The Simple Genius of a Prefabricated House – My Net Zero Home Build

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A portion of this video is brought to you
by Surfshark. I’m in the process of building a new energy
efficient, net zero modular home that’s being built in a factory. Why did I choose this path versus one of the
many other sustainable and energy efficient methods like stick built passive homes, ICF,
earthships, etc. (fill in your favorite technique)? There’s no one right way to do this, but
I think the best way to walk through why I went the path I did is to show you how Unity
Homes builds their houses.

This may spur ideas for yourself. I had the chance to see my house’s wall
panels getting built in the factory and to say it was cool would be an understatement. After seeing this, you might see why factory
building energy efficient homes and buildings might be a good path for the future. Before getting into the factory tour just
a quick recap of what’s happening here. In my previous home build video I walked through
the high level overview of what I’m doing and why.

In short, I’m trying to build an energy
efficient net zero home, which means a house that generates as much electricity as it uses
over the course of a year. I’m a big fan of passive houses, but didn’t
want to go through all of the logistical hurdles of getting actual passive house certification. That’s when I zeroed in on factory built
modular homes that have proven they can hit that level of performance with some additional
benefits. I’ll get to those in a bit, but at a high
level here is how the process works. In my case I’m working with the company,
Unity Homes, which is an offshoot of the company, Bensonwood Homes. In principle the two companies share the same
prefab, factory built methodology, but Bensonwood is on the full custom design, high end homes
side of the spectrum. They do everything from homes to office buildings. Unity is the more affordable, modular approach
side of things, which uses the same sustainable, and energy efficient principles. In fact, both Bensonwood and Unity projects
are built in their facility in Keene, NH. And before I go on, I hate that I have to
state this, but to head off the overly skeptical folks in the crowd, I have no business relationship
with Unity or Bensonwood other than being a customer who paid full price for the home
they’re building for me.

That said, it’s a really cool company that’s
the brainchild of Tedd Benson. The way it works is that you select from one
of five base models. From there you can actually customize it a
fair amount to dial it into what you want and need out of the home. The benefit of this approach is to drive down
costs. > “Unity is really completely focused on
making high performance, high quality buildings more affordable and more accessible. And so, in the Unity constellation, we have
developed five different platforms to standardize enough about the building that we can bring
costs down in the design process, in the construction process.” In our case we went with the Xyla model and
customized the design.

It’s kind of like lego blocks, so you can
flip things around, add an additional module, and dial things in to what works for you. For my wife and I, we added a connector between
the main house and an attached garage, which has my studio built off the back of it. There’s a whole bunch of reasons I did that
for my studio, which I’ll get into in future videos. I was impressed with how much we were able
to customize it within just the Xyla base plan.

At this point is when the design transitions
over to what they call virtual fabrication, which is probably one of the most important
aspects of Unity’s system. It shouldn’t be a surprise that all of this
is designed in CAD software, which is computer assisted design. However, Unity’s virtual fabrication process
is a little more sophisticated. > “One of the key elements is that we actually
build a digital twin of the building in the virtual world. And in that digital twin, everything is there. The infrastructure is there, for the mechanical
systems, the foundation is there, right down to trim and other finish elements are in that
virtual model.” Everything is in this virtual model, right
down every bolt. It takes the idea of measure twice, cut once
to a whole other level. Here’s what my model looks like… > “This is the solid model. If I was to turn it into a wire frame model,
you've got every piece.” > “So you've got sleeves, because this is
an insulated panel, you now have sleeves to get wiring to the exterior for exterior lighting
outlets … how are we going to get wiring to your office and your studio from the electrical
panels inside the building envelope?” > “We think that far ahead, so you don't
have to drill your own and make a mess.” > “We actually take the 3D model before
it gets to this elaborate stage, and cut sections at the critical areas … we do a longitude
and a latitude section cut to see what that looks like.

We'll add them to the plans. We'll call out critical code requirements,
a certain amount of insulation in your attic. Any floor changes that have to happen between,
say, the garage and the main house.” Every aspect of the house is checked, rechecked,
and checked again. I’ve talked about digital twins in other
videos, but it’s pretty cool to see this applied to building a house.

