July 13, 2010 • 24 mins
Are you stuck in the city, sweltering under the summer heat and missing the trees and grass of the natural world? Then why not transform the nearest rooftop into a garden or a park? Tune in and learn more about green roofs in this podcast.
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Episode Transcript
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Speaker 1 (00:00):
Yeah, welcome to Stuff from the Science Lab from how
stuff works dot com. Wow, hey guys, a welcome podcast.
This is Alice Manauth, the science editor at how staff
works dot com. And this is Robert Lamb, science writer
(00:20):
at how stuff works dot com. And since you guys
are listening to us, you often can't tell what shenanigans
were up to here at the house Stuff Works headquarters
in Atlanta. But one of the shenanigans we have going
on is a grilla gardening escapade. And you can talk
a little bit more about this than I can. Yeah,
a few of our co workers, um Mark, Candice and
Marie um set out to occupy our empty planners out
(00:44):
on the patio. We have a five of these things,
like big concrete monstrosities, and for like over a year,
all they've had in them have been dirt and uh,
like a few weeds and people have been I was
actually like occasionally composting like an apple core out there.
So we had a few like doomed apple trees and
you know, coming out and occasionally someone thrown orange peel
(01:05):
in or or sadly a cigarette. But but that was
all and bet I know who that was. Yeah, yeah,
I think we probably both do. But but anyway, nobody's
doing anything with it. And for there was some rumblings like, hey,
you know, we should go out here and plant this,
because for a while you're like, oh, well, maybe you know,
somebody else is gonna do it, maybe like the building's
gonna take care of it. But they're not. So they
set out. They brought in some soil, they brought in
(01:26):
some some seeds and planet like some you know, it's
like tomatoes and basil and all this and lo and
behold it's sprouted and you can go out there now
and we have planners full of green things. However, if
you walk out on the patio, you know, right now,
in the heat of the Georgia summer, it's gonna be
a whopper. The sun is going to blast your face
(01:48):
off and the heat hits you almost like a physical force. Yeah,
it just it makes you slow and it makes you stupid,
which which we found out at the Discover Your Impact
day last week when we did this service project, right
right when we were digging in the dirt. Yeah, it
just makes you Like I was having a conversation with
one of our coworkers about how we used to have
offices on the eleventh floor. But now we're in and
(02:09):
uh and how I wasn't sure if we had something
on sixteen, but I was just saying fifteen for everyone,
So it was really confusing for him and I, you know,
it's just hapt your brain. But the thing is, it's
like if you walk out on that patio after the
sun has gone down, it's still hot because there's all
that heat still emanating up off the concrete. Robert. That
has a scientific name, doesn't it. Yes, that is the
(02:30):
heat island effect. Yeah, And like you might imagine, the
heat island effect is something that's largely confined to cities.
And why because cities are, of course mostly man made structures.
Cities are made with materials that often have low albedos, right,
or the ability of objects to reflect solar radiation. So
the classic example, I think, if you're wearing a white
T shirt, it's going to have high albedo, and a
(02:52):
black T shirt has low albedo, And cities are a
lot like those black T shirts, right. And when you
think about it, I mean, what is the city it's
you know, oh, it's asphalt that that absorbs all that heat.
It's um you know, city buildings, it's tenements, it's all
this stuff. It's enormous parking lots full of full of
you know, just black asphalt. And then of course you're
(03:13):
suffering from a lack of vegetation unless maybe you do
have a lot of green roofs or guerrilla gardening going
on in your particular city. And so that means cities
don't benefit from the cooling effects of something called evapo transporation.
And evapo transporation facilitates more cooling by using heat to
evaporate water from the whatever you're you're growing the plants
in and the plant surfaces. So this is kind of
(03:34):
a handy process that we like a lot of appo transporation, right,
not happening so much in the cities, right. But yeah,
back to the patio. The patio is not a green
roof today. We're talking about green roofs. Yes, indeed, the
patio is just you know, it's good. It's it's a
it's a great thing we're doing out there. Uh you know,
it's it's making things a little prettier. Air qualities maybe
(03:55):
a little better, but maybe with some fresh tomatoes with lunch. Yeah,
But but no green roof is something um a little different, right,
So what is a green roof? I mean, on a
basic level, it's really just a layer of vegetation on
a home, on a commercial building, any structure with the roof, basically,
unless the roof is so pitched that having a green
(04:16):
roof would be impossible. Yeah, and may I know maybe
if you had like a f roof, you could like
grow things in it. I suppose so, And we could
be talking about anything from just putting groundcover up on
top of the roof to building a huge park. And
I think when most of us think things like green roofs,
we think of, you know, this lush setting. We think of,
you know, lots of plants. We think a little walk ways,
(04:38):
We think of a bench maybe to sit down and
eat your tuna fish sandwich. What's the one in Chicago
that looks amazing Chicago City Hall? Yeah, Like you see
pictures of that and it's like it's like an eden
up there. It's like the hanging you know, gardens of Babylon.
You can imagine Chicago. You can imagine what was the
mayor daily the governor. Yeah, you can just imagine him
(05:00):
up there, like being fed grapes as you like reclined
on something. You know, that's exactly what I think of, right,
So in that and that can be a green roof,
but not necessarily right, So that kind of roof that
we're talking about, this lush setting is going to be
an intensive green roof. And there are really two main types.
So intensive is one, and uh, it's gonna be park
(05:22):
like like we're getting at. And it's also going to
be a heavier load to bear on the underlying structure.
I mean, after all, you're gonna have people chomping around
up there, and uh, it's going to be more costly,
and of course you'll need an irrigation system for all
those plants, those lovely plants you'll have. But so you
still want to do a green roof, but maybe you're
not interested in something so extraordinary. So yeah, so in
(05:45):
that case, you go with what they call an extensive
green roof, right, less maintenance, it's less lush, and you're
gonna have substrate between less than an inch and six inches.
