[Bldg-sim] Radiant slab Heating Cooling

varun kulkarni seldomvarun at gmail.com
Fri Feb 24 05:15:01 PST 2012


All,
Radiant heating/cooling does not address the latent load. So if you have a
space/building served by radiant heating/cooling, you have to have a
ventilation unit (which might supply neutral air). This considerably gives
a huge amount of saving when coupled with DCV.
Another point point is that a chiller with 55F LWT and boiler with 100F LWT
would use less energy than conventional chiler/boiler LWT range. So, as
Amit said, a de-coupler is needed (may be a heat exchanger) for chilled
water and heating water to tie into other equipments in the building such
as snowmelt, air handlers..
By the ratio of radiant floor and conditioned floor output, do you mean the
ratio of energy consumed if the building was conditioned with either of the
two approach?

On Fri, Feb 24, 2012 at 12:00 AM, Hisham Ahmad <hisham at edsglobal.com> wrote:

> 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****
>>
>> Sherman Oaks, CA 91423****
>>
>> Tel; 818-305-3246****
>>
>> Mobile: 818-2191284****
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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.****
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>>  ****
>>
>>  ****
>>
>>  ****
>>
>>
>>
>>
>> -- ****
>>
>> Thanks and Best Regards,****
>>
>>  ****
>>
>>  ****
>>
>>  ****
>>
>> Sincerely,****
>>
>>  ****
>>
>> Varun Kulkarni ****
>>
>>  ****
>>
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-- 
Thanks and Best Regards,



Sincerely,

Varun Kulkarni

Note: Please do not print, unless required.
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