Appendix B 327
ment performance.
The adjustments term in equation (1) is computed by running the
simulation model under appropriate sets of conditions as needed to
bring the two energy use terms to a common set of conditions.
Accurate computer modeling and calibration to measured data are
the major challenges associated with Option D. To control the costs of
this method while maintaining reasonable accuracy, the following points
should be considered when using Option D:
1 Simulation analysis needs to be conducted by trained personnel
who are experienced with the particular software and calibration
techniques.
2 Input data should represent the best available information includ-
ing as much as possible of actual performance data from key
components in the facility.
3 The simulation needs to be adjusted (“calibrated”) so its results
match both the demand and consumption data from monthly
utility bills within acceptable tolerances. The use of actual weather
data may be necessary in cases where the actual weather data
varies significantly from the average year weather data used in
the simulation. Close agreement between predicted and actual
annual total energy use is usually insufficient demonstration that
the simulation adequately predicts the energy behavior of the facil-
ity.
4 Simulation analyses need to be well documented with paper and
electronic copies of input and output files as well as the survey and
metering/monitoring data used to define and calibrate the model.
The particular version number of the software should be declared
if it is publicly available so that any other party can fully review
the many computations within the simulation.
ASHRAE’s Guideline 14P is expected to provide technical details
on a similar method (ASHRAE 2000).
3.4.4.1 Option D: Types of Simulation Programs
Information on the different types of building simulation models
can be found in the ASHRAE Handbook (1997). DOE also maintains a
current list of public domain and proprietary building energy simula-
tion programs. This information can be obtained by accessing DOE’s