Innovation·Powers the better World
For thousands of years, people have generally assumed that the thicker the clothing worn in winter, the warmer it will be. But few stop to ask a more fundamental question:
Does thicker really mean warmer?
At its core, thermal insulation is a matter of physics—specifically, how to slow the transfer of heat from a warmer region to a colder one.
Thickness is one way to achieve this, but it is not the only approach. Modern insulation technology increasingly focuses on controlling heat transfer through the internal structure of materials rather than simply adding more bulk.
I. The Three Pathways of Heat Transfer
To understand how insulation works, we first need to understand the three primary mechanisms through which heat is transferred.
1. Thermal Conduction
Thermal conduction occurs when heat moves from a higher-temperature region to a lower-temperature region through interactions between microscopic particles within a material.
In clothing systems, conductive heat transfer occurs through fibers, fabrics, trapped gases, and other components of the garment.
In general, the lower the thermal conductivity of an insulation material, the more effectively it can reduce conductive heat loss.
2. Thermal Convection
Convection occurs when a fluid—such as air or water—moves and carries thermal energy with it.
In clothing, convection can occur in two main ways.
First, cold external air can penetrate the garment or remove the warm air layer near the body, creating what is commonly experienced as wind chill.
Second, air inside the garment can circulate as it is warmed by the body, transferring heat from warmer regions to cooler ones.
Effective insulation therefore seeks to restrict unnecessary air movement and maintain relatively stable layers of air within the garment.
3. Thermal Radiation
Any object with a temperature above absolute zero emits thermal radiation in the form of electromagnetic waves.
The human body continuously radiates thermal energy, much of it within the infrared spectrum.
Some advanced insulation systems therefore attempt not only to reduce conduction and convection, but also to influence radiative heat transfer through material composition and internal structure.
II. The Traditional Approach to Insulation: Trapping Air
Once these three heat-transfer pathways are understood, the logic behind most conventional insulation materials becomes relatively straightforward:
They use their structure to trap relatively still air.
Air has relatively low thermal conductivity compared with many solid materials. If air can be held in place and prevented from circulating freely, it becomes an effective component of an insulating system.
Down and Synthetic Fiber Fill
Down uses a highly branched, three-dimensional structure to create large volumes of loft and trap still air.
Synthetic insulation follows a similar principle, using fine polyester fibers to form a network of small air spaces.
Both rely heavily on thickness and loft to provide effective insulation.
Fleece
Fleece also works by trapping air between raised fibers.
Its relatively open structure offers good breathability, but its insulation performance depends on maintaining sufficient thickness and minimizing excessive air movement.
Aerogel
Aerogel takes a different approach.
Rather than relying primarily on large, lofted air spaces, aerogel contains an extremely fine porous structure that restricts gas movement at a much smaller scale.
Certain aerogels can achieve thermal conductivity values of approximately 0.02 W/(m·K) or lower, making them among the most efficient solid insulation materials known.
III. Nanoporous Insulation: Restricting Gas Heat Transfer at the Microscale
Heat transfer through a gas occurs largely through molecular motion and collisions.
This leads to an important phenomenon in nanoporous insulation—the Knudsen effect.
When the dimensions of a pore become sufficiently small relative to the mean free path of the gas molecules inside it, collisions between gas molecules become less frequent relative to collisions with the pore walls.
As a result, the ability of the gas to transfer heat can be significantly reduced.
In other words, extremely small pores can suppress gaseous heat conduction far more effectively than larger air spaces.
This is one of the key physical principles behind the high thermal efficiency of many nanoporous insulation materials.
IV. Y-Warm’s Approach to Thermal Insulation
Based on these principles, Y-Warm’s thermal insulation mechanism can be understood through three interacting structural effects.
First Layer: Micron-Scale Closed Cells Suppress Gas-Phase Heat Transfer
Y-Warm contains a large number of micron-scale closed cells that separate and confine the gas within the material.
By limiting large-scale gas movement and reducing convective transport within the structure, these closed cells help suppress the contribution of the gas phase to overall heat transfer.
This provides an important physical basis for the material’s thermal insulation performance.
Second Layer: A Highly Porous Solid Framework Reduces Solid Heat Conduction
The material also incorporates nanoscale cell-wall structures.
These create complex and discontinuous pathways for heat to travel through the solid phase. As thermal energy moves through the solid framework, phonon transport can be repeatedly disrupted or scattered by structural boundaries.
The result is a reduction in solid-state thermal conduction.
Third Layer: Multiple Internal Interfaces Influence Radiative Heat Transfer
The large number of internal interfaces created by the porous structure can also interact with infrared radiation.
Through repeated reflection, scattering, absorption, and attenuation within the material, these interfaces can help reduce radiative heat transfer.
The combined effect of these mechanisms allows Y-Warm to reduce its dependence on conventional loft-based insulation.
Rather than achieving thermal performance primarily by increasing thickness, it is designed to improve insulation through microstructural efficiency.
This makes it possible to achieve meaningful thermal resistance within a very thin material profile.
V. Why Lightweight, Warmth, and Moisture Permeability Can Coexist
Warmth and breathability have traditionally been viewed as competing requirements.
A garment that blocks heat loss effectively may also restrict moisture transfer, creating a warm but humid and uncomfortable microclimate during physical activity.
Y-Warm approaches this problem by combining thermal insulation with moisture permeability.
The transport mechanisms of heat and water vapor are not identical.
Heat transfer through air can involve conduction and bulk air movement, whereas water vapor can migrate through a material through diffusion driven by differences in vapor concentration and vapor pressure.
This means that a material can be structured to restrict large-scale air movement and reduce heat transfer while still providing pathways for water vapor to move outward.
In practical terms, the objective is simple:
slow heat loss without completely blocking moisture transport.
This balance is particularly important for outdoor clothing, where changes in activity level can rapidly alter the amount of heat and moisture produced by the body.
VI. How Is Y-Warm Related to Aerogel?
A common question is: What is the relationship between Y-Warm and aerogel?
From the perspective of thermal insulation mechanisms, the two materials share an important principle: both use highly porous structures to reduce heat transfer, particularly heat transfer through the gas phase.
The major difference lies in their engineering implementation.
Traditional silica aerogel offers extremely low thermal conductivity, but it is also inherently brittle. Repeated bending, compression, or abrasion can lead to cracking or powdering.
For flexible textile applications, aerogel therefore generally needs to be incorporated into composite structures, coatings, laminates, or reinforced substrates.
These additional structures help improve mechanical durability, but they can also increase manufacturing complexity, thickness, and cost.
Y-Warm takes a different engineering approach by incorporating a highly porous structure into an inherently flexible material.
This makes it more suitable for processes such as cutting, sewing, laminating, and integration into soft textile systems.
The distinction is therefore not simply about thermal conductivity. It is also about how nanoporous insulation can be translated into a flexible, processable, and wearable material platform.
Conclusion: The Future of Insulation Is Not Defined by Thickness Alone
Returning to the original question:
Does thicker really mean warmer?
Physics tells us that thickness is only one way of increasing thermal resistance.
The fundamental objective of any insulation material is to reduce heat transfer through conduction, convection, and radiation as effectively as possible.
Traditional insulation materials achieve this largely by creating thick, lofted structures that trap still air.
Nanoporous materials introduce another approach: controlling heat transfer through engineered microstructures.
This represents an important shift in the development of thermal insulation technology—from increasing bulk to improving structural efficiency.
The future of insulation may therefore depend less on how thick a material is and more on how effectively its internal structure controls the movement of heat and moisture.