July 17, 2024 • 13 mins
Summer is here, and with heatwaves forecast, how do we keep our homes cool without relying on air conditioning?
In the UK, soaring summer temperatures can be brief but powerful. So, what can we do? Nicole Miranda, from the Department of Engineering, shares practical, energy-efficient and eco-friendly strategies to help you stay comfortable during the hot months. And yes, ice creams are encouraged!
This is the final episode of this season. We hope that you have enjoyed learning the science behind the many weird and wonderful aspects of our world. If you have a big question, get in touch and we will try to find you an answer in the next season.
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
>> Emily Elias (00:06):
Ah, as the philosopher Rob Thomas from Mashbox 20
once said, man, it's
a hot one. I'll spare you the rest of the lyrics to smooth,
but summer is here. And on this episode
of the Oxford Sparks big Questions
podcast, we are asking, how do I keep
my house cool without cranking on the air
(00:26):
conditioning?
Hello, I'm Emily Elias, and
this is the show where we seek out the brightest minds at the
University of Oxford, and we ask them the big
questions. And for this one, we have
found.
A researcher who's pretty cool.
>> Speaker C (00:47):
My name is Nicole Miranda. I, am a senior
researcher at the University of Oxford,
specifically in the engineering department. And, ah, looking
at sustainable cooling.
>> Emily Elias (00:57):
Okay, so sustainable cooling. So you're a cool
lady. So the
reason we have you to here today is because obviously we're
in the thralls of summer. There are heat
waves forecasted. It is gonna be a hot
one. How do we stay
cool? So I wanted to kind of approach
this from a couple different ways. First of
(01:19):
all, let's assume that, you know, I'm
a renter, I don't have a ton of money.
What can I do to stay cool
in the hot months?
>> Speaker C (01:30):
Well, it's always recommended to go through
a passive first approach. So that means
not giving in to the urge of running to
the supermarket or a shop, and getting an
air conditioner, because air conditioners are very
energy intensive and carbon intensive.
Now that carbon intensity is falling because the
(01:50):
electricity is getting greener, however,
it's still going to be costly. So a passive
burst approach means how
we can cool ourselves without using intensive
energy, using shades, using water
bodies, using vegetation,
things that can help us in a more cost
(02:11):
effective way, but also that are quite effective.
So we always recommend a passive first. And if
you're a renter, you would find that
it's a bit difficult to do things that are the
embedded in the building because you're not the owner of the
house.
>> Emily Elias (02:26):
Exactly. If I was all of a sudden installed, air conditioning,
not only would I be out of pocket, but my landlord would probably be
pretty annoyed with me.
>> Speaker C (02:33):
Exactly. So you should always talk
to your landlord, obviously, because there is
efficient ways of putting shading outside
so that you cover the heat gains
through windows.
>> Emily Elias (02:46):
So is blocking the sun
like my number one go to thing that I should be
worried about? Yes.
>> Speaker C (02:53):
So, within the passive solutions, there's
many options. One is blocking the sun,
and easy things like drawing the curtains when
the sun is outside is very useful.
However, there's another one that we here in the UK
love to do, which is opening the windows, and that's
really effective. So if you open a window on one side of
(03:13):
the house or room, and then another wind on the
other side, you get this lovely cross
ventilation, and that makes wind go
through the house and gives you a nice
thermal comfort effect.
>> Emily Elias (03:25):
Thermal comfort, is that like fancy researcher for breeze?
>> Speaker C (03:28):
Oh, yeah. Well, it's like, how are you
comfortable regarding temperature,
humidity and the wind around you?
Are you thermally comfort, that's what it embraces.
>> Emily Elias (03:38):
Yeah, thermal comfort. Learn something new every day.
