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 Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Wed, 06/27/2012 - 12:59

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 manager

CRHI

LEEDuser Basic Member

70 thumbs up

Wed, 06/27/2012 - 13:06

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 Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Wed, 06/27/2012 - 14:17

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 manager

CRHI

LEEDuser Basic Member

70 thumbs up

Wed, 06/27/2012 - 14:20

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 Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Wed, 06/27/2012 - 14:41

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 manager

CRHI

LEEDuser Basic Member

70 thumbs up

Wed, 06/27/2012 - 15:09

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 Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Wed, 06/27/2012 - 18:13

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 manager

CRHI

LEEDuser Basic Member

70 thumbs up

Wed, 06/27/2012 - 18:37

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 Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Wed, 06/27/2012 - 19:00

The criteria only applies to the chiller portion of the building.

Tarek Dalati

Sustainbility manager

CRHI

LEEDuser Basic Member

70 thumbs up

Wed, 06/27/2012 - 19:42

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 Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Wed, 06/27/2012 - 20:04

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 manager

CRHI

LEEDuser Basic Member

70 thumbs up

Wed, 06/27/2012 - 20:06

Now you are telling me this :) i meant tallest or how many floors?

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