IES-VE User Forum

Hi,
Does anyone know how IES assessed the number of people dissatisfied?
Which aspects IES take into account?(eg temperature, humidity air velocity)

Thank you.

Hi,

I've done a little digging into this and here is a response previously sent out by my colleagues Terence and Liam that gives a little more information on Comfort in VE Vista:

Percentage of persons dissatisfied (PPD) and Predicted mean vote (PMV) both come from the work of Professor Ole Fanger.

Basically PVM 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

Hope that helps you a bit
Phil

Thank you for your answer.
I think it will help me in my project.

Regards

thus this model cannot be used on natural ventilation??, fanger studies apply on HVAC, how does the IES find the PPD in case of natural ventilation?