[Equest-users] Fwd: Modeling Reverse Acting TStat EF

Fri Oct 21 09:21:05 PDT 2016

---------- Forwarded message ----------
From: Chris Jones <Christopher.Jones at rwdi.com>
Date: Fri, Oct 21, 2016 at 5:51 AM
Subject: RE: [Equest-users] Modeling Reverse Acting TStat EF
To: Darryl Kasun <darryl.kasun at gmail.com>, Nicholas Caton <
Nicholas.Caton at schneider-electric.com>

Okay, I played with it a bit more. I set the zone supply flow equal to the
exhaust flow. I set the economizer to off, minimum OA = 0. I set an exhaust
fan to track supply flow. Now the exhaust fan cycles on when the supply fan
cycles on. The supply fan is set with 0 fan kW and the exhaust fan has a
typical fan kW. This pretty much mimics the typical reverse acting
thermostat controlling an exhaust fan in an electrical room.

*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 *Chris Jones via Equest-users
*Sent:* Friday, October 21, 2016 8:38 AM
*To:* Darryl Kasun; Nicholas Caton
*Cc:* equest-users at lists.onebuilding.org

*Subject:* Re: [Equest-users] Modeling Reverse Acting TStat EF

I have been playing around with a test case using a PSZ system with cooling
capacity = 1. The fans are set off with night cycle on any. The zone
outdoor air is set to 1 cfm. If I use no outdoor air in the zone, the
economizer doesn’t kick on. The system fan cycles on for free cooling The
space temperatures are maintained. The only issue is that the economizer is
variable. In reality, the outdoor air should go to 100% when the fan cycles
on for free cooling. I also can’t figure out how to have the exhaust fan
cycle on when the fans cycle on.

*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
<equest-users-bounces at lists.onebuilding.org>] *On Behalf Of *Darryl Kasun
via Equest-users
*Sent:* Thursday, October 20, 2016 3:10 PM
*To:* Nicholas Caton
*Cc:* equest-users
*Subject:* Re: [Equest-users] Modeling Reverse Acting TStat EF

Hi everyone,

Have these systems modeled now that they are showing unmet clg hours and
the exhaust fans are turning on when temp is above 80F.

Here's a summary of the inputs required to achieve:

- fan schedule at BOTH system and zone level to be set to always off (0)

- night cycle fan control set to "cycle on any"

- clg rate very low (1 btu/hr)

- clg t-stat required

Thanks again everyone for your help.

Darryl

On Wed, Oct 19, 2016 at 1:08 PM, Darryl Kasun <darryl.kasun at gmail.com>
wrote:

I do have a clg t-stat schedule set at 80F for all hours.  I have tried
changing the fan schedule to undefined and to on for all hours and am still
met with the fan not turning on at all.  The original fan schedule to keep
the fan off had zeros for all hours.

How to I check the custom hourly output reporting?

On Wed, Oct 19, 2016 at 12:43 PM, Nicholas Caton <Nicholas.Caton at schneider-
electric.com> wrote:

Immediate thought: Have you set a cooling thermostat schedule for the zone
with 80F at all hours?  That would explain both the lack of unmet hours and
no calls for conditioning (fan operation).

If there is a thermostat schedule, did you confirm the fan is never
operating via custom hourly output reporting?  Do you have a system fan
schedule forcing OFF behavior with zeroes and/or -1’s?  If so, try forcing
ON with 1’s and/or just not defining a fan schedule at all to permit system
fan operations when called for.

*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

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

[image: cid:image001.png at 01D189AB.58634A10]

*From:* Darryl Kasun [mailto:darryl.kasun at gmail.com]
*Sent:* Wednesday, October 19, 2016 1:18 PM

*To:* Nicholas Caton <Nicholas.Caton at schneider-electric.com>
*Cc:* Brian Fountain <bfountain at greensim.com>; Julien MARREC <
julien.marrec at gmail.com>; equest-users <equest-users at lists.onebuilding.org>
*Subject:* Re: [Equest-users] Modeling Reverse Acting TStat EF

Hi everyone,

Thanks again for all your input.

I've run into a snag.  I cannot seem to get the fan to turn on when the
temp > 80 degF.  When I look at some of the reports I see that there is no
reported unmet clg hours for this zone which is a red flag - not sure why
this is.  There is a sizable clg load in this zone: 65 MBH.  I do see on
the SS-F that the max zone temp hits 86.1 degF.  Any thoughts?

On Tue, Oct 18, 2016 at 4:00 PM, Nicholas Caton <Nicholas.Caton at schneider-
electric.com> wrote:

Hey Darryl,

This turned into a big response, but it seems the problem we’re trying to
help solve is a moving target!

