[EnergyPlus_Support] Re: Creating an artificial warm up/convergence file

["bucking_s" <sbucking@xxxxxxxxx>]

Hi James,

Interesting question. I'd first consider if you should: If your optimization is making any modifications to thermal mass, geometry, window sizes, etc., you should be using a seperate warm-up process, since it only takes a few seconds relative to minutes of simulation, to ensure the fidelity of what you are optimizing. 

I can't see how you could accomplish this without an E+ developer license. If you have some coding background, you could chop the warm-up process, manually feed initial data into the Heat Balance. This is a ton of work to shave a few seconds and you require a new developer license for each new e+ version which is added pain.  There are other options you may want to consider instead.

An E+ user wrote a ruby script that breaks down one annual simulation into several shorter time periods and runs them simultaneously with their own warm-up periods. Since warm-ups are so short, you can obtain some nice performance gains. See here:

http://f1.grp.yahoofs.com/v1/cLYxTfeUuGhncAw3GwDxU99vP444zreEQ3qmujvKa4MnXGnpBMmPmKb1adZJPk85z8mHNTQfdMSvh7xTM93PoK9Xh3YN41U/Utilities/AnnualSimulationSplitter.rb 

For improving optimization speed, personally, I focused on the running many e+ runs in parallel. GenOpt does this to some extent, but only one simulation to each core (IIRC). If you don't want to modify GenOpt, it takes around 500LOC to write your own optimization algorithm using modern languages. In my experience, I have been able to run 5 simulation batched per core at any time. If you have even a desktop with 8-cores and RAIDed harddrives you'd be laughing. 

Hope this helps,

Scott


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "a" <spincycle45@...> wrote:
>
> In an effort to reduce the runtime for a complex optimization process using GenOpt, I was wondering if there was a way to create a file that E+ could reference to that would contain all data generated during the warm up process.  In this way the simulation could skip the warm up phase and move directly to calculating the new configuration with this data.  I am also looking for a means to save this same data from the energy model in the final moment of the calculation process to then feed back into E+, resulting in a sort of `pause' button for the E+ program.
> 
> By saving a few seconds during the simulation process the time savings will add up significantly when running thousands of iterations.
> 
> Cheers -- James
>




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