[Yi]

First, you shall use sizing periods defined in the EPW files if you are modelling different climates. See http://bigladdersoftware.com/epx/docs/8-...erfiledays and http://bigladdersoftware.com/epx/docs/8-...ditiontype

About TES tank sizing is a good application of jE+ and jE+EA. If your tank model is similar to the one below, you can turn any fields such as tank volume, xx heights, and setpoint temperatures into paraemters by place @@param_name@@ tags in the object.

Code:

 ThermalStorage:ChilledWater:Stratified,
   Chilled Water Storage Tank 1,  !- Name
   @@tank_volume@@,                    !- Tank Volume {m3}
   8.0,                     !- Tank Height {m}
   VerticalCylinder,        !- Tank Shape
   ,                        !- Tank Perimeter {m}
   CW Tank Temp Schedule,   !- Setpoint Temperature Schedule Name
   2.5,                     !- Deadband Temperature Difference {deltaC}
   6.5,                     !- Temperature Sensor Height {m}
   1.0,                     !- Minimum Temperature Limit {C}
   50000,                   !- Nominal Cooling Capacity {W}
   Zone,                    !- Ambient Temperature Indicator
   ,                        !- Ambient Temperature Schedule Name
   ZN_1_FLR_1_SEC_5,        !- Ambient Temperature Zone Name
   ,                        !- Ambient Temperature Outdoor Air Node Name
   0.5,                     !- Uniform Skin Loss Coefficient per Unit Area to Ambient Temperature {W/m2-K}
   CoolSysPrimary TES Use Inlet Node,  !- Use Side Inlet Node Name
   CoolSysPrimary TES Use Outlet Node,  !- Use Side Outlet Node Name
   1.0,                     !- Use Side Heat Transfer Effectiveness
   ALWAYS_ON,               !- Use Side Availability Schedule Name
   7.85,                    !- Use Side Inlet Height {m}
   0.15,                    !- Use Side Outlet Height {m}
   autosize,                !- Use Side Design Flow Rate {m3/s}
   ,                        !- Source Side Inlet Node Name
   ,                        !- Source Side Outlet Node Name
   0.9,                     !- Source Side Heat Transfer Effectiveness
   TES Charge Schedule,     !- Source Side Availability Schedule Name
   0.15,                    !- Source Side Inlet Height {m}
   7.85,                    !- Source Side Outlet Height {m}
   5.0E-3,                  !- Source Side Design Flow Rate {m3/s}
   4.0,                     !- Tank Recovery Time {hr}
   Seeking,                 !- Inlet Mode
   6,                       !- Number of Nodes
   0.0;                     !- Additional Destratification Conductivity {W/m-K}

The high number of discomfort hours may or may not indicate sizing problem on its own. More revealing is setpoint not met hours...

Yi