>> Speaker C (03:41):
Yeah. So ventilation is a really important one, but
you just need to be careful when you're opening
windows, because if there's no breeze outside
and actually it's hotter outside
inside, you're better off keeping that
window shut. And that's a common mistake we do
here. We think, oh, it's hot and we open the windows. But
actually it's sometimes
(04:03):
more convenient to keep the hotter
temperatures outside and shield your house.
>> Emily Elias (04:08):
Is there like, a better
window to open? Like, so say
in my house, there's a sunny side of it, and there's like, a
shady side of my house. Should I open windows that are
on the sunny side of the house, or should I open windows on the
shady side of the house?
>> Speaker C (04:24):
Well, you could combine opening windows
that are on opposite side of the house,
because that will allow a ventilation, like, from one
window to the other. So it advances through the house.
Right. The wind moves and that's what you want.
But on the sunny side, I would draw the
curtain so that that sun doesn't come in
(04:44):
directly. So you still have the wind able
to escape the room and the house,
but you're shading yourself from those heat gains
from the sun.
>> Emily Elias (04:53):
And it just feels kind of like antisocial in the summer to
have your windows closed and, your curtains
drawn. But that is, that can be, I guess, in
some instances, the best solution.
>> Speaker C (05:04):
Absolutely, yeah. If you see in more
extreme heats in Africa, many
houses have tiny windows, and that's
to protect them from the heat. And so they're
quite dark inside and down. There's a lot of other
issues with that. But to combat the extreme
heat, it's lowering those heat gains
of the windows of the opening.
>> Emily Elias (05:26):
Okay, now let's just imagine I have a tiny bit more money and
I can splash out on a
device. what should I put my money
towards? Should I go for a fan
that does, like, 10,000 things and has a
computer built into it, or should I
just grab a really cool bucket and fill it with
water and ice?
>> Speaker C (05:48):
interesting. So I think a fan
is a very smart way
of cooling, especially here in the UK, because it
gets hot, but it's those couple of days in the
year where it's really uncomfortable.
So if you help yourself with a fan and it, can
be one of those mobile ones that you move it with you
(06:08):
around the house or, you know, something a bit more
flexible to use, that's a really good solution.
And you see cases like in India, which they have
extreme heat throughout the year and they have
fels on their ceilings and they have valves that
are on the windows. And
it's a big fan culture. So fans are
definitely a good option. Now,
(06:31):
a big bucket of ice, just to go back to that
one, isn't always the best solution
because the UK is quite humid at times.
And so if we don't have dry air
around us to absorb that humidity
that the bucket of ice and water is
producing, then it's just going to make us more
uncomfortable. We're going to get more humid, and that's
(06:53):
not great for that thermal comfort that we were talking
about. But in the right conditions, evaporative
cooling, which is the bucket of ice and water,
is quite effective. So we have to start
learning how to monitor humidity. If you go
out to met office, it gives you
humidity.
>> Emily Elias (07:11):
Any fine weather app will provide you what the humidity is
pretty much, yeah, yeah. Okay. Now,
you are obviously in a different area
of, science where you're not studying buckets of ice,
necessarily. You're looking more at houses
themselves. So imagine that. I am, Kevin McCloud
on grand designs. I'm
building a massive,
(07:33):
environmentally friendly house because I've got
so much money in my pockets to burn. What
should I be looking at if I was going to be knocking
down walls and trying to make my house,
as energy efficient as possible?
