CASE STUDIES: Hawaii Gateway Energy Center
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Natural Energy
Laboratory of Hawaii Authority (NELHA)
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 AIA Committee on the Environment (COTE) Top Ten Green Projects for 2007 |
2006 Northwest & Pacific Region of the AIA Citation Award |
 2005 LEED-NC® Platinum Certification for Sustainable Design |
 2005 Honolulu AIA Award of Excellence for Sustainable Design |
BACKGROUND:
Spearheaded by the State of Hawaii's Natural Energy Laboratory of
Hawaii Authority (NELHA) and funded by the U.S. Department of Energy,
the $3.5M Hawaii Gateway Energy Center (HGEC) is the first phase
of what is anticipated to develop into a campus for renewable energy
and related high technology research.
PROGRAM:
Program requirements for the HGEC project included the following:
- As a "Gateway," the new facility shall reflect 21st century cutting-edge technology, strong aesthetic, environmental stewardship, and cultural sense of place.
- Design principles of sustainable architecture shall be incorporated including consideration for zero-net energy by incorporating solar energy, advanced cooling technology, and other applicable technologies to meet the building's needs and immediate surrounding area energy demands.
- The visitor center shall provide "Front of House" facilities such as an auditorium and public restrooms to facilitate education, outreach programs, and exhibitions.
- Facility shall serve as a distributed energy facility and should emphasize the use of new and existing alternative and distributed energy concepts designed to minimize fossil fuel dependence.
- The new facility shall make optimum use of deep seawater applications and recognize the limited availability of potable water.
- The new facilities should incorporate concepts advanced in the LEED® Green Building Rating System wherever practicable.
The site of the HGEC is hot, humid, and barren. Mean average daytime
temperature is 88 to 90 degrees Fahrenheit with average relative
humidity at 85% to 90%. Rainfall is typically 10 to 15 inches per
year, and annual insolation is the highest in the United States.
The general terrain is a pahoehoe lava field covered with fire grass
and coastal shrubs.
APPROACH:
Simply put, the keystone of energy conservation is architecture.
Conventional architecture often fails to take advantage of passive
design strategies such as building orientation, shading, insulation,
daylighting, and natural ventilation. As a result, most buildings
end up consuming much more energy than necessary.
The architectural approach for the HGEC project was to design a
building which took advantage of all available sources of natural
energy, thus requiring very little electricity from the local utility
to operate. Besides energy conservation, sustainable design principles
were used throughout the design of the facility to achieve water
conservation, superior indoor environment for occupant health, and
even to establish the building's own unique visible identity as
an energy "Gateway."
SOLUTION:
The ventilation and cooling system at HGEC is a good example of
a passive design strategy that dramatically reduces the need for
electrical power from the utility. Instead of settling for an "energy
efficient" conventional HVAC system for the project, the design
team eliminated the need for conventional air-conditioning altogether.
This was achieved by "engineering" the building's architecture to
move air on its own, utilizing a unique thermal chimney design.
A thermal chimney is simply a building element that is designed
to absorb and transfer heat to the air within it, and then allowing
that air to rise and exhaust. When this occurs, replacement air
is drawn into openings lower in the chimney and a continuous thermo-siphon
is created as long as the chimney is heated. At the HGEC project,
the thermo-siphon is the "engine" that moves ventilation air.
Thermal chimneys need not look like chimneys per se. For the HGEC
project, the "chimney" is actually the curved copper roof and void
space immediately beneath it. The copper roofing transfers the heat
from solar radiation into the void space. This heat is prevented
from affecting the occupied space below by a well-insulated ceiling
system. The heated air rises and exhausts out of a series of round
ducts that emerge from the north fascia.
As the hot air exhausts, replacement air is drawn into the roof
void from the occupied space below. The air in the occupied space
is replaced by fresh air from a below-floor plenum that is connected
to an outside air inlet structure. The incoming fresh air is cooled
and dehumidified as it is drawn across coils (filled with deep seawater
at 47 degrees Fahrenheit) that are suspended in the inlet structure.
This cycle continues all day, providing 10 to 15 air changes per
hour of cooled and conditioned fresh air to building occupants (the
code allows as little as 3 air changes per hour). The only energy
consumed is for the circulating pump that delivers the deep seawater
to the coils.
As a side benefit, condensation water from the coils is collected
and used for irrigation and toilet flushing.
In addition to its thermal chimney design, the buildings are oriented
to take advantage of daylighting (eliminating the need for electric
lighting during the day), and shading (eliminating the need for
cooling by avoiding direct solar heat gain).
CONCLUSION:
For building operations (ventilation, cooling, and lighting) the
HGEC project consumes only 2.5 kWh/sf/year, while the most energy
efficient conventional building of the same type can consume 15
kWh/sf/year or more and still comply with the Model Energy Code!
Similarly, HGEC's induced ventilation system provides a healthy
12 to 15 air changes per hour of 100% outside air, compared to the
accepted industry standard of 6 air changes per hour (air that is
re-circulated with only a modest percentage of outside air). The Hawaii Gateway Energy Center is an excellent example of sustainable architecture.
Project Team/Information:
| Owner/Developer: | Natural Energy Laboratory of Hawaii Authority (NELHA) | |
| Architect: | Ferraro Choi And Associates | |
| Structural: | Libbey Heywood, Inc. | |
| Mechanical/ Electrical/ Lighting/ Energy Consultant: | Lincolne Scott, Inc. | |
| Civil Engineer : | RM Towill Corporation. | |
| Landscape Architect: | LP&D Hawaii . | |
| LEED® Management | ENSAR Group, Inc. (now known as RMI/ENSAR Built Environment | |
| Commissioning Agent: | Environmental Economics, Inc. | |
| Contractor: | Bolton, Inc. | |
| Space Frames: | Triodetic Building Products Ltd. | |
| Photography: | David Franzen |
Refer also to Sustainable Architecture: HGEC Project or Project Portfolio
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