TOGS & DUVETS
A TOG is a unit of thermal resistance used to express the insulating properties of clothing and bedding. 1 TOG is the resistance that will maintain a temperature difference of 0.l degrees C with a flux of 1 watt per square meter or, put another way, the TOG value of a textile is equal to 10 times the temperature difference between its two faces when the flow of heat is equal to one watt per square meter. 1 TOG is roughly equal to the thermal resistance of a man's summer suit or a blanket of medium quality; 10 TOGs is the maximum that is practicable to wear. The TOG ratings of duvets vary by manufacturer but, as a rule of thumb, summer duvets are around 4.5-6.0 TOGs, whereras winter duvets have a rating of 12.0-13.5.
Henry James Byron (1834-84)