Figure 2: While robust automation, control, and monitoring can deliver savings of up to 30%, evidence suggests
that 8% of these savings are lost annually without appropriate monitoring and maintenance.
■ 52 MARCH 2014 | PHARMACEUTICAL PROCESSING
environment is critical to the success of the
process – product quality and regulatory
compliance depends upon it. It has often
been found that although environmental
conditions are being maintained and there
are no complaints, it is at the expense of
significant wasted energy. Real auditing
examples regularly include basic problems
such as heating and cooling overlapping, humidity controls set much lower than product
tolerances require, and no set back to relax
conditions for non-production times.
In some cases, simple retuning of the control loop and a review of use is all that is necessary. In other cases it is just basic maintenance. As an example, during a walk through
audit, an air handling unit heating valve
found to be stuck open was calculated to be
wasting $10,000 a year – yet no issues had
been signalled to the facilities staff regarding
these conditions. The replacement cost of the
valve was less than $1,500, and as a result of
this finding, the plant changed out 25 similar
valves to mitigate future issues.
With most process air systems being 100%
fresh air, the air flow rates in HVAC systems
have a huge impact on energy costs – all the
air needs to be filtered, treated and conditioned to the correct temperature and humidity. However, in many systems it is found that
actual flow rates are much higher than design,
and sometimes even the design flow rates are
higher than needed due to change of use.
Control of motor speed is the most effective way to manage air flow rates using variable speed drives (VSD), which are easy to
retrofit. It is important to ensure that VSDs
are effectively controlled either directly at
the VSD or through the building management systems (BMS) which are straightforward applications enabling retrofits of VSDs
to be achieved with minimal disruption.
Typically pressure sensors are used to control flow, enabling automated changes to be
made according to requirements – full design flow rate during production and relaxed
levels for non-production periods. Pressure
sensors fitted across a filter can modify fan
speed to adjust for the degradation of the
filter. Control systems can be set to provide
a maintenance alert when it becomes economic to change the filter and so reduce the
fan power. Consequently, maintenance can
be scheduled at the optimum time.
In a similar manner, VSDs provide significant
energy savings in pumping systems by varying
flow rates according to system demand instead
of a fixed volume. Common applications in-
clude chilled and hot water distribution to air
handling units and cooling towers.
Occupancy monitoring: simple presence de-
tectors, CO2 monitors, and access control sys-
tems can be use to control lighting and HVAC
systems dependent upon changing needs.
Power factor and power quality correction
is often overlooked and can provide simple
measures to reduce energy losses and avoid
power supply penalties.
ACTIVE ENERGY MANAGEMENT:
MONITORING, MAINTENANCE AND
IMPROVEMENT – HOW TO ENSURE
THE BENEFITS ARE SUSTAINED
Automation can ensure that systems are
controlled reliably and in an energy efficient
way, avoiding the risk of operator error or
omission. However, even with such automation, audit experience has regularly found
control systems that are bypassed, perhaps
sometimes for good short-term operational
reasons to maintain the process. However,
these overrides can accumulate astonishing
levels of energy waste.
Many companies have seen maintenance
resources and budgets shrinking, so their
focus tends to be on the elements critical
to the process. Provided that conditions
for production are maintained, the utility
plant may be neglected. Even with regular
maintenance checks (typically annually at
best) equipment failures may go unnoticed
for many months, or longer. Consider the
heating valve mentioned previously; no indi-
cation of this was evident from monitoring
environmental conditions and it was allowed
to go on wasting energy continuously.
While robust automation, control, and
monitoring can deliver savings of up to 30%,
evidence suggests that 8% of these savings
are lost annually without appropriate moni-
toring and maintenance (see Figure 2).
To ensure the continuing efficacy of all
energy saving measures, be they passive or
active measures, and of a facility’s energy sys-
tems in general, it is essential to actively mon-
itor data from the plant, analyze and identify
anomalies, and then act upon this information.
To truly understand the energy perfor-
mance of a plant, it is essential to correlate
the variables that affect its use. For Life
Sciences HVAC systems, the weather impacts
energy consumption by varying heating, cool-
ing, and humidification requirements, as do
plant utilization and occupancy.
A correlation of the appropriate variables
in energy consumption results in a powerful
model, used as a tool to witness what is
actually happening. Modern monitoring and
targeting software provides analysis tools
to build such models. These tools may vary
from simple regression analysis to multi-vari-
able models with step functions. The step
function is particularly suited to correlating
energy usage with outside temperatures,
changing in complement to external heating
and cooling. This can reveal how well HVAC
system controls are functioning and how ef-
fectively control dead bands have been set.
Establishing a model for the plant provides
an independent baseline for future energy
management actions. It provides a basis for