[bldg-sim] EnergyPlus - DOE

Mahabir Bhandari bhandari at fenestration.com
Thu Jan 19 07:16:27 PST 2006


Vamshi,

 

Just to clarify, DOE2 does NOT use steady state analysis. The main difference in run time is due the different simulation techniques used in these two programs. DOE2 uses sequential simulation technique while EnergyPlus uses simultaneous simulation technique for loads, systems and plants. In DOE2 building zones, air handling systems and central plant equipment are simulated sequentially with no feedback from one to the other while in EnergyPus all the elements are integrated with proper feed backs and are solved simultaneously. 

Mahabir

 

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From: Vämshi Goojé [mailto:vamshi.gooje at gmail.com] 
Sent: Thursday, January 19, 2006 9:31 AM
To: bldg-sim at gard.com
Cc: bhandari at fenestration.com
Subject: [bldg-sim] EnergyPlus - DOE

 


Mahabir,
The extended run time in EPlus could be due to transient analysis vs. steady state in doe 2.
Vamshi

On 1/18/06, Mahabir Bhandari <bhandari at fenestration.com> wrote:

Brian,

 

I think one additional difference from uses' point of view, which is not reported in this report, is simulation run time. It seems EnergyPlus takes 5-10 times longer to complete a whole year simulations than DOE2. I was running a simple 5 story building with VAV system and it took me more than 40 minutes for annual hourly simulations (1 hr time step) in EnergyPlus while eQuest could run the same building in less than 5 minutes. I am interested in hearing from others on the run time issue.

 

Mahabir Bhandari

 

 

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From: Brian Fountain [mailto:bfountain at greensim.com] 
Sent: Wednesday, January 18, 2006 12:12 PM
To: bldg-sim at gard.com
Subject: [bldg-sim] EnergyPlus - DOE

 

That is a big question.

 

For a comparison of current energy simulation software, you could look at Dru Crawley's paper comparing 20 tools:

http://www.energytoolsdirectory.gov/pdfs/contrasting_the_capabilities_of_building_energy_performance_simulation_programs_v1.0.pdf

 

Main differences between DOE and EnergyPlus:  

1)       DOE calculates the space loads for each hour then calculates the system and plant response for each hour.  EnergyPlus simultaneously solves the loads the system/plant response for each timestep.

2)       DOE has a fixed 1 hour timestep, EnergyPlus has a variable timestep (down to 1 minute?).

3)       There are also key issues with the weighting factor assumptions, the wall convective coefficients.

 

I haven't used EnergyPlus much yet.  What did I miss guys?

 

Brian Fountain

 

-----Original Message-----
From: bldg-sim at gard.com [mailto:bldg-sim at gard.com] On Behalf Of Renato Sousa
Sent: January 18, 2006 10:56 AM
To: bldg-sim at gard.com
Subject: [bldg-sim] EnergyPlus - DOE

 

Hello everybody.

 

I would like to know if anybody has experience on using both EnergyPlus and DOE.

Currently I'm using an interface for EnergyPlus. From the software description I couldn't find out the main differences between EnergyPlus and DOE. Does anyone know the main differences or where can I find them?

 


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