energy
design
resources
Tortilla Manufacturing Produces
Energy-Saving Opportunities
In recent years, sales of Mission Foods’ Mexican food products have been
increasing so rapidly the company has been building an average of one to two
new production facilities a year. As demand for their product had grown in the
Inland Empire, it was decided the time had come to build a new facility in that
region. The new Mission Foods Production Facility in Rancho Cucamonga is
basically a one-story concrete tilt-up building containing approximately 50,000
square feet for administrative and support areas in a two-story office section,
125,000 square feet for manufacturing, and 134,000 square feet for warehous-
ing. The production and packaging areas are divided into three product-ori-
ented sections: flour tortillas, corn tortillas, and fried products. The warehouse
area also houses large coolers for storing products and ingredients.
Plans for the new facility indicated that the largest energy-consuming sys-
tems in the factory would include process equipment for manufacturing tor-
tillas and chips and refrigeration equipment for storing product. Because food
processing equipment transfers large amounts of heat to a manufacturing area,
space cooling would also be a major load. Since alterations to the process sys-
tems were not feasible, the design team, working with energy consultants from
the electric utility, focused on developing strategies that would reduce energy
requirements for space conditioning. Additional energy efficiency measures
included lighting and glazing efficiency improvements.
One of the primary energy-saving measures of the facility is the use of
evaporative precoolers on the air handlers that serve the manufacturing areas.
These precoolers reduce the temperature of outside air entering the building
and are particularly effective due to the dry climate conditions in the region.
Since the outside air requirement in manufacturing areas is a minimum of 50
percent, the resulting energy savings are substantial. Additionally, indirect evap-
During a meeting to discuss power
needs for the new plant, the local
electric utility offered Mission Foods
the opportunity to participate in its
new construction design assistance
program. Recognizing that they could
reduce their operating costs by
designing their new plant to be ener-
gy efficient, the managers were very
interested in participating, but con-
cerned about negative impacts on
their fast-track construction sched-
ule. As they are now saving over
three hundred thousand dollars
every year on energy costs, mission
foods managers are confident that
their decision to focus on energy
efficiency was the right one.
pg_0002
orative cooling equipment, rather that mechanical cooling, serves the manufac-
turing support areas. This measure reduces the load on the chilled water plant
without raising the humidity of the space, and subsequently reduces the
amount of energy needed for pumping chilled water.
In the refrigeration plant, a high-efficiency screw compressor chiller is used
to generate chilled water for all space conditioning in place of a conventional
centrifugal chiller. In addition, an evaporative condenser with a two-speed fan
takes the place of a conventional open cooling tower, as it takes up less space
and reduces the water pumping and chemical treatment requirements associat-
ed with a cooling tower.
Further space-conditioning enhancements include a combination of pre-
mium efficiency motors and variable speed drives (VSD). The motors were
upgraded in all air handlers and for all pumps. VSDs were installed in place of
inlet vanes in the administrative and support area air handlers to modulate the
equipment according to the space cooling and heating requirements. VSDs
were also used in place of cycling equipment in the air handlers serving the
packaging areas. Additionally, a VSD modulates the chilled water pump serv-
ing the air handlers.
One energy efficiency measure that was studied and recommended, but
not originally implemented due to first-cost restrictions, was the addition of a
VSD to the screw compressor serving the central plant chiller. This feature is
now being added to allow for more effective modulation of the chiller capacity
based on actual cooling requirements, to further increase the operational effi-
ciency of the plant.
Lighting system improvements in the facility include the use of T-8 lamps
and electronic ballasts in the office area and metal halide fixtures in the open
manufacturing areas. Occupancy sensors in all enclosed office and support areas
are used to turn off lights when these spaces are not being used.
Windows in the office areas, which are primarily on the north and east
sides of the building, use glazing with a low-emissivity coating. Skylights which
provide abundant natural light to the production and packaging areas also
include a low-emissivity glazing. The mostly invisible, metallic low-emissivity
coating helps reduce heat gain to these spaces without reducing the amount of
visible light illuminating the interior.
Mission Foods facility managers think
their plant is so successful that they
have entered a corporate-wide compe-
tition focusing on overall facility
quality. To demonstrate the ways in
which their facility outperforms
other production facilities, they
included a discussion of the energy
efficiency measures and the resulting
benefits. They believe their chances
of winning are practically assured.
CHI LLE R
B OI LE R
S UP PLY FA N
ZONE
US ED WHE N 5 0% OA
R ETU RN F A N
EX HAU ST
F A N
US ED
WH EN
1 0 0% OA
EC ONOM IZ ER
EX HA UST A I R
A DDI TI ON AL
O UTS I DE AI R
EV A P
COO LI NG
PU MP
MA KE -UP WAT ER
S EC ONDA R Y F A N
S EC ONDA R Y
O UTS I DE AI R
OUT SI DE A I R
C
/
C
H
/
C
Annual Energy (kWh)
Electric Demand (kW)
Annual Electric Cost ($)
21,834,900
17,955,000
3,628
2,998
1,786,000
1,471,700
Base Case
As-Built