ASHRAE Handbook of Fundamentals gives you some insight. In the 2009 version (it's on 4 year cycle), Chapter 18, Table 1, Representative Rates at Which Heat and Moisture Are Given Off by Human Beings in Different States of Activity.
There is a footnote a) that says:
Adjusted heat gain is based on normal percentage of men, women, and children for the application listed, and assumes that gain from an adult female is 85% of that for an adult male, and gain from a child is 75% of that for an adult male
What Activity Level (W/Person) did you use? And what's the fraction radiant you entered?
I don't know what "Number of People Schedule Name" (multiplier) you're using either, but it should include some diversity factor, not 100% of the 33 children will be present on any given day.
Disclaimer: I am in no way, shape, or form someone with experience children heat output. The following is just a napkin calculation I just put together in ten minutes (I didn't read past the abstracts of a handful of papers that popped up when I searched) because I found it interesting, so do not use it without doing your own research.
It doesn't cite sources for where that 75% value is coming from, but you could grasp how it would make sense. The heat generation is proportional to the body surface area, and depends on the metabolic rate. A quick web search would tell you that a child usually has a higher metabolic rate: around 1.2 to 1.5 met, let's say 1.5 met (which is highly convenient for the point I'm about to make :) )
But its body surface area is less.
- A child aged 7-8 years would be in the ballpark of 25kg and 120 cm. I've decided relying on my own daughter was not a good enough sample size (N=1), so I've just taken a visual look at the z-charts from the World Health Organization: https://www.who.int/tools/growth-refe...
- As a result, it would roughly have 50% of the body surface area of an average male, according to Du Bois 1916 paper titled "A formula to estimate the approximate surface area if height and weight be known". A calculator for Du Bois can be found for example here: https://www.pediatriconcall.com/calcu...
- That average individual refers to a male 30 years old with 70 kg, 1.75 m, 1.8 m2 body surface area or a female 30 years old with 60 kg, 1.70 m, 1.6 m2 body surface area.
So if I was assuming the activity level for a classroom to be similar to an office area (which is what the DOE Reference Building for Primary School does), I'd say 120 W/person Total heat generation rate.
Plugging the numbers above, I'd guesstimate the Total heat generation rate for a child aged 7-8 years old to be ... (more)