Once everything is approved this virtual model
is what’s used for the factory build. Jay Lepple, who runs production at the Keene
facility, walked me around the floor to see my house getting built. But before seeing the factory in action, I’d
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supporting the channel. Now back to the factory floor with Jay. > “Over here, we can see your project, actually. What we do is we break up the panels into
these simple, 3D geometric shapes, and we break up the whole building. We've got our exterior walls, our interior
walls, all of our truss and sheathing, and all of our open exterior things, which are
uninsulated. That could be ceilings, exterior roofs.” > “The reason we do this is so that we know,
first of all, it's our batch size. This is what we produce.

We can produce this, while we're producing
this, and while we're producing this, so we know what our CNC machines are cutting. Also, it informs us … it's always color-coordinated
as we are going to raise the building on-site, so it says, "Here's our first bundle, our
first panels. This is where we're going to start." It also informs us on our trucking and how
many trucks we need to get all the product to the site.” > “Moving over here, we have all of our
bulk inventory for the process, production app and on-site. You'll see all the bulk inventory, and once
a day, a person goes around and grabs the supplies. We have about 20 satellite carts, we call
them, out on the shop floor. This allows us to just have just in time delivery
and not overstock too much material or products, whether it be tapes, fasteners, anything that's
going to the site or the different stations here.” > “As we move through here, you're going
to see some large, engineered lumber.

A lot of this is used on your house, but this
is a little different than going to the downtown lumberyard where we have 16-foot material
being grabbed in your pickup truck. This is all 36-foot long stock that's procured
from Canada … the reason we use engineered material is because of our CNC equipment,
it becomes way more accurate to control the length of everything and to cut it, to drill
it for all the CNC processes.” This was the first area that drove home the
scale of production they’re working with. Since they know the exact amount of cut material
needed for my project, there’s very little waste.

You’re not having to buy extra wood just
for my project that may be tossed at the end of the project. This wood spans multiple projects, which helps
to reduce waste. It also means that they can buy at scale and
save on costs. This also ties right back to the virtual fabrication
model I showed earlier. Jay showed me how that translates to the factory
floor. > “What happens with those simple, geometric
shapes is there's an element routine or an algorithm that's run on this, and it automatically
knows where the door ROs are going to be, the jacks, the king studs, our headers, depending
on what type of wall component it is.” > “Right.” > “If I were to click here, this just gives
me all the attributes. It tells me it's a nine and a half inch I-joist. It's got the production number, which they
need for the shop drawings on the floor … it gives us all these different attributes that
are either color coded for the machine, or the job, or the numbers.

Then that results in a direct export to this
machine behind me here.” > “It has a giant saw blade that's able
to cut it down. Then in the front there, there's a revolver
mill, and end mill, and that's doing all the different functions, whether it be drilling
or shaping.” The benefit of using a CNC machine to produce
the parts like this is that it simplifies the assembly and can reduce the number of
parts you need. > “While we don't have all the shaping techniques
on that piece, we have a lot on something like this, our SC1 operator did for me, and
you can see at the top. That's a tenon that's done with a revolver
mill. This is also just taking out huge forms of
wood. Instead of putting in blocking in-between
studs now, they can actually take material out of the studs and put a whole linear piece
of blocking in, which just makes it really easy, and it obviously puts right where it
goes on it.

You don't have to think about that.” > “Then I always have this to show people. Just if you could imagine this being a ledger
up on the wall mounted to the wall, and this being roof rafters for a screened porch or
something like this, this takes out a lot of the guess work. Nobody's running the tape measure. This is an engineered joint. They don't have to pull out the tape, mark
the joint. It's already there.” > “This goes into that piece, so it's like
a puzzle, and you just put three stick nails in it and it's done. I don't have to then have procurement order
joist hangers. They don't have to find the joist hangers,
bring them to the correct spot, nail them all off, so there's a lot of intelligence
built in, and our engineering is very involved with all that to get us some standard specs
that we can always use.” This is when Jay walked me further down the
line to see some of my wall panels getting produced.

Along the way he took a second to walk me
through what sets Unity’s wall design apart. > “When we get to passive house levels with
totally thermal bridge free assemblies, I can show you a little something right here
that can explain a little bit of the process upfront. If we could just take a look at this section,
we've got a framing layer, which we use an I-joist on your wall. We've got our interior seven-sixteenths OSB,
which is our vapor control layer, and then we have a 2×3 stud that allows us to run all
of our mechanicals in terms of wiring and things like that. You'll see that a little better.” There’s a bit to unpack there, but in short
they use 9 inch I-beams as studs.

