Hi , I am working on a 23 story 600,000 sqft building, I am using multipliers, so I only have , Ground , Middle and Top floor, with that I have roughly close to 70 zones, it is taking close to 1 hr to run 1/3rd of simulation what can I do to increase the sim speed?
TIA
Rajat 
There are several things that can speed up the simulation.
1) set the minimum time step to 1 hour and maximum iterations to 1:
Timestep, 60;
ConvergenceLimits, 0, 1, 1, 1;
2) reduce the number of Output:Variable objects so that writing to output is minimized
3) reduce the iterations on coil performance solution:
PerformancePrecisionTradeoffs,Yes;
4) Set ShadowCalculation frequency to 30 (once per month) or 60 (every other month).
5) I am sure there are other speed up options but these are the top few. See PerformancePrecisionTradeoffs.
Once the simulation executes successfully and provide desired results you can turn these speed up techniques off and run the simulation normally.
Hi,
I have done all these options, still it is taking a lot of time to run.
Do you have many surfaces and zones? Could the number of surfaces or zones be reduced? What type of HVAC and/or plant? Have you looked at the report for number of iterations?
Run a 1 month (or 1 week) simulation and then check this information:
Ouptut:Variable,*,Air System Solver Iteration Count,hourly;
Air System Simulation Maximum Iteration Count
Air System Simulation Iteration Count
Air System Component Model Simulation Calls
Plant Solver Sub Iteration Count
Plant Solver Half Loop Calls Count
Hi, I cant reduce the zones and surfaces,I am already creating only 3 stories i a 23 story building.
If you look above I have attached all the output variables that you asked for, they are quite high.
Comments
The image above shows that your simulation terminated on the way. Have you successfully completed simulation?
No, I did not I am getting convergence error that is another question that I have asked, but based on this for 1/3rd of the year it takes more than 1 hr.