[BLDG-SIM] DOE 2.2 experiences?

Jeff Thornton thornton at tess-inc.com
Mon Jun 7 11:40:00 PDT 1999

At 10:04 AM 6/3/99 -0700, you wrote:

>We have been particularly frustrated with the ground source heat pump
>algorithms.  After a week of getting inconsistent and unexplainable results,
>a call down to LBNL revealed that the ground loop algorithms are
>"unreliable" and "should not be used."  Instead, they recommended scheduling
>water temperatures, which we eventually did.  The results still seem
>optimistic, but at least the simulation is working somewhat predictably.

You are not the only one that has had problems with the ground source
models in DOE-2.  Oak Ridge National Labs and our company (TESS) has just
finished a "simulation calibration to data" exercise of TRNSYS and DOE-2 on
a school in Lincoln Nebraska.  Howard McClain of ORNL has just published a
paper on his findings with the DOE-2 gshp model and they are not real good
(ASHRAE paper).  The results from TRNSYS using the DST ground heat
exchanger model from the University of Lund Sweden were excellent.  Richard
Gordon of AEMT in Corvallis Oregon has also struggled with the GHP routines
in DOE-2.

For the past several years we have modeled gshp systems in TRNSYS for a
variety of projects including:

1) Apartment level simulations at Fort Polk LA - the largest GHP project in
the world.
2) Feeder level calibrations/simulations (200 apartments) for Fort Polk
that predict the annual energy usage within 1% of that measured at the site.
3) Residential GHP calibrations for northern climates
4) Simulations used as the government estimates of GHP savings for a
large-scale retrofit at Oceana Naval Air Station
5) Simulations used as the government estimates of GHP savings for a
large-scale retrofit at Little Creek Naval Amphibious Base
6) Calibration to data at 4 schools in Lincoln Nebraska.
7) Calibration to data at Daniel Boone High School (TN) - in progress

Several of these projects used the DOE-2 building loads from a separate
firm and we were tasked with doing the system simulations.  I have several
reports and papers (some to be published at future ASHRAE meetings) if
anyone is interested in our findings.  The results in terms of energy
consumption, 15-minute peak demand, and max/min entering water temperatures
to the heat pumps are very close to those measured - even with the loss of
accuracy encountered by using "energy-rate" loads from DOE-2 (and ignoring
the system/building interactions that TRNSYS could handle).

As a result of the calibration exercise at a school in Lincoln Nebraska, we
have measured data of 54 separate ground source heat pumps for a period of
three years at the school.  If anyone is intersted in comparing their
statistical predictions with reality at this school, e-mail me and I can
give you the details of the building/system.  The simulation of this
building and its heat pumps is performed at 15-minute timesteps in TRNSYS
such that the demand can be estimated more accurately and the thermal
"fighting" between adjacent heat pumps in this "open architecture" school
can be studied.  We have since made a software "movie" of the fighting
between the adjacent zones over the period of a typical year and the
results are fascinating.  I can send the program to anyone who wishes to
see it.  With the simulation in place, lots of "what if" scenarios can be
studied including some recent work on the demand effects of night



Jeff Thornton
Founding Partner - Thermal Energy System Specialists
Experience: 10 Years of simulation and modeling of building and systems
with emphasis on renewable and emerging technologies.  Former TRNSYS
coordinator at the University of Wisconsin.

Jeff Thornton		    Thermal Energy System Specialists
Partner			    5610 Medical Circle - Suite 31
			    	    Madison WI 53719

Phone: (608) 274-2577	    E-mail: thornton at tess-inc.com
Fax:   (608) 278-1475	    Web Page: http://www.tess-inc.com

"Providing Software Solutions for Today's Energy Engineering Projects"

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