I have had similar concerns with the radiant fraction of radiators, especially modeling older steam systems. The last radiant panels I modeled (predate this
radiant heater object) were actual surfaces in the model and the radiant distribution was calculated automatically. The object you are modeling is a heater, often found in big box stores over cashiers near the outside doors. The devices produce a focused
radiant heat, so you have to decide how to split the output. All the output is somehow integrated into the room. The only reason to attribute any to people is if you were performing a human comfort calculation. Anything radiated to people eventually goes
to the room, but it affects the comfort perception of the occupant. To calculate the occupant fraction, you need to calculate how much of the total radiant area is occupied by a body, so you need to know something about the focus of the device and the occupancy.
Similarly, if the radiant is focused onto an exterior wall, you would get more heat loss from your building because the surface conduction would have a radiant increase.
Staying warm by the fire�lots of radiant heat in a cold house�
Ned Lyon, P.E. (MA, WV)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
617.285.2162 mobile
781.907.9009 fax
www.sgh.com
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From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Friday, December 29, 2017 4:17 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Fractions to surfaces for ZoneHVAC:HighTemperatureRadiant
Dear Forum,
I am using the ZoneHVAC:HighTemperatureRadiant object in a model and am trying to double check the fraction of radiant energy that I'm assigning to:
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People
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Walls
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Floor
At the moment (and largely using values from an example file), I'm assigning 5% to people, and the remainder to the floor.
Do any of you who are familiar with this object have recommendations regarding how to assign those radiant fractions?
Thanks in advance. Happy New Year, too!
--
James V Dirkes II, CEO / President
The Building Performance Team Inc..
1631 Acacia Dr, Grand Rapids, MI 49504
(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)
Direct / Mobile: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
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Coffee conversation:
My opinion and experience:
The gospel of Jesus is without doubt the most beautiful world view on our planet.
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Posted by: "Edward G. Lyon" <EGLyon@xxxxxxx>
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