ADVICE & OPINION
COOLING AIR
FMJ AIMS TO SUPPORT TECHNICAL EXPERTISE IN THE FM MARKET
Paul Langford, Engineering Director, Colt International expounds on the benefi ts of evaporative cooling
Evaporative cooling is an
exceptionally e icient and coste
ective means of cooling industrial
buildings, production facilities,
warehouses and data centres. It
is highly e ective in all weather
conditions and its cooling e ect is
highest when the outside temperature
is hotter – precisely when it is most
needed. It also provides 100 per cent
fresh air, maintaining good air quality
inside the building. When temperature
and air quality are an issue in a large
industrial building, housing processes
that generate high levels of heat and
toxic emissions, a well-designed
evaporative cooling system can be the
perfect solution.
External air is cooled through water
evaporation in a two-step process
The Primary Process: As the airflow
passes over the water, water evaporates
into the air. The heat energy necessary
for the evaporation is withdrawn from
the air. The sensible air temperature
decreases continuously. The evaporated
humidity absorbed by the air is also
referred to as “latent heat”.
The Secondary Process: As the
evaporative cooler cools down the
air, the secondary phase is to remove
the latent heat from the building. The
temperature in the building falls as
a result of the heat dissipation in the
desired manner. In general, the hotter
the weather, the more e icient the cooler
is. This means the Evaporative Cooling
adapts to the outside temperature,
and cools the internal environment
accordingly.
What are the health benefits that
evaporative cooling o ers your sta ?
Evaporative cooling systems can help
you ensure that the air your sta breathe
inside your buildings is actually cleaner
than the air outside of it.
Traditional air conditioning systems
re-circulate air around a building, which
means bacteria, pollen, dust and all
16 OCTOBER 2019
manner of other harmful or irritating
particles are continuously inhaled by
sta . As evaporative coolers work by
continuously pulling outside air into the
building and then pushing it out again,
these systems only use the air once. This
means fresher air all day for your sta .
A series of tests carried out for Colt as
part of the VDI 6022 certification, have
confirmed that installing Colt CoolStream
systems reduced the concentration levels
of the harmful Cladosporium bacteria
in the air (known to cause infections
with skin, sinuses and lungs). Levels
of the bacteria in the air were found to
be more than 97.7 per cent lower a er
passing through CoolStream. Large
concentrations of this bacteria can also
negatively a ect asthmatics and people
su ering from respiratory diseases.
In addition, the concentration of
Aspergillus fumigatus in the air, which is
linked to chronic pulmonary infections
in immunosuppressed individuals, was
found to be 85 per cent lower in the
‘cleaned’ air supplied by CoolStream.
In total, eight di erent groups of
bacteria genus were tested and all
were reported as showing reductions
in concentrations in the air of harmful
bacteria - some levels were reduced
so much that it was below measurable
limits. So in e ect, the air supplied to the
building will be cleaner than the fresh
outside air.
Evaporative Cooling o ers integrated
filtration within the unit allowing for
the highly e ective removal of dust,
another respiratory concern. Standard
filter modules complying to ISO
16890 up to ePM1 are available with
automatic contamination monitoring.
Also, unlike traditional airconditioning
which o en results in low
humidity air, the use of Evaporative
Cooling to cool the workplace avoids
symptoms associated with dry skin and
eyes. Because the temperature of the
air supplied is not as low as refrigerated
based systems there isn’t the same risk
of dry air and uncomfortable draughts.
How do I know Evaporative Cooling
is safe?
One question that o en comes up
when discussing a water based cooling
system, such as evaporative cooling, is
always about its safety and in particular
about the control of legionella bacteria.
Legionella is transmitted through
inhalation of aerosol droplets
containing the bacteria, and there are
two key risk areas that water based
systems need to address:
» Waterborne: Water temperature is a
key factor in controlling the growth of
the bacteria in the system. Minimising
the quantity of legionella bacteria in
the system’s water is the first step in
controlling the risk of infection. Ideally,
Evaporative Cooling systems should
only use drinking water, exchange the
water regularly, monitor its temperature
and foresees a drying cycle that kills
all legionella bacteria once a day. We
advise to choose a Evaporative Cooling
system that includes additional safety
features in case of errors, where in case
of power outage the unit bleeds o all
the water and dries itself.
» Airborne: risk of breathing in
legionella bacteria if the cooling system
atomises water bearing the bacteria.
Colt has addressed this in our system by
controlling the maximum speed of the
air as it goes through the wet desorption
medium, so that it is too slow to carry
water droplets.
Low cost and low maintenance:
Evaporative cooling units are light, can
be installed on any factory roof and have
low maintenance requirements. The
units also have minimal running costs
as they rely on the cooling power of
water and use little electricity. Correctly
designed, this solution has the added
benefit of increasing your existing
system’s cooling performance exactly
where it is needed, so you can target the
specific areas of the building where the
heat load is higher.
Improved energy e iciency and
sustainability:
Energy use is a key issue and buildings
must ensure compliance with the
European regulations on Energy Use in
Buildings. Evaporative Cooling systems
are extremely energy e icient: for 10,000
m cooled air, only 1kW of electrical
power is needed. If part of a natural
ventilation design, evaporative cooling
enables lower air volumes to be used to
still achieve the same result.
Typical running costs are four to
seven times lower than classic A/C
solutions – and for data centres even
lower. Evaporative Cooling systems
run on water only and require no
chlorofluorocarbons (CFCs) or similar
refrigerants that are harmful to the
environment. As a result they have no
F-gas compliance issues.
Depending on operating conditions,
systems consume only around 20 to 30
litres of water per hour. Unlike alternative
systems when the unit switches into free
cooling mode, water isn’t immediately
drained. This saves on energy, maximises
the use of water and ensures the cooler
is immediately ready to begin cooling
again, without delay.
FAST FACTS