And all they mean here is think about the level
that you're going to go down to plant. Right, that's
where we're at. That's what we're talking about. With a substrate,
think of your vegetative layer and then all the way
down to uh the actual roof lair. So if you
(06:07):
think of that distance, um, with an extensive green roof,
that distance is going to be about six inches, whereas
if you have an intensive green roof, the vegetation can
go down to about four ft. I've seen Yeah, I
actually got to see an extensive green roof last week
at the Woodroof Arts Center here in Atlanta, right and
you've blogged about it too. There are pictures of it.
(06:27):
What I'm saying, Yeah, from part of our energy three deal. Um. Yeah,
they let me go up there and uh and take
a look at the rooftop and it's you walk up
there and it basically looks like someone just took a
bunch of planners with like, you know, some gravel and
some little seed ums, you know, these semi succulent little
desert plants. A big fan of the seed um by
the way, I don't know if you've put a planet
(06:49):
any of those with your wife, but you know, we
have a little a little succulent garden. I think we
have set ums in there right well, and that's key
to what you plant on your roof, because of course
they're gonna be bearing the brunt of this intense sun,
especially in the summertime, it might not be getting a
lot of rain. Um, Like like in Atlanta, you know,
we're kind of prone to droughts recently, right, So you're
gonna want to make sure plants are heat and drought tolerant,
(07:10):
and then you're also going to want to supplement their
water use with the irrigation system. Depend upon what you
have going on up there. Yeah, Like for instance, the
would roof they have there what wood, Well, it's basically
walk up there. It's like a grid of planners, like
the whole rooftop flat roof grid of planners, and then
it's two different rooftops where they have this system set up.
And I believe they had somebody. It's scad um actually designed,
(07:32):
Like there's like if you really look at it, there's
like a swirl kind of pattern because they use different
varieties of seed them um. But this is basically for
if you're you know, if you're a bird, or you
live in one of the taller buildings around it, you know,
or if you're one of the you know, tour groups
or you know, or or podcasters guess to come up
on the roof. You know, you can appreciate it. But yeah,
it's just a grid work of these planners and then
(07:53):
they have they have some of the irrigation stuff up
there for you know, just in case and you know
it's you know it's becomes a drought such suation and
actually that and then the water for that comes from
you know, their their rainwater, you know, drainage systems. So
uh so, yeah, it was actually really cool but also
really hot. So you can definitely see why there are
desert plants growing up there because it's you're really blasted.
(08:17):
So what have they noticed, if anything benefits from from
their green roof? Um, well, I mean it pretty much
lines up along the accepted benefits. I mean it's um
you know, it's it's part of an overall effort that
they're doing there to to tweak their energy usage, which
involves like there's they have some smart grid technology going
on where they can track their energy usage in real time. Um.
(08:37):
They The big thing they did is that they just
like through they had a big energy add at a
few years back, and they just threw themselves at at
at revamping their heating and air conditioning, uh, in terms
of the hardware, but also in terms of like how
they use it, like they figured out how you know, like, oh, well,
you know we probably shouldn't, you know, air conditioned everything
on a weekend. You know, so it's like what can
(08:59):
we not air condition? And you know, and and then
you know, how much are we using this particular space, etcetera.
So it's you know, smart management, smart smart tech, upgraded materials,
you know, tweaking everything, so they've saved you know, bunches
of money. Um, it's really cool. Yeah, So you might
be wondering how much a green roof could cost you.
So I pulled a couple of numbers when we were
researching this podcast, and I came up with ten dollars
(09:22):
to twenty five dollars square foot according to the e
p A. And of course you're gonna have some annual
maintenance costs thrown in there, and those are going to
range from cents to a dollar fifty because again, the
idea is that you're not gonna need to go up
there a lot and manage this stuff. It's it's hardy growth.
That's the idea, right, right. Of course, some of your
(09:43):
plans are gonna die. Stuff is going to go wrong.
You will have to do some stuff, and that's where
the maintenance costs come in. But yeah, hopefully it's running
smoothly or running greenly, as the case may be. And
just for comparison, do you have any idea what the
cost of a regular roof is? I wanted to see. Oh,
thank goodness, I don't have any personal experience that yet. Yeah,
I don't really eat either until this afternoon. Um, so
(10:05):
there was a there's, of course a little handy roofing
calculator online and I ran the numbers and it's so
it's about for a roof that's thirty six ft by right,
made from your basic asphalt jingles, you know, the black
kind of sparkly jingles you see on a lot of houses.
So that's gonna be roughly five dollars per square foot
compared to the ten dollars to twenty dollars to even
(10:27):
I saw forty dollars per square foot for a green roof. Yeah,
so it's costly, but you can argue that the payment
is going to come in the long term. It's just
are you patient enough for that? Mm hmm return on investment? Okay, yeah,
they said with um at the would reflect. The main
um expense in setting it up was just using a train,
(10:48):
not a train, but using a crane to move everything
up there. That the you know, the the actual materials
were minuscule. Okay, yeah, that makes sense. Yeah, and you know,
if you don't have the funds for a green roof.
Um one of the things it we came across was
a white roof. Have you guys heard it is? Yeah,
painted white. It's like the opposite of the stone song
everyone's we have of that podcast we did on fighting asteroids. Yeah,
(11:12):
where you just if you want to deflect an asteroid,
you just painted white so that the solar radiation just
s gradually pushes it off course, right right, right, So
the idea behind a white roof is that, of course
you paint it white and you reflect more sunlight and
it can cut your energy demand during the hot months.
And it's it's kind of like rubbery almost, That's what
I read. So you have kind of this rubbery white
(11:35):
stuff on your roof now that I don't know if
it would fly. And this historic just drink that we're
trying to build a house, and yeah, your historic districts
I guess you're gonna want to go for Italy houses
that at least look like they're poorly designed, right, No,
like the you know, like you know what I'm saying,
It's like they're not gonna be cool with. Like someone
comes in, it's like, hey, I need to you know,
(11:56):
I'm using this geometric design. You know, my house is
gonna be made out of mud, you know, and it's
it's more ecologically, uh, you know, ideal for this number reason.
They're not gonna fly with that. They're gonna be like
like that, that house looks stupid. Well, so we had
to go for the before the Historic District Committee. And
one of the things that they suggested to us, so
that was passed around before we could move on in
(12:17):
the permitting process to get this house rolling, was they
thought our flat roof was going to be so ugly,
so they suggested, well, why don't you just put a
green roof on it to mask the ugliness, But that
that's not in the budget. Yeah I don't think. So
you decided to go to geodesic dome, right, Yeah, that's
the final and then in the straw Straw Bill garage
right next door, Yeah, we have a fine article on
(12:39):
straw Bill Holmes. I want to add by Molly Edmunds.
It was one of the first articles I ever did.
Ed do we have one on geodesic domes. We have
one on a couple of other alternative home styles. Cool.
Now you should look at that podcasting. We have so
many light Yeah, Like I can't even necessarily keep track
of all we have. I discovered new how stuff works
articles every week. I think. Yeah, so, how else are
(13:02):
you going to benefit from a green roof if you
decide to go this route, Well, the roots gonna last longer, right, Yeah,
that's just it. And it's another it's another layer of
insulation as well. Yeah. So I mean it's gonna be
a little cool things down, it's going to be able
to insulate your house, and it's gonna give you some shade, right,
And I feel like we should talk about we should
quantify how much cooler are we talking? So there was
(13:25):
one floor to study commissioned h They found that the
average maximum surface temperature of a green roof was eighty
six degrees fahrenheit. Meanwhile, the nearby light colored roof was
a hundred and thirty four degrees fahrenheit. Right, seriously, eighty
six degrees versus a hundred thirty four degrees, that's significant. Yeah,
it is pretty significant. Of course, I don't know how
big that steady was, and but still that's a that's
(13:49):
a that's a big difference. And also rooftop plants that
they can suck up the carbon. So yeah, we like that. Yeah,
so that's good. It's always nice to have another car
in storehouse around. Yeah, and you get it right on
top of that way. And then there's a whole stormwater
runoff issue, right, so if you have a green rooftop,
a lot of that water that's coming down during a storm,
(14:10):
it's going to hang with the plants, and you know,
as a bonus, it might be filtered and or absorbed
by the plants instead of swirling gutters and jumping directly
into a wastewater chances instead of going into the sewer.
It's it's it's generating life on your roof. Yeah, that's
pretty sweet. Um, yeah, let's see producing energy use touched
on that. You know, it's just you're more instant and
(14:31):
more insulated, so you're gonna cut down on your heating
and cooling cost and pluses that we touched on a
little bit earlier. Your neighbors like might like it. I
mean it has some aesthetic value, right, Yeah, it depends
where you where you live, Like, what is it the
Late clear Land Trust here in Atlanta, they'd be cool
with green roofs. Is that the is that the hippie
that's the hippie place? Yeah? Offcandler Yeah yeah yeah, where
(14:52):
they have like the gross stuff, and they have drum circles.
What's with drum circles? I like drum circles. I'm just
saying that as long as they complaine play djano with
their feet. Do you think they can play jangle with
their feet? That they can do all kinds of things
with their feet. Yeah, And as you were saying, um,
the green roof actually could last you longer than a
conventional roof. And then of course you have a little
(15:14):
nice sound installation and a habitat for wildlife. Which brings
me to one story that I was reading about. So
there's this Virginia man that was thinking about putting a
green roof on his log cabin and he wrote into
the U. S. Green Building Council's Green Home Guide about
you know, the wisdom of such an effort and the
consultant who answered called called that idea a real expensive
(15:37):
squirrel feeder. I was just I was just thinking about that,
Like could I just put nuts all over my roof
and have like a brown roof where it's just nothing
but fat squirrels, right, because essentially the cabin owner isn't
gonna have to worry about the urban heat island effect,
you know, being a log cabin at all. I'm assuming
the log cabin is some some nice patch of Virginia
woods not necessarily situated in the heart of Richmond, and
(15:59):
he's not gonna really gonna have to worry about the
storm water over running the sewers. But yeah, the squirrels
would definitely be down with that. But then you need
like roof snakes and stuff. It just becomes a an
arms race squirrel traps or you know. I know all
my I know a lot about keeping squirrels out of attics,
but I don't know about keeping them off of the roof,
(16:20):
because you can keep them out of the attics by
like during the winter, by like putting up some hot
peppers in there, or have you tried this, Yeah, like
I've I've known, like when we first moved into our house.
They were hot peppers hanging up to keep squirrels out,
but I didn't recognize at the time, so I took
them down. And then you can like buy like these
spicy powder pellet things that are they are made for
(16:40):
you just make it too spicy for the squirrels to
stand it. And your wife was talking about putting the
strobe lights. Yes, that was this my my my father
in law did that, I believe right, putting the strobe
light in the attic and it got rid of the squirrels. Yeah,
that's so great because they hate disco. No, no, they
hate raved music. Sorry, they might hate disco too. I
(17:01):
don't know anything that's shiny lights. I think just because
coming back Robert is it, it might be good. Um.
So what's the setup here of the screen roof? You're
probably wondering? Um, Yeah, like if I wanted a green
roof tomorrow, could I get one? Well, let's talk about
it first. Let's let's run you through some of the
layers we've got going on here. So of course you
have your plants, your vegetative layer, whether it's seto, whether
(17:22):
it's grass or maybe even a tree or two. Um.
But again, you're gonna have to think about the roots
system here, so you're not gonna get big trees, and
of course you don't want the weight of a big
tree on your roof anyway. That doesn't seem so so smart.
So these are gonna be smaller plants. And then you
have whatever the plants are growing, and you're growing medium,
and then you're gonna have a barrier, and that's going
(17:43):
to provide stuff good stuff like drainage and aeration and
water storage. And then comes your insulation, and then you
have another protective layer, and then you have a roofing membrane.
