Hi,
The building i am modeling has steel frame floor which separates the
conditioned space from unconditioned basement. There are hot water tubes
running underneath between the steel joists for radiant heating. There is no
use of insulation except for v thin aluminium foil below radiant tubes which
is fixed to the steel joists using magnets. This foil helps with high
reflectivity and low thermal absorption prevents heat transfer to the
unconditioned basement.
Can somebody give me ideas how to model this ? I am using eQUEST
Thanks,
Regards,
Shubha Mohunta
Hi,
I doubt you are able to simulate it by using eQuest. However, it is possible
to simulate it in IES VE (I guess TAS and Energy+ can do the same thing).
Radiant floor can be simulated by 1. top concrete (e.g. 2" of concrete); 2.
radiant piping zone; 3. floor assembly below the radiant piping. For your
case, reflectivity, emiissivity (probably conductivity) should be modified
accordingly between layer 2 and 3.
Regards,
Cheney
Thanks Cheney,
This project uses Heat pumps for cooling and radiant floors for heating. So
to model this i have used Heat pumps ( with just cooling) as my primary
system and attached baseboards to them to simulate radiant floors.
Do u think this would work?
Shubha
A radiant floor performs vastly different to hydronic baseboards and that
workaround is not a valid approach in my opinion. Having an understanding of
the physics involved in the performance of radiant slabs and their influence
on space heating is essential before any modeling takes palce.
Chris Flood
Hi Shubha
I agree with Chris that you could not simply use baseboard to represent
radiant heating floor, especially when you will have to further modify the
physical properties of the material (your high reflectivity and low
absorptivity foil) below hot water tubes. Modeling radiant floor in IES VE
is way more complicated than some general workaround such as using 4 pipe
fan coil without fan power. However it does trace the complicacy of the
physical performance of radiant slab. I guess the hypothesis of such
simulation is that the radiant floor with the foil can effectively 'move'
more heat to the above space? The interaction between the foil and the
radiant slab will be seamless and they can't be modelled separately in your
case. Any workaround or simplification should respect the interaction and
physical performance of radiant slab.
CMU has many professionals who know Energy Plus and other simulation
tools very well. Probably you may seek their help in the area of radiant
slab first. Good luck!
Regards,
Cheney