Cooling Audit for
Identifying Potential
Cooling Problems in
Data Centers
White Paper #40
By Kevin Dunlap
Revision 1
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Executive Summary
The compaction of Information Technology equipment and simultaneous increases in
processor power consumption are creating challenges for data center managers in
ensuring adequate distribution of cool air, removal of hot air and sufficient cooling capacity.
This paper provides a checklist for assessing potential problems that can adversely affect
the cooling environment within a data center.








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Introduction
The compaction of technical equipment and simultaneous advances in processor power have created
problems for those responsible for delivering and maintaining proper mission-critical environments. While
the overall total power and cooling capacity designed for a data center may be adequate, the distribution of
cool air to the right areas may not. With more compact equipment now being housed within a single cabinet,
and many data center managers beginning to contemplate large-scale deployments with multiple racks of
ultracompact blade servers, the increased power required and heat dissipated is causing some concern.
These new systems, as seen in Figure 1, take up far less space than traditional rack-mounted servers, but
they dramatically increase heat density. Throwing multiple high-density racks into a data center can result in
problems ranging from outright failures to unexplained slowdowns and shortened equipment life.

Figure 1 – Examples of compaction












In designing the cooling system of a data center the objective is to create an unobstructed path from the
source of the cooled air to the inlet positions of the servers. Likewise, a clear path needs to be created from
the rear exhaust of the servers to the return air duct of the air-conditioning unit. There are, however, a
number of factors that can adversely impact this objective.

In order to ascertain that there is a problem or potential problem with the cooling infrastructure of a data
center, certain checks and measurements must be carried out. This audit will determine the health of the
data center in order to avoid temperature-related electronic equipment failure. They can also be used to
evaluate the availability of adequate cooling capacity for the future. Measurements in the described tests
should be recorded and analyzed using the template provided in the Appendix. The current status should be
assessed and a baseline established to ensure that subsequent corrective actions result in improvements.
This document shows how to identify potential cooling problems that will affect the total cooling capacity, the
cooling density capacity, and the operating efficiency of a data center. Solutions to these problems are
described in APC White Paper #42, “Ten Steps to Solving Cooling Problems Caused by High Density Server
Deployment”.
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1. Capacity check
Remembering that each Watt of IT power requires 1 Watt of cooling, the first step toward providing adequate
cooling is to verify that the capacity of the cooling system matches the current and planned power load.

The typical cooling system is comprised of a CRAC (Computer Room Air Conditioning unit) to deliver the
cooled air to the room and a unit mounted externally to reject the heat to atmosphere. For more information
on how air conditioners work and to learn about the different types, please refer to APC White Paper #57,
“Fundamental Principles of Air Conditioners for Information Technology” and APC White Paper #59, “The
Different Types of Air Conditioning Equipment for IT Environments”. Newer forms of CRAC units are
appearing on the market that can be positioned closer (or even inside) data racks in very high-density
situations.

In some cases, the cooling system may have been oversized to accommodate a projected future heat load.
Over sizing the cooling system leads to undesirable energy consumption that can be avoided. For more on
problems caused by sizing refer to APC White Paper #25, “Calculating Total Cooling Requirements for Data
Centers”.

Verify the capacity of the cooling system by finding the model nomenclature on or inside each CRAC unit.
Refer to the manufacturer technical data for capacity values. CRAC unit manufacturers rate system capacity
based on the EAT (entering air temperature) and humidity control level. The controller on each unit will
display the EAT and relative humidity. Using the technical data, note the sensible cooling capacity for each
CRAC.
Likewise the capacity of the external heat rejection equipment should be of equal or greater capacity then all
the CRACs in the room. In smaller packaged systems the internal and external components are often
acquired together from the same manufacturer. In larger systems the heat rejection equipment may have
been acquired separately from a different manufacturer. In either case they are most likely sized
appropriately, however an outside contractor should be able to verify this.
If the CRAC capacity and heat rejection equipment capacity are different, take the lower rated component for
this exercise. (If in doubt when taking measurements please contact the manufacturer or your supplier.)

This will give you the theoretical maximum cooling capacity of the data center. It will be seen later in this
paper that there are a number of factors that can considerably reduce this maximum.

