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Comment by shafyy | Hacker News Reader

The use of "Carbon negative" really grinds my gears. Carbon negative would mean that by building this house, you actually remove carbon from the atmosphere. No, you don't remove CO2 from the atmosphere by buliding this house.

Yes, trees remove carbon, but now you've just cut them down and released a bunch of carbon in that process (plus all the CO2 you emit, you know, building the actual house).

Edit: Ok, looking more through their website I came across this: https://www.wikihouse.cc/product They say that the upfront carbon cost of building a WikiHouse is - 17T CO2, compared to a normal house of + 30T CO2. This is so fucking misleading, I've just lost all respect for the makers of this. I think it's a great project, but once you start bullshitting like this, you can get the hell out.

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The carbon sequestered by the trees is now in the building materials. The space the trees were in will now have more trees grown in them.

The carbon from the trees is now not in the atmosphere, it's in the wood components, and won't be in the atmosphere until the wood components reach end of life and are burned/rotted/whatever.

So yes, carbon has been removed from the atmosphere. I don't understand the objection.

> The carbon sequestered by the trees is now in the building materials.

If X amount of carbon was in the trees, X amount of carbon is now in the building materials (at best). There's no further removal of carbon from the atmosphere by this alone. And all of the future carbon the trees would have sequestered is now not going to be sequestered by those trees. So more likely carbon positive than negative.

> The space the trees were in will now have more trees grown in them.

That's an assumption. And even if it were true, those trees would take years to begin to sequester the same amount of carbon that the previously existing trees did. And even then, it's not obvious that those new trees would sequester more carbon than the previous trees would have had they been allowed to continue growing.

Plus if you're going to say that building with blocks is carbon negative, you're going to have to talk about how those trees get turned into blocks, and how the overall process including that, is somehow carbon negative.

> And even if it were true, those trees would take years to begin to sequester the same amount of carbon that the previously existing trees did.

It sounds like you might be making a stock vs flow error here. Or I could be misunderstanding you.

> And even then, it's not obvious that those new trees would sequester more carbon than the previous trees would have had they been allowed to continue growing.

1. Trees slow as they grow (after a certain point).

2. Commercial tree farms exist to grow trees. If they weren't growing trees for consumption, something else would be done with that land.

> Commercial tree farms exist to grow trees. If they weren't growing trees for consumption, something else would be done with that land

Yes, for example let the natural vegetation take over, increase biodiversity, and sequester more carbon thanks to the increased biodiversity and better soil than fucking tree farms.

- Plantations aren't worse for the soil than native vegetation most of the time. Sometimes they can be better for it.

- A lot of the time plantations are planted on less productive farmland. - Not all plantations will naturally regenerate quickly back to native vegetation.

- Those trees were planted for a reason and a lot of plantations are planted on degraded farmland or scrubland.

My understanding is that older trees have accelerated carbon uptake (because of more surface area to do photosynthesis), but younger trees can be grown more closely together, increasing the total efficiency. It does seem be to unclear which approach is ultimately "better".

> That's an assumption. And even if it were true, those trees would take years to begin to sequester the same amount of carbon that the previously existing trees did. And even then, it's not obvious that those new trees would sequester more carbon than the previous trees would have had they been allowed to continue growing.

It's a very safe assumption

By “sequestering” the carbon in building materials, we’re merely kicking the can down the road by 20-30 years. At which point the house is torn down and goes off to the dump to rot away as normal.

And we’re already doing this for centuries - using wood for making buildings - so we’re merely continuing the status quo, not magically putting more carbon away suddenly.

> The carbon sequestered by the trees is now in the building materials

You're ignoring material waste. This process doesn't consume 100% of the tree; only a portion of the tree's carbon is sequestered into the building. The rest is rotting.

> The space the trees were in will now have more trees grown in them.

Trees are renewable, but it's not quite "copy&paste". Further, the harvesting of the trees was certain to be carbon intensive.

So, on the whole, you can trust this process IS NOT CARBON NEGATIVE.

What it may be is LESS CARBON INTENSIVE than a traditional process. They are VERY FAR from crossing the neutral line and yet are trying to claim carbon negative? That's pretty brash.

Does the objection make more sense now?

Despite the all caps, your objections still don't make that much sense.

> You're ignoring material waste. This process doesn't consume 100% of the tree; only a portion of the tree's carbon is sequestered into the building. The rest is rotting.

It's ply. Apart from the root system, it's quite close to 100% indeed.

> Trees are renewable, but it's not quite "copy&paste". Further, the harvesting of the trees was certain to be carbon intensive.

Tree harvesting is pretty much fine. Transport is what pollutes the most here. The new growing trees are carbon sinks. It's not a question of renewability. It's just that you used to have CO2 in the air and now it's a house. Processing will mostly use electricity so it depends of how your local electricity is produced of course.

> They are VERY FAR from crossing the neutral line

They are probably not very far. It's not an heavily mechanised project. Assembly is mostly done by hand. Considering the amount they sequester, being neutral is not that far fetched.

> It's just that you used to have CO2 in the air and now it's a house.

