[Equest-users] Oversizing Issue in eQUEST 3.63

[King-Scott, Celia]

Hi all, 

I was wondering if anyone could help me out on an issue I have been
seeing with oversizing in eQUEST. 

I have been using eQUEST 3.63 to model commercial benchmark buildings. A
majority of them I have been just modeling in the Wizard mode and using
the EEM wizard to investigate different energy efficiency measures. Some
building types have been converted into the Detailed mode as I was
looking at more complicated systems/measures. 

In the wizard mode the only oversizing factor I have applied is in the
HVAC supply fan screen. I left this screen as default - that is
'autosize' the flow which has a 1.15 ratio set as default. 
I am then applying my own oversizing factor for the cooling and heating
capacities to the eQUEST 8760 results in a post-processing spreadsheet. 
However, when I converted some of the building models to Detailed
Interface I saw some discrepancies with the oversizing occur depending
on the HVAC system type. 
Under the 'Air-side Systems' - Basic Specifications there is a Sizing
Ratio listed there. For building types with Packaged DX Heat Pump
systems installed the value listed for this column is '1.15'. I expected
this was directly the 1.15 factor that was entered for the supply air
flow in the Wizard mode. However, for Packaged DX furnace systems, the
value under the Sizing Ratio column is '1.00'. Why has this changed if a
ratio of 1.15 for the supply air flow was specified in the fan screen of
the Wizard? 
In DOE2 the definition of SIZING RATIO is 'Multiplier on the
program-calculated values of air flow rate and coil size'. SIZING-RATIO
does not modify the heating/cooling loads calculated in LOADS. It
modifies the secondary equipment sizes only, not the primary equipment
sizes.'
How is this multiplier applied to each of those systems (i.e is it just
the supply airflow or does it include coil too?). What is secondary
equipment? Is an example the auxiliary heating I am seeing for a heat
pump system? 
I would really appreciate any clarity you can provide on this issue as
it will affect whether I can apply our own oversizing factor in our
post-processing. 
Thank you for your time. 

Best Regards,

Celia King-Scott
LEED(r) AP
Sustainable Design Consultant

KEMA Services Inc.
3605 5th Avenue, Suite A
San Diego, CA 92103
Mobile +1 619 309 7441

celia.king-scott at kema.com
www.kema.com/sustainable-buildings 
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