The calculated maximum capacity must then be compared with the heat load requirement of the data center.
A worksheet that allows the rapid calculation of the heat load is provided in Table 1. Using the worksheet, it
is possible to determine the total heat output of a data center quickly and reliably. The use of the worksheet
is described in the procedure below Table 1. Refer to APC White Paper #25, “Calculating Total Cooling
Requirements for Data Centers” for more information.

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The heat load requirements identified from the following calculation should always be below the theoretical
maximum cooling capacity. APC White Paper #42, “Ten Steps to Solving Cooling Problems Caused by High
Density Server Deployment” provides some solutions when this is not the case.

Table 1 – Data center or network room heat output calculation worksheet
Item
Data required
Heat output
calculation
Heat output
subtotal
IT Equipment
Total IT load power in Watts
Same as total IT load power
in watts

_____________ Watts
UPS with Battery
Power system rated power in
Watts
(0.04 x Power system rating)
+ (0.06 x Total IT load power)

_____________ Watts
Power Distribution
Power system rated power in
Watts
(0.02 x Power system rating)
+ (0.02 x Total IT load power)

_____________ Watts
Lighting
Floor area in square feet, or
Floor area in square meters
2.0 x floor area (sq ft), or
21.53 x floor area (sq m)

_____________ Watts
People
Max # of personnel in data center
100 x Max # of personnel

_____________ Watts
Total
Subtotals from above
Sum of heat output subtotals

_____________ Watts

Procedure
Obtain the information required in the “Data required” column. Consult the data definitions below in case of
questions. Perform the heat output calculations and put the results in the subtotal column. Add the
subtotals to obtain the total heat output.

Data Definitions
Total IT load power in Watts - The sum of the power inputs of all the IT equipment.

Power System Rated Power - The power rating of the UPS system. If a redundant system is used, do not
include the capacity of the redundant UPS.

2. Check CRAC units
If Computer Room Air Conditioning (CRAC) units in a data center do not work together in a coordinated
fashion they are likely to fall short of their cooling capacity and incur a higher operating cost. CRAC units
normally operate in four modes: Cooling, Heating, Humidification and Dehumidification. While two of these
conditions may occur at the same time (i.e., cooling and dehumidification), all systems within a defined area
(4-5 units adjacent to one another) should always be operating in the same mode. Uncoordinated CRAC
units operating in opposing modes (i.e. dehumidifying and humidifying) called “demand fighting” leads to
wasted operating costs and a reduction in the cooling capacity. CRAC units should be tested to ensure that
measured temperatures (supply & return) and humidity readings are consistent with design values.
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Demand fighting can have drastic effects on the efficiency of the CRAC system. If not addressed, this
problem can result in a 20-30% reduction in efficiency which in the best case results in wasted operating
costs and worst case results in downtime due to insufficient cooling capacity.

Operation of the system within lower limits of the relative humidity design parameters should be considered
for efficiency and cost savings. A slight change in set point toward the lower end of the range can have a
dramatic effect on the heat removal capacity and reduction in humidifier run time. As seen in Table 2,
changing the relative humidity set point from 50 to 45 results in a significant operational cost savings.

Table 2 – Humidification cost savings example at lower set point
Temperature 72°F (22.2°C)
Relative Humidity set point
50%
45%
Cooling Capacities – kW (Btu/hr)
Total Cooling Capacity
48.6 (166,000)
49.9 (170,000)
Total Sensible (temperature change) Capacity
45.3 (155,000)
49.9 (170,000)
Humidification Requirement
Total Latent (moisture removed) Capacity
3.3 (11,000)
0.0 (0,000)
lbs / hr [kg / hr] humidification required – Btu/1074 (kW / 0.3148)
10.24 [4.6]
0
Humidifier Runtime
100.0%
0.0%
kW required for humidification
3.2
0
Annual Cost of humidification (Cost per kW x 8760 x kW required)
$2,242.56
$0.00
Note: Assumptions and specifications for the example above can be found in the appendix.

Check set points
Set points for temperature and humidity should be consistent on all CRAC units in the data center. Unequal
set points will lead to demand fighting and fluctuations in the room. Heat loads and moisture content are
relatively constant in an area and CRAC unit operation should be set in groups by locking out competing
modes through either a building management system (BMS) or a communications cable between the
CRACs in the group. No two units should be operating in competing modes during a recorded interval,
unless part of a separate group. When grouped, all units in a specific group will be operating together for a
distinct zone

Set point parameters should be within the following ranges:

• Temperature – 68-77°F (20-25°C)
• Humidity – 40-55% R.H.