>> Speaker C (07:47):
So, yeah, that. Actually, I'd like to
make an important point here. The UK
has very good new build
regulations. So if you're building a new house,
there is regulations and codes
to make that house resilient
to overheating. However,
in the case that you're saying, it's like a retrofit
(08:10):
issue, and unfortunately, that's where
we need more efforts made, because most
houses that'll be here in 50 years
are already built and those houses
are not necessarily following the new regulation because
they were built a while back. So we need
to focus on programs for
(08:31):
retrofitting our houses and our beautiful
buildings because we've got great historical buildings,
but they're usually made traditionally to keep
heat in because the winters are harsher than the
summers. As climate change continues
to have its effect, we're going to have
more and more hot weather here in the
UK. Unfortunately. it
(08:53):
seems that we're going to be one of the top countries to have an
increase in relative change for cooling
needs. And that means, yeah, we need to look at
what do we do with our retrofitting. So
a passive first approach should be applied
for retrofitting as well. And that could include
ventilation. So if you have windows that are only
(09:13):
on one side of the house and they're not connected
to the other side, there should be. If you're knocking down
walls, think of that. think of, like, how are we going to
make this breeze pass when it's
needed? Think of insulation. It's a
great retrofit solution that is commonly
associated with heating. But insulation is
fantastic for cooling as well because it allows you to put a
(09:36):
barrier that will divide
the outside from the inside. So if it's really hot outside
and you've managed to cool inside, that
cool, which isn't a very scientific
term, will remain inside
better, because it's
encapsulated so.
>> Emily Elias (09:54):
Similar to, like a cooler, like an ice bag. When you're going to the park with,
like, your beers or your soda pops, shall we
say? it's the same sort of principle. Like, if you put a
bunch of ice in it, the insulator keeps the cool
in as much as if you put something hot in it, it keeps the hot
in.
>> Speaker C (10:09):
Absolutely. and then I'd also recommend
looking at those new regulation. It's part o of the
building regulate, and there's great ideas in there.
Like, for example, on top of windows, to just
put a horizontal, call it
wing, that allows for
shading. So when the sun is really high up and
it's at the hottest time of the day,
(10:31):
those windows are really shaded, they're not being hit
by those solar gains. So
there's tons of things we can do with our
retrofitting in the UK.
>> Emily Elias (10:42):
And I suppose, like, if you have like a giant sort of
shade built into the building, in the winter, it's not really
going to hurt anything, and in the summer,
you're going to benefit from the shade off of it.
>> Speaker C (10:53):
Absolutely. So in the winter, the sun
is lower, so you're still going to be
able to benefit from those heat gains because then you want them
in and the sun is lower anyway. But in the
summer, when the sun is higher, you want to shade
the right angles of the sun rays, right?
>> Emily Elias (11:11):
So it's a hot, hot
summer. What are you, Nicole
Miranda, doing to stay cool?
>> Speaker C (11:19):
I am very much paying attention to the
temperature outside to know when to close the window.
So in the morning, I wake up, it's nice and fresh,
usually before the heat comes, in,
and I open all the windows that I can.
And if I'm working from home, I'll,
keep an eye out. And as soon as I see
(11:39):
the sun moving through, the house,
I start drawing curtains where the sun is
hitting, and I start opening them where it's
shaded. So I keep an eye on the
temperature. If I take a break, a coffee break, I'll
go outside. See? Okay. It's getting too hot
outside, so I'm going to start shutting all the windows
now to keep that fresh breeze
(12:02):
from the morning inside. I'm quite lucky
because the walls in my house are quite
thick. And, so that's quite convenient, too,
to keep that heat outside. But it's
all curtains and windows
strategy.
>> Emily Elias (12:16):
That seems like a good strategy.
>> Speaker C (12:18):
Yeah. And cold drinks, of course. Yes. That
a coffee break would be an iced coffee.
And we also have fans, and we turn the
fans on at night. That just helps bring
the fresh air. So we put the
fans on the staircase to just
pull that cool air from the bottom of
(12:38):
the house up. and it's quite effective. Yeah.
>> Emily Elias (12:41):
And what is your policy on popsicles
and ice? cream sandwiches?
>> Speaker C (12:46):
Absolutely. Why not?
Delicious and refreshing.
>> Emily Elias (13:01):
This podcast was brought to you by Oxford Sparks from the
University of Oxford with music by John Lyons
and a special thanks to Doctor Nicole Miranda. we're
getting ready for our next season of the Big Questions podcast,
which will start up in autumn when it's a bit cooler.
