Do Radiant Barriers Work? - LP Techshield Review
Summary
TLDRIn this video, Jordan Smith explains the function of radiant barriers, focusing on the LP TechShield radiant barrier integrated with OSB sheathing. He discusses how heat is transferred through conduction, convection, and radiation, and demonstrates the effectiveness of the radiant barrier using an infrared thermometer. Jordan emphasizes the importance of maintaining an air gap for optimal performance and highlights how improper insulation, like spray foam, can negate the benefits of the barrier. He concludes by encouraging viewers to consider the full system when using radiant barriers for energy efficiency.
Takeaways
- 🛠️ The video is about radiant barriers, specifically LP Tech Shield, which is integrated into OSB sheathing to reduce heat transfer.
- 🌞 Heat transfers in three ways: conduction, convection, and radiation. Radiant barriers address heat transfer by radiation.
- 🌡️ The speaker uses an infrared thermometer to show a 10-degree temperature difference on a westerly-facing roof, demonstrating the radiant barrier's effect.
- 🏠 In summer, the radiant barrier is more effective as it blocks more radiative heat from the sun.
- 🚧 Conduction happens when heat transfers through solid materials, like rafters in a roof, reducing the effectiveness of radiant barriers at those points.
- 🛑 Radiant barriers require an air gap behind them to function properly; without this, they lose effectiveness.
- 💡 Insulation choice is crucial. For example, fiberglass insulation with an air gap maintains the barrier's efficiency, while spray foam negates it by creating conduction.
- 🔄 The speaker emphasizes the importance of designing the entire system to complement the radiant barrier for optimal performance.
- 📐 Advanced framing techniques can help reduce heat conduction through rafters, further improving energy efficiency.
- 📱 The speaker encourages viewers to subscribe, follow on Instagram (@JordanSmithBuild), and ask questions for further information.
Q & A
What is a radiant barrier and how does it work?
-A radiant barrier is a material, like the LP TechShield discussed in the video, that reflects radiant heat away from a space. It consists of a reflective surface, such as aluminum, that reduces heat transfer by radiation.
What are the three ways heat is transferred?
-Heat is transferred through conduction, convection, and radiation. Conduction is heat transfer through direct contact, convection involves the movement of hot air or fluids, and radiation is heat transfer through electromagnetic waves.
How does the LP TechShield radiant barrier reduce heat transfer?
-The LP TechShield radiant barrier reduces heat transfer by reflecting radiant energy away from the space, preventing it from heating the area below. This is achieved through the aluminum layer integrated into the OSB sheathing.
What role does the air gap play in the effectiveness of a radiant barrier?
-The air gap is crucial because it prevents direct contact between the insulation and the radiant barrier. Without an air gap, the heat would conduct into the insulation, reducing the effectiveness of the radiant barrier.
Why does spray foam insulation negate the effectiveness of a radiant barrier?
-Spray foam insulation, when applied directly to the roof deck, negates the radiant barrier's effect by conducting heat from the roof deck into the insulation. Without an air gap, the radiant barrier cannot reflect heat properly.
Why is it important to spread rafters apart in advanced framing?
-Spreading rafters apart in advanced framing reduces the amount of heat conduction through the rafters, which helps maintain the effectiveness of the radiant barrier by minimizing heat transfer through the framing.
How does an infrared thermometer help in demonstrating the effectiveness of the radiant barrier?
-An infrared thermometer measures radiant energy, showing how much heat is being emitted from a surface. In the video, it demonstrates the temperature difference between the radiant barrier and non-barrier areas, indicating how much heat is being reflected.
What temperature differences did the speaker measure during the demonstration?
-The speaker measured a 10-degree difference between the westerly facing wall and roof deck, which indicates that the radiant barrier is reflecting heat away even on a relatively cool day.
Why is it necessary to design a building system to take advantage of a radiant barrier?
-A radiant barrier only works effectively if the building system is designed to allow it to reflect heat. This includes maintaining an air gap and minimizing direct conductive paths like rafters or certain types of insulation.
What are the potential consequences of installing insulation incorrectly with a radiant barrier?
-If insulation is installed incorrectly, such as placing it in direct contact with the radiant barrier, the radiant barrier will not work properly, and the heat will conduct into the insulation and potentially into the living space below.
Outlines
👷 Introduction to Radiant Barriers
Jordan Smith introduces the topic of radiant barriers, specifically LP TechShield. He explains that the video will cover how radiant barriers work, demonstrate their effectiveness, and delve into the technical details of heat transfer. The radiant barrier consists of OSB sheathing with an aluminum layer that prevents heat from radiating into a building. Smith briefly outlines the three methods of heat transfer—conduction, convection, and radiation—and notes that radiant barriers primarily address radiation when used correctly.
🌡 Demonstrating the Radiant Barrier's Effectiveness
Smith uses an infrared thermometer to show how the radiant barrier reduces heat transfer. On a winter day, with overcast skies, he measures a 10-degree difference between two surfaces—an 82-degree westerly wall and a 72-degree roof. While this temperature difference may seem small, he explains that in the summer, the effect will be much more significant. This demonstration serves as proof that the radiant barrier is functioning even under less ideal conditions.
🔬 Understanding Heat Transfer: Radiation, Conduction, and Convection
Jordan dives deeper into how heat transfers through radiation, conduction, and convection. He explains how heat from the Sun reaches Earth via radiation, then transfers to air and water, which in turn distribute the heat through convection. Conduction occurs when heat is transferred through direct contact between materials.