To test the performance of the system, both return and supply temperatures must be measured. Three
monitoring points should be used on the supply and return at the geometric center as shown in Figure 2.
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Figure 2 – Supply and return temperature monitoring points


In ideal conditions the supply air temperature should be set to the inlet temperature required at the server
inlet. This will be checked later by taking temperature readings at the server inlets. The return air
temperature measured should be greater than or equal to the temperature readings taken in step 4. A lower
return air temperature than the temperature in step 4 indicates short cycling inefficiencies. Short cycling
occurs when the cool supply air from the CRAC unit bypasses the IT equipment and flows directly into the
CRAC unit air return duct. See APC White Paper #49, “Avoidable Mistakes that Compromise Cooling
Performance in Data Centers and Network Rooms” for information on preventing short cycling. The bypass
of cool air is the biggest cause of overheating and can be caused by a number of factors. Sections 6-10 of
this paper describe these circumstances.

Also, verify that the filters are clean. Impeded airflow through the CRAC will cause the system to shutdown
on loss of airflow alarm. Filters should be changed quarterly as a preventative maintenance procedure.




Monito
r point
s
(Retur
n)
Monito
r point
s
(Supp
ly)
Monito
r point
s
(Retur
n)
Monito
r point
s
(Supp
ly)
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3. Check and test main cooling circuits
This section requires an understanding of basic air condition equipment. For more information on this read
APC White Paper #59, “The Different Types of Air Conditioning Equipment for IT Environments”. Get your
maintenance company or an independent HVAC consultant to check the condition of the chillers (where
applicable), pumping systems and primary cooling loops. Ensure that all valves are operating correctly.

Chilled water cooling circuit
The condition the chilled water loop supply to the CRACs will directly affect the ability of the CRAC to supply
proper conditioned air to the room or raised floor plenum. To check the supply temperature, contact your
maintenance company or an independent HVAC consultant. As a quick check, the temperature of the piping
supply to the CRAC can be used. Using a laser thermometer, measure the supply pipe surface temperature
to the CRAC unit. In some cases, gauges may be installed inline with the piping, displaying temperature of
the water supply.

Chilled water piping will be insulated from the air stream in order to prevent condensation on the pipe
surface. For the most accurate measurement, peel back a section of the insulation and take the
measurement directly on the surface of the pipe. If this is not possible, a small section of piping is likely
exposed inside the CRAC unit at the inlet to the cooling coil on the left or right side of the coil.

Condenser water circuit (Water and Glycol Cooled)
Water and Glycol cooled systems utilized a condenser in the CRAC for transferring heat from the CRAC to
the water circuit. Condenser water piping will likely not be insulated due to the warmer temperatures of the
supply water. Measure the supply pipe surface temperature at the entry point to the CRAC unit. Direct
expansion (DX) systems should be checked to ensure that they are fully charged with the proper amount of
refrigerant.

Air cooled refrigerant piping
As with water- and glycol-cooled CRACs, refrigerant charge should be checked for the proper levels.
Contact your maintenance company or an independent HVAC consultant to check the condition of
refrigerant piping, outdoor heat exchangers and refrigerant charge.

Compare temperatures to those in Table 3. Temperatures that fall outside the guidelines may indicate a
problem with the supply loop.

Table 3 – Supply loop temperature tolerances
Chilled Water
Condenser Water
(water-cooled)
Condenser Water
(glycol-cooled)
45°F (+/- 3°F)
Max 90°F
Max 110°F
7.2°C (+/- 1.7°C)
Max 32.2°C
Max 43.3°C
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4. Record aisle temperatures
By recording the temperature at various locations between rows of racks, a temperature profile is created
which helps diagnose potential cooling problems and ensures that cool air is supplied to critical areas. If the
aisles of racks are not properly positioned hot spots can occur in various locations and may cause multiple
equipment failures. Section 9 below describes and illustrates a best practice for rack layouts. Take room
temperatures at strategic positions within the aisles of the data center1. These measuring positions should
generally be centered between equipment rows and spaced at approximately one point at every fourth rack
position as shown in Figure 3.

