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Size and number of chillers for ASHRAE 90.1 Base case model This topic is a duplicate of another discussion. You were redirected here from a duplicate topic. 19 posts by 6 authors

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surekha 1/10/09

Other recipients: Hello All, I am working on the energy modeling of a non residential building more than 6 floors with a conditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1 Appendix G. As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 Hello All,

I am working on the energy modeling of a non residential building morethan 6 floors with aconditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1Appendix G.As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 , andASHRAE90.1-2004 Table G3.1.3.7 (Type and number of chillers) says that itshouldbe "2 centrifugal chillers minimum with chiller added so that nochiller islarger than 800 tons, all sized equally."After a sizing run of the model, the tonnage came out to beapproximately 1000 tons.I can divide this into 2 x 500 tons chiller or into 4 x 250 tonschillers.In each case the COP of the chiller vary.

Which is the correct way of giving the size and number of chillers.

Thanks & Regards,

Surekha Tetali Show trimmed content Swiftech Engineering 1/10/09

Other recipients: Hi Surekha, I guess the tonnage requirement is given for the peak load. Ideally you can go for 3x400 = 1200. For a daily requirement you will run 2 chillers at a time but make sure all three are condition. i.e id A,B,C are the chillers run A,B tod Hi Surekha,

I guess the tonnage requirement is given for the peak load.Ideally you can go for 3x400 = 1200. For a daily requirement you will run 2 chillers at a time but make sure all three are condition. i.e id A,B,C are the chillers run A,B today, B,C tomorrow and C,A day after to ensure equal wear and tear of all chillers and availability of two at the time of third being in repair.

Hope this helps and request AC experts to correct if this approach does not make sense.

Sharada Nayakwadi.- show quoted text -

On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:

Hello All,



Thanks & Regards,

Surekha Tetali

Show trimmed content [email protected] 1/10/09

Other recipients: [email protected] Since the type of chiller is 'centrifugal' which are normally manufactured & used only for large capacity requirements , you should consider 2 no.s of 500 TR . Regards C.T.Satish *surekha * Sent by: greenbuil...@googleg

Since the type of chiller is 'centrifugal' which are normally manufactured & used only for large capacity requirements , you should consider 2 no.s of 500 TR .

RegardsC.T.Satish

surekha Sent by: [email protected]/01/2009 08:51 AMPlease respond [email protected]

ToGreenBuildingsIndia

cc

Subject[greenbuildingsindia:44] Size and number of chillers for ASHRAE 90.1 Base case model

- show quoted text -

Hello All,



Thanks & Regards,

Surekha Tetali


Re: [greenbuildingsindia:45] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: If the block cooling load is only 1000 TR as mentioned in the email , then there is no need to consider 1200 TR (3x400 TR). The correct base case (as i have mentioned in my earlier email) would be 2 x 500 TR. Regards C.T.Satish Voltas Limited

If the block cooling load is only 1000 TR as mentioned in the email , then there is no need to consider 1200 TR (3x400 TR). The correct base case (as i have mentioned in my earlier email) would be 2 x 500 TR.

RegardsC.T.SatishVoltas Limited

"Swiftech Engineering" Sent by: [email protected]/01/2009 09:19 AMPlease respond [email protected]

[email protected]

cc

Subject[greenbuildingsindia:45] Re: Size and number of chillers for ASHRAE 90.1 Base case model

Hi Surekha,

I guess the tonnage requirement is given for the peak load.Ideally you can go for 3x400 = 1200. For a daily requirement you will run 2 chillers at a time but make sure all three are condition. i.e id A,B,C are the chillers run A,B today, B,C tomorrow and C,A day after to ensure equal wear and tear of all chillers and availability of two at the time of third being in repair.

Hope this helps and request AC experts to correct if this approach does not make sense.

Sharada Nayakwadi.

- show quoted text -On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:

Hello All,



Thanks & Regards,

Surekha Tetali

Show trimmed content SMH Adil 1/10/09

Other recipients: Hi Surekha, Cant resist answering this one....!!! Size the chiller equally i.e. 500*2 as people have pointed out, and you must have put a 1.2 sizing factor in sizing run I suppose. The essence of these sizes and numbers is that, it has to operate Hi Surekha,

Cant resist answering this one....!!!Size the chiller equally i.e. 500*2 as people have pointed out, and you must have put a 1.2 sizing factor in sizing run I suppose. The essence of these sizes and numbers is that, it has to operate at its peak efficiency with redundancy in mind. So important point is that the chiller curve that you are using for these hypothetical base line chiller should be same in the base case.Now in your Energy Efficiency measures, you might like to play with various configuration of minimum base load which might be 40 to 50%, i.e. use a centrifugal chiller and for fixed load to achieve near ARI efficiencies, and from 50 to 100% use screw chiller, which is responsive on part load.....and also don't forget to sequence them in the simulation model for there availability that would save enormous amount of energy with out further cost.....if you observe by fixing centrifugal chiller ASHRAE 90.1 has given us opportunities for saving by applying sequencing logics in a plant....

