Re: [EnergyPlus_Support] Re: winter design day

["Jerry McManus" <jerrymcm@xxxxxxxxx>]

I could say something about "tone", but I'll refrain.

 

Yes, it is clear to me now that in the winter the outside temps are far enough below any realistic heating set point that a daily range is unneccessary.

 

I was quite interested in this topic, and I had already started work on a wikibook for EnergyPlus, but now I'm so put off by the harsh treatment towards my very first newbie question that I probably won't bother wasting anymore time here.  Thanks!

----- Original Message -----

From: Linda Lawrie

To: EnergyPlus_Support@xxxxxxxxxxxxxxx

Sent: Wednesday, June 24, 2009 12:58 PM

Subject: Re: [EnergyPlus_Support] Re: winter design day

It's the tone... 

Thanks for the quick reply, but to be honest I'm still not convinced.  If a
design day is intended to be worst case scenario (as opposed to realistic
weather simulation) then why wouldn't summer design days also have a 0 daily
temperature range?


Winter days are not just one temperature -- there is no solar (so there is no possibility that winter sun will help warm the space)  They are designated as "Winter Design Day" in our definitions that are supplied.  Usually there won't be people, etc.  Yes, Winter is usually when heating happens and equipment or people or sun into the space will help.

Summer days have range due to different diurnal climates and summer more often is about humidity.  Here it is "Summer Design Day" and the people, equipment etc are supplying extra load to the space.

The Design Days are intended to be used for "sizing" equipment giving one an idea of potential extremes of their buildings.

Read about Loads Calculations in the ASHRAE Handbook of Fundamentals (Chap 14-19 in 2009 HOF) for more information.  That will give you some background on philosophy.

EnergyPlus Development Team

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