[Equest-users] Purpose of a DESIGN-DAY CLIMATE input?

[Nicholas Caton via Equest-users]

I have a question concerning doe2/eQUEST DESIGN-DAYs.

One of the keywords for DESIGN-DAY confuses me:  CLIMATE.  I have not been able to find this documented in the current doe2 reference manual or 2.1A engineering manuals.

It appears the CLIMATE keyword can accept one of three inputs:  "SUBARCTIC," "MIDLATITUDE," or "TROPICAL."  The default is MIDLATITUDE and does not appear to reference anything else.

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So I have a few questions:

1.       What is this input used for?  Does it help to determine solar angles during design day calculations?  Does it affect how other DESIGN-DAY inputs are interpreted?

2.       Since one of the options is named "MIDLATITUDE," my best guess is this is trying to establish in a loose sense which slice of the globe the weather station is located at for solar angle purposes.  From that guess, I googled the topic for a bit<http://www.lat34north.com/cities/CitiesLatitude.cfm> and came up with this framework:

a.       SUBARCTIC latitudes are > 66.5 or < -66.5  (Inside the Arctic circles - experiences days of complete daylight/darkness)

b.       TROPICAL is between -23.5 and 23.5 (Tropic of Capricorn/Cancer - experiences the sun traversing directly overhead)

c.       MIDLATITUDE = everywhere else

3.       I struggle however with the concept of a DESIGN-DAY input based on latitude, where

a.       The latitude is already a part of the weather file required for every simulation... and pulling the exact latitude would be more accurate anyway (I confess here I have never studied solar pathing in great depth - the problem may be simpler than I realize?).

b.       These bands alone don't give you enough information to know when you're in the lower hemisphere (where solar angles based on the day/month would be flipped)

c.       This leads me to question whether there's a (meaningful) difference in solar angles experienced for loads calculations when you use the weather file instead of DESIGN-DAY inputs.

d.       Alternatively, maybe the latitude IS pulled from the weather file for solar angle purposes so I'm completely on the wrong path as to the purpose/intent for the CLIMATE input.

Can anyone set me straight on this topic?

~Nick

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Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Energy and Sustainability Services
  Schneider Electric

D  913.564.6361
M  785.410.3317
E  nicholas.caton at schneider-electric.com<mailto:nicholas.caton at schneider-electric.com>
F  913.564.6380

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

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