Regards

SMH Adil


On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:

Hello All,



Thanks & Regards,

Surekha Tetali

-- -- Best Regards,

SMH AdilBuilding Energy AnalystGlobal Evolutionary Energy DesignD-15, Abul Fazal EnclaveJamia Nagar, OkhlaNew Delhi-110025, INDIAMob: +91 9873588571 Ph: +91 11 24537371Skype : smh.adil, Location: New Delhi [email protected]://www.geedindia.org/index.html

-----------------------------------------------------------"Sustainability is not a business; neither should be used as propaganda to achieve goals in politics; It is the sacred conscious that is born with every living being on the earth and humans too, try recognizing it." ----------------------------------------------------------End of message.. Show trimmed content Vishal Garg 1/11/09

Re: [greenbuildingsindia:48] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: Thanks Adil. Still it is not fully clear. One can take either of the two options for the base case: 500T * 2 250T * 4 I think there should be no scope of ambiguity in the base case. If one takes the 250T *4 combination then the applicable COP Thanks Adil. Still it is not fully clear. One can take either of thetwo options for the base case:

500T * 2250T * 4

I think there should be no scope of ambiguity in the base case. If onetakes the 250T *4 combination then the applicable COP will be lessthan for 500T * 2 combination, hence the savings in the proposed casewill be more. So is there a limitation on the minimum Tonnage for thebase case?

Regards,

Vishal- show quoted text -

On Sat, Jan 10, 2009 at 12:47 PM, SMH Adil wrote:> Hi Surekha,> Cant resist answering this one....!!!> Size the chiller equally i.e. 500*2 as people have pointed out, and you must> have put a 1.2 sizing factor in sizing run I suppose. The essence of these> sizes and numbers is that, it has to operate at its peak efficiency> with redundancy in mind. So important point is that the chiller curve that> you are using for these hypothetical base line chiller should be same in the> base case.> Now in your Energy Efficiency measures, you might like to play with various> configuration of minimum base load which might be 40 to 50%, i.e. use> a centrifugal chiller and for fixed load to achieve near ARI efficiencies,> and from 50 to 100% use screw chiller, which is responsive on part> load.....and also don't forget to sequence them in the simulation model for> there availability that would save enormous amount of energy with out> further cost.....> if you observe by fixing centrifugal chiller ASHRAE 90.1 has given us> opportunities for saving by applying sequencing logics in a plant....> Regards>> SMH Adil>> On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:>>>> Hello All,>>>> I am working on the energy modeling of a non residential building more>> than 6 floors with a>> conditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1>> Appendix G.>> As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 , and>> ASHRAE>> 90.1-2004 Table G3.1.3.7 (Type and number of chillers) says that it>> should>> be "2 centrifugal chillers minimum with chiller added so that no>> chiller is>> larger than 800 tons, all sized equally.">> After a sizing run of the model, the tonnage came out to be>> approximately 1000 tons.>> I can divide this into 2 x 500 tons chiller or into 4 x 250 tons>> chillers.>> In each case the COP of the chiller vary.>>>> Which is the correct way of giving the size and number of chillers.>>>> Thanks & Regards,>>>>>> Surekha Tetali>>>>>>>> --> --> Best Regards,>> SMH Adil> Building Energy Analyst> Global Evolutionary Energy Design> D-15, Abul Fazal Enclave> Jamia Nagar, Okhla> New Delhi-110025, INDIA> Mob: +91 9873588571> Ph: +91 11 24537371> Skype : smh.adil, Location: New Delhi> [email protected]> http://www.geedindia.org/index.html>> -----------------------------------------------------------> "Sustainability is not a business; neither should be used as propaganda to> achieve goals in politics;> It is the sacred conscious that is born with every living being on the earth> and humans too, try recognizing it."> ----------------------------------------------------------> End of message..>> >> Show trimmed content SMH Adil 1/12/09

Re: [greenbuildingsindia:51] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: [email protected] Dear Sir, As far as I understand the COP is fixed at ARI, and rest of the operation due to the out side conditions were elaborated by the chiller curves which again are standard for centrifugal chillers ( I elaborated the significance in my prev Dear Sir,

As far as I understand the COP is fixed at ARI, and rest of the operation due to the out side conditions were elaborated by the chiller curves which again are standard for centrifugal chillers ( I elaborated the significance in my previous mail). Now if I compare cases i.e. 250 TR Chiller1,2,3 & [email protected] with 500 TR Chiller1 & [email protected] COP, The delta in energy consumption will only be due to sequencing as the load profile will be differently faced by 500*2 and 250*4 chiller sequence (this will be a better one) . Now going further, if my load profile always stays at 1000 ton i.e. constant then there wont be any difference in energy consumption in these two cases.but still the energy modeler is left with a trick of making the base case as worst as possible by selecting minimum no. of chillers and not more. large chillers would be responding bad in terms of there response to the part load profile and hence more energy consumption will lead to high base case energy usage, and that what every energy modeler wants.its a secrete trick but now made public due to your Green building India initiative...!!!!!!!!!!

let me know if i am able to communicate my point.

This is only valid for cases discussed in the mail trail, it depict my understanding towards the system behavior in a cumulative sense, this might have loop hole in it.

Sincerely

Adil - show quoted text -

On Sun, Jan 11, 2009 at 10:46 PM, Vishal Garg wrote:

Thanks Adil. Still it is not fully clear. One can take either of thetwo options for the base case:

500T * 2250T * 4


Regards,

Vishal

On Sat, Jan 10, 2009 at 12:47 PM, SMH Adil wrote:> Hi Surekha,> Cant resist answering this one....!!!> Size the chiller equally i.e. 500*2 as people have pointed out, and you must> have put a 1.2 sizing factor in sizing run I suppose. The essence of these> sizes and numbers is that, it has to operate at its peak efficiency> with redundancy in mind. So important point is that the chiller curve that> you are using for these hypothetical base line chiller should be same in the> base case.> Now in your Energy Efficiency measures, you might like to play with various> configuration of minimum base load which might be 40 to 50%, i.e. use> a centrifugal chiller and for fixed load to achieve near ARI efficiencies,> and from 50 to 100% use screw chiller, which is responsive on part> load.....and also don't forget to sequence them in the simulation model for> there availability that would save enormous amount of energy with out> further cost.....> if you observe by fixing centrifugal chiller ASHRAE 90.1 has given us> opportunities for saving by applying sequencing logics in a plant....> Regards>> SMH Adil>> On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:>>>> Hello All,>>>> I am working on the energy modeling of a non residential building more>> than 6 floors with a>> conditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1>> Appendix G.>> As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 , and>> ASHRAE>> 90.1-2004 Table G3.1.3.7 (Type and number of chillers) says that it>> should>> be "2 centrifugal chillers minimum with chiller added so that no>> chiller is>> larger than 800 tons, all sized equally.">> After a sizing run of the model, the tonnage came out to be>> approximately 1000 tons.>> I can divide this into 2 x 500 tons chiller or into 4 x 250 tons>> chillers.>> In each case the COP of the chiller vary.>>>> Which is the correct way of giving the size and number of chillers.>>>> Thanks & Regards,>>>>>> Surekha Tetali>>>>>>>> --> --> Best Regards,>> SMH Adil> Building Energy Analyst> Global Evolutionary Energy Design> D-15, Abul Fazal Enclave> Jamia Nagar, Okhla> New Delhi-110025, INDIA> Mob: +91 9873588571> Ph: +91 11 24537371> Skype : smh.adil, Location: New Delhi> [email protected]> http://www.geedindia.org/index.html>> -----------------------------------------------------------> "Sustainability is not a business; neither should be used as propaganda to> achieve goals in politics;> It is the sacred conscious that is born with every living being on the earth> and humans too, try recognizing it."> ----------------------------------------------------------> End of message..>> >>D-15, Abul Fazal EnclaveJamia Nagar, OkhlaNew Delhi-110025, INDIAMob: +91 9873588571 Ph: +91 11 24537371Skype : smh.adil, Location: New Delhi [email protected]://www.geedindia.org/index.html


Re: [greenbuildingsindia:51] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: [email protected] Thanks Adil for the details. How have you fixed the COP for the both the cases (250T *4 and 500T *2) as 6.1. I think COP for the 250T chiller should be 5.55 and COP for 500T should be 6.1 according to table 6.8.1c of ASHRAE 90.1 Vishal Thanks Adil for the details.

How have you fixed the COP for the both the cases (250T *4 and 500T *2) as 6.1. I think COP for the 250T chiller should be 5.55 and COP for 500T should be 6.1 according to table 6.8.1c of ASHRAE 90.1


