This is a video about how we design things.
It’s a video about priorities, and how
we sacrifice things like energy efficiency
for the sake of convenience and vice versa,
and why we should put meaningful consideration
towards those sacrifices we make, and the
priorities they enable.
As I’m sure you’ve gathered from the title,
we’re talking about freezers.
Well, actually, refrigeration more broadly.
But to make the point I’d like to with this
video, we’re gonna talk about
one of these little beauties.
This is a perfectly ordinary chest freezer.
It’s a box with a lid that keeps things
very cold.
Now, on its surface this isn’t remarkable
at all.
But, if you know anything about chest freezers,
you’ll know that they use an almost comically
small amount of energy to do their thing.
And the reason that’s possible is because
of their efficiency-first design.
To start, let’s consider what refrigerators
and freezers do.
Their most basic task is to move heat energy
from inside themselves to the outside world.
They’re in a constant battle with ambient
energy.
If you want there to be a space that’s colder
than its surroundings,
well you're gonna discover pretty quick that all the energy around that space
would really like to spread out
and so it will eventually find its way inside
your cold box.
Entropy’s a pernicious little monster.
The miracle of refrigeration has allowed us
to fight that impulse of nature.
Using nothing more than a compressor, a couple
of heat exchangers, a metering device, and
specific chemicals, we can say
“Screw you, entropy!”
and reverse the natural order of things.
How?
Well, we don’t need to get into the specifics
here and I know I’ve teased a video on refrigeration...
multiple times, and, uh, I’m doing that...
yet again.
I...
I really just want to find or come up with a
better demo for you all so,
sorry.
Suffice it to say that we take a chemical
and use the properties of latent heat to move
energy around on our command.
By manipulating the pressure the chemical
is under, we can change its boiling point,
and by controlling where and when it boils
and recondenses,
we can exploit the latent heat of vaporization.
The miracle of refrigeration
is that the energy we put into the system through mechanical compression of the refrigerant
is only a fraction
of the energy that the refrigerant is able to move.
In other words, say you expend 100 watts of electrical energy in a compressor of a refrigeration system.
That system is now able to move the equivalent
of 400 watts of heat energy, or possibly even more.
It’s really neat, and using refrigeration in reverse to concentrate heat energy rather than to disperse it
(we usually call this device a heat pump)
will likely be instrumental in our fight against climate change.
All we need is refrigerants with a small global
warming potential, which luckily are starting
to see commercial deployment, such as R-1234yf.
Anyway, setting aside the mechanical bits
that make the heat go out, what every single
piece of refrigeration equipment in this world
wants to do is create a thermal barrier between
its insides and the outside world.
Because no matter how miraculously efficient
your heat pump design may be,
unless you can slow the spread of energy from high concentration to low concentration,
the refrigeration device will need to run a lot, and so it will use a lot of energy.
I’m sure you’ve used one of these before.
[thud]
It’s a cooler!
The walls of the cooler are well insulated
which slows the progress of heat energy trying
to enter it.
And that lets you keep things that are inside
it colder for longer.
See, the thing you have to keep in mind is
that things that are cold
are actually devoid of energy.
Whe - I'm gonna put this down.
When you feel a cold can of your favorite
beverage from the fridge, the reason it seems
cold to you is that it’s sucking the heat
energy out of your hand,
and our bodies interpret that sudden loss of energy as a sensation of cold.
Really, your hand is warming up the can.
The can sort of steals the energy that’s
in your hand, simply because energy wants
to spread out and equalize.
Aluminum is a pretty good conductor of heat,
which makes it feel particularly cold.
If you simply take a bunch of cold cans and
put them in a grocery bag,
well the heat energy in the room
(or the environment more broadly)
 will find its way into the cans relatively unimpeded.
Air isn’t super great at heat transfer,
but it will happen.
However, if you take these cans and put them
in a cooler,
And, uh, close the lid,
well now the cooler has become a barrier.
The heat energy around the cooler has a hard
time getting through its insulated walls.
So, the cans stay colder longer.
Fill this up with ice and now you’ve got
a larger thermal mass, which means the effect
of the heat energy entering the cooler causes
a smaller temperature rise since there’s
more mass to heat up.
The upshot of which is that things stay colder
even more longerer.
And now for a fun fact.
A refrigerator or freezer is nothing more
than a fancy cooler with a small heat pump.
Side note;
here in the US we use the term heat pump to generally mean a reversible air conditioning system,
which was how I used
it earlier when I talked about how they’d
be instrumental in our fight against climate
change.
But more correctly, any refrigeration system
is a heat pump at its core.
