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

Tue Nov 29 17:54:17 PST 2016

DOE2.2 help files  indicates that  CLEARNESS and CLOUD-TYPE are now replaced by CLIMATE and VISIBILIY. It seems that CLIMATE is used for determine the clearness of sky.

Volume 3: Topics > Overview and Converting From 2.1E > LOADS

DOE-2.1E version:

HOT-CLEAR-SUMMER = DESIGN-DAY
DRYBULB-HI   = 91    DRYBULB-LO = 71
HOUR-HI      = 15    HOUR-LO    = 7
DEWPT-HI     = 65.5  DEWPT-LO   = 60
DHOUR-HI     = 16    DHOUR-LO   = 8
WIND-SPEED   = 7.5   WIND-DIR   = 10
CLOUD-AMOUNT = 0     CLOUD-TYPE = 0
CLEARNESS    = 1     GROUND-T   = 61  ..

COLD-CLOUDY-WINTER = DESIGN-DAY
DRYBULB-HI   = 6     DRYBULB-LO = -4
HOUR-HI      = 15    HOUR-LO    = 2
DEWPT-HI     = 6     DEWPT-LO   = -4
DHOUR-HI     = 16    DHOUR-LO   = 3
WIND-SPEED   = 15    WIND-DIR   = 14
CLOUD-AMOUNT = 5     CLOUD-TYPE = 2
CLEARNESS    = 1     GROUND-T   = 46  ..

Converted:

"Chicago CDD" = DESIGN-DAY
TYPE            = COOLING
DRYBULB-HIGH    = 91    DRYBULB-RANGE   = 20
HOUR-HIGH       = 15    HOUR-LOW        = 7
WETBULB-AT-HIGH = 77   
WIND-SPEED      = 7.5   WIND-DIR        = SW
CLOUD-AMOUNT    = 0     CLIMATE         = MIDLATITUDE
VISIBILITY      = HIGH  GROUND-T        = 61
..

"Chicago HDD" = DESIGN-DAY
TYPE            = HEATING
DRYBULB-HIGH    = 6     DRYBULB-RANGE  = 10
HOUR-HIGH       = 15    HOUR-LOW       = 2
WIND-SPEED      = 15    WIND-DIR       = NW
CLOUD-AMOUNT    = 5     CLIMATE         = MIDLATITUDE
VISIBILITY      = LOW   GROUND-T       = 46

On 11/30/2016 07:04， David Griffin II via Equest-users<equest-users at lists.onebuilding.org>wrote：

Nick/Joe,

I have done some light research on the topic since DOE2.3 moves in the direction of utilizing DESIGN-DAY more rigorously; e.g. if you depend on the weather file for auto sizing in DOE2.3, your simulation takes twice as long. I would refer both of you to page 23 of the DOE2.3 Volume 6 “Design-Sizing Enhancements” where it appears the eQUEST team is attempting exactly what Joe previously mentioned.

Although I believe the CLIMATE input is still available in DOE2.3 it may be ignored by the new algorithm. Maybe Jeff H. can shed some light on this situation for us.

Sincerely,

| |   |
| DAVID W. GRIFFIN II |
| BEMP
ENERGY ANALYST |
| 2505 E Parleys Way
Salt Lake City, UT 84109 |
| Office 801.924.5028 |
| archnexus.com |
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From: Joe Huang via Equest-users [mailto:equest-users at lists.onebuilding.org]
Sent: Tuesday, November 29, 2016 1:49 PM
To:equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Purpose of a DESIGN-DAY CLIMATE input?

I think this is a case of DOE-2 still using an older procedure for the solar portion of the design day calculation.  Prior to 2006, ASHRAE used a relatively crude ASHRAE Clear Sky Model to determine the hourly profile of solar radiation for the design day.  That model assumes there are different sky conditions for different latitudes, etc.  In 2006, ASHRAE TC 4.2 (Climatic Information) carried out a project to develop an entirely new ASHRAE Clear Sky Model that's a parameterization of a detailed solar model developed by Chris Gueymard.

It would be nice if DOE-2 incorporates the new ASHRAE Clear Sky Model, which isn't terribly hard, but would take work. Besides, I'm under the impression that the vast majority of DOE-2 users don't do design day calculations but rather let the program autosize the equipment anyway!

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

On 11/29/2016 9:43 AM, Nicholas Caton via Equest-users wrote:

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.

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 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

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
F  913.564.6380

|

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