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[EnergyPlus_Support] Re: Running E+ on the "cloud"

Funny how a CFD simulations expert is quite happy if his runs are in days instead of weeks, and we worry about hours instead of days. 

I strongly recommend absolutely minimizing surfaces. Splitting the model is problematic for AHUs and split systems that serve different zones over different levels. Split units and AHU who serve a common zone on one level and are supplied by a common energy source (boiler / chiller) is not always the case, which makes splitting the building difficalt.

I suggest first modelling the entire facility and connecting the systems up with design builder. Save several files of the completed model. Delete out zones that don't share common systems so that you end up with a file 1 with all the connections to a common systems in tact. Repeat this with the all in one model till all the systems each have their own file. You can then import the other system complete files as other buildings into the one you are currently investigating. DB uses these as shading from external buildings. Obviously, pay attention to adiabatic boundries and nosun nowind properties on boundries.

My experience:
My first ever project to simulate was a +_ 1000000 m2 oval shaped stadium over 6 levels. At the time DBv2 had just come out with e+v3 (if I remember correctly). The facility had 100s of rooms per level, kitchen hot kiosks, a level of offices, showers and changing, spa, 2 levels of underground parking, restaurant, VIP and normal, basically as diverse as you could make it (no swimming pool, thankfully). 

After completing the model in DB, it happened that DB would crash whilst trying to export the idf. I was forced to split the facility by level, but kept the two underground levels together. This worked well. The round shape gave me loads of surfaces. 

At the end I used a processor on 4 other collegues PCs. They didn't notice performace decreases, even those using CAD applications. The largest part, the x2 basement levels took about a week to complete, with design day runs taking more than a day. Other levels only about half a day for a design day run, with 3 days for the full year run. 

I had only idealloads hvac, using process loads (positive and negative) to simulate other equipment with ems and using equipment data sheets to approx fan and motor losses.

At the end I had a complicated spreadsheet to patch together the results. We had electric powered air cooled chillers with a buffer tank which I didn't model at all. I simply used equipment data sheets and COPs at standard ratings to work out the approx electricity usage. 

I have learnt a heck of a lot since those days. Took me about 800 hours to do this job.  

I do find that large models are the rule not the exception. Also, keep energy modeling seperate from calculated nat vent and lighting simulation. All in one models for this ends up wasting loads of time. 

Keep us updated as to how you end up tackling this.

Have a good and restfull xmass newyear season,

Till later,

Jean

 




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