The job of a heat pump is to concentrate and
relocate heat energy by means of a refrigerant.
Whether we use that to heat a space or cool
a space is entirely up to us.
Anyway,
The walls of the fridge are insulated just
like the cooler, and their job is to keep
the heat energy from the room it’s in from
getting inside and warming up your foodstuffs.
Now, it can’t keep heat out forever, it
can only slow the rate of heat transfer,
so we need a heat pump to run periodically so
we can force it back out.
That’s the job of the compressor.
Well, technically,
the compressor is only one part of the heat pump,
but it is the pump part.
When you hear someone talk about the compressor
in a refrigerator, this is the component that
makes the buzzy sound and makes the cool
happen.
[a click as a compressor switches on]
The compressor is compressing the gaseous refrigerant,
forcing it into a confined, high pressure heat exchanger known as the condenser
where it can release its excess heat and condense into a liquid as it does so,
all so that after
passing through a metering device,
the now liquid refrigerant may then enter the refrigerated space, where it will boil away thanks to the relief
of this new low-pressure heat exchanger called
the evaporator,
scavenging heat as it does so from inside the space and making it colder,
but I said we wouldn’t focus too much on the mechanics and here I go talking about it again so let’s move on.
One thing I’d like to highlight here is
that unless you load it up with a bunch of
warm food, the only thing your fridge is battling
is energy from the room it’s in getting inside.
Once it’s down to temperature, that is a
relative constant.
A lot of people will suggest that you avoid
an empty fridge because a larger thermal mass
inside it will make it run less frequently.
This is only kind of true.
The amount of energy entering it does not
change with the amount of food that’s inside it.
Which means it doesn’t impact how much it
needs to work.
What does actually change is how quickly energy
entering it from its exterior will cause the
inside temperature to rise.
Without a lot of thermal mass, the same energy
input causes a faster temperature gain.
So, the compressor might need to run more
frequently.
But!
That also means it won’t need to run as
long to get back down to temperature.
Again, less thermal mass means the same change
in energy causes a greater (or faster) change in temperature.
What you’re really avoiding with a fuller
fridge is short cycling,
where the compressor comes on more frequently in shorter bursts,
which could in theory lessen the life of your refrigerator, and may slightly impact its energy efficiency.
But it’s probably not as big of a deal as
you think.
So, if we want to increase the energy efficiency
of a refrigerator,
we have exactly two possible courses of action.
We can design a more efficient heat pump.
Or, we can minimize environmental heat intrusion
through better insulation design and application.
And here’s an important fact;
There aren’t that many gains we can find
in the heat pump part.
Yet, anyway.
We’ve gotten pretty good at this whole refrigeration
thing.
Even as we’ve discovered that the refrigerants
we used to use are…
not fantastic for many reasons
- thanks, Thomas Midgely Jr.! -
we’ve adapted with new chemicals and really we’ve got that part pretty much down.
But, there’s a lot we can do with the design
part.
And now we are back to the humble chest freezer.
These unassuming white basement boxes of last
year’s turkey and grandma’s popsicles
are really quite remarkable.
Why?
Because of their bonkers energy efficiency.
These are as close as you can get to a literal
cooler with a heat pump.
Because that’s just about what they are.
It’s a box.
With a lid.
With thick insulated walls.
And a small heat pump works to periodically
move heat from inside the box to outside the box,
keeping its temperature subzero cold
and regulated with the help of a thermostat.
Now if you go shopping online for a chest
freezer and you take a look at their energy
usage you might soon find that… well that’s
almost insignificant!
And, well, compared to a lot of things in
your home you’d be right!
I plugged this little chest freezer into a Kill-a-watt
to see for myself, and…
well I was stunned at how efficient this is.
When running, it only consumes about 100 watts
of power.
And over a period of three days, it consumed
just 600 watt hours per day.
Considering average US electricity prices,
this means that the operating cost of this
freezer is just over $2 per month.
That’s nothing!
I mean, seriously, if you put just one frozen
pizza in this freezer, that pizza would cost
more than an entire month’s worth of electricity supply
for its preservation.
You could put hundreds of dollars of food
in here, and preserve all of it for mere pennies a day.
Its absolutely thrifty energy consumption
means that you could power this easily from
the output of just one commercial solar panel.
A 250 watt panel getting an average of just
three hours of sun per day would take care
of it no problem, assuming there’s some
storage involved of course.
And this particular freezer isn’t even that
efficient!
All things considered it’s actually quite
lousy.
Considering this model with nearly double
its capacity
uses pretty much an identical amount of energy,
ehh this actually starts to seem
kinda bad.
But I mean it's still just two bucks!
That's impressive!
