Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page
Ask Your Question

Initial room conditions before simulation starts

asked 2016-01-07 17:08:22 -0500

updated 2016-01-07 19:04:28 -0500

Is there a way to manually set the start room temperatures of zones in E+? I am trying to simulate an exercise for select days to watch the thermal decay in the room with no HVAC added. Found the link below but not convinced that is that final answer.

Does this relate to how the warmup days are run to reach an equilibrium for the start conditions? Would the warmup day run results change having different start days, say in a cold and warm day resulting in a meaningful difference in the starting temperature for the zone with the prevailing conditions in days/hours before the simulation starts?


edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted

answered 2016-01-07 17:28:27 -0500

updated 2016-01-07 17:37:09 -0500

The warmup days repeat the first day of the simulation until the building is periodically stable (i.e., the temperatures and heat fluxes at the end of the day align with the beginning). What ever weather conditions and schedules are set for that first day will be used.

If you are simply performing a decay test, you can use a synthesized weather file and ideal loads to control the environment as you'd like for your test. Hold the environment constant for a period of time and then introduce a step change in either the thermostat setpoint or the outdoor drybulb in the weather file. This should give a pretty controlled way to test the thermal decay.

edit flag offensive delete link more


Thanks @Neal. I am trying the cool down test but was hoping there is a way to do that without the need to use a fabricated weather file. I am simply interested in looking at what happens, e.g. overnight, when the room temperature is supposedly at setpoint before occupants leave then the actual TMY data for the next day hits. If I understood you correctly, I will need a fabricated weather file that sets my first day outdoor temp conditions, resulting in my initial room conditions, then need to run for the next day with actual temps to get to observe the cool down/heat up effect?

Amir Rezaei gravatar image Amir Rezaei  ( 2016-01-07 17:40:10 -0500 )edit

Does it have to be at the beginning of the simulation? Can you use an Ideal loads system to control the room's temperature and then use an availability schedule to shut it down before the day you're interested in?

Neal Kruis gravatar image Neal Kruis  ( 2016-01-07 17:49:33 -0500 )edit

No it doesn't have to be at the beginning. What you said makes sense, thanks Neal.

Amir Rezaei gravatar image Amir Rezaei  ( 2016-01-08 08:26:00 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer


Question Tools

1 follower


Asked: 2016-01-07 17:08:22 -0500

Seen: 176 times

Last updated: Jan 07 '16