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Re: [EnergyPlus_Support] Re: sizing factor



Sorry for the late addition to this discussion.  While it is true that sizing 
factors of 1.1 to 1.2 are commonly used, that should not be necessary for what 
you describe.  You say that when you use a sizing factor of 1.0 and simulate 
the design days only, the setpoint temperatures are not met.  The autosizing by 
definition sizes the equipment to meet the peak loads on the design days.  This 
indicates that something in your sizing inputs is not consistent with your 
system inputs.  Check that the supply air setpoint and outside air assumptions 
in the sizing inputs match the specifications in the system description.  Also 
check that all autotsizeable fields are set to Autosize.

Mike


On 13 Jul 2004, at 23:27, pizzaalan wrote:

> When I choose 1.2 and only simulate the design days, the 
> temperatures of some zone don't reach to the setpoint. The design 
> days is described as follows, and schedule and sizing parameter 
> should be Ok because I just copied from example file, "5ZoneAuto".
> Any suggestion? Thank you.
> 
> DesignDay,
>     Minneapolis Winter,      !- DesignDayName
>     -26.7,                   !- Maximum Dry-Bulb Temperature {C}
>     0,                       !- Daily Temperature Range {deltaC}
>     -26.7,                   !- Humidity Indicating Temperature at 
> Max Temp {C}
>     98302,                   !- Barometric Pressure {Pa}
>     11.775,                  !- Wind Speed {m/s}
>     323,                     !- Wind Direction {deg}
>     .5,                      !- Sky Clearness
>     0,                       !- Rain Indicator
>     0,                       !- Snow Indicator
>     21,                      !- Day Of Month
>     1,                       !- Month
>     WinterDesignDay,         !- Day Type
>     0,                       !- Daylight Saving Time Indicator
>     Wet-Bulb;                !- Humidity Indicating Temperature Type
> 
> DesignDay,
>     Minneapolis Summer,      !- DesignDayName
>     33.3,                    !- Maximum Dry-Bulb Temperature {C}
>     12.2,                    !- Daily Temperature Range {deltaC}
>     23.8,                    !- Humidity Indicating Temperature at 
> Max Temp {C}
>     98302,                   !- Barometric Pressure {Pa}
>     3.8,                     !- Wind Speed {m/s}
>     213,                     !- Wind Direction {deg}
>     .98,                     !- Sky Clearness
>     0,                       !- Rain Indicator
>     0,                       !- Snow Indicator
>     21,                      !- Day Of Month
>     7,                       !- Month
>     SummerDesignDay,         !- Day Type
>     0,                       !- Daylight Saving Time Indicator
>     Wet-Bulb;                !- Humidity Indicating Temperature Type
> 
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Griffith, Brent" 
> <brent_griffith@n...> wrote:
> > 1.2 is a reasonable value. Think of it as a safety factor for HVAC 
> sizing. 
> > It can be the case that loads encountered sometime during an 
> annual run are higher than those during design day runs. 
> > But you should check that there isn't something wrong with your 
> design days, schedules, or autosizing commands.   
> > 
> > -----Original Message-----
> > From: pizzaalan [mailto:pizzaalan@y...]
> > Sent: Tuesday, July 13, 2004 4:50 PM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] sizing factor
> > 
> > 
> > I simulated a building and found that some zone temperatures 
> didn't 
> > reach to the setpoint. Then I tried to increase the sizing factor, 
> > zone temperatures met the setpoint. Anyone can tell me what is the 
> > function of sizing factor, what value is reasonable? Thanks.
> > 
> > Alan
> > 
> > 
> > 
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> > 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx



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