1.       The advice to enter something nominal but tiny for cooling
capacity, to avoid autosizing & prevent airstream cooling, is based on the
earlier statement that you do not intend to cool the airstream making up
the exhaust.  Going the other route of just making it “free cooling”
(EIR=0) goes against your goal of modeling reality as now the exhaust
“makeup” airstream is being conditioned on its way in, resulting in milder
interior temperatures for determining hourly zonal heat transfers.  An
equally viable alternative I generally prefer to “lock out” cooling
operations by the way is an airside system COOLING-SCHEDULE with hourly
values of zero.  An expected side effect of of crippling/breaking your
PSZ’s cooling capacity with a tiny number is that you will end up with a
justifiable quantity of unmet cooling hours – so expect & make note of that
swing in unmet hours so you can quantify &  parse it out later for your own
QC/documentation.

2.       Based on the reference help entries, I’m concerned the
night-cycle-ctrl inputs are intended specifically for the inverse case only
(reacting only to provide heating when the system is off.  I think the
effect you’re looking for (turning on only when thermostat calls request
it) can be achieved for PSZ by simply not defining a fan schedule
(right-click, default that dropdown field).  *Either way*, you can & should
check/verify intended system operation via custom hourly reports for the
associated system & control zone – include hourly zone temperatures,
associated tstat setpoints, and something like fan operation/cfm to verify
if the system is only operating when intended.

3.       I’m not certain zonal exhaust inputs are necessary at all if you
are modeling a 100% OA PSZ, but be cautious you aren’t ending up
unintentionally “double-counting” fan energies between your PSZ fan power
inputs and your zonal exhaust power inputs (or lack thereof).  I think you
can “zero out” the zonal kW/cfm or else make it a very tiny number if you
do decide zonal exhaust inputs are needed.

Ah… The fact you intend to model hot water unit heaters probably throws a
wrench into the advice/discussion so far…

“Furnace” generally implies gas combustion heating in doe2/eQUEST.  That’s
not what you want for hot water heating.

If it’s fair to assume the space is well-mixed during heating scenarios
(i.e. not much stratification), then you can probably get by with
accounting for the associated unit heater by specifying hot water
baseboards with appropriate heating capacity in the zone.  Have them
controlled by a heating temperature schedule (sounds like you want this set
to 60F all the time).  You might want to specify the associated loop and
boilers/meters first so that you can assign those in the same step.
Downside to layering in baseboards as an approach is the unit heater fan
energies won’t get picked up explicitly – the heat those contribute will
instead be supplied by the HHW loop, and the energies associated with their
fan operations for air circulation will not be picked up automatically.
You could layer that in however (if it’s pertinent) by doing an hourly
report to identify when baseboards are in operation (delivering heat), then
assigning that to the space as an equipment load, capturing the heat
contributions and electricity consumption.

If accounting for exhaust and unit heater fan energies operations
separately/distinctly is a major priority… you’ll probably need to re-think
the broader approach & system type selection.  UHT is an attractive option
for picking up unit heater operations explicitly and clearly on its own,
but that system type affords no capacity to handle OA/exhaust.  You’d
either need to accomplish the exhaust/damper operations at the zonal level
(spoon-feeding expected operations as a fractional or ON/OFF schedule since
we’ve established thermostat schedules are not presently an option).  You
could alternatively pair UHT’s with an airside-system-based approach to the
exhaust/damper operations (like the PSZ we’ve been discussing) if you split
your zone/spaces geometrically to afford separations to assign different
systems to, thermally connected with airwalls.  Advantage to this approach
is the flexibility to separate the conditioned volume if air mixing is not
going to be stellar (stratification expected) during heating.

Hope this helps steer the ship!

~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

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

[image: cid:image001.png at 01D189AB.58634A10]

*From:* Darryl Kasun [mailto:darryl.kasun at gmail.com]
*Sent:* Monday, October 17, 2016 1:26 PM
*To:* Nicholas Caton <Nicholas.Caton at schneider-electric.com>
*Cc:* Brian Fountain <bfountain at greensim.com>; Julien MARREC <
julien.marrec at gmail.com>; equest-users <equest-users at lists.onebuilding.org>

*Subject:* Re: [Equest-users] Modeling Reverse Acting TStat EF

Hi everyone - thank you so much for the replies.  Just wanted to provide as
a summary as to what I've modeled thus far - pls comment if you have any:

*SYSTEM LEVEL:*

- Modeled the reverse acting t-stat system as a PSZ with the following
inputs at the system level:

- Control zone is the zone the supply fan serves

- Supply fan kW/CFM equals that of the EF

- Delta T across supply fan = 0

- Supply fan schedule is on/off type with default off for all hours

- Night Cycle Control: On Any

- min outside air ratio = 1.0

- CLG Cap left blank

- EIR = 0

*ZONE LEVEL:*

- HTG/CLG design temps are 60/80 degF;

- E/A control is "No Airflow Tracking"

- E/A flow matching the flow of the EF (11,000 CFM)

- E/A source: infiltration

- Max clg rate left blank

*QUESTIONS REMAINING:*

- Can I simply leave the CLG capacity to be auto-sized?  Brian you had
mentioned to put in a minimal value for this input but I do not understand
why.

