to do the actual calculations, the value of "diffusivity" and "effusivity" never gets used."
Perhaps I didn't dive as deeply into the study as you, but I'm not sure what you mean. Isn't the correlation depicted in his graphs? Seems pretty plain in the face to me. I'm not really sure what you're driving at. As an aside, I see your point about air films, but I'm not sure it would 'dominate' the equation save for certain cases. I imagine as far as analysis goes, it's simply another layer of complexity to contend with.
I did find it interesting because it gave me a better understanding of the relationship between the three variables of conductivity, specific heat, and density.
Take two insulations (foam board and wood-fiber board) for example:
Let's say they have identical conductivity, but wood fiber has higher volumetric heat capacity (whether due to density or specific heat, doesn't matter, because those terms stay together in both cases).
The wood fiber will have lower diffusivity and higher effusivity. What this *means* is where it gets more complicated. And it gets back to my point about varying thermal environments, because it means very little in steady state conditions, but in varying conditions it will mean 'something.'
The example of rockwool and sandstone is perhaps a bigger can of worms. I'm not sure I fully grasp what the implications of the higher effusivity of sandstone really means in practice, especially when coupled with it's much higher conductivity (but similar diffusivity). It exchanges heat with the environment more readily, so I suppose that means its a 'battery' (or capacitor) that can take and release charge more quickly, therefore modulate steep spikes more readily. But it's a worse insulator, with the caveat that in the right 'varying' conditions, it actually *can* insulate via its thermal diffusivity). That's where it really becomes a can of worms, because its effectiveness would depend not only on temperature deltas, but temperature deltas with respect to time.
I'm trying to parse your assessment of this topic. Is your assertion that thermal capacity, diffusivity, effusivity, et al. are all entirely irrelevant? If so, is it a matter of being practically irrelevant, or are you suggesting diffusivity and effusivity are scientifically irrelevant because... their definitions were asserted... or something?
I'm saying that diffusivity and effusivity -- as defined in that article -- are irrelevant because they're not useful.
There's a saying in economics: All models are wrong, some are useful.
So let's look at diffusivity. The article defines it as conductivity divided by density times specific heat capacity. The units of that measure are meter-squared per second. That's a clue: what does that even mean?
Measuring a physical property is useful if that property behaves consistently. Two objects of the same mass will weigh the same. Two objects of the same length are the same length. But the models shown demonstrate that two objects of the same diffusivity don't absorb and release heat the same way. So the calculated property isn't useful for predicting the behavior of the material.
As Bill notes, the behavior of non-linear systems is complicated. Sometimes they can be modeled mathematically, sometimes they can't. Often times the best way to model them is the way the author of the paper did, by using a computer model that divides the object into slices of space and time and calculating the value of each slice for each increment of time.
If I were called upon to model the interaction of, say, the materials in a house, the air temperature in the house and the outside temperature, that's the kind of model I would make. It's tedious but it's not hard, you could do the whole thing in an Excel spreadsheet.
So what would be the inputs into such a model? I'd start with the dimensions of the materials. From the dimensions and the densities I'd calculate their mass. From the mass and the specific heat capacity I'd calculate the heat capacity. From the thickness and r-value I'd calculate the thermal resistance. I'd use Seigenthaler's formulas to model the transmission of heat between the structure and the interior air. I'd use something like a Manual J calculation to model heat flows in and out of the building. I'd use thermal resistance and heat capacity to model heat flows in and out of specific components.
What I wouldn't use is diffusivity or effusivity. They just aren't useful for these calculations.
DC, sometimes I swear we're on different planets. I just really struggle to follow your mentality. It often feels like you ignore the simple thing in front of you in favor of a wild tangent.
>"But the models shown demonstrate that two objects of the same diffusivity don't absorb and release heat the same way."
Yeah, did you read it? That's not diffusivity. Diffusivity is the rate of transfer of heat from one end to the other. It's not something this author made up. Is that really what you think?
https://en.wikipedia.org/wiki/Thermal_diffusivity
All your talk about modeling this and that... I have nothing to say. You have no point. And I'm not convinced you comprehended that study as it shows how those traits can be seen. That you find them irrelevant is irrelevant to science. No one's forcing anyone to use anything.
" As an aside, I see your point about air films, but I'm not sure it would 'dominate' the equation save for certain cases. I imagine as far as analysis goes, it's simply another layer of complexity to contend with."
I want to expand on this a bit. Imagine a classic "thermal mass" scenario where you've got a house that heats up to 80F during the day and cools down to 60F at night, and you're thinking of adding a concrete slab to modulate temperature swings. Let's say that slab is 100 square feet, 10x10, and is 4" thick. It weighs about 4000 lbs. Assuming concrete has a specific heat of about 0.5, that slab is going to have a heat capacity of 2000 BTU/degree F.
The outer limit of how much that slab can serve to modulate the house is given by the daily swing -- 20F -- times the heat capacity, or 40,000 BTU per day. But it could be less, and I'll offer at least three factors that could reduce it.
The first is Siegenthaler's formula for heat transfer between interior air and a surface, which is 2.0 BTU/hr per degree for surfaces heated from below, and 0.71 BTU/hr per degree for ones heated from above. So if the slab were to heat all the way to 80F during the day, and stay there when it got to 60F at night, it could produce 40 BTU/hr/sf, or 4000 BTU/hr. And during the day, if the slab were at 60F and the room at 80F, it could absorb at most 1420 BTU/hr. Those are maximum values. Finding intermediate values would take some modeling, but it should be obvious that the slab can't just flop between 80F and 60F -- and neither can the room -- it has to go through intermediate values where the heat exchange is less. There aren't enough hours in the day to extract all of the heat out of the slab, so the rate of surface exchange could be the limiting factor.
Another potential limiting factor is the thermal resistance of the slab, the rate at which heat can flow from one end to the other.
A third limiting factor is that if the slab releases heat into a cold room or removes heat from a warm room, it changes the temperature of the room. Since the temperature flow into or out of the slab is determined by temperature difference, the more effective it is at modulating the temperature, the less it is able to do so.
So which of these three factors is going to be the limiting one? I'd say it's impossible to say without doing a detailed model. But it's pretty easy to get an idea of the outer limits.
I have to reset my password every couple of weeks and edit my profile every time, yet it still doesn't keep the spam away.
it is sad...