[Bldg-sim] simulation software

Varkie Thomas thomasv at iit.edu
Thu Jan 3 11:05:53 PST 2008

I agree with Jeff.
Different programs may produce different energy savings results for USGBC LEED certification, depending on (a) the competence level of the program user, (b) the technical in-depth knowledge they have of this subject, (c) their experience in developing real buildings, (d) the design criteria that they use and (e) how well they understand the program they are using.  
Theoretically all programs should produce the same results for a given project if the inputs are identical and the programs use the same methods-equations for analyzing envelopes, systems and plants.  EnergyPlus uses the Heat-Balance method for Loads whereas all the other programs use the Transfer-Function method.  Systems & Plants depend on the performance curves of the equipment.  
Decisions have to take into account first & maintenance costs, availability of equipment parts and maintenance staff, reliability and durability of systems, positive environmental and acoustic impacts, and client preferences.  This requires experience working on real buildings.  A mechanical engineering degree and P.E. are more suitable qualifications for energy analysts than LEED A.P.
The “percent energy savings” requirement of LEED can be misleading since it is affected by different design criteria, process loads, internal loads schedules (these items have to be the same in the baseline and proposed models) and the program used.  The higher the common items in the baseline and proposed, the lower the “percent” energy saved.  Sixty percent energy savings does not necessarily mean an optimally designed, long lasting, stable and cost-effective building at the given (particularly urban) location.

----- Original Message ----- 
From: Jeff Haberl <jeffhaberl at tees.tamus.edu> 
Date: Saturday, December 29, 2007 12:29 pm 
Subject: Re: [Bldg-sim] simulation software 
To: Ardas at dfwcgi.com, bldg-sim at lists.onebuilding.org 

> FYI. 
> Whatever package you use, gaining the type of experience needed to 
> do a reliable job usually takes 2 to 5 years. Especially with 
> "custom" systems that are not easily modeled with fixed schematic 
> programs. 
> In addition, one should know what the programs is doing. All too 
> often there are posts to the different sites where it is clear the 
> user does no want to take the time to read the manual. 
> At our university we teach DOE-2 from the BDL. This takes a whole 
> semester to cover all commands. After the student takes the class, 
> I'm told it takes them another year or two to build a library of 
> their own files that they ca use to assemble an input. EQUEST is 
> then the program of choice by the students as it is based on DOE- 
> 2. In the future we will be teaching EP. 
> Using any GUI or REVIT is one or two levels above the basic code. 
> This can be very tempting -- but it requires the user to do their 
> own checking to see if the outputs make sense. Obviously, having 
> on-line help is useful but it cannot replace experience. 
> All too often I see posts where someone says that this is their 
> first time to simulate something...this is good...and I applaud 
> anyone who tries to learn this on their own. 
> But a reasonable person must ask would you want your heart surgeon 
> to be operating for the first time on you? 
> Certainly, any paid simulation job should also be approached with 
> similar respect...these are just calculations, based on algorithms 
> and assumed configurations. If you can't tell what is being 
> simulated, then you're better off using a spreadsheet or rule of 
> thumb. 
> Finally, any simulation should be reviewed by another knowledgable 
> person who makes the original coder explain what they are doing, 
> check answers, etc., and the performance of the building monitored 
> (as budget allows) to see how the simulation performed. 
> Jeff 
> BB 8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) :=') 8=) 8=) 8=? BB 
> Jeff S. Haberl, Ph.D., 
> P.E.............................jhaberl at esl.tamu.edu 
> Professor......................................................Office Ph: 979-845-6507 
> Department of Architecture.......................Lab Ph: 979-845- 
> 6065 
> Energy Systems Laboratory.......................FAX: 979-862-2457 
> Texas A&M University..............................77843-3581 
> College Station, Texas, USA.......................URL: www- 
> esl.tamu.edu 
> BB 8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) 8=? 8=) 8=) 8= BB 
> ----- Original Message ----- 
> From: bldg-sim-bounces at lists.onebuilding.org <bldg-sim- 
> bounces at lists.onebuilding.org>To: bldg-sim at lists.onebuilding.org 
> <bldg-sim at lists.onebuilding.org> 
> Sent: Tue Dec 18 09:41:15 2007 
> Subject: [Bldg-sim] simulation software 
> hi, 
> we are planning to use EQUEST or TRACE 700 for energy simulation. 
> Is eQUEST an approved software by USGBC (in Texas)? 
> Where can we get training in DFW (Dallas Fort Worth) area? 
> Which one is easier, faster? Trace 700 or eQUEST? 
> or do you know other simulation software (preferable free) that we can 
> utilize in our LEED design projects and we can get training in DFW 
> area? 
> thanks 
> Ardas 
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