And lastly, and very important, you have your structural support
too to bear up the whole endeavor. Ye, Like in
the woodroofe case, they said that the roof of the
(18:04):
existing building was it was a pretty green design anyway,
and that it was. They said the roof was just
way over engineered to begin with, so like, wait, wasn't
even an issue. Really, that's pretty cool, yeah, And so
one of the interesting things was you can get this
in a modular system. I was reading about a green
grid system that consisted of a series of pre planted
modules and they're made of recycled plastics, and well, the
(18:27):
the trays that hold the plants, not the plants. Plants
aren't made out of recycled plus that would really be
a good joke. And these modules can be easily placed
on a roof or a different structure with the capacity
for it. Well that's cool. Yeah, So business with a
suitable roof, rooftop environment already, they can just start ordering
(18:47):
these things up, right, and you're gonna you're gonna want
to think about irrigation system too, depending on what kind
of system you go with. Yeah, and you can also
get a built in place system. But the trouble with
that is that you may have to roll back vegetation
if you have to troubleshoot something going wrong. God forbid,
you know your roof starts leaking, or all of a
sudden you s brought a route coming through one of
your air events and the ceiling. That would be bad um,
(19:10):
and you could wind up waiting a while for vegetation
to grow in and be green. So the question here
is can you get one? Can I outfit my house
or a business with one? Heck? Yeah, but it's gonna
be a little bit easier if you're building new right.
It ultimately comes down to the building design to UM.
If you have really steep, you know, highly pitched rooftop
(19:31):
going on, you know, you might not be able to
put planners up there. It just depends. Yeah, I probably
might slide right back off right. Although they can do um,
they can infect you green roofs on roofs with a
slight pitch to them, like but shelving up or something,
do a terracing system. I don't know. I'm not sure, okay,
(19:52):
but the take come here is that even if you
have like a more traditional, you know, Western style roof rooftop,
you might be I think they can work with a
slight pitch. I'm not sure that they can work with
you know, the roof. You picture if you were to
draw a house on a piece of paper and you
need to do do that triangle roof in the square house body, Yeah,
I'm not sure that roof is gonna work with a
(20:13):
with a green roof unless yeah, you can go with kutzo.
And the other thing is, if you're building new, you're
gonna have to deal with you know, hopefully you have
the funds to fund it, because like we said, this
can be up to forty dollars a foot and then um,
you know, getting it past your town or city officials.
Maybe they haven't seen a green roof yet. Um, so
that could complicate the process and in the time spent
(20:36):
getting one existing structure. Yeah, you could do that. How
much do you want it though? And do you have
a flat roof? Obviously, although you can do extensive roofs.
Remember extensive is the shallower, less complicated type of green roof.
But you're gonna want to consult a structural engineer who's
gonna be able to tell you whether your old roof
is designed to handle the load of plants and you
(20:58):
tramping across the top, And often the answers is no,
it can't. So you'd have to go back and do
some retrofitting. But don't lose hope because Chicago City Hall,
the famous one that we're talking about with the twenty
herbacious plans that covers you know, square feet of rooftop
garden um, that was a retrofitted green roof. Yeah, and
(21:20):
it looks amazing. And then I wonder if you could
do like a mini green roof, maybe just do part
better than nothing? Yeah, yeah, totally, So we'd love to
hear from you guys, if you if you have a
green roof or if you're thinking about implementing one, yeah,
or if your your company happens to have a green
roof project going on, let us know about it. You
know you'd love to hear your stories. And hey, speaking
(21:43):
of hearing your stories, do we have have a little
listener mail there? We do? We do? Um. I wanted
to share a couple that we received this week. First
one is from Katie from Seattle and she's a new
listener and Katie were to tell us some pretty cool
stuff about bats. If you guys remember we did a
podcast about bats and white nose syndrome a little while back,
(22:04):
and Katie writes, I'm not sure if you've heard this,
but a couple of years ago, scientists started noticing that
thousands of bats were dead around wind turbines, but apparently
not from impact with the blades. They discovered that the
spinning of the blades causes a drop in air pressure,
which effectively causes their lungs to fill with fluid, expand,
and kill them, similarly to the effects of the bends
have on divers. Many wind farms have since started turning
(22:26):
off their turbines at night, when the bats are of
course most active, which has greatly helped the bat population.
So that's pretty interesting, Katie. I we did not, in
fact come across that when we were researching the white
nose syndrome and bats, so thanks for bringing that to
our attention. We also heard from Matt, who apparently isn't
sleeping and is instead reading Enders Game constantly. Uh, he
writes a few days A few days ago, I listened
(22:48):
to Why Science Fiction Matters, and, seeing us I'm an
English major, that podcast was particularly enticing. I happened to
be passing a bookstore just as I finished listening, so
I stopped and I bought Enders Game. I hope you
guys have all this because it it really is worthy
of moving a little sleep. It's a really good book,
just really really good. So Masas, I rate to thank
you for recommending this book to your listeners. And I've
(23:08):
read a heck of a lot of novels and Ender's
Game is at the top of my favorites list. Awesome,
Matt cool. Yeah yeah. We threw out a number of
the suggestions there, so uh and and a few different
comments back we may uh well not just may I
think we're planning to revisit science fiction at some point
in the future. We definitely will, and maybe even with
a chapter on sci fi and film. What do you
(23:29):
think about that? Maybe we'll see if you guys want
to hear it. You know, we're to write a super
science stuff that has to freak dot com. And hey,
we are all over the social media space too, so
if you haven't joined up or on Facebook, you can
find us at stuff from the Science Lab and on
Twitter we are lab stuff and you'll see us tweeting
(23:51):
about different stuff. I'll tag my stuff r L, she'll
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check it out. And thanks for listening, guys. For more
(24:11):
on this and thousands of other topics, is it how
stuff works dot Com. Want more how stuff works, check
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home page.
