DOAS MIN-AIR-SCH - schedule values for economizing?

3 posts / 0 new
Last post

For reference, I'm answering this in the context of eQuest versions prior to 3.65 build 7174... which I don't think is officially a thing yet but can be found with the label "Release Testing" at http://www.doe2.com/download/eQUEST/. Word on the street is that this and future builds/versions will feature a proper DOAS system type which could make the rest of this thread inconsequential in the future.

A 100% OA system should have all 1.0's for the MIN-AIR-SCH, independent of whether the system is variable volume. These scheduled hourly inputs are simply the ratio of OA.

MIN-FLOW-RATIO sets the flow "floor" for variable volume delivery. It should be exceeded on occasion for a VAV system.

The entry in the doe2 reference manual for MIN-AIR-SCH reads "A value of 0.001 activates the economizer."

I think a value of 0.001 in practice means "zero OA will be delivered, unless determined beneficial for economizer purposes. There is no minimum OA requirement for this hour."

In summary: Looks good, Bill!

~Nick

In sorta-related news, when I encounter this I try to steer folks away from adding custom reporting blocks under the "default" Hourly Report. Adding new blocks alongside the EM1 and FM1 blocks will throw a per-case BDL warning on loading the model. Those warnings are erroneous in this particular case (doesn't affect the simulation or outputs in any direct sense), but if you get in the habit of ignoring this class of warning you might run into a "boy who cried wolf" situation later when you didn't mean to write over another library component. I've found this to be a helpful catch in the course of manipulating and applying custom curves.

Better practice is to isolate any new/custom blocks from the default "Hourly Report" with something descriptive that'll help you/others trace what you were looking into down the line:
[cid:image006.png at 01D326F3.5DFFA5E0]
[cid:image008.png at 01D326F5.75A3D2F0]

[cid:image001.png at 01D326EF.D3BB67F0]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

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

[cid:image002.png at 01D326EF.D3BB67F0]

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Thanks Nick. I agree with your guidance below. I think the clarification on the meaning of "0.001" in the MIN-AIR-SCH is important. Basically, never use 0.001 in the schedule for a 100% OA system.
Good tip on the Report Blocks. I'll return the favor by noting that your use of combined italics and underlining is grammatically suspect. ;)
~Bill

William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

[cid:image001.jpg at 01D32707.3A1B0520] [cid:image002.jpg at 01D32707.3A1B0520]

134 South Fitzhugh Street Rochester, NY 14608

T: (585) 698-1956 F: (585) 325-6005

bbishop at pathfinder-ea.com www.pathfinder-ea.com

[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

I'll have a word with my editor, thanks!

~Nick

[cid:image004.png at 01D32721.60D1C2C0]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

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

[cid:image005.png at 01D32721.60D1C2C0]

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200