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[EnergyPlus_Support] Re: Design Day Data

Drury, Linda, THANK YOU. I'll try putting them all in.
Thanks!
Patricia

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Crawley, Drury" <Drury.Crawley@...> wrote:
>
> You can actually put all the design conditions in the .DDY into your IDF.  EnergyPlus runs them all and determines which one is most extreme--using that for sizing.
> 
> ________________________________
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Linda Lawrie
> Sent: Wednesday, October 21, 2009 7:56 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: Re: [EnergyPlus_Support] Re: Design Day Data
> 
> 
>   
> 
> Not from the weather file -- from the related design day file (extension ddy).
> 
> How to choose which design days for your simulation is contained in the ASHRAE Handbook of Fundamentals and not repeated in our documentation.
> 
> you said:
> 
> 
> 	"Likewise, normal operation specifies one 'humidity indicating temperature' which is used to calculate the humidity ratio at maximum temperature ­ this is used as the constant humidity ratio for the entire day." But I don't really understand what they mean by that. (pg 77 of the pdf).
> 
> 
> most conditions give Dry Bulb (max) and Wet Bulb (humidity indicating temperature)  at that temperature.  Using the two of those defines a "humidity ratio" which then is used as a constant to create an hourly profile for the day.
> 
> or as page 79 points out:
> Field: Humidity Indicating Conditions at Maximum Dry-Bulb
> This numeric field represents the "humidity indicating" conditions that are coincident with the
> maximum temperature for the day. The value in this field is indicated by the key value in the
> field Humidity Indicating Type. This numeric value, along with the Maximum Dry-bulb
> Temperature and Barometric Pressure, is used to determine a humidity ratio and then used
> to calculate relative humidity, wet-bulb and dewpoint temperatures at each timestep. Note
> that this field is unnecessary when you put in a relative humidity day schedule (described
> later in this section).




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