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RE: [EnergyPlus_Support] DX coil IPLV calculations - does anyone pay attention to the ASHRAE 90.1 minimums?



I am doing the same way that Jean said. Using datasets of chillers. It was very good that you did, Jim. 

I was wanting to develop exactly that but could not stop to do yet. 

I will examine in detail, so I can make comments to help improve their development. 

Again, thank you for sharing with us. 

Regards, good job for everyone.

Técg. Ivan Mezzacapa

Projetista  de Ar Condicionado / Consultor em Eficiência Energética


Celular: (11)9963-9326



To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
Date: Mon, 28 Jul 2014 07:22:57 +0200
Subject: Re: [EnergyPlus_Support] DX coil IPLV calculations - does anyone pay attention to the ASHRAE 90.1 minimums?

 

I'm in the same boat as you, Jim. I've been using a chiller dataset which best fits the type and capacity of the baseline, then adjust the COP inputs. The IPLV have been left as "conservative" as you say, because I have had no time to dabble with curves for each project.

Mit freundlichen Grüßen- Sent from my iPhone (excuse the brevity)

i. A.
Jean Marais
b.i.g. bechtold
Tel.   +49 30 6706662-23

On 28.07.2014, at 01:22, "Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Dear forum,

I and fellow forum member Francesco Passerini are working together to better represent the IPLV minimum required for DX coils (by ASHRAE 90.1 ? 2007).  I have not paid close attention to this value in the past!  My COP / EER values are ?perfect?, but my IPLV values have been much higher than are required by 90.1  This is primarily because I have used curve coefficients from example files for ?Baseline? models.  Those seemed reasonable and conservative?. But they all result in improved EER at part loads, whereas the 90.1 IPLV values allow worse EER at part load.

Francesco pointed out that an undesirable result of this is that the Baseline energy model uses less energy than if the IPLV was ?perfect? and may not gain as many LEED points for his clients.  I believe that he is correct!

 

We think that we have created a reasonable solution, and would appreciate feedback from you regarding the calculation (which is attached).  

Here is a summary of our observations so far:

·         IPLV does not apply to equipment without capacity modulation (Larger DX  equipment almost certainly has modulation, which is why 90.1 Table 6.8.1A. mentions IPLV only for capacities > 760 MBH / 220kW)

·         IPLV assumes standard conditions for indoor (evaporator) and outdoor (condenser) coils

1.       Coil entering condition: 80F/27C  dry bulb & 67F/19C wet bulb

2.       Outdoor part-load: 80F/27C dry bulb & 67F/19C wet bulb (coincidentally the same as indoor condition and applicable to ALL part-loads)

3.       Outdoor full-load: 95F/35C dry bulb & 75F/24C wet bulb

·         Two criteria must be met in an energy model regarding IPLV:

1.       The Capacity and EIR curves must result in 1.00 at the ?rating conditions? of #1 & #3 above (so EER / COP is correct)

2.       The part-load EIR must result in the proper IPLV.  (I think it can remain constant.)

 

p.s., We have not yet tested this solution, but will do so shortly.  We?re hoping for constructive criticism about our methodology.

 

 

James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653

 


<IPLV Calcs 14-0727.xlsb>



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Posted by: Ivan Mezzacapa <ivan_slip@xxxxxxxxxxx>


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