Unless you are working with a comfort model, the operative temperature has no special meaning.
For a zone, it is the average of the Mean AIr Temperature and the Mean Radiant Temperature.
I usually only look at the Zone MAT, because it is the result of the heat balance and is the value to compare with the zone set point temperature.
==============
For a zone, it is the average of the Mean AIr Temperature and the Mean Radiant Temperature.
I usually only look at the Zone MAT, because it is the result of the heat balance and is the value to compare with the zone set point temperature.
==============
Because the MRT is related to radiation, therefore, the operative temperature would vary with shading.
MRT is also activited by internal lighting and people.
=================
I do not know why you wanted to look at one day simulation of a weather file.
I do not know why you wanted to look at one day simulation of a weather file.
You make one annual weather file simulation and get the data for the whole year. You can view the data down to timesteps, or view any section of an annual graph and any cobination of the variables using the ResultViewer.
You can extract one day data from the single annual spread sheet for comparison as well.
The initialization error in digital calculaton is always there, and is minimized by the warming up process.
================
Warming up process for DesignDay is different from that for the weather file. I do not know the exact process. The 23°C was for the general temperature value initialization, and might have been changed in the current version.
=======================
When I said, "I usually run six or more days and compare the last three days.", I acatually run the same three days with the multiple simulation option, so that the similation is repeated three times with the same data. If the second set and the third set of result are nearly equal, the warming up is complete.
This was just to test the warming process and have no real application. If you believe this test, then the simulation from sixth day onwards would have negligible initialization error.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: amyquartette@xxxxxxxxxxx
Date: Tue, 7 Feb 2012 11:24:28 +0000
Subject: [EnergyPlus_Support] Re: different results with different run periods?
Thanks, Linda and Dr. Li!
The zones are not being controlled and the difference of the operative temperatures are about 2°C. Both have no shadow calculation,which I may turn it on next time with 1 day frequence. I didn't change the warmup days and convergence, since I've no idea about them.
I think I should run a 7 days periode to get a relative accurate value for the last day.
However I would like to know, what is the initial operative temperature of a weather file simulation of a giving run periode. Could someone tell?
Thanks in advance!
Amy
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
>
>
> This is a very frequent question on Zone mean temperature. The anual simulation starts from 23°C, i brief, as any digital calculation requires some initial values. Therefore the first three days are the same, if they are all from Jan 1. If the three days are from the middle of an anual simulation, the short three day one would not be the same. I usually run six or more days and compare the last three days. The DesignDay simulation repeats a few times (second groups of warm up times) until the begining midnight and ending midnight value are the same. This implies that the previouday condition is the same as the current one. Therefore, if the building does not cool down at night, the temperature of the building would be higher in the morning. A weather file simulation would look quite different, when the day is preceded by a cloudy raining day.=====================When using operative temperature, the additional check on "shadowCalculation" would be required. In the WinterDesignDay object, the skyclearance is normally set to zero.
>
> Dr. Li
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: linda@...
> Date: Mon, 6 Feb 2012 08:09:12 -0700
> Subject: Re: [EnergyPlus_Support] different results with different run periods?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Make sure that you have the "ShadowCalculation" in
> both runs set to 1.
>
>
> How far off are they? Are your zones being controlled? There
> is some influence of warmup days -- are they the same for both and
> passing convergence?
>
>
> At 08:03 AM 2/6/2012, amyquartette wrote:
>
> dear all,
>
>
> I have run an annual simulation of my e+ file for the operative
> temperatur of a zone. Then I ran with the same file with a run period
> which has only 3 days. The results of the operative temperaturs for the 3
> days of the 2 simulations are not the same.
>
>
> Could someone explain the reason and tell what I should be aware
> of?
>
>
> Thank you very much!
>
>
> Regard,
>
> Amy
>
>
>
>
>
> ------------------------------------
>
>
> Primary EnergyPlus support is found at:
>
>
> http://energyplus.helpserve.com or send a message to
> energyplus-support@...
>
>
> The primary EnergyPlus web site is found at:
>
>
> http://www.energyplus.gov
>
>
> The group web site is:
>
>
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
>
> Attachments are currently allowed but be mindful that not everyone has a
> high speed connection. Limit attachments to small files.
>
>
> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf
> under the Documentation link and press the "search"
> button.
>
> Yahoo! Groups Links
>
>
>
>
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
>
> Individual Email | Traditional
>
>
>
>
> http://groups.yahoo.com/group/EnergyPlus_Support/join
>
> (Yahoo! ID required)
>
>
> EnergyPlus_Support-digest@xxxxxxxxxxxxxxx
>
>
> EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx
>
>
>
> EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
>
>
>
>
> http://docs.yahoo.com/info/terms/
>
The zones are not being controlled and the difference of the operative temperatures are about 2°C. Both have no shadow calculation,which I may turn it on next time with 1 day frequence. I didn't change the warmup days and convergence, since I've no idea about them.
I think I should run a 7 days periode to get a relative accurate value for the last day.
However I would like to know, what is the initial operative temperature of a weather file simulation of a giving run periode. Could someone tell?
Thanks in advance!
Amy
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
>
>
> This is a very frequent question on Zone mean temperature. The anual simulation starts from 23°C, i brief, as any digital calculation requires some initial values. Therefore the first three days are the same, if they are all from Jan 1. If the three days are from the middle of an anual simulation, the short three day one would not be the same. I usually run six or more days and compare the last three days. The DesignDay simulation repeats a few times (second groups of warm up times) until the begining midnight and ending midnight value are the same. This implies that the previouday condition is the same as the current one. Therefore, if the building does not cool down at night, the temperature of the building would be higher in the morning. A weather file simulation would look quite different, when the day is preceded by a cloudy raining day.=====================When using operative temperature, the additional check on "shadowCalculation" would be required. In the WinterDesignDay object, the skyclearance is normally set to zero.
>
> Dr. Li
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: linda@...
> Date: Mon, 6 Feb 2012 08:09:12 -0700
> Subject: Re: [EnergyPlus_Support] different results with different run periods?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Make sure that you have the "ShadowCalculation" in
> both runs set to 1.
>
>
> How far off are they? Are your zones being controlled? There
> is some influence of warmup days -- are they the same for both and
> passing convergence?
>
>
> At 08:03 AM 2/6/2012, amyquartette wrote:
>
> dear all,
>
>
> I have run an annual simulation of my e+ file for the operative
> temperatur of a zone. Then I ran with the same file with a run period
> which has only 3 days. The results of the operative temperaturs for the 3
> days of the 2 simulations are not the same.
>
>
> Could someone explain the reason and tell what I should be aware
> of?
>
>
> Thank you very much!
>
>
> Regard,
>
> Amy
>
>
>
>
>
> ------------------------------------
>
>
> Primary EnergyPlus support is found at:
>
>
> http://energyplus.helpserve.com or send a message to
> energyplus-support@...
>
>
> The primary EnergyPlus web site is found at:
>
>
> http://www.energyplus.gov
>
>
> The group web site is:
>
>
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
>
> Attachments are currently allowed but be mindful that not everyone has a
> high speed connection. Limit attachments to small files.
>
>
> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf
> under the Documentation link and press the "search"
> button.
>
> Yahoo! Groups Links
>
>
>
>
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
>
> Individual Email | Traditional
>
>
>
>
> http://groups.yahoo.com/group/EnergyPlus_Support/join
>
> (Yahoo! ID required)
>
>
> EnergyPlus_Support-digest@xxxxxxxxxxxxxxx
>
>
> EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx
>
>
>
> EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
>
>
>
>
> http://docs.yahoo.com/info/terms/
>
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___