Friday, March 23, 2018

Clothing Insulation (CLO)

The insulation of clothes are often measured in the unit "CLO", where 1 corresponds to the insulating value of clothing that is needed to maintain a person in comfort, sitting at rest, in a room that is 21 C (there are other considerations but these can be ignored for game purposes).

My general concern is that players are able to determine the appropriate amount of clothing that their characters should be wearing for each temperature grade - and that they are able to easily calculate what their CLO would be if they wore this or that. Here is the table on the left as a downloaded excel file, which allows the character to write 'yes' to each piece of clothing they are wearing, to have their total CLO calculated:

"Comfort" for game purposes is defined as the character operating at all ability scores at full. As discomfort increases, however, ability scores fall - as the character becomes less able to strain, reason, endure, react or maintain a peaceful disposition. It is desirable that players should consider the weather before launching themselves upon an adventure, taking into consideration things like their lower ability stats, the amount of armor they can reasonable expect to wear and the amount of time they can engage in combat before suffering serious fatigue.

The table gives a general sense of the comfort level that is possible, depending upon the temperature grade and the amount of insulation the character has added. The comfort level is indicated by the amount of CLO that must be worn at that temperature grade. For each temperature grade the character is removed from their comfort level - whether due to the weather being hotter or colder - that counts as a 1 point reduction to their ability stats.

For example:

Albert is wearing clothing sufficient to give him a CLO of 0.8; he is residing where the temperature is warm and he is taking no action. He is therefore comfortable, as any clo between above 0.5 to 1.0 is sufficient to be comfortable.

However, Albert decides to go to the market; as he is moving about, buying things, his 0.8 CLO is now above the 0.5 maximum that is necessary for him to be comfortable. As a result, all his ability stats count as 1 point lower.

Albert sits down to rest, but the sun shines harder and it becomes balmy. He is still not comfortable, because now the maximum amount of CLO he can wear is 0.5 - so that even sitting he is -1 to all ability stats. However, he fights back and removes his doublet with sleeves, reducing his CLO to 0.5. He's bareskinned from the waist up but he's comfortable. His stats revert to normal.

The evening comes and the temperature drops down to pleasant. Unfortunately for Albert, he can't find his doublet - and now he needs to be wearing a CLO of at least 1.0 to be comfortable. Whereas before he was too warm, now he is too cold. Once again, his ability stats drop by one point.

See Also,
Temperature Grades


  1. "Temperature Grades" link points to Wikispaces.

  2. Is there a table for how the different types of armor affect clo?

    1. No one in the present world working on the subject of CLO has done any work I can find on the internet that includes the effects of wearing armor.

      On the argument that the wearer has a hauberk-chausses on under the armor, and that the armor has minimal contact with the body, the armor's temperature is that of the environment; I'm arguing (without evidence or even necessarily logic) that the temperature of the armour is a null effect, +/-, to the character.

      It is probably irrational, but it strikes me that guessing in either direction will probably produce an inaccurate result, so cie la vie.

    2. Thank you. I think I'm ok with a touch inaccurate so going to use doublet for leather armors replace with in hauberk for chain types and a coat for plate. It's a bit of a hack but should work for my purposes. Hopefully face masks will get a proper rating soon so I can merge that with a cap to make a full helm.


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