Yeah, welcome to Stuff from the Science Lab from how
stuff works dot com. Wow, hey guys, a welcome podcast.
This is Alice Manauth, the science editor at how staff
works dot com. And this is Robert Lamb, science writer
(00:20):
at how stuff works dot com. And since you guys
are listening to us, you often can't tell what shenanigans
were up to here at the house Stuff Works headquarters
in Atlanta. But one of the shenanigans we have going
on is a grilla gardening escapade. And you can talk
a little bit more about this than I can. Yeah,
a few of our co workers, um Mark, Candice and
Marie um set out to occupy our empty planners out
(00:44):
on the patio. We have a five of these things,
like big concrete monstrosities, and for like over a year,
all they've had in them have been dirt and uh,
like a few weeds and people have been I was
actually like occasionally composting like an apple core out there.
So we had a few like doomed apple trees and
you know, coming out and occasionally someone thrown orange peel
(01:05):
in or or sadly a cigarette. But but that was
all and bet I know who that was. Yeah, yeah,
I think we probably both do. But but anyway, nobody's
doing anything with it. And for there was some rumblings like, hey,
you know, we should go out here and plant this,
because for a while you're like, oh, well, maybe you know,
somebody else is gonna do it, maybe like the building's
gonna take care of it. But they're not. So they
set out. They brought in some soil, they brought in
(01:26):
some some seeds and planet like some you know, it's
like tomatoes and basil and all this and lo and
behold it's sprouted and you can go out there now
and we have planners full of green things. However, if
you walk out on the patio, you know, right now,
in the heat of the Georgia summer, it's gonna be
a whopper. The sun is going to blast your face
(01:48):
off and the heat hits you almost like a physical force. Yeah,
it just it makes you slow and it makes you stupid,
which which we found out at the Discover Your Impact
day last week when we did this service project, right
right when we were digging in the dirt. Yeah, it
just makes you Like I was having a conversation with
one of our coworkers about how we used to have
offices on the eleventh floor. But now we're in and
(02:09):
uh and how I wasn't sure if we had something
on sixteen, but I was just saying fifteen for everyone,
So it was really confusing for him and I, you know,
it's just hapt your brain. But the thing is, it's
like if you walk out on that patio after the
sun has gone down, it's still hot because there's all
that heat still emanating up off the concrete. Robert. That
has a scientific name, doesn't it. Yes, that is the
(02:30):
heat island effect. Yeah, And like you might imagine, the
heat island effect is something that's largely confined to cities.
And why because cities are, of course mostly man made structures.
Cities are made with materials that often have low albedos, right,
or the ability of objects to reflect solar radiation. So
the classic example, I think, if you're wearing a white
T shirt, it's going to have high albedo, and a
(02:52):
black T shirt has low albedo, And cities are a
lot like those black T shirts, right. And when you
think about it, I mean, what is the city it's
you know, oh, it's asphalt that that absorbs all that heat.
It's um you know, city buildings, it's tenements, it's all
this stuff. It's enormous parking lots full of full of
you know, just black asphalt. And then of course you're
(03:13):
suffering from a lack of vegetation unless maybe you do
have a lot of green roofs or guerrilla gardening going
on in your particular city. And so that means cities
don't benefit from the cooling effects of something called evapo transporation.
And evapo transporation facilitates more cooling by using heat to
evaporate water from the whatever you're you're growing the plants
in and the plant surfaces. So this is kind of
(03:34):
a handy process that we like a lot of appo transporation, right,
not happening so much in the cities, right. But yeah,
back to the patio. The patio is not a green
roof today. We're talking about green roofs. Yes, indeed, the
patio is just you know, it's good. It's it's a
it's a great thing we're doing out there. Uh you know,
it's it's making things a little prettier. Air qualities maybe
(03:55):
a little better, but maybe with some fresh tomatoes with lunch. Yeah,
But but no green roof is something um a little different, right,
So what is a green roof? I mean, on a
basic level, it's really just a layer of vegetation on
a home, on a commercial building, any structure with the roof, basically,
unless the roof is so pitched that having a green
(04:16):
roof would be impossible. Yeah, and may I know maybe
if you had like a f roof, you could like
grow things in it. I suppose so, And we could
be talking about anything from just putting groundcover up on
top of the roof to building a huge park. And
I think when most of us think things like green roofs,
we think of, you know, this lush setting. We think of,
you know, lots of plants. We think a little walk ways,
(04:38):
We think of a bench maybe to sit down and
eat your tuna fish sandwich. What's the one in Chicago
that looks amazing Chicago City Hall? Yeah, Like you see
pictures of that and it's like it's like an eden
up there. It's like the hanging you know, gardens of Babylon.
You can imagine Chicago. You can imagine what was the
mayor daily the governor. Yeah, you can just imagine him
(05:00):
up there, like being fed grapes as you like reclined
on something. You know, that's exactly what I think of, right,
So in that and that can be a green roof,
but not necessarily right, So that kind of roof that
we're talking about, this lush setting is going to be
an intensive green roof. And there are really two main types.
So intensive is one, and uh, it's gonna be park
(05:22):
like like we're getting at. And it's also going to
be a heavier load to bear on the underlying structure.
I mean, after all, you're gonna have people chomping around
up there, and uh, it's going to be more costly,
and of course you'll need an irrigation system for all
those plants, those lovely plants you'll have. But so you
still want to do a green roof, but maybe you're
not interested in something so extraordinary. So yeah, so in
(05:45):
that case, you go with what they call an extensive
green roof, right, less maintenance, it's less lush, and you're
gonna have substrate between less than an inch and six inches.