Figure 3 – ASHRAE TC9.9 hot aisle / cold aisle measurement points

Reprinted with permission ASHRAE 2004. (c) American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.,
www.ashrae.org.

Aisle temperature measurement points should be 5 feet (1.5 meters) above the floor. When more
sophisticated means of measuring the aisle temperatures are not available this should be considered a
minimal measurement. These temperatures should be recorded and compared with the IT equipment
manufacturers’ recommended inlet temperatures. When the recommended inlet temperatures of IT
equipment are not available, 68-75°F (20-25°C) should be used in accordance to the ASHRAE standard.
Temperatures outside this tolerance can lead to a reduction in system performance, reduced equipment life
and unexpected downtime. Note: All the above checks and tests should be carried out quarterly.
Temperature checks should be carried out over a 48-hour period during each test to record maximum and
minimum levels.


1 ASHRAE Standard TC9.9 gives more details of positioning sensors for optimum testing and
recommended inlet temperatures. ASHRAE (American Society of Heating, Refrigeration and Air-
Conditioning Engineers www.ashrae.org)
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5. Record rack temperatures
Poor air distribution to the front of a rack can cause the hot exhaust air from the equipment to recirculate
back into the intakes. This causes some equipment, typically those mounted toward the top of the rack, to
overheat and shutdown or fail. This step is to verify that the bulk inlet temperatures in the rack are adequate
for the equipment installed. Take and record temperatures at the geometric center of the rack front at
bottom, middle and top as illustrated in Figure 4. When the rack is not fully populated with equipment,
measure inlet temperatures at the geometric center of each piece of equipment. Refer to the guidelines in
step #2 for acceptable inlet temperatures. Temperatures not within the guidelines represent a cooling
problem for that monitoring point.

Monitoring points should be 2-inches (50 mm) off the face of the rack equipment. Monitoring can be
accomplished with thermocouples connected to a data collection device. Monitoring points may also be
measured by using a laser thermometer for quick verification of temperatures as a minimal method.

Figure 4 – ASHRAE monitoring points for equipment inlet temperatures



Reprinted with permission ASHRAE 2004. (c) American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.,
www.ashrae.org.








Monitor points
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6. Check air velocity from floor grilles
It is important to understand the cooling capacity of the cabinet is directly related to the airflow volume
delivery stated in CFM (cubic feet per minute). IT equipment is designed to raise the temperature of the
supply air by 20-30°F (11-17°C). Using the equation for heat removal, the amount of airflow required at a
given temperature rise can be quickly computed.

CFM or m3/s = the volume of airflow required to remove the heat generated by IT equipment

Q = the amount of heat to be removed expressed in kilowatts (kW)

∆°F or ∆°C = the exhaust air temperature of the equipment minus the intake temperature

F
085
.1
412
,3
°
∆
×
×
=
Q
CFM



C
21
.1
/
3
°
∆
×
=
Q
s
m



For example, to calculate the airflow required to cool a 1kW server with a 20°F temperature rise:
23
.
157
F
20
085
.1
1
412
,3
=
°
×
×
=
kW
CFM

0742
.0
C
11
21
.1
1
/
3
=
°
×
=
kW
s
m


Therefore, for every 1kW of heat removal required at a design DeltaT (temperature rise through IT
equipment) of 20°F (11°C) you must supply approximately 160 cubic feet per minute (0.076 m3/s or 75.5 L/s)
of conditioned air through the equipment. When calculating the necessary airflow requirement per rack, this
can be used as an approximated design value. However, adherence to the manufacturer name plate
requirements should be followed.
23
.
157
/
=
kW
CFM

074
.0
/
)
/
(
3
=
kW
s
m


2
.
74
/
)
/
(
=
kW
s
L


Using the design value and the typical tile (~ 25% open) airflow capacity shown in Figure 5 below, the max
power density per cabinet should be 1.25 to 2.5 kW per cabinet. This is applicable to installations utilizing
one tile per cabinet. In instances where cabinet to floor tile ratio is greater than one, the available cooling
capacity should be divided among the cabinets in the row.