This reduces the amount of material needed,
but the I-beam also reduces the thermal bridging. Zip sheathing, which acts as a vapor barrier,
is used on both sides of the I-beam with densely packed cellulose insulation in between (we’ll
see that process in a bit). And then on the inside of the wall panel they
place 2×3 studs to give space for running electrical and plumbing and attaching drywall. > “What Matt's going to do is he's just
going to start extruding this wall panel, and putting the studs on there.” All of the material you see Matt using on
this process is right there with rollers to make it easy to pull onto the line. Guides that help him make sure the alignment
is right and then the machine can saw and nail away on its own. > “That's also a direct export from our
CAD software to these machines, so there's no XY conversion or anything like that.

It's right to the machine. He just pumped up these air cylinders here
to get that assembly, and he just pops them back down, pushes it in place, and it just
… keeps firing off those stick nails right there.” After this step we followed the wall panel
to the next station on the line which is where they apply the Zip sheathing. Not only does this act as their vapor barrier,
but it also doubles as structure. > “Not only is it for the vapor control
layer, but we do this on both sides to be resilient and have a robust product being
done on-site.

Because if we see a small amount of weather,
we don't want any leaching into our panels with rain or anything like that.” > “You can see, again, ergonomically, he's
able to use this with a vacuum lift and pull sheaths. These guys do a lot of sheaths. Every day, we have five of these within the
facility.” > “What he's doing, he's tacking the last
piece of sheathing and, I believe, he then has one more little piece. Then this machine is a giant bridge that runs
over the top of this, and it will be nailing in its own pattern. It's a little wild how it nails, but it's
got two nailers on it, and then it has a router on it, so it nails everything off to spec.” Okay, so Jay said the machine that runs over
the top was “a little wild” … he was right … but he left out how loud it is.

It was kind of like watching a gigantic, terrifying
ink jet printer that shoots nails instead of ink. > “We actually have tandem ones going now
behind us as well. It looks as if it's starting with the bottom
and top plate, and then it's going around on these various different things. I don't know why, but it's going through all
the code of how it wants to nail, and that's just automatically exported in that way.” > “It's figuring out the best way to do
it?” > “Yeah.

After this is all done, the router will go
around, and these guys, they're getting so good at this now that that routing is exact,
which means that framing underneath really needs to be exact as well, or else it's not
going to look the same.” After that craziness the machine moved on
to routing out the windows, sconce boxes, and other cutouts. > “If we move down here, we can see after
this gets taped, we actually, right behind it, grab the open built layer. That'll be dragged up top here and nailed

That's actually what Evan has done here already. This has been dragged up. It's all been taped off. Even the penetrations have been taped off
just to make sure, again, that those blower door test numbers are going to work out.” > “We know it's going to be foamed later,
so we're not worried about it. We just got to make sure that when we run
the blower door test. You can see, these are 2x3s that are put in
with a five-inch nail on the studs. You can see with the SC3, we're hogging out
channels for the Romex, and so the electrician team just come in and fish wire, rather than
drilling every single stud through there.” Jumping in again here.

As I’ve mentioned before about the Passive
House standard, one of the key elements is to reduce thermal bridging through the thermal
envelope of the house. A stud in your wall can act as a thermal bridge
because it will transfer the heat through the wood bypassing any insulation you have
in between those studs. The level of thought and engineering that’s
gone into the Unity design to help account for thermal bridging was really driven home
to me at this part of the tour when Jay explained how the walls are attached to the foundation. > “I don't know if we can see it on this

Yeah, there's little holes on the bottom of
here. We actually, when this is done, we put a PT
piece of plywood that stitched this framing member and this framing member together.” > “Together, okay.” > “Then when we're at your jobsite with
the foundation and we're snapping lines, these panels will fly in with the crane. After layout, we can just go right to town
with drilling this into the concrete through these holes at every two-foot on center, and
drilling and tightening into the concrete, so we actually don't have J-bolts sticking
out of the foundation where they're somewhere inside the envelope.

They're actually all the way inside the envelope,
so not dealing with any thermal conductivity in and out.” The level of thought that’s gone into the
placement of a bolt to help reduce thermal bridging. Kind of incredible. Anyway, at this point the wall is flipped
from the interior side to the exterior side so they can inject the insulation into the
wall panel. > “This is an ISOCELL machine that has six
different ports in it … we have preset recipes within this tablet right here, either on the
platen or right on that iPad right there, and it allows us to deal with different depths,
different size cavities in length and width.” > “When I say preset recipes, that's for
getting the correct density.