And all they mean here is think about the level
that you're going to go down to plant. Right, that's
where we're at. That's what we're talking about. With a substrate,
think of your vegetative layer and then all the way
down to uh the actual roof lair. So if you
(06:07):
think of that distance, um, with an extensive green roof,
that distance is going to be about six inches, whereas
if you have an intensive green roof, the vegetation can
go down to about four ft. I've seen Yeah, I
actually got to see an extensive green roof last week
at the Woodroof Arts Center here in Atlanta, right and
you've blogged about it too. There are pictures of it.
(06:27):
What I'm saying, Yeah, from part of our energy three deal. Um. Yeah,
they let me go up there and uh and take
a look at the rooftop and it's you walk up
there and it basically looks like someone just took a
bunch of planners with like, you know, some gravel and
some little seed ums, you know, these semi succulent little
desert plants. A big fan of the seed um by
the way, I don't know if you've put a planet
(06:49):
any of those with your wife, but you know, we
have a little a little succulent garden. I think we
have set ums in there right well, and that's key
to what you plant on your roof, because of course
they're gonna be bearing the brunt of this intense sun,
especially in the summertime, it might not be getting a
lot of rain. Um, Like like in Atlanta, you know,
we're kind of prone to droughts recently, right, So you're
gonna want to make sure plants are heat and drought tolerant,
(07:10):
and then you're also going to want to supplement their
water use with the irrigation system. Depend upon what you
have going on up there. Yeah, Like for instance, the
would roof they have there what wood, Well, it's basically
walk up there. It's like a grid of planners, like
the whole rooftop flat roof grid of planners, and then
it's two different rooftops where they have this system set up.
And I believe they had somebody. It's scad um actually designed,
(07:32):
Like there's like if you really look at it, there's
like a swirl kind of pattern because they use different
varieties of seed them um. But this is basically for
if you're you know, if you're a bird, or you
live in one of the taller buildings around it, you know,
or if you're one of the you know, tour groups
or you know, or or podcasters guess to come up
on the roof. You know, you can appreciate it. But yeah,
it's just a grid work of these planners and then
(07:53):
they have they have some of the irrigation stuff up
there for you know, just in case and you know
it's you know it's becomes a drought such suation and
actually that and then the water for that comes from
you know, their their rainwater, you know, drainage systems. So
uh so, yeah, it was actually really cool but also
really hot. So you can definitely see why there are
desert plants growing up there because it's you're really blasted.
(08:17):
So what have they noticed, if anything benefits from from
their green roof? Um, well, I mean it pretty much
lines up along the accepted benefits. I mean it's um
you know, it's it's part of an overall effort that
they're doing there to to tweak their energy usage, which
involves like there's they have some smart grid technology going
on where they can track their energy usage in real time. Um.
(08:37):
They The big thing they did is that they just
like through they had a big energy add at a
few years back, and they just threw themselves at at
at revamping their heating and air conditioning, uh, in terms
of the hardware, but also in terms of like how
they use it, like they figured out how you know, like, oh, well,
you know we probably shouldn't, you know, air conditioned everything
on a weekend. You know, so it's like what can
(08:59):
we not air condition? And you know, and and then
you know, how much are we using this particular space, etcetera.
So it's you know, smart management, smart smart tech, upgraded materials,
you know, tweaking everything, so they've saved you know, bunches
of money. Um, it's really cool. Yeah, So you might
be wondering how much a green roof could cost you.
So I pulled a couple of numbers when we were
researching this podcast, and I came up with ten dollars
(09:22):
to twenty five dollars square foot according to the e
p A. And of course you're gonna have some annual
maintenance costs thrown in there, and those are going to
range from cents to a dollar fifty because again, the
idea is that you're not gonna need to go up
there a lot and manage this stuff. It's it's hardy growth.
That's the idea, right, right. Of course, some of your
(09:43):
plans are gonna die. Stuff is going to go wrong.
You will have to do some stuff, and that's where
the maintenance costs come in. But yeah, hopefully it's running
smoothly or running greenly, as the case may be. And
just for comparison, do you have any idea what the
cost of a regular roof is? I wanted to see. Oh,
thank goodness, I don't have any personal experience that yet. Yeah,
I don't really eat either until this afternoon. Um, so
(10:05):
there was a there's, of course a little handy roofing
calculator online and I ran the numbers and it's so
it's about for a roof that's thirty six ft by right,
made from your basic asphalt jingles, you know, the black
kind of sparkly jingles you see on a lot of houses.
So that's gonna be roughly five dollars per square foot
compared to the ten dollars to twenty dollars to even
(10:27):
I saw forty dollars per square foot for a green roof. Yeah,
so it's costly, but you can argue that the payment
is going to come in the long term. It's just
are you patient enough for that? Mm hmm return on investment? Okay, yeah,
they said with um at the would reflect. The main
um expense in setting it up was just using a train,
(10:48):
not a train, but using a crane to move everything
up there. That the you know, the the actual materials
were minuscule. Okay, yeah, that makes sense. Yeah, and you know,
if you don't have the funds for a green roof.
Um one of the things it we came across was
a white roof. Have you guys heard it is? Yeah,
painted white. It's like the opposite of the stone song
everyone's we have of that podcast we did on fighting asteroids. Yeah,
(11:12):
where you just if you want to deflect an asteroid,
you just painted white so that the solar radiation just
s gradually pushes it off course, right right, right, So
the idea behind a white roof is that, of course
you paint it white and you reflect more sunlight and
it can cut your energy demand during the hot months.
And it's it's kind of like rubbery almost, That's what
I read. So you have kind of this rubbery white
(11:35):
stuff on your roof now that I don't know if
it would fly. And this historic just drink that we're
trying to build a house, and yeah, your historic districts
I guess you're gonna want to go for Italy houses
that at least look like they're poorly designed, right, No,
like the you know, like you know what I'm saying,
It's like they're not gonna be cool with. Like someone
comes in, it's like, hey, I need to you know,
(11:56):
I'm using this geometric design. You know, my house is
gonna be made out of mud, you know, and it's
it's more ecologically, uh, you know, ideal for this number reason.
