[The Last Gasp] A System for Heat Exhaustion

[Varyon]

I came up with this as a tangent on a reply to the Heat and the Last Gasp thread, but before posting decided it should really function as its own thread. This system makes use of The Last Gasp.

While a character is active, he produces heat that needs to be shed to avoid exhaustion. The more active the character is, the more quickly heat builds to potentially dangerous levels. Fortunately, heat usually dissipates quickly - unless the character is wearing heavy clothing or armor.

Heat generation is determined by how many AP a character spends. The simplest way is to keep track of a heat pool of some sort (actual name and abbreviation is beyond me - Thermal Points/Pool might work, as TP; Exhaustion Points, as EP, could also work, although that could cause confusion with ER; I'll go with TP for this post). Every AP spent results in +1 TP. Every full 5 TP results in a -1 to HT for purposes of recovering FP and AP, to a maximum of 20 TP for -4.

There are two ways to handle heat dissipation - either always have it drain at some constant rate, or have it drain only on turns when the character spends no AP. I'll be using the former in this post; for the latter, double (adhering to the Size and Speed/Range - SSR - table; double is +2 steps on that table). Heat dissipation occurs at the end of a character's turn, and if his total TP exceeds 20 at this time, reduce it down to 20.

For a character wearing regular clothing in average temperatures, TP is shed rapidly, at a rate of 10 per second - meaning there's rarely any reason to track it. Summer clothing is good for +1 SSR, or 15 per second, while going nude results in +2 SSR, or 20 per second. Winter clothing is treated just like armor, below. Optionally, wearing a regular clothing hat of some sort results in -2 SSR, while a summer hat would be only -1 SSR.

For armor (and winter clothing), what is covered is more important than what it's covered by. A character who goes barefoot into battle gets +2 SSR to recovery, but only for offsetting any penalty due to other armor. Open-topped sandals are instead only +1. Covering both Legs is -1, as is covering both Arms or either Hand (covering both Hands is -2). Covering the Torso or Face is -2, and covering the Skull is -4. Overall, completely covering the body in armor is -12, dropping the normal recovery rate to 0.1 TP per second.

It is possible to design armor with ventilation to reduce its impact on recovery. Minor ventilation affects the armor front and back, and reduces weight by 7%. On a hit to the armor, roll 1d - on a 1, only half normal DR applies. Note this changes the penalty to target Chinks to only -4. Major ventilation can affect the front and/or the back - the choice is made when the armor is. Front or back only reduces weight by 7%; front and back together reduces weight by 15%. On a hit to the armor, roll 1d - on a 1, no DR applies. Minor ventilation, or major ventilation only on the front or back, lessens the recovery penalty to 3/4 normal, while major ventilation on the front and back lessens it to half normal. For consistency, maintain fractions until you've added everything together, then round down (so that -9.2 becomes -10). Armor that normally gives 5/6 or less protection - such as partial arm armor, or Chest armor without a fauld for the abdomen - can be treated as having major ventilation for the same facings it has poor protection. These weight reductions should be applied to the weight of the armor after modifications for materials and craftsmanship are made.

In hot or cold temperatures, heat dissipation is modified. For simplicity, assume a hot environment - one within or above the top 10 degrees of the character's comfort zone - imposes a -2 to TP loss rate, while a cold environment - one within or below the bottom 10 degrees of the character's comfort zone - gives a +1 to TP loss rate (you may opt to give further bonuses for colder temperatures). Optionally, a character who manages to retain at least 1 TP every round is in no risk of needing to roll to avoid freezing-induced FP loss - he's keeping sufficiently warm with his level of activity. This will rarely matter, as most characters trying to do this will run out of AP long before even the 10 minutes for strong wind passes.


The above is a first-glance, off-the-cuff, bare-bones system. I'd be interested in knowing what people think, and what sort of modifications might make it better.

[Varyon]

For reference, here's the way the armor breaks down. In the below table, Full means no ventilation, Minor means either minor ventilation or major ventilation in a single direction, and Major means major ventilation in both directions. Recovery Rate assumes normal temperatures.
In making this, I realized I left off the Neck as a hit location. Treating it similarly to Feet might work - leaving the Neck unprotected from both directions is good for a +1 for offsetting the penalties from other armors (unprotected from one direction is only good for +0.5).

