Thermal insulation of garments is measured in Tog (1 Tog = 0.1 m²·K/W).
Enter a Tog value and a temperature difference (ΔT) then click Calculate to compute thermal resistance (R) and heat flux (q = ΔT / R).
Results appear only after clicking Calculate.
Table of Contents
What is Thermal Insulation?
Thermal insulation controls heat transfer between two surfaces. A textile engineer uses insulation to keep the wearer comfortable in different climates. A fabric with higher insulation slows down heat loss. A fabric with lower insulation allows faster heat transfer.
Importance of Thermal Insulation in Textiles
Textiles provide a barrier between the human body and the environment. Garments with strong insulation protect workers in cold areas. Summer fabrics with low insulation keep wearers cool. Sportswear, workwear, and casual wear all depend on the correct level of thermal resistance.
- Winter garments need higher insulation values.
- Summer garments need lower insulation values.
- Transitional garments balance moderate insulation for spring and autumn.
Measurement of Thermal Insulation
Textile engineers use thermal resistance (R) to measure insulation. R-value shows how well a fabric resists heat flow. Industry uses different units:
- Tog Value (British buyers)
- Clo Value (American buyers)
- SI Unit: m²·K/W
Conversion Example
- 1 Tog = 0.1 m²·K/W
- 10 Tog = 1.0 m²·K/W
Higher Tog means more warmth. Lower Tog means more cooling effect.
Heat Flux Formula
The heat flux is calculated with the equation:
q = ΔT / R
where ΔT is temperature difference and R is resistance.
Example:
- At 1 Tog, R = 0.1, q = 10 W/m²
- At 10 Tog, R = 1.0, q = 1 W/m²
A higher Tog results in lower heat transfer. This is why thick winter jackets feel warmer.
Ideal Tog Values for Seasons
Consumers often ask what Tog is suitable for summer and winter. A textile engineer suggests:
- 1 to 2 Tog: Summer wear (light shirts, dresses, tropical uniforms).
- 3 to 7 Tog: Transitional wear (jackets, sweaters, sportswear).
- 8 to 15 Tog: Winter wear (padded jackets, insulated coats).
These values give buyers a simple guide for fabric and garment selection.
Textile Materials with High Insulation
Different fibers and finishes change insulation properties.
Natural Fibers
- Wool: Wool traps air and provides excellent warmth.
- Cotton: Cotton is breathable but offers low insulation.
Synthetic Fibers
- Polyester: Polyester resists moisture and retains warmth.
- Acrylic: Acrylic is lightweight and warm for sweaters.
Blended Fabrics
Engineers combine cotton, polyester, or spandex to balance comfort and insulation. Blends reduce cost while improving performance.
Role of Fabric Structure in Insulation
Fabric construction impacts insulation more than fiber alone.
- Woven fabrics: Dense weave increases resistance.
- Knitted fabrics: Open structure allows airflow and reduces insulation.
- Nonwoven fabrics: Used in padding and insulation layers.
Layered Fabrics
Multiple fabric layers trap air. Air pockets work as insulation barriers. This technique is used in jackets, quilts, and blankets.
Thermal Insulation in Technical Textiles
Thermal insulation is not only for fashion but also for technical uses.
- Workwear: Cold storage uniforms use high insulation.
- Protective clothing: Firefighters need insulation against extreme heat.
- Medical textiles: Thermal blankets help patients maintain body temperature.
- Sportswear: Athletes use garments with balanced insulation to manage sweat and heat.
Testing Methods for Thermal Insulation
A textile lab measures insulation with standard tests.
Tog Test
The Tog test measures thermal resistance directly. The sample is placed between hot and cold surfaces. Heat transfer is measured, and resistance is calculated.
Guarded Hot Plate Method
This test uses a heated plate and measures the heat passing through a fabric. It gives precise insulation values.
Manikin Test
Engineers use thermal manikins dressed in garments. Sensors measure heat loss across different body parts.
Sustainable Approaches in Thermal Insulation
Sustainability shapes textile innovation.
- Recycled polyester insulates jackets and reduces plastic waste.
- Organic wool supports eco-friendly fashion.
- Bio-based fibers reduce dependence on petroleum-based materials.
Brands use sustainable insulation to meet buyer demand and reduce environmental impact.
Practical Applications for Consumers
Consumers often check insulation values before purchase. A clear label with Tog or Clo helps them choose garments correctly. Retailers now highlight Tog values in bedding, jackets, and outdoor gear.
- Bedding industry: Duvets show Tog ratings for summer or winter use.
- Fashion industry: Jackets highlight insulation levels for buyer clarity.
- Sportswear industry: Balance of breathability and insulation is key.
Future Trends
Upcoming trends focus on smart textiles. Engineers design fabrics with adaptive insulation. These fabrics change thermal resistance with temperature or activity. Nanotechnology improves insulation with lighter weight. Smart jackets and sportswear are early examples of this trend.
Conclusion
Thermal insulation is a key property in textile engineering. A garment with correct insulation improves comfort, safety, and performance. Tog values guide both buyers and manufacturers. Engineers focus on insulation through fiber choice, fabric structure, and innovative finishes. Sustainable materials and smart textiles will shape the next generation of thermal insulation solutions.