Mindmap
Keywords
💡Radiant barrier
💡OSB (Oriented Strand Board)
💡Heat transfer
💡Conduction
💡Convection
💡Radiation
💡Infrared thermometer
💡Air gap
💡Spray foam insulation
💡R-value
Highlights
Introduction to radiant barriers and their purpose.
LP Tech Shield radiant barrier integrates with OSB sheathing to reduce heat radiation.
Heat transfer occurs in three ways: conduction, convection, and radiation.
Radiant barriers help reduce heat transfer through radiation, but they must be installed correctly to work effectively.
Demonstration using an infrared thermometer to show the temperature difference on the surface of a radiant barrier.
Infrared thermometers are effective at measuring radiant energy rather than absolute temperature.
A 10-degree temperature difference observed between a westerly facing wall and roof deck using radiant barriers.
In summer, radiant barriers will show a more significant temperature difference.
Explanation of how the sun transfers heat to Earth through radiation, which is then transferred through convection.
Convection occurs in building assemblies, with rafters conducting heat if not properly insulated.
The effectiveness of radiant barriers can be diminished by improper installation, especially if insulation touches the barrier.
Advanced framing techniques can reduce heat conduction through rafters, improving the radiant barrier's performance.
Maintaining an air gap between insulation and the radiant barrier is crucial for effective heat rejection.
If insulation, like spray foam, is applied directly to the roof deck, it negates the radiant barrier's effectiveness.
The entire system must be built to maximize the radiant barrier’s properties—correct installation is essential for optimal results.
Transcripts
howdy y'all it's Jordan Smith today I
want to talk to you about radiant
barriers I'm going to talk a little bit
about how they worked and I'm going to
show you that it's actually working and
then I'm gonna talk a lot about how it
works some of the geeky stuff so let's
get right into it this is LP Tech shield
radiant barrier and what's cool about
this is it's a radiant barrier that is
integrated into our oh s be sheathing so
the board looks like this we have OSB
and then it has this aluminum
barrier right there that keeps heat from
radiating into the space so a little bit
about how it works is he conducts in
three ways convection conduction and
radiation or I should say heat transfers
in three different ways
conduction convection and radiation so
this takes care of one part of our heat
transfer and that is radiation but only
if you do it right so now I'm going to
show you that it actually works I've got
an infrared thermometer right here now
infrared thermometers aren't great at
showing what temperature's things
actually are but they are great at
showing how much radiant energy infrared
light is coming off of this board here
so we're at 82 degrees on this board
right now it's a Texas winter day
overcast so it's not the greatest day to
be showing this but the time the summer
rolls around this will all be covered up
and I think it should show you what I'm
wanting to show this is my roof deck on
the same side so I just tested over
there the westerly facing wall now I'm
going to show you here on a westerly
facing roof and I've got 72 degrees
don't you see that 72 71 and a half 72
degrees so we have a 10 degree Delta on
a day where it's really not all that hot
out here so just imagine what it's
actually doing in the summer we've got a
westerly facing wall which isn't taking
near as much radiative energy as the
and we still have 18 degree Delta now
let me talk a little bit about how it
works so like I said three different
ways that heat is transferred we have
convection conduction and radiation
radiation is how we get the heat from
the Sun right in space it's a vacuum so
there's no way for that heat to get from
the Sun it's to the to the earth except
through ultraviolet light so it's
actually sending ultraviolet light as
heat into our atmosphere and it heats up
our air and our water and those transfer
heat by something called convection so
as those move around as the water flows
and as the air flows we get the hot air
particles or water particles moving from
one point to another transferring that
heat with them the other way that it
works is through convection and that is
very important in building assemblies
because right here where we have this
rafter touching our roof deck we have
convection right here so even though we
have the same aluminum backer it doesn't
do us any good right here at this rafter
because we have negated our radiant
energy and we are conducting our Heat
straight from the roof deck into here
that's why things like advanced framing
which this roof is not framed with but
if we can spread these rafters out
further than we have less conduction
through our rafters and a radiant
barrier can do a good job the last thing
that you need to keep in mind is
depending on how you insulate this you
can totally negate how your radiant
barrier works so for example in this
cavity here we're going to be doing
fiberglass insulation I've upgraded to 2
by 10 rafters which allows me to have my
r-value that I need in my roof while
still maintaining an air gap between my
insulation and my roof that that air gap
allows this radiant barrier to work
because it's not going to emit the heat
into the cavity it's going to turn
around and reject it out the outside but
if I took my insulation and I put it all
the way up against here now I'm
conducting the heat from my roof deck
into my insulation
if I do this and then I go with a spray
foam here if I came and I spray foamed
all this well I shouldn't use the LP
tech shield product because it's not
doing any good as soon as I spray foam
all the way up to there it's conducting
the heat from the roof deck into the
spray foam and the spray foam will then
reradiates
or conduct the heat into the living
space below so if you spend the money
for a a radiant barrier make sure that
you build the whole system to take
advantage of the radiant barrier don't
just put it up there and hope that it
magically happens cuz that's not how it
works you have to have an air gap on the
backside of this in order for the
radiant barrier properties to kick in
there's a whole lot more about heat
transfer that I'd love to get into but
I'm out here on the jobsite and can't
really get into it if you want to see a
video more about heat transfer comment
below let me know thanks so much for
watching subscribe if we've earned it go
follow us over on Instagram at Jordan
Smith build at Smith house if you have
any other questions about how we built
this house or a specifically LP tech
shield comment below and we'll see you
next time on Smith house
[Music]
Weitere ähnliche Videos ansehen
5.0 / 5 (0 votes)