Environmental Data Center Management & Monitoring

Overview

The paper opens by noting that legacy rooms were often held near 60 F (16 C), while the ASHRAE recommended range it cites is 65-80 F (18-27 C) and 20-80 % RH. Around 80 F is also where server fans begin to speed up. As operators push toward the top of that range, knowing each rack's inlet condition matters more than a room-average reading, and the text argues that measurement must cover several quantities, not temperature alone.

The sensor inventory has eight headings: temperature, humidity, differential pressure, airflow, leak, door, shock/vibration and air quality. The placement rule is concrete. Put at least one measuring point every 10-30 ft (3-9 m) of aisle or on every fourth cabinet, and measure aisle temperature about 4.9 ft (1.5 m) above the floor. That spacing is meant to expose a hot spot at aisle scale instead of leaving it hidden between sensors.

Psychrometric worked examples show why humidity gets its own sensor. Outside air at 40 F and 50 % RH, warmed to roughly 80 F, ends below 15 % RH, under the 20 % recommendation. In the opposite direction, 75 F air at 50 % RH carries about 0.019 lb of water per lb of air but saturates at about 0.004 lb/lb at 32 F, so the excess condenses on cold glass. Both cases tie economiser operation and cold surfaces to a measurable risk.

For vibration, the limit follows the most sensitive device in the cabinet: if two servers tolerate 5 g and 12 g peak shock, the cabinet should stay below the lower 5 g value. The closing section lists buying criteria, with an example specification of +/-2 C temperature accuracy, +/-5 % RH accuracy and up to 32 sensor packages cascaded over Cat5/6, plus DCIM integration. The author is a manufacturer, so the product-selection part reflects a vendor view.

Key points

1. Legacy rooms were often held near 60 F (16 C); the cited ASHRAE recommendation is 65-80 F (18-27 C) and 20-80 % RH.
2. About 80 F is near the point where server fans speed up.
3. Place one measuring point every 10-30 ft (3-9 m) of aisle or every fourth cabinet.
4. Aisle temperature is measured about 4.9 ft (1.5 m) above the floor.
5. 40 F / 50 % RH outside air warmed to about 80 F falls below 15 % RH.
6. 75 F / 50 % RH air holds about 0.019 lb/lb of water but only about 0.004 lb/lb at 32 F, so it condenses on cold glass.
7. Cabinet vibration limit equals the weakest installed device (5 g in a 5 g / 12 g pair).
8. Example sensor spec: temperature +/-2 C, RH +/-5 %, up to 32 sensor packages cascaded.

Using it in design

• In the layout tool, auto-place temperature/humidity sensors at least every fourth cabinet or every 3-9 m of aisle, at inlet heights including about 1.5 m, and flag aisles with none.
• Warn on direct outside-air economisation in cold climates without humidification, since RH can fall below 20 %.
• Let rack records carry a vibration tolerance and compute the cabinet limit as the minimum across installed devices.
• Add sensor catalogue fields for type, accuracy and cascade limit.

Who should read it

Engineers laying out white-space environmental monitoring and operators selecting a sensor system.

Related standards

• ASHRAE TC 9.9 Thermal Guidelines
• ISO 14644

Publication details

Authors

Legrand

Publisher

Legrand

Year

2024

Document language

English

Source type

Manufacturer

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation