Data Center Airflow Management at 100F
Upsite Technologies blog · Ian Seaton
Ian Seaton's 2019 article examines what happens when data centres exploit the upper allowable classes with supply air in the 93-103 F range in hot US climates.
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Overview
The piece is an expert article by Ian Seaton on the Upsite Technologies blog, published in 2019. It examines what happens when data centres exploit the upper allowable classes, with supply air in the 93-103 F range, in hot US climates.
The allowable maxima are A2 95 F, A3 104 F and A4 113 F, with supply set 2 F below the inlet limit (93 F for A2, 103 F for A3). The author counts annual hot hours and mechanical cooling needs for Denver, Houston, Las Vegas and Phoenix under air-side economization at A2 and A3 setpoints. Hours above 90 F are 111 (A2) and 226 (A3) in Denver, and 694 and 1,817 in Phoenix. The mechanical cooling share for A2 versus A3 is 9.1% versus 8.2% in Houston, 13.4% versus 3.5% in Las Vegas and 19.6% versus 6.8% in Phoenix. The article also discusses indirect evaporative cooling.
The author flags the risks. Faster server fans carry acoustic risk: hearing conservation programmes start at 85 dBA, and an acoustics engineer should be involved before inlets near 95 F are allowed. Server fan energy can flatter PUE. At 95 F supply and 25 F delta-T, return air can reach about 120 F, and bypass would erase high-temperature gains, so rigorous airflow management is needed. Limit: the data covers four US cities, and as a blog article it is not a peer-reviewed study.
Key points
- Allowable maxima: A2 95 F, A3 104 F, A4 113 F; supply set 2 F below the inlet limit (93 F for A2, 103 F for A3).
- Air-side economization hours above 90 F: Denver 111 (A2) / 226 (A3); Phoenix 694 / 1,817.
- Mechanical cooling share A2 vs A3: Houston 9.1% vs 8.2%; Las Vegas 13.4% vs 3.5%; Phoenix 19.6% vs 6.8%.
- Hearing conservation programmes start at 85 dBA; involve an acoustics engineer before allowing inlets near 95 F.
- At 95 F supply and 25 F delta-T, return air can reach about 120 F; bypass would erase high-temperature gains.
- Server fan energy can flatter PUE.
Using it in design
- When high-temperature (A2/A3 allowable) set points are selected, report hot-hour and mechanical-cooling percentages from site weather.
- Estimate hot-aisle return temperature.
- Raise warnings for hot-aisle noise (near 85 dBA) and worker heat exposure.
- Treat the rise in server fan energy separately when reading PUE; an improved PUE may not reflect real efficiency.
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Who should read it
Cooling designers and operations engineers planning high-temperature operation and air-side economization.
Related standards
- ASHRAE Thermal Guidelines for Data Processing Environments
Publication details
- Authors
- Ian Seaton
- Publisher
- Upsite Technologies blog
- Year
- 2019
- 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
Ian Seaton (2019). Data Center Airflow Management at 100F. Upsite Technologies blog. https://www.upsite.com/blog/data-center-airflow-management-at-100-f/
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Related sources
All sources on this topicUpsite Technologies blog 2017
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