Share your fav environmentally-friendly building tech!
We've all heard about solar PV panels, but that's not the be-all and end-all of technologies which could make buildings more efficient and less harmful to their environments. May I ask what else have folks got up their sleeves?
Dimensions of environmental friendliness
All good technical discussions start with a host of term definitions and context statements, so I'll attempt to start this one off on strong footing! I figure that anything which checks one or more of these checkboxes (reasoning included) works, but please feel free to colour outside of the lines -- this is just a kicking off point. Note that anti-ticking a checkbox is fine; everything has trade-offs, and sometimes paired solutions can negate each others' downsides. Magnitude is always a factor, too, since this field is rarely black and white.
(no need to bring receipts, mind; I'm sure we can keep this light hearted so as to avoid digging into comparative EPD critiques :3)
- Low embodied carbon (the kgCO2e emitted per a cradle-to-grave analysis (EPD, often) of a product),
- Low operational resource consumption (anything which works as well as an inefficient equivalent, but uses less energy/consumables -- LED vs. incandescent bulbs, heat pumps vs. nat gas furnaces, insulation vs. no insulation, etc.),
- Includes water conservation, too!
- Durability over design life (per the Canadian Wood Council (they're ... a little biased), the median service life of buildings is <90 years, so adjust amortization periods accordingly),
- Includes things like wildlife-urban interface-safe materials, as well as clay bricks and whatnot.
- Sustainability (if we can't do it for more than a century, let alone a few decades, it's probably not worth the sunk costs),
- Low environmental toxicity (no point trying to save the environment if it's all a toxic swamp afterwards),
- Supportive of local ecology (built environments tend to be biodiversity deserts -- cobblestone boulevards, brick walk ups, and tin roofs are hostile everything but pigeons and rats. Think native planting, green retaining walls, planted pavers, etc.).
(full disclosure: I'm probably going to borrow several of these at some point, so this is a half-discussion, half-I'm-outsourcing-my-research post 😅 hopefully that's acceptable ...)
I've been looking into this a bunch, so I'll cut myself off at three categories to avoid blowing hours on this. But it's, if nothing else, a nice opportunity to brain dump after all this time 😅 (and hopefully chat with interested folks about it!)
Structural
Landscaping
Water
Of these the concrete free slab on ground is the most novel (and the only one I haven't heard of) and from my point of view over here, the most nuts. At first glance I can't understand why they are spending so much effort avoiding a standard lightweight timber framed floor with vented space under. It has some of the disadvantages of a concrete slab on ground, such as the difficulty of later moving things like plumbing and electrics, combined with some new disadvantages, such as the vulnerability of the membrane, only 38mm under the top of the "slab". The article indicates that they believe they get better thermal performance than with a normal ventilated lightweight floor but I have trouble immediately imagining why this would be.
Aah, you're certainly more up to date than I, then!
Re. the concrete free slab on grade, I was mostly looking into it so as to easily accomplish a level entry, while keeping embodied carbon lower. I'd imagine it'd be easier to make more rigid, too, in case bearing strength is important (e.g. storing heavy equipment -- I was looking into it for a workshop)? On top of your concerns, I'd also add that it's not code compliant anywhere I've looked, so it'll require some ... convincing of the relevant authorities 😅
My guess is that it's just similar to something they were already doing (a concrete slab on grade) so it was easier to get their trades and customers onboard?
Hrm. I've been trying to link people at least one new, weird sustainable building thing, but I get the impression you're likely to have seen all of these XD hmmm. OK here are a few for anyone else reading, but please feel free to share something you figure I haven't seen!
I shouldn't say I've heard of them all, I certainly haven't heard of each initiative, but many are new ways to implement very old tech - borated timber is a long standing treatment, but I couldn't tell you any companies doing it, for example. I've never heard of carbicrete but I'm broadly aware of efforts to decarbonise concrete. Etc.
The ply on ground would have very low deflection but don't muddle up deflection with load bearing capacity. They are usually related but aren't the same thing. In a workshop not being built under a permit I'd consider trying something like it for the hell of it. Getting a permit for it would essentially be impossible.
Acetylated timber is actually quite common here in windows and doors, it is extremely durable. It's also very expensive, which is why that's all it's used for. The brand name is Accoya.
Uncommented, because not able to focus, but interesting tech anyway:
Hempcrete! Basically concrete with hemp and lime added to it. It’s added to the point that the concrete is less sturdy but it makes it into a carbon sink and more importantly it reduces sound and heat transfer, meaning it’s a great way to insulate a house.
Aircrete is another interesting innovation in concrete. It basically adds soap foam in place of an aggregate. It has somewhat similar properties to hempcrete but it’s not quite as environmentally sound.
Mmhm, those're both pretty great! IIRC another advantage of any lime-based cementitious structure is that it tends to be self healing, too, so you don't wind up with unslightly/water intrusive cracks. Plus, hempcrete has all that extra fibre reinforcement which can help cut down on cracking as well.
You may be interested in autoclaved aerated concrete, too, if that's your jam! It's kind of an evolution of aircrete, where -- because it's poured in factory controlled conditions -- it can be relied on to have specific, engineered structural properties (although per that article it still has had failures).
IMO I figure that cementitious products shine best as exterior cladding: that way you have a hard wearing, fire resistant surface, and can get the best of both worlds (i.e. use structural wood where it's protected from decay, and use non-structural cementitious panels where it need not support anything other than its own weight). It's also cheaper, which helps!
These are all awesome, but my favorite tech is still just putting a tree where it shades your house in the summer and lets all the light in once the leaves fall off.
Ach, sorry for not getting to these sooner!
