Do Radiant Barriers Work? - LP Techshield Review

Jordan Smith

17 Jan 202005:56

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

00:00

👷 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.

05:01

🌡 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

A radiant barrier is a material, often aluminum, designed to reflect radiant heat away from a building, reducing heat transfer. In the video, Jordan describes the LP Tech Shield radiant barrier, which is integrated into OSB (Oriented Strand Board) sheathing to prevent heat from radiating into living spaces. This helps reduce the overall heat gain in buildings, particularly during hot weather.

💡OSB (Oriented Strand Board)

Oriented Strand Board (OSB) is a type of engineered wood similar to plywood, made by compressing layers of wood strands together. In the video, Jordan mentions that the radiant barrier is integrated into OSB sheathing, demonstrating how the material is used in construction to both provide structural support and help manage heat transfer.

💡Heat transfer

Heat transfer refers to the movement of heat from one place to another via conduction, convection, or radiation. Jordan explains that radiant barriers specifically target radiant heat transfer, while heat conduction occurs when materials, like rafters, directly conduct heat through contact. Proper insulation methods are essential to manage all three forms of heat transfer in buildings.

💡Conduction

Conduction is the transfer of heat through direct contact between materials. In the video, Jordan highlights that when rafters are in direct contact with the roof deck, heat is conducted into the building, reducing the effectiveness of the radiant barrier. Advanced framing techniques can help reduce this conduction by spacing out rafters.

💡Convection

Convection is the transfer of heat through fluid movement, such as air or water. Jordan briefly mentions convection as the process by which heat from the sun heats the Earth's atmosphere, which then circulates. In buildings, convection can occur when warm air moves between spaces, and proper insulation can help mitigate this.

💡Radiation

Radiation is the transfer of heat via electromagnetic waves, such as ultraviolet (UV) light from the sun. Jordan explains that radiant barriers reflect this type of heat, preventing it from entering buildings. He notes that radiant heat from the sun is what primarily causes heat buildup in structures, especially during summer.

💡Infrared thermometer

An infrared thermometer is a device that measures surface temperature by detecting infrared radiation. Jordan uses this tool to demonstrate the temperature difference between surfaces with and without the radiant barrier, showing that the barrier reduces the amount of heat radiating into the space by about 10 degrees, even on a cool, overcast day.

💡Air gap

An air gap is a crucial space between a radiant barrier and the insulation or building material that allows the barrier to function effectively. Jordan emphasizes that if insulation is placed directly against the radiant barrier, it will conduct heat instead of reflecting it. The air gap ensures that the radiant heat is rejected and not absorbed.

💡Spray foam insulation

Spray foam insulation is a material used to insulate buildings by expanding and sealing gaps. Jordan warns that using spray foam against a radiant barrier negates its effectiveness because the foam will conduct heat from the roof deck. This example demonstrates the importance of proper insulation methods to preserve the benefits of a radiant barrier.

💡R-value

R-value measures a material's ability to resist heat flow, with higher values indicating better insulation. Jordan mentions upgrading to 2x10 rafters to accommodate more fiberglass insulation and achieve the necessary R-value for the roof. This ensures that the building is well-insulated while maintaining an air gap for the radiant barrier to function.

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.