Thermal Zone Multipliers

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David,

Zone multipliers do not seem to be picked up in the total thermal zone count of 
the building shown in the Compliance Report.

The attached file shows 2 restroom spaces that are served by one thermal zone.  
Within the thermal zone the HVAC Zone Count has been changed to 2 but this does 
not seem to update the Zone Multiplier.  Additionally, the Zone Mulitplier 
cannot be edited; this may be the issue.

Thanks, Noah  

Original issue reported on code.google.com by ncz...@archenergy.com on 7 Mar 2014 at 11:53

Attachments:

• 11-Acme-Final.cibd

[GoogleCodeExporter]

Robert - I will compile this issue and others in a consolidated list and then 
send them to you.

Original comment by nka...@archenergy.com on 10 Mar 2014 at 9:30

• Added labels: Priority-Medium, Subtype-CBECC-NRes
• Removed labels: Priority-High

[GoogleCodeExporter]

Noah,
This issue may stem from a misunderstanding of the purpose/difference between 
the ThrmlZn:HVACZnCnt and ThrmlZn:Mult properties.

ThrmlZn:HVACZnCnt is the number of independent HVAC zones contained within a 
modeled thermal zone, before applying any multipliers. HVAC zones are defined 
section 2.2.1 of the ACM, but in the context of your example model, by setting 
the property to 2, you are basically saying the modeled ThrmlZn represents the 
combination of two distinct thermal zones, but combined because they have the 
same HVAC characteristics. It is important to track this since if a proposed 
ThrmlZn is made of up of many small HVAC zones, each with separate zone 
equipment, but the user has modeled, for simplicity, just one piece of zone 
equipment with Cnt > 1, the baseline zone equipment efficiencies should be 
based on the (average) capacity of equipment for each HVAC zones, not the 
capacity of the aggregate ThrmlZn. I think the most common application of 
multiple HVAC zones for a ThrmlZn are:
- Blocks of apartments or hotel/motel units on the same orientation of the res 
building
- Multiple independent offices arranged along the same orientation of a nonres 
building.

ThrmlZn:Mult is used to multiply zone loads, and therefore the energy 
consumption related to loads, of modeled thermal zones.  It is currently 
primarily used to support floor multipliers.  That is, the ThrmlZn:Mult echoes 
the Spc:Mult, which in turn, echoes the parent Story:Mult. The Spc:Mult and 
ThrmlZn:Mult are not editable in CBECC UI and DEFAULT rules currently 
automatically update these values to be consistent with Story:Mult.  An error 
is logged under ThrmlZn:Mult if there are inconsistencies from third-party 
inputs; though I just noted I need to move the PostError message from DEFAULT 
to CHECKCODE rules.

In summary. ThrmlZn:Mult is only > 1 if there are floor multipliers, and 
ThrmlZn:HVACZnCnt should only be > 1 if the thermal zone represents a separate 
HVAC zones that have been combined into one zone for modeling purposes.  If 
HVACZnCnt is > 1, the referenced HVAC system "Cnt" properties should be 
consistent with these inputs.

In reviewing these properties, I am seeing opportunities for improving the 
DEFAULT and CHECKCODE/CHECKSIM rules, and will work on this. If after reading 
this summary the conventions are still confusing or you have recommendations on 
changes, please post them here or give me a call to discuss. I will leave this 
issue open until I complete the updates to CHECKCODE/CHECKSIM rules.

Original comment by da...@360-analytics.com on 14 Mar 2014 at 6:06