That's definitely cool! I've been in love with the idea of a big deciduous tree in the backyard, cooling the house in the summer, and (ideally) providing a snack of some fruits or whatnot in the harvest season (not to mention all the free leaf browns for compost!)
One of the concerns in my area, though, are wildfires: the same dense tree cover that makes for an excellent sunshade can also readily catch embers and cause fires to jump up (broadly: slowing down wildfires is a game of removing ground-level fuel sources, and preventing ground fires from spreading "up" into a canopy). In those situations -- or in urban buildings/second storey structures, where planting isn't (easily) possible -- exterior venetian blinds are a decent alternative! I think there are some that're rated for high winds and actual wildfires, too, in order to protect windows like a shutter would? They're a pretty fantastic piece of technology which doesn't seem to have penetrated the North American market very well, but hopefully that'll change in the coming decades.
This is more of an indirectly/adjacent environmentally-friendly one, but you may be curious about Passive houses.
Here’s a quite cool video showcasing some techniques which allow these houses to use little to no external energy while in use (so AFAICT this is mostly about after construction has finished).
I am indeed, thank you! I think the various passive house standards (passivhaus, PHIUS, etc.) are fantastic, and imo definitely fit in the "low operational resource consumption" category :D
A bunch of this has been getting folded into local building standards, too, which has been neat to see: British Columbia (Canada (we're up near Washington state)), for example, will require net-zero construction as of 2032, and has a progressively tightening building code to enforce it. I'm admittedly a little biased and would like to see more work in this area, since the passivhaus/PHI standards were first set thirty+ years ago now.
One example: the CMHC (Canadian Mortgage and Housing Corporation) ran a contest to find/build a healthy home -- one that tried to push the boundaries and do the most ecologically friendly things possible. A Toronto house wound up winning: on an infill lot (i.e. splitting up an existing property in the burbs, basically), they managed to be net-zero energy (photovoltaics) and nearly-net-zero water (onsite water recycling), while also keeping the occupants healthy with good ventilation, a solid material palette, and architectural best practices. In 1992.
A bunch of research has been done into building super-insulating and air sealing residential homes, ensuring that they could run through the coldest Canadian winters, without breaking a sweat. We figured out construction best practices that could be built by any carpenter (with a little adjustment) and at a very low cost to the entire building (we're talking a percentage point of overall price, if even). In the 1980s.
In closing, as I step down from my soap box (sorry), I think that passive houses are very cool! We should absolutely do them, and then continue on to the next thing, since there's still waaaaay more work to be done :3
Thanks, there's a bit of interesting reading I'll be doing as a result of your list.
I may have more to say later but here's a quick couple:
Micropile footings Put a little steel plate on the ground and jack hammer pins through it. Call it a footing. I've used them, they work well, are very stable and are cheaper than bored piers. They work quite well on sites with a moderate level of floaters, unlike things like screw piles. There's more than one manufacturer, I've just linked to one product.
Straw building panels These are old tech, they used to be called Stramit panels here, I think the tech came from Sweden or something originally? Good for partitions and some other things. I wish they were more insulative.
Re. micropile footings, that's neat! I didn't realize it was a broad product category -- we have Diamond Piers up here, but I've never had any first hand experience.
I've been trying to add wee bits of additional links when people respond, but I don't have much else to contribute re. footing tech 😅 I suppose vibro-aggregate piers are an interesting solution to a problem I'm unlikely to ever deal with (they seem like they're only for relatively heavy structures, on relatively poor soils), but are an ecologically friendly alternative to tonnes of steel or concrete! Just a bunch of carefully placed aggregate in a hole.
Re. straw building panels, I'm super jealous! I was trying really hard to source something similar in Canada, but afaict nothing's on the market (without a crazy markup, and made out of hemp).
May I ask why it'd help for it to be insulating? I suppose I expected that they'd be e.g. 5/8" (15.9mm?) thick -- like gypsum boards -- and even replacing them with foam would only get you a couple of additional R-value in the wall assembly. Perhaps you're in an intense climate, and would appreciate every little boost possible?
Let's say you've got an old solid 230 or 350mm brick wall that needs to hit the usual R2.5 ish value in a renovation. (My R values, probably not yours and not European u values either. Why can't we standardise this?) If you've got any sense you'll bear in mind the need for such a wall to breathe and not put foam on it. If I could put some stand-offs on the wall, pin any services to it and then just stand up a panel that was both insulation and wall lining, with no battening or other structure needed, I'd be very happy indeed.
Hah, yeep, it's pretty great XD we're stuck with the Imperial units (sqft*h*F/Btu) and it looks like y'all're on the metric system (m^2*K/W). The best part is that we don't even agree with the Americans: our R-values are the same, but we report in metric U-factors vs. their Imperial units (BTU/(h*sqft*F)). I have to use peoples' accents to figure out what unit they're using, when watching videos XD
Re. insulation in wall cavities, makes sense! I'm glad I don't need to worry about structural brick walls; that sounds like a pain to deal with 😅 (especially around moisture ingress and air sealing!)
(for context, our code minimum walls are now R-22 -- so I think that's R-3.9 ish equivalent? Hopefully you get some benefit from that thermal mass, though)
Bear in mind the temperature here gets below freezing, for about five minutes, roughly once a decade. Our code is generally performance based and an energy simulation of the building is used to generate the build requirements but R2.5 to 2.7 is a common wall value.
Mmhm, makes sense! Definitely cool to hear how they do it elsewhere in the world; it'd be nice to see more folks here try to follow our performance targets instead of the prescriptive code.
I don't have something specific but I follow a guy on YouTube that does a lot of this Matt Risinger https://youtube.com/@buildshow?si=LBNeJ00ajkZtfkyi