Location	Full	Minor	Major
Skull		-4	-3	-2
Face		-2	-1.5	-1
Torso		-2	-1.5	-1
 Chest		-1	-0.75	-0.5
 Abdomen	-1	-0.75	-0.5
Arms		-1	-0.75	-0.5
 1 Arm		-0.5	-0.375	-0.25
Hands		-2	-1.5	-1
 1 Hand		-1	-0.75	-0.5
Legs		-1	-0.75	-0.5
 1 Leg		-0.5	-0.375	-0.25

Total		-12	-8	-6
Recovery Rate	0.1	0.5	1

[DemiBenson]

It's a good start, but complicated. Perhaps rewrite into more of a table form, and base it on being completely nude or light clothing, instead of different start points for various body parts.

Also keep in mind that humidity and wind have HUGE effects on the ability to sweat.

So would having an usual number of limbs (more arms/legs, or wings); and anyone with thin/overweight/etc.

[Varyon]

Originally Posted by DemiBenson

It's a good start, but complicated. Perhaps rewrite into more of a table form, and base it on being completely nude or light clothing, instead of different start points for various body parts.

It's based on wearing regular clothing, which includes shoes but not necessarily a hat (or turban or whatever). I'm not certain how to reduce the complication - although I'm open to suggestions - and I'm not certain what sort of table I could provide, aside from the one I already have and perhaps a worked version of the SSR relationship for this case, like the following:

Rate	TP shed per second
+6	100
+5	70
+4	50
+3	30
+2	20
+1	15
0	10
-1	7
-2	5
-3	3
-4	2
-5	1.5
-6	1
...
(-6)	x0.1

Originally Posted by DemiBenson

Also keep in mind that humidity and wind have HUGE effects on the ability to sweat.

Yeah, those do influence heat dissipation quite a bit. The above rules would assume average humidity and negligible wind. High humidity might justify up to -4 to dissipation, while low humidity might justify up to +2*. Of course, if the character is wearing enough armor that you need to bother with TP, he's going to have created a rather humid environment inside the armor, making humidity's effect markedly reduced; I'd probably just go with -1 for high humidity, -2 for 100% humidity, +1 for low humidity.

*Evaporation rate is apparently about linear with humidity, and evaporative cooling makes up around 80% of heat dissipation during exercise. If average humidity is around 50%, that means you boost that 80% to 160% at 0% humidity (adding back in the 20% is 180%, which is close enough to count as 200%, for +2 SSR). You drop it to 0% at 100% humidity, for a remaining 20%, which is -4 SSR.

Wind is going to boost both evaporative and convective cooling. Slightly modifying the effect of wind on B430 for a smoother progression, I'd go with light wind (10 mph+) giving a +1, moderate wind (20 mph+) giving a +2, and strong wind (30 mph+) giving a +3. Going solely off of B430, that would instead be +2 for light and +3 for strong, with no such thing as "moderate wind."

Originally Posted by DemiBenson

So would having an usual number of limbs (more arms/legs, or wings); and anyone with thin/overweight/etc.

I'd leave build alone*, but more limbs could be a potential concern. Each extra arm and leg is going to result in more heat generated but also in more surface area to shed it from - it would be simplest to just have the above entries be percentage based (so the Arms entry is 100% of arms, the 1 Arm entry is 50% of arms), although using it as-is and adding +1 to heat dissipation for each additional unarmored limb might work out alright. Wings, however, have massive surface areas for their volume and are going to shed heat quite rapidly. I'd probably have unarmored small wings be worth +1 each - the same as an extra arm or leg - and unarmored large wings be worth +2 each. Having feathers or substantial fur on the wings might reduce these somewhat, but I'd probably ignore that.

*I have no clue how to price it, but it seems appropriate for there to be a trait that modifies how quickly one normally sheds TP. A single level in either direction might be realistic for an otherwise-normal human, while Skinny could justify a further +1 and Overweight a further -1 (Fat/Very Fat might justify yet another -1, although that's pushing it). Another trait that modifies how many TP are necessary for each penalty (maxing out at 4x this number, for -4) might also be appropriate.