[EnergyPlus_Support] Re: Design Day Data

["Patricia" <patricia@xxxxxxxxxxxxxxxx>]

You know what else is weird? When I look at the data in the ddy file, the max dry bulb temp for a winter day is -0.2 degrees C. I know that it is warmer than that in Tucson in the winter. Is my file wrong?

--- 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).
> 
> At 05:08 PM 10/21/2009, Patricia wrote:
> 
> 
> 	I have a few questions related to what Daniel below asked. When I go to put in my SizingPeriod:DesignDay data. I add two objects. One will be SummerMax and the other WinterMax. 
> 	
> 	On page 77 (of 2007) of the InputOutputReference.pdf file (alt. pg#30), it states that I should go to my weather file (which I did), open it up and copy and paste the values into the fields.
> 	
> 	I open my weather file and there are multiple areas of data for summer and winter. I'm not sure which to pick. As Daniel states below, there are 4 options for the Winter Design Day:
> 	
> 	1: ! Tucson International Ap_AZ_USA Annual Heating 99.6%, MaxDB=-0.2°C
> 	2: ! Tucson International Ap_AZ_USA Annual Heating 99%, MaxDB=1.3°C
> 	3: ! Tucson International Ap_AZ_USA Annual Humidification 99.6% Design Conditions DP=>MCDB, DP=-17°C
> 	4: ! Tucson International Ap_AZ_USA Annual Humidification 99% Design Conditions DP=>MCDB, DP=-14.1°C
> 	
> 	For the Denver example on pages 83 and 84 of the same PDF file, they use 
> 	! DENVER_STAPLETON_CO_USA Annual Heating 99%, MaxDB=-16°C
> 	for winter
> 	
> 	and 
> 	! DENVER_STAPLETON_CO_USA Annual Cooling (DB=>MWB) 1%, MaxDB=32.6°C MWB=15.5°C
> 	for summer. 
> 	
> 	Any advice on how one should pick which data to use for the design days?
> 	
> 	Again I apologize if this is in the documentation and I didn't catch it. It does say something about using "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).
> 	
> 	Thanks so much for your help!
> 	Patricia
> 	
> 	--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie <linda@> wrote:
> 	>
> 	> Those are abbreviations from ASHRAE.
> 	> 
> 	> MWB - Mean Wet Bulb
> 	> MCDB - Mean Coincident Dry Bulb.
> 	> Not sure where you see D DP,
> 	> DP=>MDB -- would be DewPoint with Mean Dry Bulb
> 	> 
> 	> Linda
> 	> 
> 	> At 07:52 AM 8/20/2008, Daniel Solís wrote:
> 	> >In .stat and in .ddy appears several data for design days, but, where
> 	> >the meaning of the abbreviations (MWB, D DP, MCDB, etc.) can be found?
> 	> >
> 	> >More specifically, DesignBuilder asks for "Max Dry-Bulb
> 	> >Temperature", "Coincident Wet-Buld Temperature" and "Min Dry-Buld
> 	> >Temperature" for cooling design. I find the first one, but the other
> 	> >two I don't know which abbreviations correspond.
> 	> >
> 	> >Thanks,
> 	> >
> 	> >Daniel
> 	> >
> 	> >
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