So what makes this so efficient?
Well, a couple of things.
First, this is a manual defrost freezer, meaning
it will build up frost over time and needs
periodic downtime to melt that away.
But, it doesn’t need that to occur all that
often because of the second fact
that makes it so efficient.
Its door is on the top.
Like a cooler!
Consider what happens when you open the lid.
The air inside the freezer is very, very cold.
Which means it’s very dense.
You’ve undoubtedly heard before that warm
air rises and cold air sinks.
Well, if this is full of cold air, and there
are walls on four sides holding it all in,
opening the lid does… almost nothing.
There’s a sharp temperature gradient maintained
just by the boundary between the warm air
in the room and the dense, cold air held in
the freezer.
If the door is on the front, as it is for
an upright freezer or any refrigerator,
every time you open it up the cold air inside of
it falls right out.
You’ve probably seen this happen on a humid
day when opening your freezer
- the clouds of steam you see falling down are the result
of the cold air in the freezer mixing with
the warm air in the room, pulling the water vapor out of the air and making it visible as it falls to the floor.
It literally is a cloud in your kitchen.
And of course, if all that cold air has fallen
out, it must have been replaced by the warmer,
less dense air in the room.
You’ll likely have noticed before that when
you close the door to your freezer,
the door seems to get sucked in after you close it,
making it hard to re-open immediately.
This happens because the warm air that entered
it as you browsed your Food Netflix is now
sealed in the freezer, so it cools rapidly
thanks to all the cold stuff inside,
and in effect shrinks.
This creates a dramatic pressure imbalance
between the inside and outside,
making it hard to open the door again until the pressure
equalizes.
And of course, the freezer will eventually need to work to remove that added heat energy introduced
by this warm air.
This hardly happens at all with a chest freezer.
There is some suction force when you close
the lid, but it’s very weak and very brief.
Almost unnoticeable.
That’s because hardly any new air makes it
in thanks to the literal tub full of cold, dense air.
It can’t just spill out.
Want proof?
If you get a leaf blower and shove a bunch
of the room’s air in there with hurricane force,
now when you close the lid there is
notable suction.
And it lasts quite a while.
So there you go, proof right there that the
walls of the freezer hold the cold air in place.
Seriously, if you’ve got a chest freezer
and a leaf blower, try this at home!
It’s fun!
And going back to the defrosting part, the
fact that the cold, dense air stays inside
helps minimize the need to defrost it.
In this freezer and many like it, the evaporator
(which is the part that gets cold)
is embedded in the walls of the freezer.
That means the walls get very very cold, and
moisture in the air condenses on them and
subsequently freezes.
Over time this causes ice to build up.
But, since the amount of ambient air that
enters the cooled space with each opening
is quite small, that buildup is relatively
slow.
Here’s the thing, though.
Chest freezers, as neat as they obviously are,
are not the easiest things to live with.
While they have most certainly been endorsed by
The Royal Society for Putting Things 
on Top of Other                         Things,
the fact of the matter is filling these up with food means burying some of your other food
in food.
If accessibility is at all important to you,
this design frankly sucks.
I am very happy to have a chest freezer full
of food right about now,
but getting to the food on the bottom involves a fair bit of rummaging.
And of course, that means rummaging through
ice cold food.
You might want to consider investing in a pair of warm
gloves should you decide to purchase a chest freezer.
And of course, if you want a freezer with
a larger capacity to hold food,
well in the land of chest freezers that means you need more floor space.
You can’t simply make the chest deeper...
well OK, you could, but...
good luck with that,
so instead it must be wider.
If on the other hand you have an upright freezer, you
can make the freezer taller, granting you
more interior volume with the same floor space.
And thus, we’ve circled back to the introduction.
Chest freezers are undoubtedly the best design
if energy efficiency is your main goal.
But, to achieve that goal, you must make sacrifices
in convenience.
And I think it’s OK to be unwilling to make
those sacrifices.
But, that doesn’t mean we shouldn’t think
about them.
I’d argue, as is the case for most things
in life, there's a sweet spot to be found.
That might be different from person to person,
but I think it’s a little too easy to be
swept up by what’s in and popular without
thinking about whether that actually fits your needs.
And refrigerators more broadly are just one
of many places where we see this in action.
Let’s go shopping for a fridge, shall we?
We’re gonna take a look at various models
and compare how much energy they use.
You’ll soon find that the design of the fridge has a significant impact on its energy consumption.
And let’s start with a weirdly counterintuitive
fact;
Freezers tend to use less energy than a refrigerator
of the same size.
Let’s look at this big 15 cubic foot chest
freezer.
