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tog

A unit of thermal resistance used to describe textiles. The name is variously said to come from Thermal resistance Of Garments or Thermal Overall Grade, but clearly it was chiefly inspired by the slang “togs” meaning garments. It is mainly used to describe how “warm” duvets, sleeping bags and baby buntings were. One tog is one square meter-Kelvin per watt, multiplied by ten and rounded to the nearest whole number.

formula for the tog

Some typical values:

	Thermal Resistance in togs
ICRC/IFRC & UNHCR/UNICEF low thermal synthetic blanket “for indoor use, on a bed, in a house with heating facilities”	1.5
sheet of polyethylene	2
baby bunting; ICRC/IFRC & UNHCR/UNICEF medium thermal synthetic blanket for use indoors without heat minimum for hot or temperate climates outdoor use	2.5
summer quilt or sleeping bag; ICRC/IFRC & UNHCR/UNICEF high thermal synthetic blanket for outdoors	4
Outdoors, no wind, 0°C (needed acccording to ICRC/IFRC)	6
Outdoors, no wind, −10°C (needed acccording to ICRC/IFRC)	8
Outdoors, no wind, −20°C (needed acccording to ICRC/IFRC)	9.5
winter quilt or sleeping bag	12

The tog was devised by the Shirley Institute in Britain in the 1960's, who also produced an instrument to measure it, the Shirley Togometer.

The tog is often converted into the clo at the rate of 1 tog = 0.645 clo. However, the clo measures clothing, the tog measures cloth.

The tog has been replaced by the comfort ratings required by European Norms, EN13537 for sleeping bags and EN12934 for quilts.

standards

BS4745

British standard describing the tog test.

ISO 5085-1

examples

The values were expressed in togs (the tog value of a fabric is defined as 10 times the temperature difference in °C between its two faces when the heat flow is equal to 1 w/m²). For example, the thermal resistance of an unbrushed blanket is 15 tog.

Anne-Louise Ponsonby, Terence Dwyer, Laura E Gibbons, Jennifer A Cochrane, Michael E Jones and Michael J McCall.
Thermal environment and sudden infant death syndrome: case-control study.
BMJ, vol 304, page 278 (1 Feb 1992)

In previous publications, the Thermal Resistance was given as ToG. It is important to note that ToG = 1 is identical with Rct = 0.1 m².K/W. The major difference is the laboratory equipment to control these values. The Rct test is more accurate than the ToG test.

As part of the push to minimize the use of special names like tog with SI, around 2016 international agencies switched from specifying thermal insulance in togs to Rct, which is purely SI units. Thus, for example, the above quotation from https://itemscatalogue.red cross.int/relief--3/household--8/bedding-and-clothes--7/blanket-synthetic--HSH EBLAN02.aspx