noun
heat dissipation; heat radiating property
Technical term used in engineering and materials science to describe how well a material or device releases heat.
この素材は放熱性が高いので、電子機器の冷却に適している。
This material has high heat dissipation, so it is suitable for cooling electronic devices.
熱伝導性 is thermal conductivity (how well heat passes through a material), whereas 放熱性 is about releasing heat to the surroundings.
Compound of 放熱 (heat release) + 性 (property, characteristic).