ASHRAE Journal - July 2022 - 28

COLUMN DATA CENTERS
FIGURE 4 Class A1 to A4 Recommended Envelopes, Fifth Edition of Thermal Guidelines.3 Left figure is for spaces with low levels of gaseous pollutants; right figure is for
spaces with high levels of gaseous pollutants.
FIGURE 5 New Class H1 Recommended and Allowable Envelopes, Fifth Edition of Thermal Guidelines.3 Left figure is for spaces with low levels of gaseous pollutants; right
figure is for spaces with high levels of gaseous pollutants.)
with which liquids can transport heat relative to air. One
note: for IT designs that meet the higher supply temperatures
as referenced in Table 3.1 of the Fifth Edition guidelines,
enhanced ITE thermal designs are required to
maintain liquid-cooled components within the desired
temperature limits.
The environmental classes for liquid-cooled ITE listed
in the guideline are:
* Class W17/W27 (62.6°F to 80.6°F [17°C to 27°C]):
These are typically data centers that are traditionally
cooled using chillers and a cooling tower, but with an
optional waterside economizer to improve energy efficiency,
depending on the location of the data center.
* Class W32/W40 (89.6°F to 104°F [32°C to 40°C]):
For most locations these data centers may be operated
without chillers. Some locations may still require chillers,
but they may not need to be sized for the full cooling
load.
28
ASHRAE JOURNAL ashrae.o rg
J U LY 2022
FIGURE 6 Allowable temperature derating for Classes A1 to A4 and H1 as a function
of altitude.3
122
113
104
95
86
77
68
59
50
41
32
A4
A3
A2
A1
H1
A1 (Lower Boundary Only)
A2
A3, A4
1 1,640 3,280 4,920 6,560 8,200 9,840 11,480 13,120 14,760
Altitude (ft)
* Class W45/W+ (113°F+ [45°C]): These data centers
are operated without chillers to take advantage of energy
efficiency and reduce capital expense. The temperature
Dry Bulb Temperature (°F)

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ASHRAE Journal - July 2022

Table of Contents for the Digital Edition of ASHRAE Journal - July 2022

Contents
ASHRAE Journal - July 2022 - Intro
ASHRAE Journal - July 2022 - BB1
ASHRAE Journal - July 2022 - BB2
ASHRAE Journal - July 2022 - Cover1
ASHRAE Journal - July 2022 - Cover2
ASHRAE Journal - July 2022 - 1
ASHRAE Journal - July 2022 - Contents
ASHRAE Journal - July 2022 - 3
ASHRAE Journal - July 2022 - 4
ASHRAE Journal - July 2022 - 5
ASHRAE Journal - July 2022 - 6
ASHRAE Journal - July 2022 - 7
ASHRAE Journal - July 2022 - 8
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ASHRAE Journal - July 2022 - Cover4
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