The biggest cost in operating a HVAC system comes from energy consumption; therefore, the insulation parameters of the ducts directly affect the overall energy efficiency of the system. Fiberglass ducts are widely used in air conditioning and ventilation systems, and their thermal performance is a core indicator determining energy-saving performance.

Firstly, there's the thermal conductivity (λ value). Fiberglass materials contain numerous tiny pores, and air is a medium with extremely low thermal conductivity. Therefore, the thermal conductivity of fiberglass ducts is typically between 0.032 and 0.040 W/m·K. This data means that relatively thin fiberglass ducts can achieve high insulation capacity, reducing heat loss during transport and improving the efficiency of the air conditioning system.

Secondly, there's the thermal resistance (R value). Thermal resistance is related to material thickness. Common fiberglass duct thicknesses are 25mm, 32mm, and 40mm, etc. The higher the thermal resistance, the more significant the insulation effect. For example, the thermal resistance of a 32mm thick fiberglass duct is generally between 0.85 and 1.05 m²·K/W, meeting the energy-saving requirements of most commercial buildings.

Furthermore, fiberglass ducts possess excellent thermal stability. Their typical operating temperature range is -40℃ to 80℃, making them suitable for both hot and cold air systems. In environments not exceeding 100℃, the fiberglass will not melt or undergo significant structural changes, thus ensuring reliability in various systems including fresh air, exhaust, and return air.

The surface finish of the duct also affects its insulation performance. Common finishes include aluminum foil composite films and PVC finishes, which have high surface reflectivity, further reducing radiative heat transfer and improving the overall insulation coefficient.

Insulation performance is also affected by humidity; therefore, the moisture absorption rate of fiberglass ducts is a critical parameter. Generally, a moisture absorption rate of ≤2% is desirable, and maintaining a low moisture content prevents a decrease in insulation capacity due to moisture absorption, which is particularly important in humid environments like those in southern regions.

In summary, the thermal insulation performance of fiberglass ducts mainly comes from their low thermal conductivity materials and stable structure, which enable them to maintain high energy efficiency during long-distance cold air delivery. They are a commonly used duct material in energy-saving buildings and large commercial projects.