- This zone also has HW UHs serving it - how to I implement them?  I see at
the system level there's an option for the Zone Heat Source to be furnace
which provides the opportunity to account for a UH's fan energy but looks
like a furnace cannot be connected to a HW loop.

 - Any advice of thermostat type?

Thanks again

Darryl Kasun

On Mon, Oct 17, 2016 at 11:04 AM, Nicholas Caton <Nicholas.Caton at schneider-
electric.com> wrote:

Hey Brian,

You’re absolutely right – I should have double-checked before posting.  In
my mind’s eye, I recalled assigning a temperature schedule to zonal exhaust
inputs, but it does appear I misremembered and that isn’t a direct option.

Tricking an airside system as you’re describing into the intended behavior
must be how I’ve managed this in the past.  A thermostat schedule is
minimally needed at the system to define the intended “trigger
temperatures,” and one could optionally also specify a fan schedule to go
beyond intermittent and enforce off/on hours as might happen in the real
world via tstat + relays.

~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

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

[image: cid:image001.png at 01D189AB.58634A10]

-----Original Message-----
From: Brian Fountain [mailto:bfountain at greensim.com]
Sent: Monday, October 17, 2016 9:55 AM
To: Nicholas Caton <Nicholas.Caton at schneider-electric.com>; Julien MARREC <
julien.marrec at gmail.com>; Darryl Kasun <darryl.kasun at gmail.com>
Cc: equest-users <equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Modeling Reverse Acting TStat EF

Does this mean the exhaust fan can cycle based on zone temperature?   I had
thought that the exhaust fan schedule was just on/off, on/off/flag and
fraction. That means you have to pre-define the expected schedule rather
than having the EF respond to the hourly space timestep temperature.

What we have done in the past is to model the EF as a PSZ with the fan
power as the supply fan power and the "indoor fan mode" as intermittent.
Cooling capacity set to a small non-zero value (as zero invokes
auto-sizing).

  Original Message

From: Nicholas Caton via Equest-users

Sent: Monday, October 17, 2016 10:39 AM

To: Julien MARREC; Darryl Kasun

Reply To: Nicholas Caton

Cc: equest-users

Subject: Re: [Equest-users] Modeling Reverse Acting TStat EF

From: Nicholas Caton

Sent: Monday, October 17, 2016 9:38 AM

To: 'Julien MARREC' <julien.marrec at gmail.com>; Darryl Kasun <
darryl.kasun at gmail.com>

Subject: RE: [Equest-users] Modeling Reverse Acting TStat EF

Yep - Julien has the right idea!

The other input of interest for your case is that at the same input screen,
you can select the exhaust source as "infiltration," which means the
associated makeup airstream = outside conditions.

~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

15200 Santa Fe Trail Drive

Suite 204

Lenexa, KS 66219

United States

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

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
<equest-users-bounces at lists.onebuilding.org>] On Behalf Of Julien MARREC
via Equest-users

Sent: Saturday, October 15, 2016 3:41 PM

To: Darryl Kasun <darryl.kasun at gmail.com>

Cc: equest <equest-users at lists.onebuilding.org>

Subject: Re: [Equest-users] Modeling Reverse Acting TStat EF

Zonal exhaust fan has an option to control that on a temp schedule if I
recall correctly.

Open the zone, tab "outside air" then at the right you can specify a zonal
exhaust fan. (All this from memory so might differ slightly)

Cheers,

Julien

Envoyé de mon iPhone

> Le 15 oct. 2016 à 20:57, Darryl Kasun via Equest-users <
equest-users at lists.onebuilding.org> a écrit :

>

> Hi eQUESTers,

>

> First off, you probably will not likely appreciate this and I'll preface
this with saying that I'm a total bandwagon jumper but I am okay with that.

>

> GO JAYS!!!

>

> Now that that's out of the way I am trying to model a very simple system
that I'm sure many of you have modeled before.

>

> I have a zone that has an exhaust fan in it. When the temp. reaches above
80 degF, an exhaust fan turns on and a damper opens to draw OA into the
zone.

>

> I've been fooling around with a few systems trying to figure out a good
way to model this but haven't come up with one yet.

>

> Let me know if have any recommendations.

>

> Thanks!

> Darryl

>

> _______________________________________________

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