Belfast International Airport drops its carbon emissions by 500 tonnes per year
May 1st 2007 The enormous capacity of variable speed drives to
offer huge energy savings, while making a
substantial contribution to the fight against global
warming, has been clearly demonstrated at Belfast
International Airport where annual energy savings
will top 1,000,000kWhrs following the refurbishment
of a number of the terminal's air handling units.
Following the previous success of
retrofitting VSDs to two 30kW
circulating pump drives, Airport
Technical Supervisor Colin Sloan decided
to fit variable speed drive control to the 28
fans on the AHUs covering 35 - 40 % of
the main airport "From past experience
we knew that VSDs could offer substantial
energy savings and with rapidly rising
electricity prices, and prompted by the
availability of a 30% grant from our energy
supplier, Energia, under their Energy
Efficiency Scheme, we decided to
refurbish a number of our air handling
units with variable speed drive control."
Belfast International Airport handles over
5,000,000 passengers per year and the air
conditioning system is in operation
continuously to guarantee passenger
comfort. Some 28 fans, totalling 240kW of
installed load, represent a significant
proportion of the airport's annual energy
bill. Initially the fans were running
uncontrolled at full speed with direct online
start and preliminary measurements
had indicated that the motors were
oversized and running inefficiently and well
below full capacity. Fitting variable speed
control would not only offer energy
savings but would improve passenger
comfort throughout the airport.
The building management department
of Belfast company VIS-Security Solutions
carried out a detailed site survey of
existing loads and presented a report with
showed that with only a 20% turndown on
fan speed, the system would return energy
saving sufficient to pay for itself in under 1
year. It highlighted that conditions within
the airport, varying widely with daily and
seasonal temperature conditions and
passenger numbers, could be stabilised
by linking the drives through ModBus &
BACnet communications with CO2
monitors in each of the passenger
processing areas, and that this would
return the maximum energy savings.
Subsequently, 28 Danfoss VLT®6000
HVAC drives, supplied by local Danfoss
partner Greenville Electrical, were installed
and commissioned, initially with the drive
outputs limited to 30 – 37Hz, pending full
commissioning of the air quality monitors.
Despite the hot summer conditions, during
which the air-con system functioned
satisfactorily with the fans at 80% speed,
the actual savings exceeded expectations
and the energy bill was down by over
£15,000 for the three month period. In
cooler weather conditions, it is anticipated
that savings will be even greater, especially
with the AHUs under full automatic
environmental control.
According to Colin Sloan "the first
quarter savings indicate we'll get a return
on our investment in less than 8 months
and comfort conditions for our customers
will certainly be improved. It was vital that
there should be minimal disruption to the
airport during the refurbishment so VIS
took every opportunity to simplify the
installation process. The use of fieldbus
communications reduced the complexity
and cost of the control wiring and the new
control panels were pre-built and installed
with the existing control panels used
temporarily as a junction box. All of the
work was carried out during normal
working hours but nonetheless, downtime
was absolutely minimal during the
changeover and neither the staff nor the
passengers noticed any disruption. These
savings are so spectacular we're currently
looking at the remainder of our AHUs and
indeed every variable load device right
across the airport, with a view to fitting
variable speed drives to them and making
even greater savings."
Once the full climate control system is
commissioned, it is anticipated that the
annual energy savings will exceed 1
million kWhrs., saving the airport well in
excess of £60,000 per year. The green
benefit also has to be considered and
Belfast Airport's new installation will
contribute a reduction in carbon emissions
of over 500 tonnes annually.
Danfoss VLT® Drives
Capswood, Oxford Road, Denham
Tel: 0870 241 7100
Fax: 0870 241 7150
E-mail: uk.drives.sales@danfoss.com
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