[Bldg-sim] How to model floor using aluminium foil to prevent heat transfer?

[Cheney]

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

LinkedIN @ http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b



On Thu, Apr 14, 2011 at 10:12 AM, Chris <floodyc at gmail.com> wrote:

> 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.
>
> On Thu, Apr 14, 2011 at 09:40, Shubha Mohunta <shubha.mohunta at gmail.com>wrote:
>
>> 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
>>
>> On Tue, Apr 12, 2011 at 4:53 PM, Cheney <chenyu73 at gmail.com> wrote:
>>
>>> 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
>>>
>>> LinkedIN @ http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b
>>>
>>>
>>>
>>>   On Tue, Apr 12, 2011 at 12:02 PM, Shubha Mohunta <
>>> shubha.mohunta at gmail.com> wrote:
>>>
>>>>   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, LEED Green Assoc.
>>>> M.S. Sustainable Design
>>>> Carnegie Mellon University
>>>>
>>>>
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>>
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>
>
> --
> Chris Flood BSc (Eng)
> Senior Building Analyst
>
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