He has a chart above the tablet there that
tells us what the density requirements are for each square foot, or sorry, cubic foot. We actually take core samples, that's part
of our checklist, and weigh them with that tube that he's got right there. He weighs them to make sure he's within the
density requirements for that size cavity.” > “Right.” > “We try to get, typical density is 3.5
per cubic foot. We try to get a little higher than that. We're putting these vertically. They're being driven over the road, kind of
an agitator, and so we try to make sure we go a little bit more dense so there's no settling
that occurs.” If you’re curious what the insulation value,
or R value, is when the wall is complete, it will be R-35. So after the insulation it has more sheathing
applied and nailed down, then taped to get an airtight and waterproof seal.

After that’s all complete the wall is stood
upright and slid onto a track where the triple paned, European style doors and windows are
installed. > “These are tilt, turn mid-mount windows,
and what we're able to do with these, these are some of your fixed windows, but we'll
see some operable ones in a minute. We're able to take these fixed units, you
can see this suction cup machine right here, this lifter, this is a heavy lift window. This is triple glazed, two guys minimum, or
they might get hurt, so we have this nice vacuum lifter. We actually can pick this up and pre-tape
all of the frame here.” > “Then what it would look like then is this. We would foam all of this. We've got an easy-opening window. You want to try out your window?” > “I do want to try out my window. I’ve got to try this out. This is pretty cool.” > “We actually have a door installed over
here.” > “Oh, this is a living room wall.” > “See, you know it.” > “I know exactly where this is.” > “Yup. Again, we've got a tilt, turn window but now
we have a swing door here that's ready to go.

This is a little different. This is hard in the panelized world, so we
actually create what we call a door buck. There's actually going to be a knockout in
your foundation.” Am I weird for being super excited for those
European style, triple glazed, tilt/turn windows? After all of the panels were completed, they
were packaged up, wrapped, and set aside for final delivery. As you can see from their process, they’re
applying building science to build more sustainable, energy efficient homes, in a more cost efficient
way. In a general sense, when you can improve mass
manufacturing of pretty much anything, you can drive down the costs to make it. It’s no different when it comes to building
a home like this or the latest smartphone.

If you were building a home from scratch on
site to the same specifications, it would be more expensive to produce than using the
methods Unity is doing inside a climate controlled facility. You don’t have to worry about weather impacting
production, the materials you’re using, or excess waste. However, as I mentioned near the beginning,
one of the things that sets this whole process apart is the virtual fabrication.

When I asked Tedd Benson what was next for
Unity, he mentioned this… > “We're developing a software platform
to make this automation that you're seeing in the actual production of panels and so
on. We want to bring that into the software world
so that when you produce a plan, it is ready for production. So that's been a big project of ours for quite
a few years. And for the last three years, we've actually
had a development team on the project. And we're going to bring a new company to
market in the next year.” > “Is that software going to be available
to other companies to take advantage of?” > “Yes. Yep. Yeah.” > “That's fantastic.” > “It'll be open source, and we'll certainly
be connected to the development of it, but one important aspect of it is that it will
certainly be neutral and available to other companies like ours, even the competitors
and to others in the marketplace, architects, and builders, and developers, and supplier
manufacturers as well.” Tedd has been trying to push the building
industry forward for decades now to build resilient, long lasting, sustainable homes.

The fact they’ll be open sourcing this software
for anyone to use, shows that commitment. After seeing this in person, my main thought
was, “why aren’t we doing this everywhere?” There’s still a lot more to come for my
net zero home build, including everything from drilling for my geothermal well, the
on-site assembly and finishing of everything from the factory, solar and battery storage,
etc. Stay tuned because there’s a lot more to
come. So what do you think? Do you think systems like this are the way
to go for construction? Jump into the comments and let me know and
be sure to check out my follow up podcast Still TBD where we’ll be discussing some
of your feedback, and for more of my interview with Tedd. If you liked this video, be sure to check
out one of these videos over here. And a huge thank you to Tedd, Jay, and the
rest of the Unity team for inviting me in to see my house getting built. Every single person I had a chance to meet
was amazing.

It was an incredible experience. And thanks to all of you for watching. I’ll see you in the next one..

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