100W is what I've always understood. It equates (in old money) to about 2.5 kCal per day. Burger, fries and a beer. Any more and you put on weight, unless you do external work.
Two problems then: For your own design, you know your own weight and metabolism, and so should use the best (conservative) value: At only 155 lbs, but eating more calories per day than the "average person", I'd have to account for more heat energy than "the generic average." You'll want (need!) to be comfortable under "worst case" riding conditions, but able to proceed without duress when temperatures rise (later in the afternoon for example) or fall - after a storm or shower or after dark.
Second: You're in the wind (very important!) and in outdoors conditions for specific periods of time directly exposed to the weather and cold, NOT the "average" generic TV-watching couch potatoe doing average "nothings" for an average 24 hour day indoors. Balancing that exposure to wind and temperature is the fact that you will be sitting/riding, not running the Boston Marathon.
Allow some testing. Some adjustment. A throttle valve. Or two. A zipper.
in the mean time you might put a cooler in the saddle bags,, fill it with ice and a bit of water, circulate the water through your jacket with small pump, you sort our the generic heat loads well enough without having to solve all of the design problems
The caloric content of excrement in the energy balance is accounted for in the variable "P"; however, as the amount of beer increases, "P" tends to become constant.
Please find attached representative rates at which heat and moisture are given off by a human being in two different states of activity (from fundamentals AHRAE 2005)
- Seated at theater
Total heat : 95 W
Sensible heat : 65 W
Latent heat : 30 W
- Moderately active office work
Total heat : 130 W
Sensible heat : 75 W
Latent heat : 55 W
(Adjusted values are based on 24 °C room dry-bulb temperature and rounded to nearest 5 W)
Regards
That's interesting, but ASHRAE's focus is people inside a building, so unless they have numbers for gymnasiums and the like, the values are not necessarily applicable.
Don't forget the solar load! Of course it is good to consider the body heat load. At best you can use an order of magnitude estimate for that, because it is highly variable with time. And the heat load from the environment, including the sun on your back and head, can be larger than the internal heat load.