Testing the airflow of a vented floor tile
Measuring the amount of available cooling capacity on a given floor tile can be accomplished simply laying a
small piece of paper on it. If the paper gets sucked into the floor tile this means that air is being drawn back
under the raised floor which indicates a problem with the rack and CRAC positioning. If the paper is
unaffected it could be that there is not air getting to that tile. If the paper moves up off the floor tile this is an
indication that air is being distributed from that tile. However, depending on the power density of the
equipment being cooled, the amount of air from the tile may not be enough. In this case a grate or air
distribution device may be required to allow more air to flow to the front of the racks.

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Figure 5 – Available rack enclosure cooling capacity of a floor tile as a function of per-tile airflow.



7. Visual inspection of enclosures
Unused vertical space within rack enclosures causes the hot air output from equipment to take a “short
circuit” back to the inlet of the equipment. This unrestricted cycling of hot air causes the equipment to heat
up unnecessarily which can lead to equipment damage or downtime. The use of blanking panels to combat
this effect is described in more detail in APC White Paper # 44, “Improving Rack Cooling Performance Using
Blanking Panels”. Visually examine each rack. Are there any gaps in the u positions? Are CRT monitors
being used? Are blanking panels installed in these racks? Is an excess of cabling impeding the airflow?

If there are visible gaps in the U space positions, blanking panels are not installed or there is excessive
cabling in the rear of the rack, then airflow within the rack will not be optimal as illustrated in Figure 6 below.







0
1
2
3
4
5
6
7
0
100
[47.2]
200
[94.4]
300
[141.6]
400
[188.8]
500
[236.0]
600
[283.2]
700
[330.4]
800
[377.6]
900
[424.8]
1000
[471.9]
Tile Airflow (CFM) [ L/s ]
Cooling Capacity per Tile (kW)Typical
Capability
With
Effort
Extreme
Impractical
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Figure 6 – Diagrams of rack airflow showing effect of blanking panels
6A: Without blanking panels
6B: With blanking panels


8. Check air paths below floor
Check sub-floors for cleanliness and / or obstructions. Any dirt and dust present below the raised floor will
be blown up through floor grills and will be drawn into the IT equipment. Floor obstructions such as network
and power cables will obstruct airflow and have a negative effect on the cooling supply to the racks.
Subsequent addition of racks and servers will result in the installation of more power and network cabling.
Often, when servers and racks are moved or replaced, the redundant cabling is left beneath the floor.

A visual inspection of the floor surface should be conducted when a raised floor is utilized for air distribution.
Voids, gaps and missing floor tiles have a damaging effect on the static pressure of the floor plenum. The
ability to maintain airflow rates from perforated floor tiles will be diminished with the presence of unsealed
areas on the raised flooring.

Missing floor tiles should be replaced. The floor should consist of solid or perforated floor tiles in every
section of the grid. Holes in the raised flooring tiles used for cabling access should be sealed using brush
strips or other cable access products. Measurements conducted show that 50-80% of available cold air
escapes prematurely through unsealed cable openings.


Side
Side
Blanking Panel
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9. Check aisle and floor tile arrangement
With few exceptions, most rack-mounted servers are designed to draw air in at the front and exhaust at the
back. With all the racks facing the same way in a row, the hot air from row one is exhausted into the aisle
where it will mix with supply or room air and then enter into the front of the racks in row two. This
arrangement is shown is Figure 7. As air passes through each consecutive row the IT equipment is
subjected to hotter intake air. If all the rows have the cabinets arranged so that the inlets of the servers face
the same direction equipment malfunction is imminent.

Figure 7 – Rack arrangement with no separation of hot or cold aisles


Configuring the rack in a hot aisle / cold aisle configuration will separate the exhaust air from the server
inlets. This will allow the cold supply air from the floor tiles to enter into the cabinets with less mixing as
illustrated in Figure 8 below. For more on air distribution architectures in the data center refer to APC White
Paper #55, “Air Distribution Architecture for Mission Critical Facilities”.

Figure 8 – Hot aisle / cold aisle rack arrangement


Improper location of these vents can cause CRAC air to mix with hot exhaust air before reaching the load
equipment, giving rise to the cascade of performance problems and costs described previously. Poorly
located delivery or return vents are very common and can erase almost all of the benefit of a hot-aisle-cold-
aisle design.


