How BlueTex™ Insulation Helps Keep Heat Inside Your Building During the Winter
When cold weather rolls in, everyone wants the same thing—to keep the heat inside the building, not leaking out into the chilly air. If you’re heating a metal building, shed, workshop, or garage, you may wonder: Can BlueTex insulation actually help during the winter?
Yes — absolutely. And the science behind it is pretty cool (literally). BlueTex™ isn’t just a “summer insulation.” It works year-round by controlling radiant heat, which is one of the three ways heat moves (the other two are conduction and convection).
This page explains how BlueTex™ works in the cold months, why your building might need a heat source, and why both BlueTex™ Pro (2mm) and BlueTex™ Supreme (6mm) help retain heat inside—even though one may be the better fit depending on your climate.
First Things First: You Need a Heat Source
BlueTex™ is a radiant barrier, which means it controls radiant heat transfer. But here’s something important:
BlueTex cannot create heat. A heat source must be present first.
So whether you use:
- a propane heater,
- a wood-burning stove,
- a electric heater, or
- any other heater that warms the air and surfaces inside your building…
..that heat will start radiating in all directions. Radiant heat behaves just like light—it travels in straight lines until it's either reflected or absorbed. This is where BlueTex™ comes into play.
BlueTex™’s job is to help keep that radiant heat inside your building.
How Aluminum Stops Radiant Heat Transfer
BlueTex™ uses high-performance, durable, pure aluminum foil, and aluminum has two superpowers:
1. Reflectivity (bouncing radiant heat away)
In the summer, the shiny aluminum surface reflects radiant heat coming into the building from the sun. This keeps your building cooler.
2. Emissivity (not giving off radiant heat)
In the winter, the aluminum works differently. Instead of reflecting heat, it uses its low emissivity to hold radiant heat inside.
Low emissivity means:
The aluminum does NOT easily give up the heat it absorbs.
So when you turn on your heat source and heat up the building, your BlueTex™ layer keeps radiant heat from escaping through your walls and roof. Think of it as a “radiant heat dam” slowing down how quickly warmth can leak out.
This emissivity property of aluminum radiant barriers is the star of the show in winter.
Why Emissivity Matters Inside a Metal Building
Metal buildings lose heat fast because:
- metal conducts heat very easily, and
- metal surfaces have high emissivity (they “give off” heat readily).
But aluminum foil has extremely low emissivity.
This means when you line your building with BlueTex:
- The warm surfaces inside don’t radiate their heat out through the metal.
- The aluminum dramatically slows radiant heat loss.
- Your heater doesn’t have to run as long to maintain comfort.
It's a small layer that makes a big difference.
Do I Need to Install BlueTex™ with the Foil Side Facing the Heat Source?
Nope!
Because BlueTex benefits come from the air gap, not from facing the heater.
As long as you install BlueTex with an air gap on at least one side (and we recommend sealed seams for moisture control), you get full radiant-barrier performance.
Want the foil facing inward?
Go for it—some people prefer the look.
Prefer it facing the building shell?
Works just the same.
Either way, the aluminum surface will “switch roles” throughout the year:
- Summer: It reflects radiant heat away.
- Winter: It uses low emissivity to hold radiant heat inside.
No special seasonal installation required!
BlueTex™ Pro vs. BlueTex™ Supreme for Winter Heat Retention
Both products help keep heat inside:
- BlueTex™ Pro (2 mm) – excellent radiant performance + vapor barrier for minimal moisture control (in mild/mixed climates)
- BlueTex™ Supreme (6 mm) – same radiant performance + thicker vapor barrier for maximum moisture control (cold/wet climates)
So which should you choose?
Choose the 2mm BlueTex™ Pro if:
- your climate is cold but not especially wet, and
- you heat your building for occasional use (less than 8 hours/week)
Choose the 6mm BlueTex™ Supreme (6 mm) if:
- your climate is cold AND wet,
- and you heat your building more than 8 hours per week, but you're not heating full-time
The Supreme’s reinforced foil surface thicker and denser foam core help manage moisture and reduce condensation—two common issues when a metal building is heated regularly in a humid climate.
For more help on which product you should use, you can visit our guide here: Help Me Choose the Right Product
For Best Results on Winter Heat Retention in Your Building: Fully Encapsulate & Seal All Seams
To get the maximum winter performance:
✔ Fully encapsulate the building: Cover all walls and the ceiling continuously with a layer of BlueTex™.
✔ Seal your seams with our 3" wide vapor-barrier seam tape. Un-sealed seams act like leaks in a boat—small, but they add up fast. Remember, having sealed seams give you the best thermal and moisture control in your vapor barrier.
BlueTex™ insulation isn’t just a summer solution. It's a year-round, radiant-heat-control system that keeps your building more comfortable in every season.
To recap, in the winter:
- Start with a heat source to generate radiant heat.
- BlueTex™’s low-emissivity aluminum helps keep that radiant heat inside.
- Both 2 mm Pro and 6 mm Supreme work—but the Supreme is the best choice for wet climates or frequent heating.
- Installation is the same no matter the season - face the foil toward an air gap.
- Covering walls and the ceiling and sealing your seams gives you the best overall winter performance.
If you’re heating a metal building this winter, BlueTex™ can make a noticeable difference in comfort, energy efficiency, and moisture control.