## **Western Digital: Comprehensive Cleanroom Facility Renovation and Cleanliness Upgrade**

##### Facility Description

![](media/image1.png){width="2.2395833333333335in"
height="1.6847222222222222in"}The high-tech factory shown in figure 1 is
located outside Kuala Lumpur, the capital of Malaysia, and is owned and
operated by Western Digital, Inc., a US based computer hard disk drive
manufacturer. Western Digital (WD) set out to renovate an existing
semiconductor manufacturing plant to create a state-of-the-art hard
drive manufacturing facility. The renovation called for an increase in
floor area from 80,000 to 90,000 square feet and an increase in the
cleanliness requirements for the cleanroom from class 10,000 to class
10.

###### **Project Description**

It was expected that the increase in floor area and cleanliness would
increase loads substantially. Instead, through innovative design and
careful attention to system effects on energy efficiency, the remodeled
building used 44% less energy than the original facility. In addition to
the efficient components of the design, WD was able to eliminate the use
of environmentally harmful CFCs used in the chillers.

The total renovation cost of the efficient design was equivalent to the
proposed renovation costs of other project bidders who offered standard,
less efficient designs. In fact, with the efficient design some costs
were lower. For example, due to low pressure drops through the air and
chilled water systems, the efficient design required for fewer, smaller
pumps and fans. Project staff estimates that any additional efficiency
related costs paid for themselves within the first year of operation.

## Selected Components of the Design

##### [Recirculation Fan System]{.smallcaps}

The recirculation fans, which provide air filtration, are the largest
single energy users in a cleanroom facility of this size. Fan energy
requirements were reduced by lowering the pressure drop in the ducting
and air filtration system. Typical designs of these systems result in 6
to 8 inches of total system pressure drop. The efficient design resulted
in a total system pressure drop of 1.5 inches. This extremely low
pressure drop was accomplished through the careful use of low pressure
drop filters, low velocity duct design, and low pressure drop, single
pass cooling coils. In addition, fans were selected to operate at 82%
efficiency (typical fan efficiency is ranges from 40% to 50%) with
energy efficient motors operating at 92% efficiency. Each fan was
coupled with a variable speed drive, which allows demand-controlled
ventilation providing 550 air changes per hour during peak hours and
reducing ventilation to 100 to 200 air changes per hour on low usage
days like holidays and weekends. The variable speed drives save fan
energy by slowing down the fan when the flow requirements are reduced.

##### [Chillers]{.smallcaps}

Before renovation of the old factory, the chilled water load was
carefully monitored for several months. The data from this monitoring
was combined with estimates of the loads for the new facility to
determine that the maximum cooling load for the new facility would be
between 210 to 220 tons. The existing cooling plant consisted of two 300
ton CFC refrigerant chillers with an efficiency of 0.65 kW/ton. Instead
of replacing the chillers, they were retrofitted with a CFC to HCFC
conversion kit. The conversion resulted in reduction of chiller capacity
to 250 tons each (still large enough for one chiller to cover the load
and with the second for backup) with a resulting efficiency of 0.61
kW/ton. The cost of the conversion was one quarter of the cost of a new
chiller and both chillers were now safer for the environment and more
efficient.

##### ![](media/image2.png){width="2.227777777777778in" height="1.676388888888889in"}

Before the renovation, large counterflow cooling towers were used. These
towers were replaced with new, more efficient cooling towers (shown in
figure 2). All of the cooling tower fans were fitted with variable speed
drives enabling all cells to operate in parallel at slower speeds. Along
with the raw efficiency improvement, parallel operation saves
substantially more energy than operating fewer cells at full capacity
due to the cube law for fans. Parallel operation also saves chiller
energy because lower condenser water supply temperatures are achieved by
spreading the water out over all of the cells.

##### ![](media/image3.png){width="2.2395833333333335in" height="1.65in"}

As with the air handlers, the chilled water and condenser water piping
system design focused on low pressure drop. Figure 3 shows a sample of
the smooth, low pressure drop piping layout that was installed. This
type of piping layout provides for reduced turbulence due to minimal
pipe friction, thus reducing the amount pump energy required to move the
water through the system. The original system had pressure drops of
around 100 feet, but the new layout was able to reduce that to about 35
feet. So, smaller pumps, and fewer of them, were required for the
system. In addition, the new pumps were selected with efficiency in
excess of 70% and 92% efficient motors.

