PMV calculation - clothing parameters

StellaDimitriou
Posts: 7
Joined: Fri Nov 11, 2016 11:44 am

PMV calculation - clothing parameters

Postby StellaDimitriou » Thu Feb 23, 2017 11:30 am

Dear Forum members, Dear Administrators,

I am currently working with the free version of Envi-met 4.1, for a European Research Project (http://www.cyi.ac.cy/index.php/eewrc/re ... -isle.html). The case study is in Cyprus and I face the following issue regarding the clothing parameter (clo): Since the summers in the island are extremely hot, I need to change the default clothing from 0.9clo to 0.5clo. Nonetheless, when I change it the results for PMV are worse than when using 0.9clo. Attached you may find the outcome visualised using Leonardo for both the 0.9clo and the 0.5clo alternatives.
If there is a parameter I should also consider in order to obtain correct results, please let me know.
I would really appreciate your help.

Thank you,
Stella
Attachments
Limassol_Map_Summer_09clo.jpeg
Limassol_Map_Summer_09clo.jpeg (51.02 KiB) Viewed 119 times
Map_Limassol_Summer_05clo.jpeg
Map_Limassol_Summer_05clo.jpeg (51.12 KiB) Viewed 119 times

enviadmin
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Re: PMV calculation - clothing parameters

Postby enviadmin » Fri Feb 24, 2017 8:38 pm

No,

this correct in the way PMV sees the world.
If you lower your clo, more parts of the body are calculated to been exposed to the sun (which is logical) and the more you will react on the outdoor climate. And if it is hot, PMV will rise.
To be, say, naked, will be the lowest clo, but then all of your body will be exposed to the sun (more or less) so at the end your average skin temperature will be higher compared to you wearing a ski suit.

In the latter case, outdoor climate will be more or less irrelevant as you are only interacting with your clothing (if it is a good ski suit).

So, if someone sitting on a beach in a ski suit will be have more heat stress compared to s.o. naked, probably no in terms of equations.
Probably YES in terms of psychology....
Also the person in the ski dress on the beach will face other problems...

Michael

StellaDimitriou
Posts: 7
Joined: Fri Nov 11, 2016 11:44 am

Re: PMV calculation - clothing parameters

Postby StellaDimitriou » Sat Feb 25, 2017 7:49 pm

Dear Michael,

Thank you for your answer. It is very much appreciated.
In order to comprehensively understand the way PMV is calculated I would like to clarify if the person is considered to "exist" in the space momentarily (ie for some seconds). If this is the case, I can indeed grasp the resulting lower discomfort from wearing a 1.9clo than 0.6clo in summer conditions.
If this is not the case, I want just to point out that when a person is walking, sitting etc outdoors in typical midday summer weather in Cyprus, the heat stress s/he will feel when wearing a "full ski suit" will not be primarily psychological, but physical. This is why people in the island tend to wear light, air-penetrable clothing during the summer, at least those not restricted by any cultural or religious obligations.

Thank you again for the previous reply.
Stella

enviadmin
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Re: PMV calculation - clothing parameters

Postby enviadmin » Sat Feb 25, 2017 11:17 pm

Hi
The ENVI-met implementation of PMV is a total standard one.
Like all the other indices, it is a static index- hence it assumes that the energy balance of the person is balanced.
This is not the case for persons walking through different climate environments or just appering for a short time.
That is an non-stationary situation.
Ser the Plea Papers on Botwold in our elib on that

Michael

StellaDimitriou
Posts: 7
Joined: Fri Nov 11, 2016 11:44 am

Re: PMV calculation - clothing parameters

Postby StellaDimitriou » Sat Feb 25, 2017 11:27 pm

Dear Michael,

Ok! Thanks a lot,
Stella


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