On Mon, Jan 12, 2009 at 12:48 PM, SMH Adil wrote:Dear Sir,




Sincerely

Adil



500T * 2250T * 4


Regards,

Vishal

On Sat, Jan 10, 2009 at 12:47 PM, SMH Adil wrote:> Hi Surekha,> Cant resist answering this one....!!!> Size the chiller equally i.e. 500*2 as people have pointed out, and you must> have put a 1.2 sizing factor in sizing run I suppose. The essence of these> sizes and numbers is that, it has to operate at its peak efficiency> with redundancy in mind. So important point is that the chiller curve that> you are using for these hypothetical base line chiller should be same in the> base case.> Now in your Energy Efficiency measures, you might like to play with various> configuration of minimum base load which might be 40 to 50%, i.e. use> a centrifugal chiller and for fixed load to achieve near ARI efficiencies,> and from 50 to 100% use screw chiller, which is responsive on part> load.....and also don't forget to sequence them in the simulation model for> there availability that would save enormous amount of energy with out> further cost.....> if you observe by fixing centrifugal chiller ASHRAE 90.1 has given us> opportunities for saving by applying sequencing logics in a plant....> Regards>> SMH Adil>> On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:>>>> Hello All,>>>> I am working on the energy modeling of a non residential building more>> than 6 floors with a>> conditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1>> Appendix G.>> As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 , and>> ASHRAE>> 90.1-2004 Table G3.1.3.7 (Type and number of chillers) says that it>> should>> be "2 centrifugal chillers minimum with chiller added so that no>> chiller is>> larger than 800 tons, all sized equally.">> After a sizing run of the model, the tonnage came out to be>> approximately 1000 tons.>> I can divide this into 2 x 500 tons chiller or into 4 x 250 tons>> chillers.>> In each case the COP of the chiller vary.>>>> Which is the correct way of giving the size and number of chillers.>>>> Thanks & Regards,>>>>>> Surekha Tetali>>>>>>>> --> --> Best Regards,>> SMH Adil> Building Energy Analyst> Global Evolutionary Energy Design> D-15, Abul Fazal Enclave> Jamia Nagar, Okhla> New Delhi-110025, INDIA> Mob: +91 9873588571> Ph: +91 11 24537371> Skype : smh.adil, Location: New Delhi> [email protected]> http://www.geedindia.org/index.html>> -----------------------------------------------------------> "Sustainability is not a business; neither should be used as propaganda to> achieve goals in politics;> It is the sacred conscious that is born with every living being on the earth> and humans too, try recognizing it."> ----------------------------------------------------------> End of message..>> >>Global Evolutionary Energy DesignD-15, Abul Fazal EnclaveJamia Nagar, OkhlaNew Delhi-110025, INDIAMob: +91 9873588571 Ph: +91 11 24537371Skype : smh.adil, Location: New Delhi [email protected]://www.geedindia.org/index.html

-----------------------------------------------------------"Sustainability is not a business; neither should be used as propaganda to achieve goals in politics; It is the sacred conscious that is born with every living being on the earth and humans too, try recognizing it." ----------------------------------------------------------End of message..

Show trimmed content SMH Adil 1/12/09

Re: [greenbuildingsindia:51] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: [email protected] You are right ! I haven't noticed this.....any way This can be explained as limit defined by 90.1 not to chose small chiller, which might be operating at its peak all the time. This is justifying the concept of going for large chillers any way to g You are right ! I haven't noticed this.....any wayThis can be explained as limit defined by 90.1 not to chose small chiller, which might be operating at its peak all the time. This is justifying the concept of going for large chillers any way to get maximum loss in bad part load operations for base case

Adil- show quoted text -

On Mon, Jan 12, 2009 at 1:24 PM, Vishal Garg wrote:Thanks Adil for the details.


Vishal





Sincerely

Adil



500T * 2250T * 4


Regards,

Vishal



-- -- Best Regards,



Re: [greenbuildingsindia:56] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: So where is the limit defined in ASHRAE? Vishal So where is the limit defined in ASHRAE?Vishal- show quoted text -

On Mon, Jan 12, 2009 at 1:46 PM, SMH Adil wrote:You are right ! I haven't noticed this.....any wayThis can be explained as limit defined by 90.1 not to chose small chiller, which might be operating at its peak all the time. This is justifying the concept of going for large chillers any way to get maximum loss in bad part load operations for base case

AdilOn Mon, Jan 12, 2009 at 1:24 PM, Vishal Garg wrote:Thanks Adil for the details.


Vishal





Sincerely

Adil



500T * 2250T * 4


Regards,

Vishal



-- -- Best Regards,



Show trimmed content jyotirmay mathur 1/13/09

Re: [greenbuildingsindia:60] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: Vishal and Adil, the discussion you had in past 2-3 days would be very useful for the entire community (LEED or non-LEED) for selection of appropriate chiller size. my feeling in this issue is (of course not written in ASHRAE) that the number of Vishal and Adil, the discussion you had in past 2-3 days would be very useful for the entire community (LEED or non-LEED) for selection of appropriate chiller size. my feeling in this issue is (of course not written in ASHRAE) that the number of chillers is the base case should be same as in proposed case. doing so, you address the situation of operating smaller chillers at peak load or large chiller at very low load. currently one can take advantage of the situation since this is not written very explicitly and he make the base case much worse by selecting different number of chillers (depending upon his load diversity) but this won't be ethically correct and IGBC/ECBC should take a call on this matter by restricting the scope of fiddling with the base case . jyotirmay- show quoted text -On Mon, Jan 12, 2009 at 9:54 PM, Vishal Garg wrote:So where is the limit defined in ASHRAE?Vishal

On Mon, Jan 12, 2009 at 1:46 PM, SMH Adil wrote:You are right ! I haven't noticed this.....any way This can be explained as limit defined by 90.1 not to chose small chiller, which might be operating at its peak all the time. This is justifying the concept of going for large chillers any way to get maximum loss in bad part load operations for base case



Vishal





Sincerely

Adil



500T * 2250T * 4


Regards,

Vishal



-- -- Best Regards,



-- Dr.-Ing. Jyotirmay MathurCoordinator, PG Program in Energy EngineeringReader, Mechanical Engineering DepartmentMalaviya National Institute of TechnologyJ.L.N. Marg, Jaipur (India) -302 017Phone: +91-141-2529109 (R)+91-141-2529061 (o), 2713211 (direct)+91-94142-50329 (mobile)http://jyotirmaymathur.tripod.com/ Show trimmed content Vishal Garg 1/13/09

