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PMV output is too low

asked 2018-08-20 14:57:02 -0500

feilongdang's avatar

updated 2018-08-25 11:08:46 -0500

I run my case to get the thermal comfort results with Fanger, AdaptiveASH55 and AdaptiveCEN15251 model respectively. The zone has air conditioning, operating from 8:00-17:00, with set point 24.5℃. The input for internal heat gains: People can see as below:

P_1W,                    !- Name
1W,                      !- Zone or ZoneList Name
Office schedule,         !- Number of People Schedule Name
People,                  !- Number of People Calculation Method
6,                      !- Number of People
,                        !- People per Zone Floor Area {person/m2}
,                        !- Zone Floor Area per Person {m2/person}
0.4,                     !- Fraction Radiant
,                        !- Sensible Heat Fraction
People Activity,         !- Activity Level Schedule Name
,                        !- Carbon Dioxide Generation Rate {m3/s-W}
,                        !- Enable ASHRAE 55 Comfort Warnings
ZoneAveraged,            !- Mean Radiant Temperature Calculation Type
,                        !- Surface Name/Angle Factor List Name
WORK_EFF_SCH,            !- Work Efficiency Schedule Name
ClothingInsulationSchedule,  !- Clothing Insulation Calculation Method
,                        !- Clothing Insulation Calculation Method Schedule Name
CLOTHING_SCH,            !- Clothing Insulation Schedule Name
AIR_VELO_SCH,            !- Air Velocity Schedule Name
Fanger,                  !- Thermal Comfort Model 1 Type
AdaptiveASH55,           !- Thermal Comfort Model 2 Type
AdaptiveCEN15251;        !- Thermal Comfort Model 3 Type

which People activity is always 70, WORK_EFF_SCH is 1, WORK_EFF_SCH is 0.5, and AIR_VELO_SCH is 0.2.

But when I get the results of

1.Zone Thermal Comfort Fanger Model PMV

2.Zone Thermal Comfort Fanger Model PPD

3.Zone Thermal Comfort CEN 15251 Adaptive Model Category I Status

4.Zone Thermal Comfort ASHRAE 55 Simple Model Summer Clothes Not Comfortable Time

I found that the during occupied hours the PMV is about -7 and PPD is 100%, which means the it is too cold in Fanger model. However the later two results 3 and 4 are almost 1 and 0 respectively, which means that it is comfortable when the Air conditioning operates.

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answered 2018-08-23 14:38:49 -0500

People activity is always 70, WORK_EFF_SCH is 1, WORK_EFF_SCH is 0.5, and AIR_VELO_SCH is 0.2.

The Fanger model is the only one that uses the above inputs. The other models only look at temperature and humidity. The air velocity is reasonable. An activity level of 70W is equivalent to sleeping. Yet, the work efficiency schedule of 0.5 is saying that half of the 70W is going towards moving something and only 35W are left to warm the body. That's why the PMV and PPD values indicate the people are cold. For an office setting, work efficiency is typically set to zero, and the activity level somewhere between 100-150W/person. Reference table of metabolic rates in the People section of the Input Output Reference.

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Hi Witte, Thank you very much for your kind help. I made a mistake, the value of 0.5 is the clo insulation in summer. I followed your advice and set the activity level as 150W, however the PMV is still too low, about -3.5

feilongdang's avatar feilongdang  ( 2018-08-24 15:24:35 -0500 )edit

What is the WORK_EFF_SCH? Set that to zero.

MJWitte's avatar MJWitte  ( 2018-08-28 15:46:23 -0500 )edit

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Asked: 2018-08-20 14:57:02 -0500

Seen: 434 times

Last updated: Aug 23 '18