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Comment by shermantanktop | Hacker News Reader

Note that the walls and interior floors are equally thick and as insulated as the roof. It is not a sensible or efficient use of materials, given how the physics of heat work.

It is great, however, if your approach to construction was formed by playing Minecraft.

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Or perhaps if you're prioritizing things other than maximally efficient use of materials? It seems like they're prioritizing standardization, especially of methods, more than almost anything else.

AFAICT we have far more excess material than excess labor, so it doesn't seem particularly crazy to me?

Using a unique block construction system that 99% of builders have never used is not really in the spirit of standardization.

As for materials, for a theoretical 2 story 20Wx50Lx20H home (2000 ft^2), you have 1,000 ft^2 of roof (assuming flat) and floor, as well as 20,000 ft^2 of wall.

Cheap fiberglass insulation is $1.32 per ft^2 10 in thick (1/10/24) https://www.homedepot.com/p/Owens-Corning-R-30-Faced-Fibergl...

Assuming we use this for everything that is $29K

I'm going to pull some ratios roughly out of this article.

https://www.greenbuildingadvisor.com/article/how-much-insula...

This is in the high energy efficiency area of construction but I'm using this to illustrate the inefficiency of a standard floor/wall/roof thickness, take it with these caveats.

So if you were building to this insulation cost would be:

1,0001.32 + 20,0001.32(2/3) + 1,0001.32*(1/6) = $19K

You could view that as $10K of wasted material or, if you chose not to fill the blocks with full thickness material, calculate how much of their volume is being wasted to achieve a standardized thickness. Lots of ways to look at it but, to put it simply, I think however you look at it, it's not optimal to be unable to adjust your floor/wall/roof thickness.

Can't edit it but it should read: "1,000x1.32 + 20,000x1.32x(2/3) + 1,000x1.32x(1/6) = $19K

Is that so? Materials went crazy expensive during Covid and didn’t come back down.

Lumber, for one, went back down to prepandemic pricing.

“It is freezing honey” “I know dear, but the house was built efficiently”

Not very apt; The accusation here is that the insulation use is overkill, which just means you are installing (and paying for) more material to yield the same performance as less material.

Note that it is an open source project and you are free to adjust the parameters to your liking

Does efficient use of materials matter compared to efficient use of labour/financing to get homes built?

Electron is regularly considered a horrible waste of "materials" in the tech world. It is still sensible to use as RAM is far more abundant than tech labour.

Labour costs in construction is highly variable and situational, but 30-50% is a typical range. Material costs are a serious consideration in construction. Tradeoffs of material vs labour/capital costs have to take into consideration the specifics of the application.

Not so. If you want high thermal performance in a building, insulation (therefore thickness) is crucial in the entire building envelope. As the beardier building retrofit types say, your house needs a hat (loft insulation) boots (floor insulation) and jacket (wall insulation).

Consider this: if you're raising the temperature of your floor to say, 25C, that won't do much if you're doing so on an uninsulated floor where the temperature of the ground beneath is 10C or so. UFH at that temperature is very efficient and thermally comfortable.

Consider further that you might then have walls which let all that lovely heat out even if your ceiling and floor are well insulated. It makes sense for them to be just as good, not least because your windows will in all likelihood be the worst part of the room in terms of insulation. Having as uniform a u-value across the room (and building) makes for uniform temperatures throughout. It lends itself to using heat pumps, further raising the efficiency of the building.

Further, lifetime emissions of the building are increasingly front loaded in construction as operational emissions drop. Standardising will presumably cut down on costs as well as emissions at that stage.

Building physics is an entire subject of its own and is worth studying. I'd suggest looking at the Association of Environmentally Conscious Builders and their CarbonLite course to learn more.

They were referring to insulation in internal walls and floors. That is, the floor between the first and second story or the wall between bedrooms.

It's also clear that the floor between levels doesn't have insulation. I'm not sure where the OP got that all the blocks/insulation was the same.

Still good if you want zoning etc, but point taken

Not sure where you got that from, but their product page states:

"WikiHouse Skylark blocks include a cavity for 250mm insulation in the walls, and 350mm insulation in the roof, giving exceptional levels of thermal insulation."

In my country, central a/c is rare and heating only occupied rooms using individual a/c units is the norm. I think heavy insulation on interior walls would be great here.

It’s a pop-up so I can’t link to it, but their bit about interior walls shows them as thinner.

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