12-month load calculation in EnergyPlus

From a recent conversation on load sizing here:

"1. Trace700 usually will run all 12 cooling design months and so it may happen that a zone does not peak in same month as the summer design OADB and this may be due to a higher solar component in the off month. So I always recommend, whether running Trace or E+, to run all 12 months for cooling design."

This seems to be a common reason for differences in cooling design sizing between Trace and OpenStudio/EnergyPlus.

The solution is to add in 'SummerDesignDay' 'SizingPeriod:DesignDay' objects for each month. From what I can tell, most .ddy files packaged with the TMY3 datasets include 'SizingPeriod:DesignDay' objects for only 1 month for heating and 1 month for cooling.

12 month design day data are available

So it's possible to do a 12-month cooling design load calc by taking the 12-month data, finding the appropriate 'SizingPeriod:DesignDay' objects for the site, copying them over to the .ddy file, and then reimporting that into OpenStudio.

It's a bit tedious.

Does anyone know if there is a .ddy dataset available online that includes 12-month 'SizingPeriod:DesignDay' objects for TMY3 locations?

EDIT: http://ashrae-meteo.info/ is a website that shows a map of ASHRAE design day data. No .ddy capability, but still very useful.

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mdahlhausen

asked 2016-04-01 19:45:39 -0500

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__AmirRoth__

updated 2020-01-20 12:11:56 -0500

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I downloaded the 12 month design day from the link but it has the same days information than the .ddy file.

obuchely (2016-09-12 15:04:12 -0500) edit

@obuchley, try this link: http://energyplus.helpserve.com/knowledgebase/article/View/130/47/design-conditions-definitions-monthly-all-regions-for-all-ashrae-2013-design-condition-locations

mdahlhausen (2016-09-12 16:39:39 -0500) edit

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I don't know of a .ddy dataset and I haven't looked for it (I'm assuming you've searched online prior to posting).

But it'll be very easy to create... The link you gave has .imf file. It's basically a collection of the SizingPeriod:DesignDay objects encompassed in if statements.

##ifdef KEY
SizingPeriod:DesignDay (1st for the location)
...
SizingPeriod:DesignDay (12th for the location)
##endif
##ifdef ANOTHER_KEY
SizingPeriod:DesignDay (1st for the location)
...
SizingPeriod:DesignDay (12th for the location)
##endif

The key can be found in the csv file.

So if you need a couple locations, do it manually.

Otherwise, you can write something that'll parse it out and save as individual files in 10 or less lines of code.

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Julien Marrec

answered 2016-04-03 06:04:10 -0500

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Thanks. I guess I'll settle for manually now. If someone does parse it out, perhaps they can host it on @Mostapha Roudsari's epwmap page.

mdahlhausen (2016-04-04 11:32:51 -0500) edit

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Not to my knowledge of ddy file includes 12 months design conditions. But monthly design conditions are available in ASHRAE handbook and can be added manually into the OS.