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@yahoogroups.com, 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
> >
> >
> >------------------------------------
> >
> >The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> >
> >The group web site is:
> > http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> >Attachments are not allowed -- please post any
> >files to the appropriate folder in the Files area of the Support Web Site.
> >
> >EnergyPlus Documentation is searchable. Open
> >EPlusMainMenu.pdf under the Documentation link and press the "search" button.
> >Yahoo! Groups Links
> >
> >
> >
>

------------------------------------

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.

EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    mailto:EnergyPlus_Support-digest@yahoogroups.com
    mailto:EnergyPlus_Support-fullfeatured@yahoogroups.com

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@yahoogroups.com

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/