Re: [greenbuildingsindia:61] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: Dear Dr. Mathur, Thank you for your comments. My feeling is that the base case should not depend on the proposed case. In proposed case we might have 50T x 20 nos water cooled VRVs! regards, Vishal Dear Dr. Mathur,

Thank you for your comments. My feeling is that the base case should not depend on the proposed case. In proposed case we might have 50T x 20 nos water cooled VRVs!

regards,


On Tue, Jan 13, 2009 at 8:57 AM, jyotirmay mathur wrote:Vishal and Adil, the discussion you had in past 2-3 days would be very useful for the entire community (LEED or non-LEED) for selection of appropriate chiller size. my feeling in this issue is (of course not written in ASHRAE) that the number of chillers is the base case should be same as in proposed case. doing so, you address the situation of operating smaller chillers at peak load or large chiller at very low load. currently one can take advantage of the situation since this is not written very explicitly and he make the base case much worse by selecting different number of chillers (depending upon his load diversity) but this won't be ethically correct and IGBC/ECBC should take a call on this matter by restricting the scope of fiddling with the base case . jyotirmayOn Mon, Jan 12, 2009 at 9:54 PM, Vishal Garg wrote:So where is the limit defined in ASHRAE?Vishal




Vishal





Sincerely

Adil



500T * 2250T * 4


Regards,

Vishal



-- -- Best Regards,



-- Dr.-Ing. Jyotirmay MathurCoordinator, PG Program in Energy EngineeringReader, Mechanical Engineering DepartmentMalaviya National Institute of TechnologyJ.L.N. Marg, Jaipur (India) -302 017Phone: +91-141-2529109 (R)+91-141-2529061 (o), 2713211 (direct)+91-94142-50329 (mobile)http://jyotirmaymathur.tripod.com/


Re: [greenbuildingsindia:62] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: The essence of ASHRAE 90.1 recommendation on this point is a) *minimum number of chillers to be considered for base case* (but not less than two) b) all sized equally c) no chiller is larger than 800 tons Hence the base case consideration for

The essence of ASHRAE 90.1 recommendation on this point is a) minimum number of chillers to be considered for base case (but not less than two)b) all sized equallyc) no chiller is larger than 800 tons

Hence the base case consideration for various examples should be a) For say 1000 TR load , the base case consideration would be 2 x 500 TRb) For say 1500 TR load , the base case consideration would be 2 x 750 TRc) For say 2000 TR load , the base case consideration would be 3 x 666.66 TR (and not 2 x 1000 TR here as it would exceed 800 TR limit)

The point is the number of chillers to be considered for base case should be as low as possible (but not less tan two and also no chiller more than 800 tons).

If this was not the case, then one would end up with selecting numerous options for the base case which would not tbe correct. The base case should be only one option and hence the above justification.

I hope the above makes sense .

Vishal Garg Sent by: [email protected]/01/2009 09:17 AMPlease respond [email protected]

[email protected]

cc


Dear Dr. Mathur,


regards,

Vishal

On Tue, Jan 13, 2009 at 8:57 AM, jyotirmay mathur wrote:Vishal and Adil, the discussion you had in past 2-3 days would be very useful for the entire community (LEED or non-LEED) for selection of appropriate chiller size. my feeling in this issue is (of course not written in ASHRAE) that the number of chillers is the base case should be same as in proposed case. doing so, you address the situation of operating smaller chillers at peak load or large chiller at very low load. currently one can take advantage of the situation since this is not written very explicitly and he make the base case much worse by selecting different number of chillers (depending upon his load diversity) but this won't be ethically correct and IGBC/ECBC should take a call on this matter by restricting the scope of fiddling with the base case . jyotirmayOn Mon, Jan 12, 2009 at 9:54 PM, Vishal Garg wrote:So where is the limit defined in ASHRAE?Vishal




Vishal





Sincerely

Adil On Sun, Jan 11, 2009 at 10:46 PM, Vishal Garg wrote:


500T * 2250T * 4


Regards,

Vishal

On Sat, Jan 10, 2009 at 12:47 PM, SMH Adil wrote:

> Hi Surekha,> Cant resist answering this one....!!!> Size the chiller equally i.e. 500*2 as people have pointed out, and you must> have put a 1.2 sizing factor in sizing run I suppose. The essence of these> sizes and numbers is that, it has to operate at its peak efficiency> with redundancy in mind. So important point is that the chiller curve that> you are using for these hypothetical base line chiller should be same in the> base case.> Now in your Energy Efficiency measures, you might like to play with various> configuration of minimum base load which might be 40 to 50%, i.e. use> a centrifugal chiller and for fixed load to achieve near ARI efficiencies,> and from 50 to 100% use screw chiller, which is responsive on part> load.....and also don't forget to sequence them in the simulation model for> there availability that would save enormous amount of energy with out> further cost.....> if you observe by fixing centrifugal chiller ASHRAE 90.1 has given us> opportunities for saving by applying sequencing logics in a plant....> Regards>> SMH Adil>- show quoted text -> On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:- show quoted text -