10. Check placement of CRAC units
The position of the CRAC units relative the aisle is important for air distribution. Depending on the air
distribution architecture, CRAC units should be placed perpendicular to the aisle on either a cold or hot aisle
as shown in Figure 9. When using a raised floor for distribution, the CRAC units should be placed at the
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end of the hot aisles. The hot air return path to the CRAC is directly down the aisle without pulling air over
the tops of aisles where the opportunity for air to be re-circulated is increased. With less mixing of the hot air
in the room, the capacity of the CRAC units will be increased by warmer return air temperatures. This could
potentially lead to a requirement for fewer units in the room.

Figure 9 – Hot aisle positioning of CRAC units

When a slab floor is used, the CRAC should be placed at the end of the cold aisle. This will distribute the
supply air to the front of the cabinets. Some mixing will exist in this configuration and it should be
implemented only when low power densities per rack exist.

Conclusion
Routine checks of a data center’s cooling system can identify potential cooling problems early on to help
prevent downtime. Changes in power consumption, IT refreshes and growth can change the amount of heat
produced in the data center. Regular health checks will most likely identify the impact of these changes
before they become a major issue. Achieving the proper environment for a given power density can be
accomplished by addressing the problems identified through the health checks provided in this white paper.
For more information on cooling solutions for higher power densities refer to APC White Paper #42, “Ten
Steps to Solving Cooling Problems Caused by High Density Server Deployment”.


About the Author:
Kevin Dunlap is the Product Marketing Manager for cooling solutions at American Power Conversion
(APC). Kevin has been involved in the industry since 1994, first with a provider of power management
hardware and software, and then with APC as a Product Manager.

Kevin has been involved in multiple industry panels, consortiums and ASHRAE committees for thermal
management and energy efficient economizers.
CRAC
CRAC
CRAC
CRAC
COLD AISLEHOT AISLECOLD AISLEHOT AISLECOLD AISLE
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Appendix
Assumptions and specifications for Table 2
Both scenarios in the humidification cost savings example in Table 2 are based on the following
assumptions:
•
50kW of electrical IT loads which results in approximately 50kW of heat dissipation
•
Air temperature returning to CRAC inlet is 72°F (22.2°C)
•
Based on 1 year operation (7x24) which equates to 8,760 hours
•
CRAC unit volumetric flow of 9,000 CFM (4.245 m3/s)
•
Ventilation is required but for simplification it was assumed that the data center is completely
sealed - no infiltration / ventilation
•
Cost per kW / hr was assumed to be $0.08 (U.S.)
•
CRAC unit specifications based on an APC FM50:
- Standard downflow
- Glycol cooled unit (no multi-cool or economizer)
- Electrode steam generating humidifier (Plastic canister type with automatic water level
adjustment based on water conductivity)
- Humidifier capacity is 10 lbs/hr (4.5 kg / hr)
- Humidifier electrical consumption is 3.2kW
- Voltage is 208 VAC

