[Bldg-sim] Radiant slab Heating Cooling

[Hisham Ahmad]

Hi Varun

As a work around in DOE2. You may model the actual design temperatures and
increase/decrease the indoor set points for cooling/heating by some margin.


Regards
Hisham Ahmad

Energy Analyst
Environmental Design Solutions Pvt Ltd.
www.edsglobal.com
New Delhi, India
+91-9873065488


On 24 February 2012 09:38, Peter Simmonds <peter.simmonds at ibece.net> wrote:

>  Varun, you might want to graduate from the HAP program. Unless you have
> two chillers one for 42F water and another for 55F, then most systems
> produce 42F water and then blend to 55F, so the potential savings are
> difficult to obtain. By the way what is the ratio of your radiant floor to
> conditioned air output?****
>
> ** **
>
> Peter Simmonds, Ph.D., ASHRAE Fellow and DL****
>
> Head of the Advanced Technology Group,****
>
> IBE Consulting Engineers,****
>
> 14130 Riverside drive, suite 201****
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> Sherman Oaks, CA 91423****
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> *From:* varun kulkarni [mailto:seldomvarun at gmail.com]
> *Sent:* Thursday, February 23, 2012 11:05 AM
>
> *To:* Peter Simmonds
> *Cc:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Radiant slab Heating Cooling****
>
> ** **
>
> Thanks Peter,****
>
>  ****
>
> I am using Carrier HAP and when I model a fan coil unit, I am asked to
> input the design supply temperatures for heating and cooling (which is
> usually 95F and 55F). Now, i think these are going to drive my energy
> consumed at the boiler and chiller. The whole point (not the only point but
> a major though) of using radiant slab heating and cooling is lower temps
> for heating, higher temps for cooling and also the fact that water has
> higher energy carrying capacity then air. So if you are not able to take
> credit for that in modeling then obviously, the energy consumption number
> is not right. Thats my reason to segregate the different temperatures.****
>
> On Thu, Feb 23, 2012 at 11:38 AM, Peter Simmonds <peter.simmonds at ibece.net>
> wrote:****
>
> Varun, your perception is nearly true, but it depends on what you are
> modeling? If you are modeling the energy performance of a building a four
> pipe fan coil works just fine as it maintains the required energy balance.
> It is true that the actual performance of a radiant floor is different than
> a fan coil, but you are looking at energy and not optimal modeling.****
>
> Your thoughts on stratification are somewhat correct. I would tend to
> think that stratification is caused by space heat load and air movement,
> especially displacement. Yes, there is a convective flow from the floor but
> this is quite small as the temperature difference between the floor surface
> temperature and the space operating temperature.****
>
> Regarding temperature; this depends on what program you are using and why
> you want to segregate the different temperatures?****
>
>  ****
>
> *Peter Simmonds, Ph.D. *
> *Senior Associate
> Head of the Advanced Technology Group
> **IBE Consulting Engineers*
> *14130 Riverside Drive, Suite 201*
> *Sherman Oaks, CA 91423
> d: (818) 305-3246 o: (818) 377-8220 f: (818) 377-8230
>
> **www.ibece.com
> **Ideas for the built environment*****
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> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *varun kulkarni
> *Sent:* Thursday, February 23, 2012 5:34 AM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Radiant slab Heating Cooling****
>
>  ****
>
> Good Morning everyone,****
>
>  ****
>
> I have been reading through the archives for modeling radiant slab heating
> and cooling.****
>
> Most popular and the closest to real world approach I found was using a 4
> pipe fan coil unit and making the fan energy zero.****
>
> I still have following questions:****
>
> ·         Did anyone think of using a factor, which when multiplied to
> the energy usage by fan coil system, give us the actual energy usage by
> radiant system. (I would guess it would be <1)****
>
> ·         As radiant heating and cooling forms a stratification layer in
> the space. And  we care about first 6-8 feet to be within desired
> temperature range. So to take that into account while modeling “it”  as fan
> coil unit, can we lower the ceiling height. Does that mean the conduction
> load from ceiling/roof or the wall above 6-8 feet doesn’t count ?****
>
> ·         The temperature range for heating water (95F-105F) and cooling
> water (55F-65F) pumped in the radiant system is different from the typical
> chilled water (44F-45F) and heating water (170F-180F). How do we make sure
> our model reflects this while using fan coil unit.****
>
>  ****
>
> I am sure there are more questions you would have come across but these
> were some of my major concerns and I would appreciate any inputs/
> suggestions.****
>
> PS: This is a aspiring LEED platinum building.****
>
>
>
> -- ****
>
> Thanks and Best Regards,****
>
>  ****
>
>  ****
>
>  ****
>
> Sincerely,****
>
>  ****
>
> Varun Kulkarni ****
>
>  ****
>
> Note: Please do not print, unless required.****
>
>  ****
>
>  ****
>
>  ****
>
>
>
>
> -- ****
>
> Thanks and Best Regards,****
>
>  ****
>
>  ****
>
>  ****
>
> Sincerely,****
>
>  ****
>
> Varun Kulkarni ****
>
>  ****
>
> Note: Please do not print, unless required.****
>
>  ****
>
>  ****
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