>>>> Hello All,>>>> I am working on the energy modeling of a non residential building more>> than 6 floors with a>> conditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1>> Appendix G.>> As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 , and>> ASHRAE>> 90.1-2004 Table G3.1.3.7 (Type and number of chillers) says that it>> should>> be "2 centrifugal chillers minimum with chiller added so that no>> chiller is>> larger than 800 tons, all sized equally.">> After a sizing run of the model, the tonnage came out to be>> approximately 1000 tons.>> I can divide this into 2 x 500 tons chiller or into 4 x 250 tons>> chillers.>> In each case the COP of the chiller vary.>>>> Which is the correct way of giving the size and number of chillers.>>>> Thanks & Regards,>>>>>> Surekha Tetali>>>>>>>> --

> --- show quoted text -> Best Regards,>> SMH Adil> Building Energy Analyst> Global Evolutionary Energy Design> D-15, Abul Fazal Enclave> Jamia Nagar, Okhla> New Delhi-110025, INDIA> Mob: +91 9873588571> Ph: +91 11 24537371> Skype : smh.adil, Location: New Delhi> [email protected]

> http://www.geedindia.org/index.html>> -----------------------------------------------------------> "Sustainability is not a business; neither should be used as propaganda to> achieve goals in politics;> It is the sacred conscious that is born with every living being on the earth> and humans too, try recognizing it."> ----------------------------------------------------------> End of message..>> >>

Global Evolutionary Energy DesignD-15, Abul Fazal EnclaveJamia Nagar, OkhlaNew Delhi-110025, INDIAMob: +91 9873588571 Ph: +91 11 24537371Skype : smh.adil, Location: New Delhi [email protected]

http://www.geedindia.org/index.html


-- -- Best Regards,

SMH AdilBuilding Energy AnalystGlobal Evolutionary Energy DesignD-15, Abul Fazal EnclaveJamia Nagar, OkhlaNew Delhi-110025, INDIAMob: +91 9873588571 Ph: +91 11 24537371Skype : smh.adil, Location: New Delhi [email protected] show quoted text -

http://www.geedindia.org/index.html



Show trimmed content Vishal Garg 1/13/09

Re: [greenbuildingsindia:63] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: Sounds good. However, I could not find where is it mentioned that the number of chillers should be minimum. ASHRAE says: Type and Number of Chillers (Systems 7 and 8). Electric chillers shall be used in the baseline building design regardless of th Sounds good. However, I could not find where is it mentioned that the number of chillers should be minimum. ASHRAE says:

Type and Number of Chillers (Systems 7 and8). Electric chillers shall be used in the baseline buildingdesign regardless of the cooling energy source, e.g., directfiredabsorption, absorption from purchased steam, or purchasedchilled water. The baseline building design's chillerplant shall be modeled with chillers having the number andtype as indicated in Table G3.1.3.7 as a function of buildingconditioned floor area.

-Vishal- show quoted text -

On Tue, Jan 13, 2009 at 1:30 PM, wrote:

The essence of ASHRAE 90.1 recommendation on this point is a) minimum number of chillers to be considered for base case (but not less than two)b) all sized equallyc) no chiller is larger than 800 tons

Hence the base case consideration for various examples should be a) For say 1000 TR load , the base case consideration would be 2 x 500 TRb) For say 1500 TR load , the base case consideration would be 2 x 750 TRc) For say 2000 TR load , the base case consideration would be 3 x 666.66 TR (and not 2 x 1000 TR here as it would exceed 800 TR limit)




Vishal Garg Sent by: [email protected]/01/2009 09:17 AMPlease respond [email protected]

[email protected]

cc


Dear Dr. Mathur,


regards,

Vishal

On Tue, Jan 13, 2009 at 8:57 AM, jyotirmay mathur wrote:Vishal and Adil, the discussion you had in past 2-3 days would be very useful for the entire community (LEED or non-LEED) for selection of appropriate chiller size. my feeling in this issue is (of course not written in ASHRAE) that the number of chillers is the base case should be same as in proposed case. doing so, you address the situation of operating smaller chillers at peak load or large chiller at very low load. currently one can take advantage of the situation since this is not written very explicitly and he make the base case much worse by selecting different number of chillers (depending upon his load diversity) but this won't be ethically correct and IGBC/ECBC should take a call on this matter by restricting the scope of fiddling with the base case . jyotirmay

On Mon, Jan 12, 2009 at 9:54 PM, Vishal Garg wrote:So where is the limit defined in ASHRAE?Vishal


Adil

On Mon, Jan 12, 2009 at 1:24 PM, Vishal Garg wrote:Thanks Adil for the details.