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Cooling Audit Checklist
Capacity Check
CRAC
Model
Total Capacity
Sensible Capacity Quantity
Unit 1
Unit 2
Unit 3
Unit 4
Unit 5
Unit 6
Unit 7
Unit 8
Unit 9
Unit 10
Heat Load Requirement
IT Equipment
Total IT load power in watts
UPS with Battery
Power system rated power in watts
Power Distribution
Power system rated power in watts
Lighting
Floor area in square feet, or floor area in square
meters
People
Max # of personnel in data center
Total
Subtotals from above
CRAC Monitoring Points
Supply (average of three monitoring points for each)
CRAC 1 ________
CRAC 6 ________
CRAC 2 ________
CRAC 7 ________
CRAC 3 ________
CRAC 8 ________
All within range
CRAC 4 ________
CRAC 9 ________
1-2 out of range
CRAC 5 ________
CRAC 10________
>2 out of range
Return (average of three monitoring points for each)
CRAC 1 ________
CRAC 6 ________
CRAC 2 ________
CRAC 7 ________
CRAC 3 ________
CRAC 8 ________
All within range
CRAC 4 ________
CRAC 9 ________
1-2 out of range
CRAC 5 ________
CRAC 10________
>2 out of range
Cooling Circuits
Chilled Water
Condenser Water - Water Cooled
Condenser Water - Glycol Cooled
Air Cooled
Aisle Temperatures
Measurement points at 5 feet (1.5 meters) above the floor at every 4th rack (averaged for aisle)
Aisle 1 ________
Aisle 6 ________
Aisle 2 ________
Aisle 7 ________
Aisle 3 ________
Aisle 8 ________
All within range
Aisle 4 ________
Aisle 9 ________
1-2 out of range
Aisle 5 ________
Aisle 10________
>2 out of range
Total Usable Capacity = SUM (Sensible Capacity x Quantity)
Same as total IT load power in watts
100 x Max # of personnel
Sum of heat output subtotals
(0.04 x Power system rating) + (0.06 x
Total IT load power)
Capacity is equal to or greater than heat output?
Acceptable
Averages: Temp. 58-
65F (14-18C)
Meets Tolerance (check one)
(0.02 x Power system rating) + (0.02 x
Total IT load power)
2.0 x floor area (sq ft), or
21.53 x floor area (sq m)
Acceptable
Averages: Temp. 68-
75F (20-25C),
Humidity 40-55%
R.H.
Meets Tolerance (check one)
Should be checked by qualified HVAC contractor
Meets Tolerance
(check one)
45F (+/- 3F), 7.2C (+/- 1.7C)
Max 90F (32.2C)
Max 110F (43.3C)
Acceptable
Averages: Temp. 68-
75°F (20-25°C)
Meets Tolerance (check one)
Yes
No
Yes
No
Yes
No
Yes
No
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18



Rack Temperatures
Measurement points at 5 feet (1.5 meters) above the floor at every 4th rack (averaged for aisle)
R1 ____ R2 ____ R3 ____
R46 ____ R47____ R48 ____
R4 ____ R5 ____ R6 ____
R49 ____ R50____ R51 ____
R7 ____ R8 ____ R9 ____
R52 ____ R53____ R54 ____
R10 ____ R11____ R12 ____
R55 ____ R56____ R57 ____
R13 ____ R14____ R15 ____
R58 ____ R59____ R60 ____
R16 ____ R17____ R18 ____
R61 ____ R62____ R63 ____
R19 ____ R20____ R21 ____
R64 ____ R65____ R66 ____
R22 ____ R23____ R24 ____
R67 ____ R68____ R69 ____
R25 ____ R26____ R27 ____
R70 ____ R71____ R72 ____
R28 ____ R29____ R30 ____
R73 ____ R74____ R75 ____
R31 ____ R32____ R33 ____
R76 ____ R77____ R78 ____
R34 ____ R35____ R36 ____
R79 ____ R80____ R81 ____
R37 ____ R38____ R39 ____
R82 ____ R83____ R84 ____
R40 ____ R41____ R42 ____
R85 ____ R86____ R87 ____
R43 ____ R44____ R45 ____
R88 ____ R89____ R90 ____
Airflow
Check all perforated tiles (where applicable), compare to tolerances
All within range
1-2 out of range
>2 out of range
Inspecting the Rack
Blanking Panels
Meets Tolerance
(check one)
Air Path Below the Floor (where applicable)
Visible obstructions
Missing tiles, gaps and voids
Aisle and floor tile arrangement
Perforated floor tile positions
CRAC positioning
Do the CRACs line up with the hot aisles?
Hot aisle, cold aisle layout
Are blanking panels installed in all rack spaces where IT equipment is not
Meets Tolerance
(check one)
Is there separation between hot and cold aisles (racks not facing the same
direction)?
Are blanking panels installed in all rack spaces where IT equipment is not
installed?
Are all floor tiles in place? Are cable access openings adequately sealed?
Meets Tolerance
(check one)
Perforated floor tiles
Airflow measurement (positive airflow check),
volume tests should be carried out by a qualified
HVAC contractor
Acceptable
Averages: => 160
cfm/kW
(75.5 L/s) / kW
Are blanking panels installed in all rack spaces where IT equipment is not
installed?
Meets Tolerance (check one)
Acceptable
Averages: Temp. 68-
75°F (20-25°C), Top
to bottom
temperatures in
each rack should not
differ more than 5F
(2.8C)
Meets Tolerance (check one)
All within range
1-2 out of range
>2 out of range
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No