eQUEST - new user

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Hi all,

I've just started creating my first model on eQuest and can really do
with some advice.

The project is quite complex and consists of 2 high quality office
towers and an 8-storey trading and banking building.

The HVAC systems serving the 3 buildings vary from VAV, chilled beams,
perimeter trench heating, AHUs with reheat to CHPs.

I have the following questions please:

1. What things should I consider when creating the HVAC zones?

2. How should I model the different HVAC systems? For example, when
one or more AHUs are serving multiple floors, do I define each AHU
separately and assign them to the various HVAC zones?

3. How can I model a combined heat and power (CHP) system?

Your help is very much appreciated.

Kind regards,

Aswan Ali

Aswan Ali's picture
Joined: 2011-09-30
Reputation: 0

Hi Aswan,

1. This depends partly on what the model is for. If this is a LEED model,
the zones should be modeled as designed in the mechanical plan. If it's
not, you may want to simplify further, combining zones with similar uses and
exposures as long as you are pretty confident that the hourly heading and
cooling loads will be similar. Definitely err on the side of simplicity and
whatever you do, don't model closets separately.

2. You can define one AHU that serves multiple spaces, regardless of where
those spaces are. You might have to do some fine-tuning in detailed edit
mode in order to get everything set-up the way you want. There is no
chilled beam in eQuest. You'll have to modify an airside cooling system to
approximate the chilled beam. Search the archives for info on how to do
this. There have been at least a few discussions on the list serve in the
past regarding this issue.

3. It's possible to model CHP systems in detailed mode. Basically, create
an electric generator, select the fuel source and select the heat reject
loops. You can adjust the performance curves to match the type of equipment
you want to model. A word of caution: eQuest does not know the temperature
at which the generator is rejecting heat. Therefore it's possible to model
a generator that rejects heat at 85 F into a loop that needs to be
maintained at 180 F, but this violates the laws of thermodynamics!


No Username provide's picture
Joined: 2011-09-30
Reputation: 200

Hi Karen,
In response to your comment about making sure you do not model closets separately, how do you treat small janitor and mech/electrical closets (small rooms)? How you should model these areas gets complicated because of the LEED requirement that all zones must be modeled as being heated and cooled, even though these types of areas are typically supplied with just an exhaust and they "steal" some heating and cooling from surrounding spaces. I have been grouping all these areas into one HVAC system and assigning a "dummy" heating and cooling system. What is wrong with this approach? Let's take for example an open office area floor plan. Should the closets just be included in the open area zone or should they be assigned to their own zone?

Also, I am currently working on building a model of a system with active chilled beams. I believe eQuest can closely approximate a chilled beam system with the available Induction Unit HVAC system type. Do you have any experience using the Induction Unit to represent the active chilled beam systems?

Thanks for all your help.

Josh Doherty

Josh Doherty's picture
Joined: 2011-09-30
Reputation: 0


I have not used the induction unit as I believe that system limits
ventilation air heat recovery options, and most of my buildings use
ventilation heat recovery. Regarding modeling of zones, in offices, I
usually include closets in the office zone. It's silly to model these tiny
spaces separately as it just complicates the model and doesn't add any
significant accuracy. Now, if you have a large storage area in the middle
of an open office that might have different use patterns, and is treated as
a core zone, then you'd want to model it separately.

Regarding mechanical spaces... I usually model these spaces as "minimally
conditioned spaces" meaning that they are supplied with heating and
cooling, but the thermostat is set low for heating and high for cooling. Of
course this is consistent in both the baseline and proposed design. The
section in Appendix G on schedules allows some flexibility as long as it's
approved by the rating authority. Then, your "dummy" system won't use much
energy as the bulk of the energy will be transferred from other spaces.
This might be easier to deal with in other programs that model airflow
between spaces, so you could model exhaust airlfow and have it transfer from
another space.


Zones can be simplified a little bit. Basically, use your judgment. Sorry
I can't be of more use. If you want to outline zones on a floorplan and
send it directly to me, I could give you some feedback.


No Username provide's picture
Joined: 2011-09-30
Reputation: 200

Hi all,

Hope someone has few minutes to look into this please.

Since eQuest does not allow multiple systems to a single zone is it
possible to make the VAV the main system and apply the duty loads from
the CO2 systems as process loads in the spaces where the CO2 equipment
is located as shown on the sketch.

My concerns are:

1. The receptacle or process loads options available in the DD
wizard are for Non-HVAC Enduses
2. How to model the heat rejection from the liquid CO2 loop to the
chilled water loop

Please let me know your thoughts on this.

Many thanks,


Aswan Ali's picture
Joined: 2011-09-30
Reputation: 0