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[EnergyPlus_Support] Re: E+ runtime speed



Dear E+ Support,

May I have an update on this post?

In summary, this old post says that:
  1. Does  more cache memory help?
  2. Does the operating system (especially Windows XP vs. Vista) make a difference?
  3. If 2GB memory is good, is 4GB twice as good?
  4. Same question for processor speed.
I am now using a 1.7GHz Core Duo PC with 2GB of RAM.  Time is money, and 8-10 minutes seems too long to wait for 20 zones and a full weather year, so I'm evaluating options.

Thanks in advance!

p.s., The advantage of being impatient is that I've learned numerous ways to speed things up on my "too slow" PC from this forum that I would otherwise not know about.


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie <linda@...> wrote:
>
> For simple buildings, EnergyPlus can be quite fast. However, there
> are a few hints to help the runtimes.
>
> 1. Plain and simple, get the most memory into your computer that you
> can. We have one file that is a 4 zone building and reports many
> variables. On a 1.8GHZ computer with 768MB memory, it was running
> about 8 minutes for a full annual run. On my newer 2.1 GHZ computer
> with 2G of memory it is about 2 minutes.
>
> 2. We continually try to hack away at the run times. Some
> developers are more atuned to reducing runtimes than others.
>
> 3. There are some other hints to try to use: Report on only the
> variables you need and report on them at hourly or less
> resolution. Use a lower time step frequency (i.e. 4 rather than 6
> times per hour).
>
> 4. "Does E+ have a "shoebox mode" where is lumps every thing into a
> simplified building? I know it has an option to lump windows, but from what
> I've seen this is not enough." Not really -- however, if shadowing
> is not that important, you can use the "minimal shadowing" option on
> the BUILDING object. I am not sure how much that helps.
>
> Manually, you can lump like orientation and construction walls into
> one giant wall -- but this takes considerable work. As you noted you
> can put multipliers on windows (and in V1.4 doors).
>
> 5. "I noticed that Running without HVAC was MUCH faster. What are best
> settings to speed up the HVAC code?" Also, you could try the
> purchased air solution for HVAC -- that should be much faster than
> other HVAC modes. If you are comparing multiple buildings, the
> decrease in accuracy of the results may not be as important as
> getting them running quickly. We also have the System Convergence
> Limits object -- that can be used to try to fine tune the HVAC results.
>
> 6. "If I get a new 4 processor computer, __._,_.___

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