I disagree on your accounting (largely because the house is torn down one day and further a CNC throws wood dust everywhere and this project requires one front and center), but none of that matters. Carbon negative is a strong claim that requires strong evidence. Of which, none has been offered.

> "The rest is rotting"

Is it, though? Because operations I've been to use every last available ounce of the tree. Trunk and limbs are sawn, small limbs, branches, bark, and offcuts are ground for biomass heating. Yes, it's burnt, but releasing no more carbon than it captured in its lifecycle and to provide a tangible end result that would otherwise be achieved with fossil fuels.

Root stumps rot, yes, but providing a breeding ground for insects and hence birds and small mammals and hence predators. They also fix soil beneficial bacteria and fungi, and having spent all their energy breaking up the soil and then breaking down they prepare the best soil bed for the new tree to take its place and sequester more carbon.

It's not the perfect process, by any means, but wood as a building material is infinitely more sustainable than concrete, gypsum and stone.

> It's not the perfect process, by any means, but wood as a building material is infinitely more sustainable than concrete, gypsum and stone.

Cool, show me the part where any of that means this company has a right to claim carbon negative?

Onus isn't on me here.

That's not what I said.

I just pointed out that your emotional response that backs your argument isn't necessarily reflective of what actually happens.

Well put. If they just would say "less carbon intensive than using concrete or bricks", I would buy it. But carbon negative is just a straight up lie.

While I very much doubt if the entire process is going to be carbon negative, "straight up lie" is very strongly worded. In essence, by building wooden structures you can store CO2 in urban environments that are currently dominated by concrete. To be sure, to be carbon negative the whole process needs proper thought; the trees for the wood of course needs to be replanted and the energy used in milling, construction and transportation need to be sourced durable, I get that.

But I mean, if we want anything to be carbon negative we need to capture carbon from the atmosphere and put it somewhere; e.g. reclaiming land for forests or putting carbon back into the ground where we got it from, but putting carbon in constructions as part of the solution, why not? For dealing with climate change, the important part is getting it out of the atmosphere.

The problem is that people believe this type of greenwashing (as can be seen by other comments on this thread). Building a house is never going to be carbon negative. Carbon neutral at best, but even that is going to be almost impossible to achieve.

They say that the upfront carbon cost of building a WikiHouse is - 17T CO2, compared to a normal house of + 30T CO2. This is so fucking misleading, I've just lost all respect for the makers of this.

I'm not sure what "upfront" means here, but it makes sense if talking about overall net CO2 usage. The amount of CO2 in the atmosphere after building would be 17T less than before the tree started growing. Ie the tree absorbs 17T more during its growth than is emitted during harvesting, transport and construction. Whereas an equivalent brick building puts 30T more into the atmosphere than the (unharvested) tree absorbs.

"carbon negative" isn't BS: since the CO2 already sequestered in the wood remains there (mostly), while the trees cut down for that wood are replanted eventually capturing more CO2, thus ultimately removing more CO2 from the atmosphere than was released through the sourcing of the wood. Now considering everything involved in the building process, the house as a whole is probably not "carbon negative" -- and perhaps that's your objection -- but when it comes to the primary material (wood vs concrete/steel) it can be carbon negative.

There are few wrong assumptions with your statement:

1) The wood the house is built with will not be there forever, some day the house will be torn down and the wood burned or rotten

2) Cutting down trees and planting new ones is not a good way of carbon sequestration. Otherwise, why not cut down all trees and just plant new ones? Bam, carbon negative, climate problem solved.

People need to understand that trees should not be seen as a renewable resource in the context of climate change. Not for building, not for burning as fuel.

You’ve just asserted that this is bullshit without explaining why. Could you explain why you feel this is misleading?

I am also deeply skeptical of the net-negative claim, mostly because of the outsized role plywood appears to play in the building productions demonstrated. There are several energy-intensive steps required to manufacture plywood that are not present with standard lumber production. Additionally, transport overhead is higher due to the comparative rarity of the specialized mills used to create plywood. Unfortunately I haven't been able to find any kind of real numbers comparing the carbon footprint of lumber vs plywood to demonstrate exactly how much more carbon it takes to manufacture plywood vs lumber.

FWIW, plywood (OSB, chip board, etc) are already heavily used in house building. Floors, roofs, sheathing, etc.

Yep. And as stated by others upthread those houses are mostly designed to last about as long as OSB does under normal conditions.

I am also skeptical but I would not call the claim bullshit. Building from wood could in theory be carbon negative. Unclear though if this process is.

Another thing worth considering is that building small houses uses a lot of land, land which might have had forests. That needs to be considered too.

I've explained why pretty clearly. Trees are not a renewable resource in the context of climate change. They take dozens of years to grow, they are part of an biodiverse ecosystem, and just cutting down forests has a much bigger effect on the ecosystem and its carbon sequestration capacity than the tree alone. And don't get me started with tree farms.

This carbon negative claim taken to the extreme would mean, that we should just cut down all trees and plant new ones. I think you can see why this is ridiculous?

I wouldn't outright call it bullshit, but the cost and effort involved make it only a marginal improvement over traditional buildings. Plus it doesn't scale as good as the US based 2x4 wood system, which can be mass-produced / prefabricated much easier.

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