[esp-r] Re: Start-up days and quasi steady-state

[Ferguson, Alex]

Hi Liam,

 

You can access the start-up data if you've compiled a version of ESP-r
with support for XML output. When running bps, select "configure H3K
Reports" from the integrated simulator menu. Then:

 

-         Select "a H3K Reports >> disabled" to enable the facility.

-         Select "e Report startup period"

-         Select "f All data"

 

When run, bps will produce a file called out.csv, which will contain
(among other things) the temperatures of all layers in the building. 

 

I'm not sure I understand what you mean by "Basically, the temperature
graph of the thermal mass drops from 22C to 19C in an instant".
Remember, results from a discrete simulation do not imply that state
variables remain constant over the entire time-step. The solution at
each time-step reflects the estimated instantaneous temperatures at that
point in time, based on the prevailing conditions at the current and
previous time-steps. Results from an hourly simulation showing a
temperature change from 22C to 19C suggests a 3 degree drop over an
hour. Increasing the time resolution to five-minutes or one-minute may
help you discern the cause of this temperature change.

 

Hope that helps,

 

- Alex 

 

________________________________

From: esp-r-bounces at lists.strath.ac.uk
[mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Liam O'Brien
Sent: Friday, January 25, 2008 17:57
To: esp-r at lists.strath.ac.uk
Subject: [esp-r] Start-up days and quasi steady-state

 

One more question:

I am interested in observing the effects of a particular climate pattern
for a single day that is repeated many times (i.e. quasi steady-state is
reached).  I am simulating 36 start up days (to be safe) for a
simulation period that lasts only one day.  I acknowledge that the
ambient temperature should not necessarily be continuous (i.e.
temperature at beginning of the day will not match the end).  However, I
am puzzled by the fact that a large thermal mass in my building does not
appear to show any effects at 12:30am of the stored heat from the day
before.  Basically, the temperature graph of the thermal mass drops from
22C to 19C in an instant.  This indicates that a huge amount of energy
disappears.  I have copied the temperature of the node at the center of
the mass:

00h30      19.45

01h30      19.34

02h30      19.24

03h30      19.13

04h30      19.03

05h30      18.93

06h30      18.83

07h30      18.73

08h30      18.66

09h30      18.63

10h30      18.71

11h30      18.92

12h30      19.28

13h30      19.77

14h30      20.36

15h30      20.99

16h30      21.61

17h30      22.15

18h30      22.56

19h30      22.82

20h30      22.93

21h30      22.92

22h30      22.82

23h30      22.66    

Since the performance data cannot be viewed for the start up days, it's
difficult to see what's really happening.  Can anyone suggest what might
be happening here?

I am using the native Windows version.

Any insights would be very helpful.  Thanks.

Liam O'Brien








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