This huge freezer still manages to use less
than a kilowatt hour per day.
And it’s a freezer.
It has to keep its insides at near zero degrees
fahrenheit, or minus 17 celsius.
All of its insides.
So its entire inside space may be fighting
a 60 or 70 degree temperature difference.
Likely more.
Now let’s look at a basic kitchen refrigerator.
This one is about the same size as our chest
freezer, just a little smaller.
Your intuition might tell you that this should
consume less energy.
After all, the bulk of its insides are at
a warmer temperature than a freezer.
It shouldn’t need to work as hard.
And yet… it actually uses more energy.
Not a lot more.
But… still more.
What’s going on?
Well, there are three basic differences here.
The use of one heat pump for two temperature
zones.
The design and weaknesses of its thermal barriers.
And whether or not the device has an automatic
defrost function.
Now, spoiler alert, that last bit is less
important than I thought it was gonna be.
It does still matter a little bit, but let’s
set it aside for now and start with the first part.
The vast vast majority of residential refrigerators
have only one heat pump.
Really, what they are is a small freezer with
an additional compartment that leeches off
the freezer a little bit to get some cold air
You’ll no doubt have noticed the whirring
of a fan at some point, and this is what that’s for.
Or at least one of them.
There may very well be multiple fans in your
fridge’s design.
And of course there are exceptions, feel free
to comment about them, it boosts engagement!
This may not seem super important.
After all, it’s a pretty clever use of resources!
Just oversize the heat pump for the freezer
a little bit, and use part of its efforts for the fridge.
But you’d be surprised how much of a difference
it makes where you put the freezer.
I mean, just compare these two fridge models.
Same overall size.
Same manufacturer.
And no difference in features, other than
the fact that the position of the freezer
and refrigerator is reversed.
The freezer-on-bottom model uses about 20%
more energy.
That’s… significant.
Now, I’ve been trying to get a firm answer
as to why this is.
At some point in the past I had heard, and it makes intuitive sense, that because cold air tends to sink
as it’s denser, it takes less added effort
to move the output from the freezer into the
refrigerator if the freezer is on the top.
Just sorta let the denser air fall down into
the fridge compartment.
Whereas if the freezer is on the bottom, or
even on the side, you need to actively move
air around to achieve the same results.
And that might take more energy.
But I couldn’t find a definitive answer
as to whether or not this is the precise case.
Regardless of the exact root cause, conventional
freezer-on-top models tend to be the most
energy efficient design.
Just take a look at the list of most efficient
refrigerators on the Energy Star website.
The vast majority are models with the freezer
on top.
There are exceptions to be found…
but not many.
And freezer placement is only one part of
the equation.
One of the more surprising things I found
was that turning the freezer into a slide-out drawer
causes another 17% increase in energy consumption.
That’s… honestly really interesting to me.
I wouldn’t think that would make much of
a difference but apparently it does.
Uh-oh! Confounding variable alert!
The bottom-drawer model has an ice maker whereas
the swing-out door one does not.
That will cause an increase in energy consumption
so long as it’s making ice since it needs
to remove energy from the water it's introducing to itself.
Without knowing the specifics of how the energy
guides account for that, it’s not necessarily
fair to assume the slidey drawery bit is what’s
making it work harder.
So… OK, specifics unclear,
but speaking of ice!
Another significant factor in a refrigerator’s
energy consumption is whether or not it has
an in-door ice dispenser.
Because, and here’s a fun fact if you've never realized this before
that means it has a hole in its door!
Yeah sure it probably has a flap or something
to seal the hole when it’s not vomiting
ice chunks into your glass at an entirely
unpredictable rate,
but a thin plastic flap does not a good thermal barrier make.
That would be a wonderful place
for ambient energy to find its way inside.
Also… how does that even work with a bottom-freezer
french door fridge?
Is there... is there...
is there like an entire...
like a, a whole ice maker inside the door?
How…
[various noises of confusion]
well anyway, this is such
an important factor in the energy consumption
of a refrigerator that it’s specifically
noted on the energy guide whether or not the
particular model has it.
It’s kind of a big deal.
But… on the other hand, is it really?
I mean, let’s look at the energy guide again.
Sure, there’s a big swing from the low end
to the high end.
But honestly, even the least energy efficient
refrigerators out there
still cost less than $8 a month to run.
It gets a little worse with bigger models,
but if you happen to have an electric water heater,
well in comparison to that… even
the worst refrigerator is peanuts.
However.
We all have refrigerators.
Lots of us have more than one.
And that means that while there’s little
noticeable difference to our individual pockets
when it comes to our electric bills,
well a hundred million refrigerators using an additional 250 kilowatt-hours per year
means that we're using another 25 Billion (!) kilowatt hours.
