The human body as a radiator - Air conditioning

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SUMMARY

The human body radiates approximately 86 watts of energy on average throughout the day, primarily as waste heat and blackbody radiation. This energy output varies based on several factors, including body mass, pulse rate, physical activity, caffeine levels, caloric intake, and state of consciousness. Designers of air conditioning systems utilize these variables to calculate the heat generated by individuals, both awake and asleep. Understanding these parameters is crucial for optimizing air conditioning efficiency in environments with human occupancy.

PREREQUISITES
  • Understanding of thermodynamics and heat transfer principles
  • Familiarity with human physiology and energy expenditure
  • Knowledge of air conditioning system design and calculations
  • Basic concepts of blackbody radiation and energy conversion
NEXT STEPS
  • Research human metabolic rates and their impact on energy output
  • Explore air conditioning load calculations for human occupancy
  • Learn about the effects of caffeine on human physiology and heat production
  • Investigate the principles of blackbody radiation in thermal systems
USEFUL FOR

This discussion is beneficial for HVAC engineers, human physiologists, and anyone involved in designing or optimizing air conditioning systems for environments with human presence.

eemaestro
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After reading the thread "how many watts does the human body use?"

I calculated that my body requires 86 W of energy on average throughout the day.

However, I am wondering how much excess energy my body radiates as waste heat (and blackbody radiation) ? Obviously this depends on a lot of variables--body mass, pulse rate, rate of expenditure of physical energy, how much caffeine is in my body (causes blood vessels to dilate), energy of the Kcalories that have been eaten (as opposed to the
Kcalories my body actually needs), state of consciousness, etc.

I am just interested in a rule-of-thumb that people who design air conditioning systems use for waste heat dumped by people, awake and sleeping.
 
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You've accounted for all of it. All of the energy we produce by burning food gets radiated (or convected) away as heat.

And your number sounds about right.
 

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