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Re: [EnergyPlus_Support] Transient simulation of building structure and indoor air
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
> > >
> > >
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