[Bldg-sim] Two Questions for the esteemed members of this fine list

Jones, Christopher cjones at halsall.com
Tue Sep 23 07:55:19 PDT 2014

Before you jump into DOE2.3, make sure you read DOE23Vol6-NewFeatures.  The first section lists the DOE2.2 features not currently included in DOE2.3.  For example OA-FROM-SYSTEM is not implemented.

Christopher Jones, P.Eng.
Tel: 416.644.4226 • Toll Free: 1.888.425.7255 x 527

From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of RobertWichert
Sent: Tuesday, September 23, 2014 10:33 AM
To: Jeff Hirsch; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Two Questions for the esteemed members of this fine list

Thanks to all who have replied.  This has been very helpful, as always.  I was not aware of the eQUEST option of using DOE-2.3 with data center additions.  This sounds quite well suited to my situation.

Jeff, are you an experienced user of this version with data center additions?  Can you recommend someone who is?

I have posted this, as recommended, to unmethours.com and I will consider posting it to the eQUEST list as well.

Thanks to all!

Robert Wichert P.Eng. LEED AP BD&C



+1 916 966 9060

FAX +1 916 966 9068

On 9/20/2014 2:46 PM, Jeff Hirsch wrote:
You might be interested in trying the DOE-2.3 version with data center additions. We have not done an “official” release of eQUEST with 2.3 but it is activated in eQUEST 3.65 by setting DOE2Version=2 (instead of zero, the default) in the eQUEST.INI file in the eQUEST 3-65 Data directory. Be care file not to change other parameters you are not familiar with (and best to make a backup of the file in case you mangle it) and change the value back to 0 if you want DOE-2.2 on the next startup of eQUEST.

There are data center addition to the wizard but at least on bug incorrectly set the CW loop design temp to zero, so you have to fix that. We are trying to get all the lumps out of this version of eQUEST and DOE-2.3 to make it an official release, but you might find it interesting to try.

From the DOE-2.3 help file on this topic (look in help under doe23 for the chm):


Data centers typically have equipment loads varying between 20 W/sq.ft. to over 150 W/sq.ft. Because these equipment loads dwarf the loads found in typical commercial facilities such as office buildings, data centers offer unique opportunities for achieving energy savings in the HVAC systems. Many existing technologies are already applicable to data center HVAC systems, such as economizers, and others are currently in research and development.

To facilitate the analysis of data centers, several new features have been incorporated into the program, including:

•      Hot aisle / cold aisle simulation - conventional HVAC air distribution results in spaces in which the temperature is relatively uniform from floor to ceiling, and from side to side. In contrast, the equipment racks in data centers may be configured in rows, with the air intakes oriented to one row and the air exhaust to another row; creating cold aisles and hot aisles. Further, if all supply air is distributed to the cold aisles, and physical barriers constructed to reduce air circulation between the hot aisles and the cold aisles, then significant stratification may be achieved between the supply temperature introduced into the cold aisles, the average cold aisle temperature, and the return air temperature. This stratification can make economizers more effective, and can also enhance the performance of chilled-water coils or DX systems.

•      Equipment sizing based on supply/return temperature differentials - For sizing airflows into a zone, the airflow is typically calculated based on the zone load, and the differential between the MIN-SUPPLY-T and the DESIGN-COOL-T. An alternative has been added to allow the differential to be directly specified.

•      Multiple HVAC systems serving the same zone - Data centers typically have more than one HVAC unit serving the same space. The program has been enhanced to allow multiple identical HVAC systems to serve the same zone. Units may be either all run in parallel, or may be staged on/off according to the load.

•      Thermostat location - The ability to specify whether the zone thermostat is located in the zone (measuring average cold aisle temperature), or in the return air.

•      A new cooling tower control strategy - Because data centers typically operate with a cooling load 24 hours per day, and new control scheme has been implemented to allow the cooling tower temperature setpoint to be reset based on wetbulb temperature.

•      Waterside economizer - This version of the program supports a waterside economzer fully integrated into the chilled water loop. The waterside economizer is upstream of the chillers, and precools the return water prior to entry into the chillers. This feature is presented in a separate section in this document, "CHW-Loop Economizer Cooling".

•      Underfloor air distribution supply plenums served by single-zone systems - Data centers often have the supply air delivered via an underfloor supply plenum. Previously, the program could simulate underfloor supply plenums for single duct systems such as variable-air volume systems with multiple zones. This capability has been extended to single zone systems such as SZRH and PVVT; systems which are typically used in data centers. Underfloor air distribution is discussed in a separate section, "Underfloor HVAC Air Distribution".

Jeff Hirsch
James J. Hirsch & Associates
12185 Presilla Road -  Camarillo, CA 93012-9243 USA
phone: (805) 553-9000 mobile: (805) 532-1045 fax: (805) 532-2401
email: James.J.Hirsch at gmail.com<mailto:James.J.Hirsch at gmail.com>

From: RobertWichert<mailto:robert at wichert.org>
Sent: Saturday, September 20, 2014 12:25 PM
To: bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Subject: [Bldg-sim] Two Questions for the esteemed members of this fine list

I am working on modeling a small computer room.  The computers are the
major load.  The space is served by a small water cooled chiller and an
air handler, with economizer.  The questions are:

1)  Does EnergyPlus lend itself to such models, and are there specific
tools that might be useful?  I am interested in accurately modeling the
computer with varying loads over the year, and with the economizer
enabled to show the difference in various supply air temperatures and
cooling tower strategies (multiple versus one cooling tower, variable
versus multiple fans) as well as various economizer strategies (return
air versus supply air control and the resulting chiller loading).  I am
also interested in detailed chiller modeling, as the load varies from
full economizer to full chiller and the chiller part-load performance is
a key attribute. The chiller supply temperature will be higher than
typical for chilled water coil cooling, so that must be flexible as well.

2)    Is there any specialized modeling tool that anyone knows about
that is especially good for such modeling?  I would instinctively say
EQuest is NOT good for that, but I may be mistaken.  I could make
EnergyPro work, but I do not believe that the cooling tower / chiller
interface is detailed enough using DOE.2.

Your thoughts are appreciated.


Robert Wichert P.Eng. LEED AP BD&C
+1 916 966 9060
FAX +1 916 966 9068


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