Re: [EnergyPlus_Support] People Sensible vs Latent Load

["Michael J. Witte" <mjwitte@xxxxxxxx>]

The equation on p. 169 of the Engineering Reference (v1.1.1.012) determines the 
sensible heat gain from people as a function of metabolic rate and air 
temperature (dry bulb).  The latent gain is the difference of total gain less 
the sensible gain.

Figure 72 on p.169 (pdf-p.189) shows plots of sensible gain vs. metabolic rate 
(total gain) at various air temperatures.  Whenever the curves show a value of 
sensible gain that is equal to or greater than the total gain, there will be no 
latent gain from the people.  This occurs at low metabolic rates and low air 
temperatures.  For example, at 21.1C (70F, the magenta line) shows sensible >= 
total at metabolic rates below approximately 80W.  Sensible gains which are 
greater than the total are artifacts of the curve-fitting process and are set 
in the algorithm to equal the total which results in 100% sensible gains from 
people at those conditions.

Mike


On 8 Dec 2003, at 15:24, Ian Doebber wrote:

> I have two conditioned zones that are maintained at roughly the same comfort
> conditions.  The latent percentage of the human emitted heat in one of the zones
> seems fine, roughly varying between 20 to 30%.  Yet my other zone reports the
> latent percentage at 0 most of the time and at the maximum 1%.  I looked at the
> engineering document to verify this but the equation does not show how such low
> latent percentages could appear.  The heat given off in the first zone is 96 W
> while the second zone is 64 W.  If someone could clear this up I would
> appreciate it.
> 
> Thanks
> Ian
> 
> [Non-text portions of this message have been removed]
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx


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