They're not gonna fly with that. They're gonna be like
like that, that house looks stupid. Well, so we had
to go for the before the Historic District Committee. And
one of the things that they suggested to us, so
that was passed around before we could move on in
(12:17):
the permitting process to get this house rolling, was they
thought our flat roof was going to be so ugly,
so they suggested, well, why don't you just put a
green roof on it to mask the ugliness, But that
that's not in the budget. Yeah I don't think. So
you decided to go to geodesic dome, right, Yeah, that's
the final and then in the straw Straw Bill garage
right next door, Yeah, we have a fine article on
(12:39):
straw Bill Holmes. I want to add by Molly Edmunds.
It was one of the first articles I ever did.
Ed do we have one on geodesic domes. We have
one on a couple of other alternative home styles. Cool.
Now you should look at that podcasting. We have so
many light Yeah, Like I can't even necessarily keep track
of all we have. I discovered new how stuff works
articles every week. I think. Yeah, so, how else are
(13:02):
you going to benefit from a green roof if you
decide to go this route, Well, the roots gonna last longer, right, Yeah,
that's just it. And it's another it's another layer of
insulation as well. Yeah. So I mean it's gonna be
a little cool things down, it's going to be able
to insulate your house, and it's gonna give you some shade, right,
And I feel like we should talk about we should
quantify how much cooler are we talking? So there was
(13:25):
one floor to study commissioned h They found that the
average maximum surface temperature of a green roof was eighty
six degrees fahrenheit. Meanwhile, the nearby light colored roof was
a hundred and thirty four degrees fahrenheit. Right, seriously, eighty
six degrees versus a hundred thirty four degrees, that's significant. Yeah,
it is pretty significant. Of course, I don't know how
big that steady was, and but still that's a that's
(13:49):
a that's a big difference. And also rooftop plants that
they can suck up the carbon. So yeah, we like that. Yeah,
so that's good. It's always nice to have another car
in storehouse around. Yeah, and you get it right on
top of that way. And then there's a whole stormwater
runoff issue, right, so if you have a green rooftop,
a lot of that water that's coming down during a storm,
(14:10):
it's going to hang with the plants, and you know,
as a bonus, it might be filtered and or absorbed
by the plants instead of swirling gutters and jumping directly
into a wastewater chances instead of going into the sewer.
It's it's it's generating life on your roof. Yeah, that's
pretty sweet. Um, yeah, let's see producing energy use touched
on that. You know, it's just you're more instant and
(14:31):
more insulated, so you're gonna cut down on your heating
and cooling cost and pluses that we touched on a
little bit earlier. Your neighbors like might like it. I
mean it has some aesthetic value, right, Yeah, it depends
where you where you live, Like, what is it the
Late clear Land Trust here in Atlanta, they'd be cool
with green roofs. Is that the is that the hippie
that's the hippie place? Yeah? Offcandler Yeah yeah yeah, where
(14:52):
they have like the gross stuff, and they have drum circles.
What's with drum circles? I like drum circles. I'm just
saying that as long as they complaine play djano with
their feet. Do you think they can play jangle with
their feet? That they can do all kinds of things
with their feet. Yeah, And as you were saying, um,
the green roof actually could last you longer than a
conventional roof. And then of course you have a little
(15:14):
nice sound installation and a habitat for wildlife. Which brings
me to one story that I was reading about. So
there's this Virginia man that was thinking about putting a
green roof on his log cabin and he wrote into
the U. S. Green Building Council's Green Home Guide about
you know, the wisdom of such an effort and the
consultant who answered called called that idea a real expensive
(15:37):
squirrel feeder. I was just I was just thinking about that,
Like could I just put nuts all over my roof
and have like a brown roof where it's just nothing
but fat squirrels, right, because essentially the cabin owner isn't
gonna have to worry about the urban heat island effect,
you know, being a log cabin at all. I'm assuming
the log cabin is some some nice patch of Virginia
woods not necessarily situated in the heart of Richmond, and
(15:59):
he's not gonna really gonna have to worry about the
storm water over running the sewers. But yeah, the squirrels
would definitely be down with that. But then you need
like roof snakes and stuff. It just becomes a an
arms race squirrel traps or you know. I know all
my I know a lot about keeping squirrels out of attics,
but I don't know about keeping them off of the roof,
(16:20):
because you can keep them out of the attics by
like during the winter, by like putting up some hot
peppers in there, or have you tried this, Yeah, like
I've I've known, like when we first moved into our house.
They were hot peppers hanging up to keep squirrels out,
but I didn't recognize at the time, so I took
them down. And then you can like buy like these
spicy powder pellet things that are they are made for
(16:40):
you just make it too spicy for the squirrels to
stand it. And your wife was talking about putting the
strobe lights. Yes, that was this my my my father
in law did that, I believe right, putting the strobe
light in the attic and it got rid of the squirrels. Yeah,
that's so great because they hate disco. No, no, they
hate raved music. Sorry, they might hate disco too. I
(17:01):
don't know anything that's shiny lights. I think just because
coming back Robert is it, it might be good. Um.
So what's the setup here of the screen roof? You're
probably wondering? Um, Yeah, like if I wanted a green
roof tomorrow, could I get one? Well, let's talk about
it first. Let's let's run you through some of the
layers we've got going on here. So of course you
have your plants, your vegetative layer, whether it's seto, whether
(17:22):
it's grass or maybe even a tree or two. Um.
But again, you're gonna have to think about the roots
system here, so you're not gonna get big trees, and
of course you don't want the weight of a big
tree on your roof anyway. That doesn't seem so so smart.
So these are gonna be smaller plants. And then you
have whatever the plants are growing, and you're growing medium,
and then you're gonna have a barrier, and that's going
(17:43):
to provide stuff good stuff like drainage and aeration and
water storage. And then comes your insulation, and then you
have another protective layer, and then you have a roofing membrane.
