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Re: [EnergyPlus_Support] Transient simulation of building structure and indoor air
Mike and Ned,
Thank you very much for your reply. I tried to do what
you had suggested:
1).select an epw file, e.g., Chicago, and change it
into a csv file using the WeatherConverter;
2). Change the values in the csv spreadsheet and
convert it back to epw.
Step 1 was successful. However, Step 2 was not. When I
changed some values in csv and tried to convert it
back to epw, there was an error message and no epw
file was created. The original epw file I used was
directly downloaded from the website of EnergyPlus.
Step 2 failed Even I just retyped the same value in a
cell and save it without changing anything in the csv.
I still have the question about the thermal response
of building structures. In the output file, I could
see the temperatures of the inside and outside
surfaces of the walls. I would like to see
representative temperature of each wall (node?) to see
if we can take advantage of the thermal storage
capacity. Can I find such temperatures with
EnergyPlus?
Best regards,
Zhuo
--- "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> For your comparison, you need to establish the same
> starting
> conditions in each program. In EnergyPlus, the only
> way to control
> the starting conditions is to make a custom weather
> file as Ned
> describes below.
>
> Mike
>
>
> On 15 Jan 2003, at 14:49, Edward Lyon wrote:
>
> > so if you make your own weather file and set
> inside conditions and
> > outside conditions equal for a couple of days
> without any other loads,
> > such as solar, night sky radiation or occupancy,
> you will get a
> > starting condition of constant temperature after
> which you can change
> > the weather and interior set points to your cycle
> conditions and watch
> > the response of whatever you like....
> >
> > Ned Lyon
> >
> > Senior Staff Engineer
> > Simpson Gumpertz & Heger Inc.
> >
> > 41 Seyon Street
> > Building #1, Suite 500
> > Waltham, MA 02453
> >
> > Phone: 781-907-9000
> > Fax: 781-907-9009
> >
> >
> > >>> chenzhuo_99@xxxxxxxxx 01/15/03 02:18PM >>>
> > Mike,
> >
> > Thank you very much for your reply.
> >
> > Actually, what exactly I'm trying to do is to
> > repeatedly apply a one-day (24-hour) outdoor air
> > temperature boundary condition to a building for x
> > days and find out the temperature responses of the
> > indoor air and the building structures during
> these x
> > days. That's said, I'm not only interested in the
> > steady-state performance after x days as can be
> done
> > with EnergyPlus design-day simulation, but also
> (more)
> > interested in the transient process during the
> warm-up
> > or cool-down period. This is to find the
> intermediate
> > temperature profile during the warm-up period
> before
> > the steady state. Is it possible to find this kind
> of
> > results with energyplus? You mentioned EnergyPlus
> > could tell us how many warm-up days are needed to
> > reach the periodic steady state, but I really want
> to
> > know the values during those warm-up days to
> compare
> > against other softwares.
> >
> >
> >
> > Best regards,
> >
> > Zhuo
> >
> > --- "Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
> > > Zhuo:
> > >
> > > The design day simulations are repeated for
> several
> > > days in order to
> > > reach a periodic steady state. The "warmup"
> days
> > > end when the
> > > changes in temperatures and loads from one day
> to
> > > the next are within
> > > the tolerances specified in the BUILDING object.
>
> > > The number of
> > > warmup days is reported in the eio output file
> and
> > > it is limited to
> > > 25 days. If the tolerances have not been met
> within
> > > 25 days, then a
> > > warning is issued (Loads Initialization did not
> > > Converge) and the
> > > simulation proceeds. So, the design day
> simulation
> > > may already be
> > > doing what you want.
> > >
> > > If you prefer more direct control, you can make
> a
> > > custom epw weather
> > > file. The easiest way to do this is to take an
> > > existing epw file for
> > > the location you wish to model and use the
> Weather
> > > Converter to
> > > convert it into csv format. You can then edit
> the
> > > csv data in a
> > > spreadsheet program and then convert it back to
> epw
> > > format.
> > >
> > > Mike
> > >
> > >
> > > On 14 Jan 2003, at 12:51, lengjing lengjing
> wrote:
> > >
> > > > Hi,
> > > >
> > > > I抦 trying to compare several softwares
> > including
> > > > EnergyPlus in terms of their transient
> simulation
> > > > capabilities. I have used EnergyPlus for
> design
> > > day
> > > > analysis before, which is steady state and can
> be
> > > done
> > > > by selecting the location and then the
> design-day
> > > > temperature profile is automatically generated
> by
> > > > EnergyPlus.
> > > >
> > > > However, in order to compare the transient
> > > performance
> > > > of EnergyPlus with several other softwares
> that
> > > are
> > > > not based on the epw weather format, I would
> like
> > > to
> > > > use some randomly generated hourly temperature
> > > values
> > > > as the same input for all the programs. To put
> it
> > > > simple, I want to compare the temperature
> > > responses of
> > > > the indoor air and the walls (or even
> different
> > > layers
> > > > of the walls) under both steady-state and
> > > transient
> > > > conditions. For example, use a 24-hour
> temperature
> > > > data as the periodic weather input and find
> the
> > > > temperature responses until the temperatures
> of
> > > indoor
> > > > air and the walls have reached steady states.
> It
> > > might
> > > > take several days, say, x days, for the
> > > temperatures
> > > > to reach steady states. Is this possible with
> > > > EnergyPlus? If so, could you please tell me
> how to
> > > put
> > > > in my own temperature values? If not, can I
> just
> > > run a
> > > > design day and look at the temperatures of air
> and
> > > > walls during these x days from warmup until
> steady
> > > > state? Thank you very much in advance for your
> > > help.
> > > >
> > > >
> > > > Regards,
> > > >
> > > > Zhuo
> > > >
> > > >
>
>
>
========================================================
> EnergyPlus Testing and Support
> EnergyPlus-Support@xxxxxxxx
>
>
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