in the project we are modelling, hot water system is preheated from the building power generators by using recovery system isntalled on the genertars ( same principle of the recovery chillers) but the saving is much higher.
The problem in my opinion is that :in my country the power go off 3 hours daily so the generators will run 3 hours daily and the saving ( as per supplier can be up to 30%) due to the high temperature of water used to preheat the hot water system which otherwise would be cooled by the generator cooling system and wasted to the atmosphere.
does USGBC accept my calculation based on 3 hours run per day?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 27, 2012 - 8:59 am
Heat recovery from a generator should be acceptable. You will need to account for the fuel to run the generator in your modeling.
Tarek Dalati
Sustainbility managerCRHI
92 thumbs up
June 27, 2012 - 9:06 am
thank you for your reply
As I checked in equest,The generator heat recovery will be modeled based on the fraction of heat recovered and not based on the time the generator runs is this acceptable or I need to show more information?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 27, 2012 - 10:17 am
Sounds odd to me. Since you can only recovery heat when the generator runs I am not sure how you get energy saved just on a fraction of heat recovery.
Tarek Dalati
Sustainbility managerCRHI
92 thumbs up
June 27, 2012 - 10:20 am
lets consider it as efficiency of the heat recovery system.
My question is how do i need to specify how many hours the generator run.
have you ever used this system before in equest ( i tried over the net specially www.onebuilding.org) but nothing
can you tell me how should i simulate that ?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 27, 2012 - 10:41 am
Not sure off the top of my head. We would have to research that one.
t d - since you frequently post here any chance we could see your actual name?
Tarek Dalati
Sustainbility managerCRHI
92 thumbs up
June 27, 2012 - 11:09 am
sure,But if equest can model this system do i need to provide further documentation.
and another question ashrae point 6.5.6.2.1 but the dominant baseline system is PTAC how can i recover the heat if system 8 ( offices ) what will i do if the DWH system load is bigger than the cooling tower size? shall i recover 60% only as mentioned in the point? what if heat rejection is less than 60% of DHW what shall i do?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 27, 2012 - 2:13 pm
If eQUEST can model it you should not need much further documentation but it is often a good idea to explain how complex systems have been modeled to help the reviewer understand.
6.5.6.2 applies to chillers not generators. It is a prescriptive measure so your Proposed design is not required to do this but your Baseline would if the criteria listed apply to the Baseline. 6.5.6.2.2 addresses the capacity issues.
Nice to know your name, thanks.
Tarek Dalati
Sustainbility managerCRHI
92 thumbs up
June 27, 2012 - 2:37 pm
I know it applies for chillers so what shall i do if in baseline only offices which constiture only 20% are cooled by chiller while the 80% is residential and is cooled by PTAC what can i do?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 27, 2012 - 3:00 pm
The criteria only applies to the chiller portion of the building.
Tarek Dalati
Sustainbility managerCRHI
92 thumbs up
June 27, 2012 - 3:42 pm
Thank you ,after your answer I read again the clause and i didnt find it terrifying as I thought in the begining ...Just to satisfy my curisority what is the highest LEED certified building in the world does anybody know
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 27, 2012 - 4:04 pm
First rule of energy modeling don't panic when you don't understand something right away, you will be in panic all the time! :-)
Tallest or most points?
Tarek Dalati
Sustainbility managerCRHI
92 thumbs up
June 27, 2012 - 4:06 pm
Now you are telling me this :)
i meant tallest or how many floors?