IES-VE User Forum

In the MicroFlo viewer, there are several icons in grey on the top right of the window. One of them is "comfort" : is it the visualization of pedestrian comfort (du to building and interactions with wind ?) How is it calculated ?

Hi,
MicroFlo is not my area of expertise but surely I can guide you.
I have copied a link for the user guide of MicroFlo.

http://www.iesve.com/downloads/help/CFD/MicroFlo.pdf

Hopefully it will solve your issue.

Thanks, but in fact I already have this documentation. I've read it but it never speaks of the "comfort" variable.
Nethertheless, I read in the document "IES VE tutorial" that the external analysis mode of MicroFlo is used to "evaluate pedestrian comfort"...
I wonder if this comfort variable could be a combination of velocity and turbulence variables...but I don't know how to use (or just display maybe?) it.

In the MicroFlo viewer, there are several icons in grey on the top right of the window. One of them is "comfort" : is it the visualization of pedestrian comfort (du to building and interactions with wind ?) How is it calculated ?

All the comfort variables in Microflo are only applicable to internal flows and are not avialable for external flows. There is "PMV", "PPD" and "Comfort".

PMV and PPD (predicted mean vote and percentage persons dissatisfied) are the internationally recognised comfort variables from the work of Fanger. The "Comfort" variable uses the following scale (page 40 in the current VISTA manual):

1: very cold, danger
2: cold, shivering
3: cool, unpleasant
4: cool, acceptable
5: slightly cool/acceptable
6: comfortable, pleasant/cool
7: comfortable, pleasant
8: comfortable, pleasant/warm
9: slightly warm/acceptable
10: warm, acceptable
11: warm, unpleasant
12: hot, very uncomfortable
13: very hot, danger
14: unoccupied
15: non-sedentary

I would ignore this and use PMV which is more recognised.

I don't believe that there is any CFD program that can display pedestrian comfort. Typically a CFD wind study will do a number of wind directions and wind speeds using a steady state CFD model for each scenario. And will only use a transient model if using a more complex turbulence model such as LES. Even if using LES there will have to some work out side the CFD program comparing CFD results to a weather data set in order to infer pedestrian comfort.

I'd like to see a program that could handle exterior pedestrian comfort... I personally don't feel comfortable if there is a person wearing a track suit nearby.

Seriously tho, either the manual is wrong or you have picked it up wrong - you can't account for exterior comfort really - okay it can be hot/humid/windy but you are going to need something pretty amazing to handle that and even then it'll be wrong. the IES-CFD is a simple interior (ignore the exterior other than simple flow pattern) building CFD. If you want specialist - go specialist.

Zap.

I have always used the Lawson criteria to analyse pedestrian comfort which ignores temperature and humidity, and concentrates on wind speeds and gust speeds to say if an area is OK for sitting, standing, walking etc. To do that though I have used site or nearby weather data combined with CFD simulations to calculate how pedestrian comfort varies over a year of weather data. You can probably work out how to do it with some Google searching for pedestrian comfort and Lawson.

There are other methodologies to analyse pedestrian comfort other than Lawson's but I think Lawson's is used regularly. I would be interested to hear if anyone has used or seen another methodologies being used in our industry.

I am very interested in this topic.
Can anybody tell me the which are "Lawson method" criteria?

I used google but I do not know if I found the right data, as some other criteria are mentioning, like "Bottema Comfort Criteria for walking" and "Hunt safety criteria".


Can somebody post the "Lawson" criteria please?

Thank you.

See Table 18.1 "Lawson’s Comfort Assessment Criteria" in

http://www.pam.ealing.gov.uk/PlanNet/do ... 1_01_A.PDF

There will be lots of other places you can find it on the web as well.

Thanks Liam.

I owe you a beer for this mate.

Liam, if I understood it correctly, the pedestrian comfort can be "measured" (bad word maybe) by applying the "Lawson’s Comfort Assessment Criteria".

Now "Lawson’s Comfort Assessment Criteria" gives 4 wind speeds categories, which must not be exceeded, depending on the pedestrian activity (Sitting, Standing, Leisurely walking, Business walking).



For example, I made a wind velocity analysis for a city plaza. On the plaza, the pedestrians will be sitting, standing and walking. This means, that in order to achieve the Lawson’s Comfort Assessment Criteria to be positive, the maximum wind velocity on the plaza, must not exceed 4 meters per second?

And that is the whole thing about the Pedestrian comfort analysis?