[Bldg-sim] Residential System Sizing

[Bereket Nigusse]

 Hello All,

I have a problem with DOE2.1E cooling system sizing.  The cooling capacity reported by DOE2.1e in SV-A and LS-B reports are quite different and shows different sensitivity trends depending locations.  

Question 1
For the case with out door air flow ratio input set to zero DOE2.1E calculated cooling capacity and the peak coolig load are shown below.   I assume that the out door air contribution to the system load is zero for zero out door air fraction and with this assumption the system cooling capacity will be different from the peak cooling load only due to difference in ARI and the peak cooling load hour weather conditions.  What else could cause the cooling capacity to be different from the peak load for zero out door air flow rate case?  I have looked into to DOE2.1E manual but wasn't able connect the steps from the peak cooling load to the system capacity?  

Question 2
Does the change from the peak cooling load to the  system cooling capacity seem a reasonable for the different loacations given below? 
The building is 2100 sqft conditioned floor area, two story, single family house.  Each floor is modeled as a single zone.


    Report AV-A Report LS-B     
Locations Supply Flow, CFM Cooling Capacity, kBtu/hr Peak Cooling Load, kBtu/hr Outdoor DB Temp at Peak Load, oF Outdoor WB Temp at Peak Load, oF 
 Baltimore, MD  850.0 25.7 22.1 93 73 
 Houston, TX  813.0 27.0 20.2 93 78 
 Chicago, IL  1054.0 29.3 20.3 89 72 
 Minneapolis, MN  1226.0 33.5 20.3 89 79 
 Duluth, MN  1258.0 34.8 18.1 87 72 
 Phoenix, AZ  1281.0 37.4 31.6 114 71 


Thank you in advance for the help,


Bereket


      
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