The Use of Computational Fluid Dynamics in Natural Ventilation
David Banks, Cermak
Peterka Petersen Inc.
Robert V. Schroeder,
P.E., Glumac International
This presentation illustrates the manner in which Computational
Fluid Dynamics (CFD) can be used to model internal flows for natural
ventilation in research buildings. The presentation will describe
both the strengths and limitations of CFD for this type of analysis.
The objectives of our presentation will illustrate the process
of how computational fluid dynamics fine tunes the building into
a model of energy efficiency and promote natural ventilation strategies.
The key is to provide the CFD modeling very early in the project,
when the ability to change the architectural features is easy to
accomplish. This is true because CFD modeling typically identifies
subtle nuances that will allow natural ventilation to occur, provided
the building architecture is willing. This will always include tradeoffs,
and those can be easily made in the early stages of the design.
This process is highlighted in our presentation.
The next objective is to get the end user occupant to buy in on
all of these considerations. This will allow more of the building
to open up to the outside and have more occupant control. Once buyoff
is accomplished, systems can be downsized and reduce operating hours.
The energy implications are obvious.
A CFD analysis allows an estimate of the energy savings due to
natural ventilation to be made. By performing a CFD analysis as
a design tool at an early stage of the building formation, the locations
of natural ventilation inlets and exhausts can be selected to take
advantage of external wind pressures patterns on the building.
We would also like to discuss what worked well in terms of final
design features and what did not due to other constraints. This
produces tradeoffs between building architectural, structural, electrical
and mechanical components that led to a best fit to satisfy everyones
concerns. In some cases natural ventilation strategies had to be
modified and rerun through the CFD model to determine performance
characteristics. We would also like to discuss the implications
of commissioning on the project as it relates to these intricate
systems to ensure that ventilation strategies are employed.
The Labs21 approach is akin to the LEED process for laboratory
buildings and looks at whole building analysis. Towards that end,
our experience is that mechanical and electrical systems can be
simpler and more straight forward assuming that the architectural
building is fully integrated and takes advantage of natural architectural
elements and outdoor environmental considerations. We would like
to discuss the aspects of the energy and CFD models that relate
to fine tuning of the building relative to these subsystems. As
always, a green building promotes energy conservation through all
of its components and this will be illustrated on our project. The
issue of productivity is one that is brought up a lot in concert
with sustainable buildings and feel that natural ventilation strategies
through CFD modeling will truly promote a working environment that
is more desirable.
David Banks completed
his Ph.D. in Wind Engineering at Colorado State University in 2000.
His dissertation focused on the fluid dynamics of roof corner vortices.
It produced four refereed publications was awarded the Robert H.
Scanlan Outstanding Ph.D Award at the 2001 Americas conference on
Wind engineering. He has both masters and bachelors degrees in Aerospace
Engineering from the University of Toronto. He worked for several
years as computer code review specialist at Canada's nuclear regulatory
agency. At CPP, he has recently worked on a range of internal flow
CFD simulations, including animal holding rooms, atrium fires, and
an external flow pollutant dispersion validation study.
Robert V. Schroeder,
P.E., is an Associate Principal at Glumac International. He has
extensive experience in all phases of the design, including supervision
of multi-disciplinary teams; preparation of all mechanical construction
drawings and specifications; construction observation; and cost
estimating. His expertise includes interfacing with clients, tracking
project schedules and budgets, and supervising engineering and CADD
personnel. Mr. Schroeder's project experience includes complete
mechanical system design for health care (hospitals and medical
office buildings), higher education (libraries, laboratories, and
campus buildings), commercial and institutional buildings; industrial
and municipal facilities, high tech (laboratories and clean rooms),
correctional facilities, museums, and cultural centers.