[Equest-users] Airflow Schedule based on Occupancy - switch statements and symbol values

Wed Oct 26 07:20:17 PDT 2016

The DOE22Vol3-Topics_48y.pdf manual includes a section on keyword expressions. You can find all the functions and the abbreviations in that section. #SV is for SymValue, for example.

Christopher Jones, P. Eng.
Rowan Williams Davies & Irwin Inc.
Consulting Engineers & Scientists
901 King Street West, Suite 400, Toronto, Ontario, M5V 3H5
T: (519) 823-1311 ext 2052
M: (416) 697-0056

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill via Equest-users
Sent: Wednesday, October 26, 2016 10:13 AM
To: Daric Adair; Darryl Kasun
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Airflow Schedule based on Occupancy - switch statements and symbol values

I retained the case numbers from the default DOE-2 expression for MIN-FLOW-RATIO below. The switch statement is based on symbol values according to the symbol table for system TYPE. The symbol tables are found in a file called BDLKEY.OUT which, for eQUEST 3-65, is found in Documents -> eQUEST 3-65 Data -> DOE-2.
A short cut to determining which case numbers to use with switch statements is to enter a user expression for an appropriate keyword. For system TYPE, you could enter, “#SV(#P("TYPE"))” as a user expression for a zone keyword such as MIN-FLOW/AREA to see which symbol value matches the zone’s system type.

~Bill

From: Daric Adair [mailto:Daric.Adair at hei-eng.com]
Sent: Tuesday, October 25, 2016 4:23 PM
To: Bishop, Bill <bbishop at pathfinder-ea.com<mailto:bbishop at pathfinder-ea.com>>; Darryl Kasun <darryl.kasun at gmail.com<mailto:darryl.kasun at gmail.com>>
Subject: RE: [Equest-users] Airflow Schedule based on Occupancy

Bill;

Can you expand/explain where the “case #” / “case ##” elements come from/are defined (help files, manual?). I can’t seem to place my finger on where they are….thanks!

Thanks,
DARIC R. ADAIR  PE, C.E.M.
Henderson Engineers, Inc. | Mechanical Engineer, Energy Analyst
dir 913 742 5530  tel 913 742 5000  fax 913 742 5001  tx id #F-001236  email daric.adair at hei-eng.com  www.hei-eng.com<http://www.hei-eng.com/>
Licensed in KS. 

From: Bishop, Bill via Equest-users [mailto:equest-users at lists.onebuilding.org]
Sent: Tuesday, October 25, 2016 1:41 PM
To: Darryl Kasun <darryl.kasun at gmail.com<mailto:darryl.kasun at gmail.com>>
Cc: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Airflow Schedule based on Occupancy

Hi Darryl,
First, I would use a user expression for ZONE: MIN-FLOW-RATIO for any zones that you want to control to 6 ACH minimum. Then I would create and apply a ZONE: MIN-FLOW-SCH with values of 1.0 during occupied hours and -999 for unoccupied hours. The expression below for MIN-FLOW-RATIO should give you 6 ACH . It will give you an error if a value is entered for ASSIGNED-FLOW that is less than 6 ACH.
Regards,
~Bill

/* This expression for ZONE:MIN-FLOW-RATIO calculates and enters
   a value based on a desired minimum ACH. */

if (#P("MIN-CFM-RATIO") == unused)
    then unused
    else switch #SV(#P("TYPE"))
    case  2 : unused
    case 17 : unused
    case 19 : unused
    case 26 : unused
    case 27 : unused
    case 28 : unused
    case 29 : unused
    default : if (#RV(#L("AIR-CHANGES/HR")) == 0
                .AND. #L("AIR-CHANGES/HR") = 6) then 1  $ 6 ACH
         else if (#RV(#L("ASSIGNED-FLOW")) == 0) then
          6*#LR("SPACE","HEIGHT")*#LR("SPACE","AREA")/60/#L("ASSIGNED-FLOW")
          else no_default endif
              endif
    endswitch
   endif

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

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Darryl Kasun via Equest-users
Sent: Tuesday, October 25, 2016 1:54 PM
To: equest <equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>>
Subject: [Equest-users] Airflow Schedule based on Occupancy

Hi everyone,

I have a zone that is served by a VAV system.  The controls for the zone state that when the zone is occupied, the VAV box should be fully opened and when unoccupied, the zone supply air be reduced to 6 ACH.  There are multiple zones controlled in this manner.

To model this I am thinking of creating a min airflow schedule that matches occupancy schedule.  The minimum hourly fraction within the min airflow schedule would be equivalent to the airflow fraction of 6 ACH.

In other words, if there are hourly fractions in the min airflow schedule (which is a copy of the occupancy schedule) that are below the equivalent fraction of 6 ACH, those hours would be changed to the 6 ACH fraction.

Hopefully that makes sense to you.

This method seems fine to me but a bit tedious as it will require developing multiple min airflow schedules.

Any thoughts?

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