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

[Jon Hand]

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 [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
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