[esp-r] Re: Modeling HVAC power demand by seconds

[Achim.geissler]

In addition to the below I can verify that setpoints can be "easily" given
at time steps well below an hour via the "tdf" functionality (to date, I
have used 15 min intervals successfully - going shorter should only be a
question of generating the increasing amounts of data necessary).

Best
Achim



--------- Original-Nachricht --------
 Von: "Jon Hand" 
 An: "Max Epstein" , "esp-r at lists.strath.ac.uk" 
 Betreff: [esp-r] Re: Modeling HVAC power demand by seconds
 Datum: 07/07/10 12:03
 
 
 Some questions about HVAC frequency and reporting....  Initial answers
below each question.  Those
 who sped a bit more time with system components will hopefully provide
further clarification...
 ________________________________________
 From: esp-r-bounces at lists.strath.ac.uk
(mailto:esp-r-bounces at lists.strath.ac.uk" class="autolink)
[esp-r-bounces at lists.strath.ac.uk] On Behalf Of Max Epstein
[mepstein at enertaq.com]
 Sent: 06 July 2010 20:03
 To: esp-r at lists.strath.ac.uk (mailto:esp-r at lists.strath.ac.uk"
class="autolink)
 Subject: [esp-r]  Modeling HVAC power demand by seconds
 
 Hello, I would like to model commercial building HVAC operation and
especially power demand at a 2-10 second time-step. I read about ESP-r on
eere.energy.gov (US) that: “Building and flow simulations can be
undertaken at frequencies of one minute to one hour and system simulations
can be from fractions of a second to an hour.” Does this mean power
demand data can be output/recorded as fast as every 2-10 seconds?
 
 :: The zone solver can go down to a frequency of one minute. The systems
solver runs at a multiple of the zone solver and so
    it is possible to run at a one second timeframe for the system side
although many users would be happy with a longer timestep.
 
 :: Power demand needs some clarification -  some of the performance
attributes of components are available for
    analysis but some components do not include a full description of
electrical characteristics so everything that
    you want might not be available or only available if you fully define
the power characteristics of the building (the
    kind of stuff that an electrical engineer deals with).  
 
 Also, can thermostat setpoint adjustments be made dynamically while the
simulation is running in response to changing building conditions? Or can
many 10second (duration) simulations be strung together and automated with
dynamic thermostat setpoints implemented in between, according to
predetermined logic and evolving building conditions?
 
 :: The shortest simulation is one day.  One can schedule setpoints but I
don't think anyone has tried to do this at the minutely or
    sub-minutely time frame.  What kind of setpoint adjustments?  One of our
PhD students is working on a predictive control that
    takes in live data and uses the simulator as a virtual BEMS so all kinds
of things are possible if you have a lot of passion.
 
 I read on ESP-r’s capabilities page that modules can be driven by
scripts to automate tasks. Could you please elaborate on that functionality
in regards to the potential for modeling a building with dynamic thermostat
setpoint adjustments every 2-10 seconds, or at least every minute?
 
 :: For those working on Linux or OSX or Unix the scripting options would
fill a book.  Essentially ESP-r can be run in a text mode
    and take instructions from an outside agent.  The Install script creates
or updates about 190 models on the fly using scripts
    and scripts can be use to run standard assessments and extract reports. 
Some of this is dicsussed in the ESP-r Developers
    guide (on the ESRU web pages).
 
 Regards, Jon Hand
 
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