So if you've got a big question and you'd like it answered,
reach out to us. We are on the Internet at
(13:21):
Oxfordsparks, and we have a website, Oxfordsparks
ox aC UK.
I've said it once, said it before.
I'll say a thousand times. Come on, guys, send us
your questions. I'm Emily
Elias. Bye for now.
Ah, as the philosopher Rob Thomas from Mashbox 20
once said, man, it's
a hot one. I'll spare you the rest of the lyrics to smooth,
but summer is here. And on this episode
of the Oxford Sparks big Questions
podcast, we are asking, how do I keep
my house cool without cranking on the air
(00:26):
conditioning?
Hello, I'm Emily Elias, and
this is the show where we seek out the brightest minds at the
University of Oxford, and we ask them the big
questions. And for this one, we have
found.
A researcher who's pretty cool.
>> Speaker C (00:47):
My name is Nicole Miranda. I, am a senior
researcher at the University of Oxford,
specifically in the engineering department. And, ah, looking
at sustainable cooling.
>> Emily Elias (00:57):
Okay, so sustainable cooling. So you're a cool
lady. So the
reason we have you to here today is because obviously we're
in the thralls of summer. There are heat
waves forecasted. It is gonna be a hot
one. How do we stay
cool? So I wanted to kind of approach
this from a couple different ways. First of
(01:19):
all, let's assume that, you know, I'm
a renter, I don't have a ton of money.
What can I do to stay cool
in the hot months?
>> Speaker C (01:30):
Well, it's always recommended to go through
a passive first approach. So that means
not giving in to the urge of running to
the supermarket or a shop, and getting an
air conditioner, because air conditioners are very
energy intensive and carbon intensive.
Now that carbon intensity is falling because the
(01:50):
electricity is getting greener, however,
it's still going to be costly. So a passive
burst approach means how
we can cool ourselves without using intensive
energy, using shades, using water
bodies, using vegetation,
things that can help us in a more cost
(02:11):
effective way, but also that are quite effective.
So we always recommend a passive first. And if
you're a renter, you would find that
it's a bit difficult to do things that are the
embedded in the building because you're not the owner of the
house.
>> Emily Elias (02:26):
Exactly. If I was all of a sudden installed, air conditioning,
not only would I be out of pocket, but my landlord would probably be
pretty annoyed with me.
>> Speaker C (02:33):
Exactly. So you should always talk
to your landlord, obviously, because there is
efficient ways of putting shading outside
so that you cover the heat gains
through windows.
>> Emily Elias (02:46):
So is blocking the sun
like my number one go to thing that I should be
worried about? Yes.
>> Speaker C (02:53):
So, within the passive solutions, there's
many options. One is blocking the sun,
and easy things like drawing the curtains when
the sun is outside is very useful.
However, there's another one that we here in the UK
love to do, which is opening the windows, and that's
really effective. So if you open a window on one side of
(03:13):
the house or room, and then another wind on the
other side, you get this lovely cross
ventilation, and that makes wind go
through the house and gives you a nice
thermal comfort effect.
>> Emily Elias (03:25):
Thermal comfort, is that like fancy researcher for breeze?
>> Speaker C (03:28):
Oh, yeah. Well, it's like, how are you
comfortable regarding temperature,
humidity and the wind around you?
Are you thermally comfort, that's what it embraces.
>> Emily Elias (03:38):
Yeah, thermal comfort. Learn something new every day.
>> Speaker C (03:41):
Yeah. So ventilation is a really important one, but
you just need to be careful when you're opening
windows, because if there's no breeze outside
and actually it's hotter outside
inside, you're better off keeping that
window shut. And that's a common mistake we do
here. We think, oh, it's hot and we open the windows. But
actually it's sometimes
(04:03):
more convenient to keep the hotter
temperatures outside and shield your house.