You can make whatever comparisons you’d
like with that figure, but the one I’ll make right now
is that if every single US citizen
who drives to work drove an electric car,
so that’s 128,000,000 cars,
based on a rather
conservative 3 miles per kilowatt-hour,
every single commuter could drive 585 miles with that extra energy, or about 3 entire weeks of commuting.
Small gains, when applied across the board,
add up a lot faster than you'd think.
Which is of course why we have regulations
regarding how much energy appliances can consume
and why utilities offer rebates for purchasing
more energy efficient appliances
but before we get too far down THAT particular opinionated path,
let me just repeat that I think it’s OK for us to accept some losses in efficiency
if it improves our lives.
The question we need ask ourselves is how
far we’re willing to take that.
As is the case for nearly everything in this
world, well there’s a happy medium.
You might be wondering why chest refrigerators
don’t exist.
Well, they almost do;
A lot of people living off the grid will convert
chest freezers into chest refrigerators
by modifying their thermostats.
I mean, if it can cool down to zero degrees, surely
it can just stop at 35
and be a wildly efficient refrigerator.
And… it can.
But the people who make this modification
do it because to them, energy consumption
is the single greatest concern.
They’re willing to make the sacrifices necessary
to achieve that end.
And more power to them!
But we don’t all need to go to that extreme.
Then again, it’s possible to end up on the
other extreme.
The most popular style of refrigerator these
days (and by that I mean the most desirable)
(whatever that means)
seems to be the french door, bottom freezer
models.
And…
well, they’re kinda the worst design
for energy efficiency.
At least, the way manufacturers build them
today.
I have no reason to think their efficiency
couldn’t be improved.
Some manufacturers like Samsung use separate
evaporators for the freezer and fridge, meaning
that while there is still only one compressor
and condenser, each compartment is in effect
cooled separately which might help reduce
energy consumption.
And in fact one of these french door, bottom
freezer models has made it on the Energy Star list.
But what does it say that the model we all
seem to lust for is also the most expensive to run?
I’m not here to pass judgement.
No matter how much I’d like to.
Because I think it’s OK for us to have different
priorities.
But I am here to suggest that we think about
them a little more.
The entire reason we have energy guides in
the first place is to encourage consumers
to make the more frugal choice.
Both for their wallet and for the environment.
If there’s anything I’d suggest we do
change, it would be that we make focusing
on that label just a little bit…
cooler.
Thanks for watching!
Yes it's still there!
And I hope that you learned something interesting
with this video, and that it gets you thinking
about your personal sacrifices and priorities.
Again, I’m not here to be judgey.
I hope you didn’t think that was what I
wanted to accomplish.
I really just want to get your mind gears
turning.
It can be easy to go above and beyond our needs every day, and I am guilty of that in many respects!
But now and again, I think it’s worth considering
reeling that back a bit.
Oh, and the thing about defrosting!
So… this is probably the main reason conventional
refrigerators use more power than a standalone freezer.
Since nobody wants to deal with defrosting
their refrigerators anymore, we design them
with means to eliminate the ice on the evaporator.
Usually this is done by running the fans while
it’s not cooling and/or using heating elements
to melt the ice.
There’s no free lunch, so that takes more
energy.
But… also it’s not anywhere near as big of a deal as
I thought.
It turns out that we have a direct comparison
between an upright freezer without auto defrost,
and one which does have auto-defrost.
And it’s not as dramatic a difference as
I thought it would be.
Indeed, the freezer still manages to use less
power than most refrigerators of a similar size.
So… that’s why I left it for herea at the end!
I would never suggest anyone look for a manual-defrost
kitchen refrigerator, if they even exist,
because I would not wish that burden on anyone.
And now, the bloopers!
♫ chillingly smooth jazz ♫
I believe you all have a right to know that
I have been wearing Simpsons Christmas pajamas
during the filming of this video
It’s a cooler.
The wall ---
Oversi -- overheat the size pump.
I almost said that.
I didn’t!
But then it got in my brain.
And then I couldn’t keep going.
...inside of it falls right out… that fff
there was a weird noise on the f there!
Yeah that sentence is a… ooo, why did I
write it like that?
I’ll try to rework it on the fly, which
always goes….
Great.
Nope.
I said “enser” not “enter”
and…
gotta start over
Most desirable….
desirable.
ahh, I was saying desired and then I read
what the real word was and then I Realized
“abort!”
so was this video cool, or what?
I'm particulary fond of the part where we talked about freezers.
Also, no iMacs were harmed in the making of this video.