Vishal





Sincerely

Adil



500T * 2250T * 4


Regards,

Vishal

On Sat, Jan 10, 2009 at 12:47 PM, SMH Adil wrote:> Hi Surekha,> Cant resist answering this one....!!!> Size the chiller equally i.e. 500*2 as people have pointed out, and you must> have put a 1.2 sizing factor in sizing run I suppose. The essence of these> sizes and numbers is that, it has to operate at its peak efficiency> with redundancy in mind. So important point is that the chiller curve that> you are using for these hypothetical base line chiller should be same in the> base case.> Now in your Energy Efficiency measures, you might like to play with various> configuration of minimum base load which might be 40 to 50%, i.e. use> a centrifugal chiller and for fixed load to achieve near ARI efficiencies,> and from 50 to 100% use screw chiller, which is responsive on part> load.....and also don't forget to sequence them in the simulation model for> there availability that would save enormous amount of energy with out> further cost.....> if you observe by fixing centrifugal chiller ASHRAE 90.1 has given us> opportunities for saving by applying sequencing logics in a plant....> Regards>> SMH Adil>> On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:>>>> Hello All,>>>> I am working on the energy modeling of a non residential building more>> than 6 floors with a>> conditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1>> Appendix G.>> As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 , and>> ASHRAE>> 90.1-2004 Table G3.1.3.7 (Type and number of chillers) says that it>> should>> be "2 centrifugal chillers minimum with chiller added so that no>> chiller is>> larger than 800 tons, all sized equally.">> After a sizing run of the model, the tonnage came out to be>> approximately 1000 tons.>> I can divide this into 2 x 500 tons chiller or into 4 x 250 tons>> chillers.>> In each case the COP of the chiller vary.>>>> Which is the correct way of giving the size and number of chillers.>>>> Thanks & Regards,>>>>>> Surekha Tetali>>>>>>>> --> --> Best Regards,>> SMH Adil> Building Energy Analyst> Global Evolutionary Energy Design> D-15, Abul Fazal Enclave> Jamia Nagar, Okhla> New Delhi-110025, INDIA> Mob: +91 9873588571> Ph: +91 11 24537371> Skype : smh.adil, Location: New Delhi> [email protected]> http://www.geedindia.org/index.html>> -----------------------------------------------------------> "Sustainability is not a business; neither should be used as propaganda to> achieve goals in politics;> It is the sacred conscious that is born with every living being on the earth> and humans too, try recognizing it."> ----------------------------------------------------------> End of message..>> >>

Global Evolutionary Energy DesignD-15, Abul Fazal EnclaveJamia Nagar, OkhlaNew Delhi-110025, INDIAMob: +91 9873588571 Ph: +91 11 24537371Skype : smh.adil, Location: New Delhi [email protected]://www.geedindia.org/index.html


-- -- Best Regards,





Re: [greenbuildingsindia:64] Re: Size and number of chillers for ASHRAE 90.1 Base case model Other recipients: Table G3.1.3.7 mentions "2 centrifugal chillers minimum with chillers added so that no chiller is larger than 800 tons , all sized equally". The above *implies* (and not strictly going by the wordings) that minimum number of chillers but not less

Table G3.1.3.7 mentions "2 centrifugal chillers minimum with chillers added so that no chiller is larger than 800 tons , all sized equally".

The above implies (and not strictly going by the wordings) that minimum number of chillers but not less than 2 is to be considered. To ensure that someone do not take advantage of selecting 2 chillers even when the load is very high say 4000 TR , the maximum limit of 800 TR on the capacity of each chiller is put so that they take 5 x 800 TR instead of 2 x 2000 TR.

Basically centrifugal chillers are used for large capacity requirements. That is why they are specified for Building-conditioned Floor areas > 240,000 sft . Practically too , no one would use more number of smaller capacity centrifugal chillers when they can do with smaller number of larger capacity units . But since it is not advisable to use only one chiller (because if that one chiller has a breaksdown then entire HVAC system is down) , the minimum number of 2 is specified. And also to prevent someone to take advantage of selecting only 2 chillers of very high capacities , the maximum limit of 800 TR per chiller is put.

Ofcourse all the above justifications are as per my reading of the subject.

RegardsC.T.Satish

Vishal Garg Sent by: [email protected]/01/2009 01:40 PMPlease respond [email protected]

[email protected]

cc


Sounds good. However, I could not find where is it mentioned that the number of chillers should be minimum. ASHRAE says:

Type and Number of Chillers (Systems 7 and8). Electric chillers shall be used in the baseline buildingdesign regardless of the cooling energy source, e.g., directfiredabsorption, absorption from purchased steam, or purchasedchilled water. The baseline building design's chillerplant shall be modeled with chillers having the number andtype as indicated in Table G3.1.3.7 as a function of buildingconditioned floor area.

