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2020-03-08 11:29:37 -0600 received badge  Popular Question (source)
2015-08-31 13:11:21 -0600 commented answer OA below specified minimum for zone served by VAV

Thanks for the response Daniel--the behaviour you describe in the the wizard model you created is exactly what I'm experiencing. I will try that workaround. For what it's worth, I ended up just setting up a spreadsheet to calculate for each zone MAX(0.4, OA / AREA), and then just pasted the results into eQuest. (which works because in eQuest I'm dealing with a 100% OA system).

2015-08-31 10:25:02 -0600 commented answer OA below specified minimum for zone served by VAV

Thanks for the response. As I mentioned in my question, I'm already using the "set by critical zone" sizing method, which is part of what makes this behaviour so puzzling...

2015-08-31 10:25:02 -0600 received badge  Commentator
2015-08-28 17:36:20 -0600 commented answer OA below specified minimum for zone served by VAV

Hey Chris, where can I find the group you refer to?

2015-08-27 17:05:01 -0600 commented answer Is there a way to schedule maximum zone airflow in eQuest?

Weird. If the rate can't be exceeded, "minimum" seems like a bit of a misnomer. In any case thanks for your help and answer.

2015-08-27 17:01:29 -0600 asked a question OA below specified minimum for zone served by VAV

I'm attempting to model a pretty simple multiple zone VAV system in eQuest. This system serves a large gymnasium and a few small offices and storage rooms in a cold climate (Calgary, Canada). The problem I'm having is that the outdoor air rate being supplied to the gymnasium is below the minimum I've specified.

I've selected the "Pkgd Var Vol" system type, and specified minimum outdoor air flow rates for each zone (6313 cfm in the case of the gym). At the system level, I've selected the "fraction of design flow" OA control method, and the "set by critical zone" OA sizing method. The gymnasium zone terminal has a reheat coil, and the zone also has baseboard heaters.

I've set the minimum supply air flow for the gymnasium zone to 0.4 cfm/ft2, which works out to 2652 cfm. The problem is that this number seems to be taking precedence over the required O/A of 6313 when DOE-2 determines the zone's minimum flow. (Because there are baseboards in the zone, the S/A continually rides the minimum).

It seems to me that the "minimum" ought to be the larger of the specified minimum S/A and the minimum O/A... is this just not how it works? If so, is there any way to force eQuest/DOE-2 to work like this?

2015-08-20 10:19:46 -0600 commented answer Is there a way to schedule maximum zone airflow in eQuest?

To be honest I was a bit bewildered by this answer as I couldn't understand how my perspective would affect the simulation... but I tried it, and it worked! So thanks for your help! That said, it still doesn't really make sense to me; the name of the field ("MIN-FLOW-SCH") and documentation seem to suggest that this schedule sets a minimum supply air value--i.e. one that could theoretically be exceeded if necessary--but during the hours when I put the minimum to 0, no supply air will flow, even as the zone temperature falls well below its setpoint. Do you have a sense of why this might be?

2015-08-19 11:17:05 -0600 asked a question Is there a way to schedule maximum zone airflow in eQuest?

I'm attempting to model in eQuest a school that uses a simplified method of DCV.

In each classroom there is a vacancy sensor that, if it does not detect motion for a set period of time, generates a signal that is used to both turn off the lights in the classroom and also shut its supply air damper.

I'm wondering: is there some sort of method that can be used to schedule zone-level airflow that I could use to model this? What I'd like to do is simply schedule these dampers to close during the school's unoccupied hours. I see that eQuest/DOE has the ability to schedule minimum airflow at the zone level, but really what I need is the ability to schedule the maximum airflow.

Any help would be much appreciated. I'd also be open to other approaches to modelling this.

2015-08-12 18:16:53 -0600 commented answer eQuest "Heating" type Equipment Control

@LyleK thanks a lot for the answer. I had to make one switch to get it working: in the "load range 2" tab I changed the "seq" field for B-2 to 1. Does this make sense? Looking at PS-C after this I seem to be getting results close to what I was expecting...

2015-08-12 16:37:41 -0600 asked a question eQuest "Heating" type Equipment Control

I'm wondering exactly how to set up a "heating" type Equipment Control in eQuest.

Specifically, I have a system with two boilers, B-1 and B-2. I'd like to set it up so that B-1 handles the entire heating load until a given threshold, after which B-1 and B-2 share it equally.

Would I set it up like so?

image description

Also: would I be correct in assuming that the units in the "Max Load" field are MBtu/h?

2015-07-24 16:14:38 -0600 commented answer eQuest under-slab insulation assemblies

Thanks Neal; still a little bit unclear, as the descriptions in eQuest don't correspond exactly with those in the document, but definitely helpful. I'm trying to model was is described in the document you link to as "perimeter" insulation; my best guess is that "horz int" is what I'm after...

2015-07-24 15:30:06 -0600 asked a question eQuest under-slab insulation assemblies

I've been scouring the documentation and I can't find any description of the assemblies available as options for under-slab insulation in the "Building Envelope Construction" screen of eQuest's DD Wizard (see photo).

image description

For example, I'm not exactly sure what "horz int bd" describes/means. I'm wondering if anyone could point me toward some documentation that describes this...

