Myth #4 – Containment increases
the return air temperature to
cooling units.
This is untrue because the return air
temperature is determined by the
volume of air moving through the room,
the IT heat load and the cooling unit set
point. Cooling units work to maintain
the set point (air return temperature
to the cooling unit), unless supply-side
control is in operation. It is possible for
containment to result in portions of
warmer air flowing back to the cooling
unit, but the average temperature of
all air flowing back to the unit will be
the same. Containment does create an
environment where you can raise both
return and supply-side control set points,
which will increase both unit capacity
and efficiency.
Myth #5 – Full containment is
essential; curtains and partial
containment don’t work.
This myth typically generates from
observing curtains ‘flapping in the
breeze’ or blowing out. It’s true that
Installed Costs ($)
Energy Savings ($/yr)
ROI (months)
Aisle® Modular Containment
System by Upsite Technologies
$36,180
$32,172
13.5
Legacy Containment System
$70,993
$35,520
24.0
*Cost estimates are based on full installation in a 5,280 ft² (490m²) computer room.
curtains or partial containment will not
contain excess conditioned air delivered
into a cold aisle, but the problem is not
the curtains or lack of full containment.
There is excess conditioned air being
supplied to the aisle, which is a state of
deficient airflow balance.
Cost Savings
The white paper titled AisleLok
Modular Containment vs. Legacy
Containment: A Comparative CFD
Study of IT Inlet Temperatures
and Fan Energy Savings, shows an
in-depth analysis of the two types
of containment and their measured
return-on-investment. Using a CFD
model created with Future Facilities’
6Sigma software, the report examines
a typical 5,280 Sq Ft (490m²) U.S. data
centre. The conditions of the room were
analysed using three distinct approaches:
approach 1 had no containment (the
base line), approach 2 had contained
cold aisles using AisleLok Modular
Containment, and approach 3 had
contained cold aisles using a legacy (or
full) containment system. Assuming
a $.10/kWh energy cost rate, the
paper showed that AisleLok Modular
Containment yielded an annual
energy savings of about $32,000 - a
substantial amount of savings for such
a simple installation. Legacy cold aisle
containment provided slightly more
annual energy savings, at about $35,000.
Although the savings were slightly
higher for full containment the return
on investment of partial containment
is very attractive. AisleLok Modular
Containment can pay for itself in about
13.5 months, while legacy containment
takes at least 24 months to fully pay for
itself.
Conclusion
After full containment has been installed on the cold aisle the flow rate of
conditioned air into the aisle remains unchanged at 10 units, however the IT
equipment still only requires a total 4 units of conditioned airflow. Since there is
nowhere for the excess conditioned airflow to escape it is pushed through the
IT equipment. So even though full containment has been installed there is still 6
units of bypass airflow, it just happens to be through the IT equipment.
www.netcommseurope.com
When it comes to proper and effective
Airflow Management (AFM) for your
data centre, there’s no ‘one-size-fits-all’
method or magic solution - no matter
what anyone tells you. Whether it’s
containment or another method or
product, AFM requires a measured,
holistic, and verifiable approach.
NETCOMMS europe Volume V Issue 5 2015 41