-VishalOn Tue, Jan 13, 2009 at 1:30 PM, wrote:

The essence of ASHRAE 90.1 recommendation on this point is a) minimum number of chillers to be considered for base case (but not less than two) b) all sized equally c) no chiller is larger than 800 tons

Hence the base case consideration for various examples should be a) For say 1000 TR load , the base case consideration would be 2 x 500 TR b) For say 1500 TR load , the base case consideration would be 2 x 750 TR c) For say 2000 TR load , the base case consideration would be 3 x 666.66 TR (and not 2 x 1000 TR here as it would exceed 800 TR limit)




Vishal Garg Sent by: [email protected]/01/2009 09:17 AM

Please respond [email protected]

[email protected] show quoted text -

cc



Dear Dr. Mathur,


regards,

Vishal

On Tue, Jan 13, 2009 at 8:57 AM, jyotirmay mathur wrote: Vishal and Adil, the discussion you had in past 2-3 days would be very useful for the entire community (LEED or non-LEED) for selection of appropriate chiller size. my feeling in this issue is (of course not written in ASHRAE) that the number of chillers is the base case should be same as in proposed case. doing so, you address the situation of operating smaller chillers at peak load or large chiller at very low load. currently one can take advantage of the situation since this is not written very explicitly and he make the base case much worse by selecting different number of chillers (depending upon his load diversity) but this won't be ethically correct and IGBC/ECBC should take a call on this matter by restricting the scope of fiddling with the base case . jyotirmay

On Mon, Jan 12, 2009 at 9:54 PM, Vishal Garg wrote: So where is the limit defined in ASHRAE?Vishal

On Mon, Jan 12, 2009 at 1:46 PM, SMH Adil wrote: You are right ! I haven't noticed this.....any way This can be explained as limit defined by 90.1 not to chose small chiller, which might be operating at its peak all the time. This is justifying the concept of going for large chillers any way to get maximum loss in bad part load operations for base case

Adil

On Mon, Jan 12, 2009 at 1:24 PM, Vishal Garg wrote: Thanks Adil for the details.


Vishal

On Mon, Jan 12, 2009 at 12:48 PM, SMH Adil wrote: Dear Sir,

As far as I understand the COP is fixed at ARI, and rest of the operation due to the out side conditions were elaborated by the chiller curves which again are standard for centrifugal chillers ( I elaborated the significance in my previous mail). Now if I compare cases i.e. 250 TR Chiller1,2,3 & [email protected] with 500 TR Chiller1 & [email protected] COP, The delta in energy consumption will only be due to sequencing as the load profile will be differently faced by 500*2 and 250*4 chiller sequence (this will be a better one) . Now going further, if my load profile always stays at 1000 ton i.e. constant then there wont be any difference in energy consumption in these two cases. but still the energy modeler is left with a trick of making the base case as worst as possible by selecting minimum no. of chillers and not more. large chillers would be responding bad in terms of there response to the part load profile and hence more energy consumption will lead to high base case energy usage, and that what every energy modeler wants. its a secrete trick but now made public due to your Green building India initiative...!!!!!!!!!!



Sincerely

Adil



500T * 2250T * 4


Regards,

Vishal

On Sat, Jan 10, 2009 at 12:47 PM, SMH Adil wrote:> Hi Surekha,> Cant resist answering this one....!!!> Size the chiller equally i.e. 500*2 as people have pointed out, and you must> have put a 1.2 sizing factor in sizing run I suppose. The essence of these> sizes and numbers is that, it has to operate at its peak efficiency> with redundancy in mind. So important point is that the chiller curve that> you are using for these hypothetical base line chiller should be same in the> base case.> Now in your Energy Efficiency measures, you might like to play with various> configuration of minimum base load which might be 40 to 50%, i.e. use> a centrifugal chiller and for fixed load to achieve near ARI efficiencies,> and from 50 to 100% use screw chiller, which is responsive on part> load.....and also don't forget to sequence them in the simulation model for> there availability that would save enormous amount of energy with out> further cost.....> if you observe by fixing centrifugal chiller ASHRAE 90.1 has given us> opportunities for saving by applying sequencing logics in a plant....> Regards>> SMH Adil>> On Sat, Jan 10, 2009 at 8:51 AM, surekha wrote:>>>> Hello All,>>>> I am working on the energy modeling of a non residential building more>> than 6 floors with a>> conditioned area greater than 3,00,000 sq ft, following ASHRAE 90.1>> Appendix G.>> As per ASHRAE 90.1-2004 Table G3.1.1A it comes under system 8 , and>> ASHRAE>> 90.1-2004 Table G3.1.3.7 (Type and number of chillers) says that it>> should>> be "2 centrifugal chillers minimum with chiller added so that no>> chiller is>> larger than 800 tons, all sized equally.">> After a sizing run of the model, the tonnage came out to be>> approximately 1000 tons.>> I can divide this into 2 x 500 tons chiller or into 4 x 250 tons>> chillers.>> In each case the COP of the chiller vary.>>>> Which is the correct way of giving the size and number of chillers.>>>> Thanks & Regards,>>>>>> Surekha Tetali>>>>>>>> -- > -- > Best Regards,>> SMH Adil> Building Energy Analyst> Global Evolutionary Energy Design> D-15, Abul Fazal Enclave> Jamia Nagar, Okhla> New Delhi-110025, INDIA> Mob: +91 9873588571> Ph: +91 11 24537371> Skype : smh.adil, Location: New Delhi> [email protected]> http://www.geedindia.org/index.html>> -----------------------------------------------------------> "Sustainability is not a business; neither should be used as propaganda to> achieve goals in politics;> It is the sacred conscious that is born with every living being on the earth> and humans too, try recognizing it."> ----------------------------------------------

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