Chris Litten: Building Research Association expert on whether more insulation makes your house too hot

A new study from the Building Research Association has found that indoor summer temperatures have gone up 6 to 10 percent in the last 20 years.

The new insulation standards that came into force in 2023 aren't to blame for these changes, according to the report.

Chris Litten from the Building Research Association unpacks what could be causing these changes.

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Episode Transcript

Speaker 1 (00:00):
A study from the Building Research Association has found that
indoor summer temperatures have gone up six to ten percent
in the last twenty years. That's inside during summer tempts
up six to twenty It's two ten percent in the
last twenty years, and the new insulation standards that came
into force in twenty twenty three aren't to blame for this.

(00:23):
The study found that homes of all ages are overheating.
Doctor Chris Listen is a Building Research Association General manager
of Research. Welcome to the show, Chris.

Speaker 2 (00:33):
Hi, Ryan, how are you? Yeah? Good?

Speaker 1 (00:34):
Thank you. First of all, I asked Laura, who's our
producer here. I wanted to find out whether you've got
any skin in the game here are you? You know,
you've got shares and insulation companies anything like that. But
you're you're quite independent. I've found out.

Speaker 2 (00:49):
Yeah, we're completely independent. I am. Brains is all about
providing some ex independent advice into the system. So that's
what we're about. Brilliant.

Speaker 1 (00:57):
Okay, So two things. One, it's getting hotter in the side.
What's the temperature? I mean, how hot are we talking
in summer?

Speaker 2 (01:05):
Some people are saying it's somewhere between twenty five and
thirty degrees and that's for some people that feels really hot.
And I think one of the really interesting things from
the study shows that Willingtonians are likely to say it's
too warm when they're homes despite them actually being colder
than the people in Auckland who are saying it's quite comfortable.
So it's really about perception about what people are actually

(01:25):
feeling like they're in their homes.

Speaker 1 (01:27):
What do people feel like is a good temperature.

Speaker 2 (01:31):
Again, that really comes down to personal preference. Like I'm
in Wellington. I think if my home was twenty five
degrees I'd feel that's pretty warm. But you know that
would be quite different to someone else than from Auckland
or from christ Church. But I think at the end
of the day, there's actually no agreed definition of when
it's too hot. The world health organizations see something between
over forty degrees is probably not good, which is probably right,

(01:54):
but it's not actually a real measure of plants saying
when it's when hot is too hot.

Speaker 1 (01:59):
Now, one of the things you looked at was the
new insulation standards that came into fours in twenty twenty three.
You've said that they're not to blame for our houses
getting warmer. That doesn't make sense to me.

Speaker 2 (02:11):
There's two parts of actually. First of all, none of
the houses in the survey actually had that new insulation
levels in them, so we can certainly say that didn't
make any difference. But I think the other thing that
we have shown in this worker insulation but also keeps
the heat out, so no one is it keeping you
warm in winter, which is a really great thing, but
also keeps the heat out in summer. I think what

(02:32):
we're really seeing is that homes are really complex, complex constructions.
There's a lot that you need to think about. There's insulation,
there's the amount of windows you've got, how much sun's
coming in, how much shade you haven't, haven't got they
facing north or south. It's really complex, and that's what
we're really trying to trying to get across to everybody.

(02:54):
Really right, there's to design things right and to build
them properly. They need to actually if you're living, then
you need to open the window and insulate them.

Speaker 1 (03:02):
So none of the homes you looked at actually had
the new standard of insulation, so that's correct. So therefore
you can say, well, they're still getting hot, but how
do you know that they wouldn't have gotten even hotter
had they had that level.

Speaker 2 (03:16):
Well, again, that comes back to that complex relationship between
everything that's in the in the house. There is that
there's a lot there's a lot of people who don't
have any shaving at all coming into your really large
open windows and onto concrete flour. So insulation is one
part of it, but it's not that it's not the
only thing that's contributing to things getting warmer.

Speaker 1 (03:35):
Okay, is there anything you want changed? You know, whether
it's to do with insulation or anything else with the
building code, anything you want change to cool our houses down?

Speaker 2 (03:47):
I think the building code has always been updated and
people are always thinking about That's not our job. We
provide advice to the government that does do that. But
at the end of the day, people need to think
of the gain. That's the whole the whole building code,
the whole strom as hellistic. Things are a complex. You
change one thing and something else will change. You need
to consider that in the whole process of designing and

(04:09):
building your homes.

Speaker 1 (04:09):
Okay, does everyone get will we all need air conditioning
at some point? And if so, when do you think
that might be.

Speaker 2 (04:18):
I don't know about that. I think there's always some
way to operate your home better. It doesn't have to
be with air conditioning. You could intellate properly. You can
close the windows that you know, close your blinds at
the right time. You can put some shaving, plant a
big tree outside your window. There's lots of ways to
cool things down when you actually need to put a

(04:39):
calling pump and the air conditioning. And I don't know
that's going to be very gay, very much for people
how they feel that their perception of living in their
homers interesting.

Speaker 1 (04:47):
Chris, thank you for that. I appreciate your time. Welcome
doctor Christ Building Research Association General manager of research, very
independent man.

Speaker 2 (04:54):
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