>> Emily Elias (04:08):
Is there like, a better
window to open? Like, so say
in my house, there's a sunny side of it, and there's like, a
shady side of my house. Should I open windows that are
on the sunny side of the house, or should I open windows on the
shady side of the house?
>> Speaker C (04:24):
Well, you could combine opening windows
that are on opposite side of the house,
because that will allow a ventilation, like, from one
window to the other. So it advances through the house.
Right. The wind moves and that's what you want.
But on the sunny side, I would draw the
curtain so that that sun doesn't come in
(04:44):
directly. So you still have the wind able
to escape the room and the house,
but you're shading yourself from those heat gains
from the sun.
>> Emily Elias (04:53):
And it just feels kind of like antisocial in the summer to
have your windows closed and, your curtains
drawn. But that is, that can be, I guess, in
some instances, the best solution.
>> Speaker C (05:04):
Absolutely, yeah. If you see in more
extreme heats in Africa, many
houses have tiny windows, and that's
to protect them from the heat. And so they're
quite dark inside and down. There's a lot of other
issues with that. But to combat the extreme
heat, it's lowering those heat gains
of the windows of the opening.
>> Emily Elias (05:26):
Okay, now let's just imagine I have a tiny bit more money and
I can splash out on a
device. what should I put my money
towards? Should I go for a fan
that does, like, 10,000 things and has a
computer built into it, or should I
just grab a really cool bucket and fill it with
water and ice?
>> Speaker C (05:48):
interesting. So I think a fan
is a very smart way
of cooling, especially here in the UK, because it
gets hot, but it's those couple of days in the
year where it's really uncomfortable.
So if you help yourself with a fan and it, can
be one of those mobile ones that you move it with you
(06:08):
around the house or, you know, something a bit more
flexible to use, that's a really good solution.
And you see cases like in India, which they have
extreme heat throughout the year and they have
fels on their ceilings and they have valves that
are on the windows. And
it's a big fan culture. So fans are
definitely a good option. Now,
(06:31):
a big bucket of ice, just to go back to that
one, isn't always the best solution
because the UK is quite humid at times.
And so if we don't have dry air
around us to absorb that humidity
that the bucket of ice and water is
producing, then it's just going to make us more
uncomfortable. We're going to get more humid, and that's
(06:53):
not great for that thermal comfort that we were talking
about. But in the right conditions, evaporative
cooling, which is the bucket of ice and water,
is quite effective. So we have to start
learning how to monitor humidity. If you go
out to met office, it gives you
humidity.
>> Emily Elias (07:11):
Any fine weather app will provide you what the humidity is
pretty much, yeah, yeah. Okay. Now,
you are obviously in a different area
of, science where you're not studying buckets of ice,
necessarily. You're looking more at houses
themselves. So imagine that. I am, Kevin McCloud
on grand designs. I'm
building a massive,
(07:33):
environmentally friendly house because I've got
so much money in my pockets to burn. What
should I be looking at if I was going to be knocking
down walls and trying to make my house,
as energy efficient as possible?
>> Speaker C (07:47):
So, yeah, that. Actually, I'd like to
make an important point here. The UK
has very good new build
regulations. So if you're building a new house,
there is regulations and codes
to make that house resilient
to overheating. However,
in the case that you're saying, it's like a retrofit
(08:10):
issue, and unfortunately, that's where
we need more efforts made, because most
houses that'll be here in 50 years
are already built and those houses
are not necessarily following the new regulation because
they were built a while back. So we need
to focus on programs for
(08:31):
retrofitting our houses and our beautiful
buildings because we've got great historical buildings,
but they're usually made traditionally to keep
heat in because the winters are harsher than the
summers. As climate change continues
to have its effect, we're going to have
more and more hot weather here in the
UK. Unfortunately. it
(08:53):
seems that we're going to be one of the top countries to have an
increase in relative change for cooling
needs. And that means, yeah, we need to look at
what do we do with our retrofitting. So
a passive first approach should be applied
for retrofitting as well. And that could include
ventilation. So if you have windows that are only
(09:13):
on one side of the house and they're not connected
to the other side, there should be. If you're knocking down
walls, think of that. think of, like, how are we going to
make this breeze pass when it's
needed? Think of insulation. It's a
great retrofit solution that is commonly
associated with heating. But insulation is
fantastic for cooling as well because it allows you to put a
(09:36):
barrier that will divide
the outside from the inside. So if it's really hot outside
and you've managed to cool inside, that
cool, which isn't a very scientific
term, will remain inside
better, because it's
encapsulated so.
