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Computer rendering of the new
federal building to be built in San Francisco. The building
was designed with the aid of the EnergyPlus software distributed
and partly developed by Berkeley Lab. |
Licensed Technologies - EnergyPlus Software
EnergyPlus Saves Federal Building $9
Million in Energy Costs
By Robin Johnston, June 2002
EnergyPlus software a building energy simulation program
distributed by Berkeley Lab has been integral to the design
of a new federal office building to be built in San Francisco. EnergyPlus
contributed to nearly $9 million in energy costs savings projected
over 20 years, according to Tim Christ, project manager for the
buildings lead design firm, Morphosis. The modeling tool was
also used to simplify the buildings facade, saving taxpayers
an additional $1.5 million in construction costs. Groundbreaking
for the building is scheduled for July 15.
The simulation program allows designers to calculate the impacts
of different heating, cooling, and ventilating systems, as well
as that of various types of lighting systems and windows. EnergyPlus
was developed as a collaborative effort between Berkeley Labs
Simulation Research Group, led by Fred Winkelmann of the Environmental
Energy Technologies Division, the University of Illinois at Urbana-Champaign,
and the U.S. Army Construction Engineering Research Laboratory,
with assistance from other research organizations. The DOE Office
of Building Technologies funded the project.
We are the first people to use EnergyPlus to model natural
ventilation flows for a major building, notes Philip Haves
of the Commercial Buildings Systems Group at Berkeley Lab.
The new San Francisco building will use natural ventilation to
provide cooling without the use of fans or refrigeration. Most of
the year the building will be cooled by natural airflow through
the windows. In hot weather, interior heat is absorbed during the
day by exposed heavy weight ceiling slabs; the stored heat then
dissipates at night when the air is cooler. Cooling and ventilation
were maximized by orienting the building and its windows to take
advantage of natural wind conditions.
Erin McConahey of Arup, the engineering consultants on the project,
says, Basically, other energy simulation programs cant
deal with the natural ventilation issues. The combination of air
flow and energy modeling in a single package not only allowed us
to predict energy performance, but also to calculate surface temperatures,
track air change rates, and predict thermal comfort. The Berkeley
Lab modeling tool provided crucial corroboration of our design work.
Implementation of natural ventilation required a complete rethinking
of interior office space design. Instead of having cellular
offices around the outside of the building and open plan office
space in the interior, free air flow required open plan office space
on the exterior and cellular offices and other enclosed spaces along
the spine. These enclosed spaces have lowered false ceilings with
space above to allow air driven by wind pressure to flow from one
side of the building to the other, explains Haves. Although
this stands traditional hierarchical office structure on its head,
the concept was ultimately accepted by the General Services Administration,
the federal client for the project.
In 2000, when the San Francisco federal building project was in
its infancy, architects with Morphosis were interested in using
only natural ventilation for the top 13 floors. Security concerns
mandated that the lower floors be completely sealed. They were hesitant
to move forward with the idea, however, without some validation
through modeling to assure them that the building could meet comfort
standards without air conditioning. An EnergyPlus modeling analysis
conducted by Haves convinced the design team and its clients that
natural ventilation would keep the building comfortable during San
Franciscos brief but significant episodes of hot weather.
When we first started, we werent sure which modeling
program would enable us to gain a full understanding of how the
building systems would all come together, says Christ. The
EnergyPlus model gave us a more accurate picture and led to a considerable
increase in efficiency and direct savings in construction costs.
We would not have been able to get there without Phils input.
Although Berkeley Labs contribution to the design of the
building has been completed, Haves is still working on the project,
helping the designers with strategies to optimize indoor comfort
by opening and closing windows at different times of the day.
One problem designers still need to address is how to reconcile
these automated strategies aimed at overall building comfort with
the desire to allow individuals to open and close windows near them.
The use of operable windows and day-lit interiors was found to contribute
to the productivity, health, and workplace satisfaction of building
occupants, according to studies conducted by Gail Brager, a professor
at UC Berkeley.
Seth Rosen of Berkeley
Labs Technology Transfer Department explains, Our software
licensing strategy for EnergyPlus was designed to create a community
of contributing developers whose skill and expertise could complement
the core EnergyPlus development team. Its gratifying to see
this strategy succeed.
Editor's update:
As of September 30, 2007, the program has been licensed by over 55,000 end users, 97 collaborative developers, and 27 commercial distributors.
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