And lastly, and very important, you have your structural support
too to bear up the whole endeavor. Ye, Like in
the woodroofe case, they said that the roof of the
(18:04):
existing building was it was a pretty green design anyway,
and that it was. They said the roof was just
way over engineered to begin with, so like, wait, wasn't
even an issue. Really, that's pretty cool, yeah, And so
one of the interesting things was you can get this
in a modular system. I was reading about a green
grid system that consisted of a series of pre planted
modules and they're made of recycled plastics, and well, the
(18:27):
the trays that hold the plants, not the plants. Plants
aren't made out of recycled plus that would really be
a good joke. And these modules can be easily placed
on a roof or a different structure with the capacity
for it. Well that's cool. Yeah, So business with a
suitable roof, rooftop environment already, they can just start ordering
(18:47):
these things up, right, and you're gonna you're gonna want
to think about irrigation system too, depending on what kind
of system you go with. Yeah, and you can also
get a built in place system. But the trouble with
that is that you may have to roll back vegetation
if you have to troubleshoot something going wrong. God forbid,
you know your roof starts leaking, or all of a
sudden you s brought a route coming through one of
your air events and the ceiling. That would be bad um,
(19:10):
and you could wind up waiting a while for vegetation
to grow in and be green. So the question here
is can you get one? Can I outfit my house
or a business with one? Heck? Yeah, but it's gonna
be a little bit easier if you're building new right.
It ultimately comes down to the building design to UM.
If you have really steep, you know, highly pitched rooftop
(19:31):
going on, you know, you might not be able to
put planners up there. It just depends. Yeah, I probably
might slide right back off right. Although they can do um,
they can infect you green roofs on roofs with a
slight pitch to them, like but shelving up or something,
do a terracing system. I don't know. I'm not sure, okay,
(19:52):
but the take come here is that even if you
have like a more traditional, you know, Western style roof rooftop,
you might be I think they can work with a
slight pitch. I'm not sure that they can work with
you know, the roof. You picture if you were to
draw a house on a piece of paper and you
need to do do that triangle roof in the square house body, Yeah,
I'm not sure that roof is gonna work with a
(20:13):
with a green roof unless yeah, you can go with kutzo.
And the other thing is, if you're building new, you're
gonna have to deal with you know, hopefully you have
the funds to fund it, because like we said, this
can be up to forty dollars a foot and then um,
you know, getting it past your town or city officials.
Maybe they haven't seen a green roof yet. Um, so
that could complicate the process and in the time spent
(20:36):
getting one existing structure. Yeah, you could do that. How
much do you want it though? And do you have
a flat roof? Obviously, although you can do extensive roofs.
Remember extensive is the shallower, less complicated type of green roof.
But you're gonna want to consult a structural engineer who's
gonna be able to tell you whether your old roof
is designed to handle the load of plants and you
(20:58):
tramping across the top, And often the answers is no,
it can't. So you'd have to go back and do
some retrofitting. But don't lose hope because Chicago City Hall,
the famous one that we're talking about with the twenty
herbacious plans that covers you know, square feet of rooftop
garden um, that was a retrofitted green roof. Yeah, and
(21:20):
it looks amazing. And then I wonder if you could
do like a mini green roof, maybe just do part
better than nothing? Yeah, yeah, totally, So we'd love to
hear from you guys, if you if you have a
green roof or if you're thinking about implementing one, yeah,
or if your your company happens to have a green
roof project going on, let us know about it. You
know you'd love to hear your stories. And hey, speaking
(21:43):
of hearing your stories, do we have have a little
listener mail there? We do? We do? Um. I wanted
to share a couple that we received this week. First
one is from Katie from Seattle and she's a new
listener and Katie were to tell us some pretty cool
stuff about bats. If you guys remember we did a
podcast about bats and white nose syndrome a little while back,
(22:04):
and Katie writes, I'm not sure if you've heard this,
but a couple of years ago, scientists started noticing that
thousands of bats were dead around wind turbines, but apparently
not from impact with the blades. They discovered that the
spinning of the blades causes a drop in air pressure,
which effectively causes their lungs to fill with fluid, expand,
and kill them, similarly to the effects of the bends
have on divers. Many wind farms have since started turning
(22:26):
off their turbines at night, when the bats are of
course most active, which has greatly helped the bat population.
So that's pretty interesting, Katie. I we did not, in
fact come across that when we were researching the white
nose syndrome and bats, so thanks for bringing that to
our attention. We also heard from Matt, who apparently isn't
sleeping and is instead reading Enders Game constantly. Uh, he
writes a few days A few days ago, I listened
(22:48):
to Why Science Fiction Matters, and, seeing us I'm an
English major, that podcast was particularly enticing. I happened to
be passing a bookstore just as I finished listening, so
I stopped and I bought Enders Game. I hope you
guys have all this because it it really is worthy
of moving a little sleep. It's a really good book,
just really really good. So Masas, I rate to thank
you for recommending this book to your listeners. And I've
(23:08):
read a heck of a lot of novels and Ender's
Game is at the top of my favorites list. Awesome,
Matt cool. Yeah yeah. We threw out a number of
the suggestions there, so uh and and a few different
comments back we may uh well not just may I
think we're planning to revisit science fiction at some point
in the future. We definitely will, and maybe even with
a chapter on sci fi and film. What do you
(23:29):
think about that? Maybe we'll see if you guys want
to hear it. You know, we're to write a super
science stuff that has to freak dot com. And hey,
we are all over the social media space too, so
if you haven't joined up or on Facebook, you can
find us at stuff from the Science Lab and on
Twitter we are lab stuff and you'll see us tweeting
(23:51):
about different stuff. I'll tag my stuff r L, she'll
tag her stuff a L, and you can just check
out whatever we're talking about at the time. Yeah, we
are always thinking about science, so if you write to
check it out. And thanks for listening, guys. For more
(24:11):
on this and thousands of other topics, is it how
stuff works dot Com. Want more how stuff works, check
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