>> Emily Elias (09:54):
Similar to, like a cooler, like an ice bag. When you're going to the park with,
like, your beers or your soda pops, shall we
say? it's the same sort of principle. Like, if you put a
bunch of ice in it, the insulator keeps the cool
in as much as if you put something hot in it, it keeps the hot
in.
>> Speaker C (10:09):
Absolutely. and then I'd also recommend
looking at those new regulation. It's part o of the
building regulate, and there's great ideas in there.
Like, for example, on top of windows, to just
put a horizontal, call it
wing, that allows for
shading. So when the sun is really high up and
it's at the hottest time of the day,
(10:31):
those windows are really shaded, they're not being hit
by those solar gains. So
there's tons of things we can do with our
retrofitting in the UK.
>> Emily Elias (10:42):
And I suppose, like, if you have like a giant sort of
shade built into the building, in the winter, it's not really
going to hurt anything, and in the summer,
you're going to benefit from the shade off of it.
>> Speaker C (10:53):
Absolutely. So in the winter, the sun
is lower, so you're still going to be
able to benefit from those heat gains because then you want them
in and the sun is lower anyway. But in the
summer, when the sun is higher, you want to shade
the right angles of the sun rays, right?
>> Emily Elias (11:11):
So it's a hot, hot
summer. What are you, Nicole
Miranda, doing to stay cool?
>> Speaker C (11:19):
I am very much paying attention to the
temperature outside to know when to close the window.
So in the morning, I wake up, it's nice and fresh,
usually before the heat comes, in,
and I open all the windows that I can.
And if I'm working from home, I'll,
keep an eye out. And as soon as I see
(11:39):
the sun moving through, the house,
I start drawing curtains where the sun is
hitting, and I start opening them where it's
shaded. So I keep an eye on the
temperature. If I take a break, a coffee break, I'll
go outside. See? Okay. It's getting too hot
outside, so I'm going to start shutting all the windows
now to keep that fresh breeze
(12:02):
from the morning inside. I'm quite lucky
because the walls in my house are quite
thick. And, so that's quite convenient, too,
to keep that heat outside. But it's
all curtains and windows
strategy.
>> Emily Elias (12:16):
That seems like a good strategy.
>> Speaker C (12:18):
Yeah. And cold drinks, of course. Yes. That
a coffee break would be an iced coffee.
And we also have fans, and we turn the
fans on at night. That just helps bring
the fresh air. So we put the
fans on the staircase to just
pull that cool air from the bottom of
(12:38):
the house up. and it's quite effective. Yeah.
>> Emily Elias (12:41):
And what is your policy on popsicles
and ice? cream sandwiches?
>> Speaker C (12:46):
Absolutely. Why not?
Delicious and refreshing.
>> Emily Elias (13:01):
This podcast was brought to you by Oxford Sparks from the
University of Oxford with music by John Lyons
and a special thanks to Doctor Nicole Miranda. we're
getting ready for our next season of the Big Questions podcast,
which will start up in autumn when it's a bit cooler.
So if you've got a big question and you'd like it answered,
reach out to us. We are on the Internet at
(13:21):
Oxfordsparks, and we have a website, Oxfordsparks
ox aC UK.
I've said it once, said it before.
I'll say a thousand times. Come on, guys, send us
your questions. I'm Emily
Elias. Bye for now.
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