##### [Lighting]{.smallcaps}

The factory floor lighting before the renovation consisted of 40-Watt
fluorescent lamps and standard magnetic ballasts. All of the lighting
was replaced with triphosphor T-8 lamps, electronic ballasts and
reflectors. The resulting lighting energy use is 0.5 W/ft^2^. This is
contributes a significantly to energy savings since lights are often on
twenty-four hours a day and seven days a week.

##### [Compressed Air]{.smallcaps}

The compressed air system was retrofitted to use refrigerant drying
instead of desiccant drying. This saved 15% of the compressed air that
was inadvertently vented in the drying system. These savings allowed the
air compressors to run lees frequently, thus saving compressor energy.

##### [Vacuum Air]{.smallcaps}

The new vacuum pumps were 30% to 40% more efficient than before. This
provides huge energy savings because vacuum air is required throughout
the day in the facility. The new units are also controlled by variable
speed drives such that the pump motors require less energy when less
vacuum air is required.

With conscientious design, the WD plant was made extremely efficient
without an increase in the cost of the project, even though the facility
was changing to a higher cleanliness class. The first cost for this
project was equivalent to what an inefficient design would have cost.
Even though airflow increased significantly to meet the higher
cleanliness requirements, the remodeled building uses 44% less energy
than the original building. These energy savings will increase the
profits of the company by reducing energy related expenses. All of these
measures involve common equipment and can be implemented in almost any
cleanroom, especially during renovations.

Renovation Project Summary

+-------------------------+-----------------------+-------------------+
| ###                     | ### Before            | ### After         |
+-------------------------+-----------------------+-------------------+
| ### Total Plant Area    | ### 80,000-ft^2^      | ### 90,000-ft^2^  |
+-------------------------+-----------------------+-------------------+
| ### Function            | ###                   | ###               |
|                         | Semiconductor Factory | Hard Disk Factory |
+-------------------------+-----------------------+-------------------+
| ### C                   | ### Class 10,000      | ### Class 10      |
| leanroom Classification |                       |                   |
+-------------------------+-----------------------+-------------------+
| ### Peak Demand         | ### 1,350 kW          | ### 850 kW        |
+-------------------------+-----------------------+-------------------+
| ###                     | ### 16.9 W/ft^2^      | ### 9.4 W/ft^2^   |
+-------------------------+-----------------------+-------------------+

##### Applicability of Plant-Wide Efficiency Improvement to the Cleanroom Industry

Renovations are common in large facilities because the industry changes
on a daily basis. These renovation projects are a great opportunity to
take advantage of available energy efficiency opportunities because
retrofit work and new equipment are often already required. In addition,
when the facilities are not able to shutdown during construction, many
of these types of efficiency measures can still be implemented using
techniques such as hot tapping and with careful planning.

While energy efficiency can be improved dramatically in virtually all
cleanroom facilities worldwide, acquiring funding for energy efficiency
is often difficult, especially in renovation applications. One key to
the success of this project was that the project cost did not change due
implementation of energy efficiency measures. This may seem impossible,
given the fact that energy efficient equipment is typically more
expensive than standard efficiency equipment. What is not obvious is
that the efficient design that considers that entire system allows for
installation of smaller equipment, which offsets added cost for improved
efficiency equipment. For example, the improved piping design at WD
allowed the required pump power to be reduced and even reduced the
number of pumps required for the plant. This type of saving cascades all
the way back to the large chillers by reducing parasitic loads generated
by the pumps, fans, and other systems, inevitably reducing the size and
cost of the chiller -- a huge part of the total cost of the plant
renovation.

Many, if not most, companies are seldom able to renovate existing
facilities when a new facility is required. Most companies simply build
a new plant. This is likely due to the fact that the largest driving
factor in locating facilities is cost of operation (hence, the trend
toward construction in Asia), not proximity to existing facilities or
cost of construction. Of course, any new plant is ripe for energy
efficient design at an even lower cost than in any possible retrofit
application because the changes can be made on paper prior to
construction. Unfortunately, a common barrier to implementation of
energy efficiency in new facilities is management, whose need to build
the plant fast (to meet rising consumer demand) is paramount, and which
views efficiency as a stumbling block that will slow design and
construction, possibly preventing the biggest goal: being
first-to-market.