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I've got the result of the end use between baseline and proposed
design, everything seems logical except the boilers consumption.
Boilers are the same type in the baseline and proposed design.

Boilers in the baseline are sized by eQUEST, in the proposed boilers
are given calculated by the engineers.

The only difference is in the proposed design we used air-cooled
chillers and FCU and for the baseline water-cooled and packaged VAVs.

Any suggestion about this difference in BTU consumption. And why in
baseline desing in June July we have BTU consumption while in the 2
designs have same temperatures and same schedules.

thanks

Paul S.'s picture
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with the VAV system, it is likely that your boiler is being used to re-heat
cool air. This can account for significant additional boiler energy use, as
well as boiler energy use in the summer. If this is an Appendix G baseline,
take a look at the controls required for water temperature. Also, due to
the high increase in boiler energy use between the proposed and baseline,
I'm guessing there may be a space that requires significant cooling all
year. If this is the case, you may be required to provide a separate
cooling system for this space.

--
Karen

No Username provide's picture
Joined: 2011-09-30
Reputation: 200

I would think the difference is in your ventilation. Your proposed
seems to be bringing in much more outside air.
Bruce

Bruce Easterbrook's picture
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Thanks for your reply,

- This baseline is according to appendix G. If it?s the case of
re-heat, the BTU consumption seems high, (it's an advantage for us)
but how to be sure this is valid.

- If this is the case, how to stop the re-heat.

- There is no space that requires significant cooling all year.

Thanks

Paul S.'s picture
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Hi Folks,

I?m working on three Insulated Concrete Form buildings and am looking for layer by layer construction for them.
If anybody has done these any input would be greatly appreciated.
Thanks much,

Rich Beedle, Assoc. AIA, LEED AP-BD&C

Rich B's picture
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Thank you for your suggestions.

I am actually revising the model after it was reviewed by GBCI.
The model that was submitted had these spaces attached to PTAC systems (chilled water and hot water coils). My first thought was just to change a hot water coil to heat resistance in proposed. However, one of the reviewers comments was that all non-residential spaces should be modeled as system type #5 ( if the total conditioned building area is less than 150,000sf) or system type #7 (exceeds 150,000 sf). They also gave me an option of using system type #3 ( PSZ) for spaces where load varies substantially from other non-residential units. The model was done by someone else, but even if I had built this model I would not use VAV systems. I would probably go with PTAC for stairs and PSZ for mechanical rooms. Now, I am completely confused.

Besides, when I model for LEED, I usually make my HVAC systems so that they serve identical areas in baseline and proposed design. Is this good understanding of Appendix G?
Any thoughts and suggestions are appreciated.

Ana

Ana N.'s picture
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Thank you for your suggestions.

I am actually revising the model after it was reviewed by GBCI.
The model that was submitted had these spaces attached to PTAC systems (chilled water and hot water coils). My first thought was just to change a hot water coil to heat resistance in proposed. However, one of the reviewers comments was that all non-residential spaces should be modeled as system type #5 ( if the total conditioned building area is less than 150,000sf) or system type #7 (exceeds 150,000 sf). They also gave me an option of using system type #3 ( PSZ) for spaces where load varies substantially from other non-residential units. The model was done by someone else, but even if I had built this model I would not use VAV systems. I would probably go with PTAC for stairs and PSZ for mechanical rooms. Now, I am completely confused.

Besides, when I model for LEED, I usually make my HVAC systems so that they serve identical areas in baseline and proposed design. Is this good understanding of Appendix G?
Any thoughts and suggestions are appreciated.

Ana

Ana N.'s picture
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Joined: 2011-09-30
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Ana,

I agree with Bill Bishop?s comments using PTAC?s or PTHP for residential (depending on heating source.)
Not sure why the LEED reviewer says System type #5 or #7. Exceptions to G3.1.1 may apply-not sure if you?re conditioning the stairs.
I had similar problem a while back (heating only by design proposed res bld, that per AHSRAE Appx G requirements needed cooling added the same as the baseline PTAC)

It?s been a while since I?ve worked on residential, but I remember the baseline PTAC fan power was coming too high using table G.3.1.2.9 and the lighting savings were substantial compared to baseline (I used the dormitory lighting at 1.1w/sf for the baseline, proposed was much lower LPD and how to justify it??.)

I have same understanding for serving identical areas, but we may be wrong.
Any other comments from the users? Anyone with res experience and LEED situation like this, so we can all learn?

Thanks,
Nikola

Nikola Kravik's picture
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Nikola,

I agree with you that justifying lighting savings in residential spaces is not an easy task . While ASHRAE Std. provides LPD for dormitory and multyfamily units , it is clear that we cannot take credit for lighting in residential dwellings unless we provide exceptional calculations according to CIR, dated 03/23/2007. We also need to include the unregulated lighting that is modeled identically in baseline and proposed. I had slightly higher fan power in baseline as compared to proposed, but I used addendum and CIR to calculate brake house power .

Thanks,
Ana

Ana N.'s picture
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Hi everybody,
?
Is there any training provided in?Washington DC/Baltimore area?that anybody knows of in
the near future??
Is there?any list somewhere that?mentions when and where
training is available?

Thanks.

irina_velicu's picture
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