IES-VE User Forum

Hi,

I am trying to get my head around the comfort settings in Vista.

Do they have to be set prior to running a simulation in Apache or can they be applied afterwards in Vista?

Which variables do they effect? I was expecting the 'air speed' setting to effect the 'dry resultant temperature' but changing it didn't make any difference.

Thanks

Ross

They are used in the predicted mean vote (PMV) & percentage of persons dissatisfied (PPD) calculations.

Both come from the work of Professor Ole Fanger.

Basically PMV is calculated from the bodies heat balance equation: heat production - heat loss from convection, radiation, respiration, sweating etc.

Fanger defined PMV as "the difference between the internal heat production and the heat loss to the actual environment for a man kept at the comfort values for skin temperature and sweat production at the actual activity level".

PPD is calculated from PMV using the equation:

PPD = 100-95*exp(-0.03353*PMV^4 - 0.2179*PMV^2)

IES uses Fanger's equations so you can find many resources on the web, e.g.

http://www.healthyheating.com/solutions.htm

The software inherently solves for air temp, mean radiant temp, humidity during the thermal analysis. Air velocity, metabolic rate and clothing level are all user inputs in the thermal comfort dialogue.