Just beware that you are trading accuracy for speed. The alternative solution would be� get a faster computer! J
Yi
Dr Yi Zhang, PhD CEng MCIBSE MASHRAE
Director
Energy Simulation Solutions Ltd. (UK)
T: +44 (0)7809 572863
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: 28 January 2015 14:44
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] simulation settings to shorten the run time
I actually am calculating the yearly energy use now, instead of the 4 dates that I mentioned above. So need to change some more settings. The ones I tried are:
1. changing the timestep from 2 to 1
2. max. HVAC iterations is reduced from 20 to 5 (but did not make much difference)
3. minimum system timestep is 0, instead of 1
So instead of shading with fins, I might use overhangs. Also the zone schedules might make a difference maybe, but I havent tried anything yet. Any ideas??
On Wed, Jan 28, 2015 at 4:39 PM, dru.crawley@xxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
Those 4 months may not be the peak months for temps or solar. The design data provided with most weather files (.DDY) includes the hottest and coldest month � the months used for the design conditions are the hotttest and coldest:
! Washington Dc Dulles IntL Ar_VA_USA Annual Heating 99.6%, MaxDB=-11.8°C
SizingPeriod:DesignDay,
Washington Dc Dulles IntL Ar Ann Htg 99.6% Condns DB, !- Name
1, !- Month
21, !- Day of Month
�.
! Washington Dc Dulles IntL Ar Annual Cooling Design Conditions Wind Speed=4m/s Wind Dir=290
! Hottest Month=JUL
! Washington Dc Dulles IntL Ar_VA_USA Annual Cooling (DB=>MWB) .4%, MaxDB=34.1°C MWB=23.9°C
SizingPeriod:DesignDay,
Washington Dc Dulles IntL Ar Ann Clg .4% Condns DB=>MWB, !- Name
7, !- Month
21, !- Day of Month
�.
You can find the hottest and coldest month in the CSV file included with the install: C:\EnergyPlusV8-2-0\PreProcess\WeatherConverter\ ASHRAE_2013_Yearly_DesignConditions.csv (these are the same data as the 2013 ASHRAE Fundamentals Chapter 14 Climatic Data Information).
Column N has the ‘ColdestMonth’ and column AD has the ‘HottestMonth’.
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Wednesday, January 28, 2015 9:00 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] simulation settings to shorten the run time
Create 4 different RunPeriods, one for each of the days you mention - something like this:
On Sat, Jan 24, 2015 at 7:13 AM, ipekgursel@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
Hi,
I am linking EnergyPlus (and Radiance) to an evolutionary optimization tool that I am developing. To be able to generate and evaluate many design alternatives, I need to significantly shorten the simulation run time. The 4 calculations I am doing are heating load (21 dec.), cooling load (21 june), and lighting load (21 mar and 23 sep). what are the simulation settings that I can change?
I already simplified the model as much as I can. My question is only about the simulation...
thanks in advance!!!
--
James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504
Direct: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
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Posted by: "Dr Yi Zhang" <yi@xxxxxxxxxx>
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