The new City of Santa Clarita Transit Maintenance Facility, designed by HOK
has been certified a LEED® Gold building by the U.S. Green Building Council.
Through an unconventional use of materials, the project has become one of the
first LEED-certified straw-bale buildings in the world. The LEED (Leadership
in Energy and Environmental Design) Green Building Rating System is a voluntary,
national standard for developing high-performance, sustainable buildings.
In an effort to improve air quality in the Santa Clarita Valley, the City of
Santa Clarita's municipal transit system decided to convert its entire bus fleet
from diesel to Compressed Natural Gas (CNG), a conversion that required a modern
maintenance headquarters. Completed in May 2006, the new facility includes a
22,000-square-foot administration building, 25,000-square-foot maintenance building,
bus wash facility, CNG fueling island for City buses, and publicly accessible
CNG fueling station. The $20-million project is designed to accommodate more
than 150 buses and nearly 160 staff, with room for future expansion.
Consistent with its effort to operate in an environmentally conscious manner,
the City sought to achieve the highest LEED rating possible within budget. The
integrated design team, consisting of the owner, architect, MEP engineering
consultant and landscape architect, determined that straw-bale construction,
an uncommon technique generally used in residential development, would best
meet the City's needs.
Although highly innovative today, straw-bale construction was pioneered more
than a century ago. Its durability, resistance to burning and pest infestation,
and high insulation value make straw bales one of the most efficient, cost-effective
building materials for one- and two-story applications.
The Santa Clarita building envelope is constructed of straw bales with a lime
plaster layer on both the interior and exterior. This creates an efficient,
super insulated building perimeter to complement the large day-night temperature
swings of the surrounding desert climate.
"Straw-bale construction may be a rediscovered technology, but it is appropriate
and sustainable by today's standards. When combined with more recent technologies
such as under-floor air distribution, high-performance glazing, and daylighting--as
it is in this project--it can be part of a powerful strategy for creating an
energy and resource-efficient building," said HOK's Charles Smith, Senior
Project Manager. "We were able to exceed California Energy Efficiency Standards
by over 40 percent."
"Straw-bale construction opens up the possibility of a whole new aesthetic
as well. It's one in which only essential materials are needed to render form
while achieving a cost- and energy-efficient building and promoting a healthier
indoor environment--the basis of a sustainable design."
Not only does the technique save on the use of traditional, non-renewable materials,
it also provides the added environmental benefit of reducing the quantity of
straw burned. In California, readily available and inexpensive rice straw is
a waste product of the grain farming industry. Until recently, the burning of
rice straw was the single largest contributor to air pollution in the state.
Additional sustainable features of the building include: skylights and clerestory
daylighting, a well-insulated "cool" roof with deep overhangs to shade
clerestories and protect straw-bale walls from moisture, on-site stormwater
collection and treatment, water-efficient plumbing fixtures, a gray water reclamation
system, an under-floor air system, water-source heat pumps, a courtyard and
native plant garden, 25% fly ash paving, and efficient use of local, recycled
materials. The project's less-is-more approach has resulted in a facility with
a high level of sustainability on a budget consistent with conventional buildings
of the same type and size.
"Recognition from the USGBC is an honor to receive because it acknowledges
our City's commitment to environmental stewardship and social responsibility.
Each year our City strives to reduce operating costs and conserve our natural
resources to create a cleaner, healthier Santa Clarita," commented City
Mayor Marsha McLean.
The Santa Clarita Transit Maintenance Facility represents HOK's 12th project
to earn LEED recognition from the U.S. Green Building Council.