2015-07-22 11:15:52 -0600 asked a question eQuest simplified glass input method

I'm preparing a LEED EAp1/c2 model for which the construction documents specify glazing in terms of performance (i.e. U-value, SHGC, etc.). This makes inputting glass via the glass library tricky, as it basically amounts to reverse-engineering performance specifications. Much simpler would be entering these specifications directly using the "simplified" input mode, but I have heard rumblings here and there about this method being less accurate.

I'm wondering: what exactly is the difference, and how significantly will this affect model performance? Are there particular conditions under which using this input method might be more or less acceptable?

2015-07-16 14:45:58 -0600 commented answer Plenums necessary for LEED model?

Thanks @nfonner. My main uncertainty relates to your first paragraph: the exterior wall area would be the same in either case (plenums or no plenums), and because the thermal resistance of the ceiling is negligible, at a steady state the temperature of the plenum and the conditioned space below it would be more-or-less equal. So it seems to me that by removing the plenums, all you're removing is essentially a bit of thermal capacitance, which might not have all that large of an effect...

2015-07-16 13:14:53 -0600 asked a question Plenums necessary for LEED model?

I'm preparing an energy model to be used for a LEED 2009 EAp1/c1 submission. The building I'm modelling is a single storey school, which has a mix of exposed ceilings and drop ceilings, as well as a few spaces (e.g. the gymnasium) with higher ceiling heights than the rest of the building.

I'm using eQuest, and without getting into too much detail I will just say that based on my experience with eQuest, my life will be a lot easier if I just model the entire building as exposed ceilings--in other words, remove the ceiling plenums. It seems to me this would have a very marginal effect on the model results, as I wouldn't be changing the exterior surface area, but I wanted to see if anyone had any experience with this.

Basically I'm wondering if removing the ceiling plenums in the manner described above:

  • Would unduly affect the accuracy of my simulation results
  • Would be kosher for LEED

Any insights would be much appreciated!

2015-04-21 10:26:17 -0600 commented answer eQuest: insufficient AHU heating coil capacity

Very helpful, thanks a lot Daniel.

I'm wondering: is there a document somewhere that maps eQuest's inputs to the corresponding DOE-2 keywords?

2015-04-20 14:55:03 -0600 asked a question eQuest: insufficient AHU heating coil capacity

I'm attempting to model a school in eQuest and I'm having some trouble with unmet hours.

The building is located in a cold climate (Calgary, Alberta) and I've selected the "Pkgd Var Vol" system type. The problem seems to have something to do with with way that I've set up this system. In ATTN report I'm getting a warning like so:

PREHEAT/HEATING-CAPACITY in SYSTEM AHU-1                           
             is too low to provide the requested supply temperature for
             the calculated mixed air temperature using total ZONE loads
             (on LS-A/B) and SYSTEM design parameters, plus outside air
             conditions (on LS-C), and specified capacities & air flows.
             Requested temperature is  55.00 calculated is  11.80
             DESIGN-HEAT-T, and ZONE loads for consistency.

I can eliminate the unmet hours by jacking up all of the baseboard and reheat coil capacities but this results in a completely absurd level of heating energy consumption, and it also doesn't eliminate the above error.

I've noticed that manually setting the "Hot Deck Max Leaving Temp" to 95 F seems to correct the above error message, but doesn't fix the underlying problem of the unmet hours/absurd energy consumption. I've also tried manually entering an extremely high value in the "heating capacity" field of the "Heating"/"Coil Cap/Control" menu of the system and it doesn't have any effect.

A couple of strange things I've noticed that might provide some clues as to what the problem is:

  • the value listed for "heating capacity" in the SV-A report is 0 (unless I enter a Max Hot Deck Leaving Temp as described above)
  • the minimum zone temperature listed in the SS-F report for the underheated zones is just ridiculous--like -253.1 F for one zone.

Any ideas or suggestions would be very, very greatly appreciated.

2015-04-20 11:40:44 -0600 commented answer How to autosize baseboard heaters in eQuest detailed mode?

That does it, thanks a lot!

2015-04-20 11:40:35 -0600 received badge  Supporter (source)
2015-04-20 11:14:07 -0600 asked a question How to autosize baseboard heaters in eQuest detailed mode?

I'm wondering how to autosize baseboard heaters in eQuest's Detailed Data Edit mode.

If I delete the value entered in the baseboard capacity in either the zone menu or the spreadsheet view, when I leave the field it's filled with a zero--in which case I end up with a baseboard capacity of 0 for the zone in question (at least this is what my simulation results seem to indicate).

Is there something I can enter in this field to have the baseboards autosize?

2015-04-17 11:29:47 -0600 marked best answer eQuest fan static pressure units

I'm attempting to model a school in eQuest and my fan energy seems much too low. In searching for the source of the low fan energy I noticed that the input screen in eQuest for AHU fan static pressure lists "Static in WG" for units, while the SV-A output report lists the units for the AHU fan in "IN-WATER."

What throws me is that the value in both is exactly the same: that is, I've entered a fan static pressue of 0.4 inches hg in eQuest, and the static pressure value which appears in the SV-A report in inches water is also 0.4.

Has anyone encountered this oddity? Anyone aware of what the source might be? I don't yet have a good grasp of how the unit conversions work between eQuest and DOE...