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Taking a look at 'Virtual People'

by Bill Gregg
6th Civil Engineer Squadron energy manager

Who are the Virtual People? Actually, they are all around us and costing energy dollars.

Here's how it works:

Heat energy is measured in British Thermal Units. Studies have been done to determine the body heat production of humans at different tasks. This information helps in determining heating and air conditioning loads when designing a building.

The following chart lists some 'BTU' numbers for a human at different tasks:

Activity / Body Heat Production in BTU per hour
Sleeping / 255
Awake, prone / 300
Seated at rest / 380
Sedentary / 400
Standing at ease / 430
Walking, 2 MPH / 780
Walking, 4 MPH / 1,400
Maximum exertion / 3,000 - 4,800

Now let's make sense of it by comparing to something we can relate to. A 100 watt light bulb generates about 340 BTU per hour. Compare that to the sedentary person in the chart above.

So here is where we are going with this information. Consider a computer lab with 30 personal computers, all of them on, and each consuming about 200 watts; Airmen in the lab, functioning somewhere between 300 and 430 BTU per hour. If we use 680 BTU per hour per computer and the 400 BTU per hour for the Airman we see that the computer is really another well behaved 1.7 people. If there are 30 Airmen and 30 computers, that's like having 81 Airmen in the room.

To complete the picture, it takes approximately 1/3 of a watt of electrical energy to remove 1 watt of heat in a space. So that "Virtual Airman" equal to 1.7 of the real thing, is also consuming 67 watts of air conditioning and costing even more energy dollars.

Solution: Turn the "virtual people" off whenever possible. The virtual people can actually double the air conditioning load for a space that probably was not designed for 81 people. Your real Airmen, Soldiers, Sailors and Marines, the base energy budget and the environment will all benefit.



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