Hello all,
For EQc7.1 in LEED NC 2009, I need to provide detailed calculations for
"operative temperature".
ASHRAE 55 appendix C gives you the formula to calculate operative
temperature, but that requires mean radiant temperature. And the formula for
"mean radiant temperature" requires globe temperature.
I am trying to find a graph/chart/table from which I can obtain the "globe
temperature" or do I even need to find globe temperature ?
Any insights, suggestions would be appreciated.
--
Thanks and Best Regards,
Sincerely,
Varun Kulkarni
I never knew that the MRT calculation would require Globe Temp. My
understanding of this is that the Globe Temperature is actually a function
of Air Temp, MRT and the convection (air speed effects.) The MRT is
calculable from the temperature of the surrounding surfaces. If the Op Temp
calculation includes air temp, MRT, RH, and air speed, then there is no need
to ever know Globe Temp. Opinions here, maybe not facts!
Regards,
Larry O. Degelman, PE, HBDP/BEMP
Yes, MRT needs Globe Temperature.
Globe temperature requires a Globe Thermometer. Radio Shack used to carry them.
There are no tables that could give you a Globe Temperature, because the reading depends on the specific space you're studying.
Bass
Bass Abushakra, Ph.D.
Right,
Because if you see the formula for MRT, as the air velocity approaches to
zero, MRT gets closer to globe temperature.
So MRT is equal to globe temperature, but only with zero air movement.
I am still not able to figure out a way to document the MRT calculations as
there is no way I would be able to measure the actual globe temperature.
How am I suppose to show the PMV/PPD calculations and operative temperature
calculations in LEED documentations ?
Are you able to claim that the operative temperature equals the air
temperature based on the 4 criteria listed in Appendix C? All my LEED
projects have met those criteria and GBCI accepted it. Don't know what to
tell you, though, if the criteria do not apply . sorry.
Alright,
I'll try to float my boat this way.
Thanks a lot :)
Varun,
MRT, strongly depends on envelope properties and most of time Globe
temperature is considered as MRT but it is not acceptable always. MRT
is calculated by three different ways-
-by calculating surface angle view factor
-through globe temperature
-using Rayman Model
hope this is useful to you.
shivraj