These reports may be ordered, free of charge, from the Simulation Research Group at
Lawrence Berkeley National Laboratory.
Kathy Ellington
MS: 90-3147
Lawrence Berkeley National Laboratory
Berkeley, CA 94720
USA
Fax: 510-486-4089
Email:
info@gundog.lbl.gov
LBL-37979
COMPARISON OF DOE-2 WITH MEASUREMENTS IN THE PALA TEST HOUSES
Abstract:
The predictions of the DOE-2 program for building energy analysis have
been compared with measurements in the Pala test houses near San Diego,
California. This work is part of the California Institute for Energy
Efficiency's "Alternatives to Compressor Cooling in California
Transition Zones" project in which DOE-2 is being used for parametric
analysis of cooling strategies that reduce peak electrical power in hot
and dry climates. To establish the validity of DOE-2 for this kind of
analysis the program was compared with room air temperature
measurements in a "low-mass" however with conventional insulated stud
wall construction and a "high-mass" house with insulated concrete
walls. To test different aspects of the DOE-2 calculation, four
different unconditioned thermal configurations of these houses were
considered: unshaded windows, shaded windows, white exterior surfaces,
and forced night ventilation. In all cases, DOE-2 agreed well with the
air temperature measurements, with a mean deviation between
simulation and measurement ranging from 0.2 to 1.0K depending on
configuration and type of house. Using a development version
of DOE-2, comparisons with inside surface temperature measurements
were also made. These comparisons showed good agreement.
LBL-37300
DEVELOPMENT OF A SIMULATION TOOL TO EVALUATE THE
PERFORMANCE OF RADIANT COOLING CEILINGS
Abstract:
Hydronic cooling systems are particularly suited to the dry
climates typical of California. These systems have been used for more
than 30 years in hospital rooms to provide a draft-free, thermally
stable environment. However, the energy savings and peak-load
characteristics of these systems have not yet been systematically
analyzed. Moreover, adequate guidelines for their design and control
systems do not exist. This has prevented their widespread application
to other building types. . . . The scope of this project is to develop
a model that can accurately simulate the dynamic performance of
hydronic radiant cooling systems. The model, SPARK, provides a
methodology for describing and solving the dynamic, non-linear
equations that correspond to complex physical systems. The potential
for hydronic radiant cooling systems applications can be determined by
running this model for a variety of construction types
in different California climates.
ASH1
MODELING THE SOLAR HEAT GAIN REFLECTED
FROM NEIGHBORING STRUCTURES
Abstract:
The authors have developed algorithms based on a ray-tracing program to
calculate the contribution of reflected solar radiation from
neighboring structures to the solar gain in a building. The algorithms
are optimized for accuracy and computation time, can be linked to
building energy simulation programs, and run on DOS machines. This
paper reviews the common approaches for calculating the exchange of
radiation between surfaces, describes the algorithms, and presents
results for a small commercial building. The results compare the
influence of diffusely and specularly reflecting surroundings.
Specularly reflecting surfaces can increase solar gain through windows
by more than 10 times the amount of that through a window with only the
ground reflecting back to it. Results from detailed calculations are
also compared with those that have been optimized for time and
accuracy.
EB-1
A DIRECT TRANSLATOR FROM NEUTRAL MODEL FORMAT TO THE SPARK SIMULATION ENVIRONMENT
Abstract:
The neutral model format (NMF) provides generic, machine-readable
descriptions of equation-based component models of a physical system in
a building description. It is intended to allow model interchange
between different simulation environments. The simulation problem
analysis and research kernel (SPARK) is a simulation environment that
generates source and executable code for solving non-linear
differential-algebraic equation systems. It is intended to automate the
generation of modular, easy to maintain simulation programs. The goal
is to generate simulation code automatically from NMF models
transparently to the user. A translator achieving this goal is
described herein; it transforms NMF syntax into SPARK syntax through
the use of LEX and YACC for parsing and numerical inversion techniques
to generate SPARK code. Thus, the practicality of NMF as a common
description language for building simulation is demonstrated for the
case of simulation environments developed independently from NMF. The
purpose of this paper is to give an account of the experience of
building a translator from a general model
representation format (NMF) to a particular simulation environment. We
first present the NMF format, then the SPARK building simulation
environment, Then the first translator from NMF to SPARK via a computer
algebra system is presented, along with examples. That translator
being too circuitous, a newer and direct translator is then presented
along with practical examples. Thus are demonstrated the usefulness of
the NMF concept and the methodology for building a translator from it
to an independently developed simulation environment for building
science.
IBP95-1
HVAC COMPONENT MODEL LIbr FOR EQUATION-BASED SOLVERS
Abstract:
This paper discusses development of a library of equation-based
models for building HVAC system simulation. The main source
of the models is the ASHRAE Secondary Systems
Toolkit Brandemuehl 1993), augmented with primary system models from
other sources in order to provide a library sufficient to model common
HVAC systems. While the target of this work was the Simulation Problem
Analysis Research Kernel (SPARK), a number of issues arising in
construction of the library are of interest whenever models are to be
expressed in equation-based non-algorithmic form. Among other results
it is shown that models of this nature benefit from finer modular
granularity than equivalent component-oriented models, and that there
are important issues of connectability and computational efficiency
that can be addressed with a new approach to modeling units
of physical measure.
LBL-35439
SYMBOLIC MODELING IN BUILDING ENERGY SIMULATION
Abstract:
We show how symbolic modeling is used in the Simulation Problem
Analysis and Research Kernel (SPARK) for solving complex problems in
building energy simulation. After a brief overview of SPARK, we
describe its symbolic interface, which reads equations that are entered
in symbolic form and automatically generates a program that solves the
equations. The application of this method to solving the partial
differential equations for two-dimensional heat flow is illustrated.