Commissioning critical facilities (Prendergast, Whorton and Riley)

Overview

The article was published in Consulting-Specifying Engineer in 2008 and was written by three commissioning practitioners. It explains how the phased process of ASHRAE Guideline 0 should be applied with more depth to data centers, from the owner's project requirements (OPR) through the first year of operation. Commissioning runs from pre-design through the first 12 months of occupancy so that four seasons are captured. Electrical distribution, critical-space HVAC, fire detection and suppression and the BAS must be commissioned, while ancillary systems may be optional.

The article also covers the allocation of responsibility, the independence of the commissioning authority and how commissioning costs shift between the commissioning authority and contractors. Concrete examples illustrate the depth of testing. A three-chiller lead/lag plant must be tested staging 1-2-3 and back under all three lead-chiller configurations. Integrated tests use 30 kVA suitcase load banks spread across the raised floor, plus infrared scanning to check CRAC heat removal and staging. The utility recloser scheme should also be researched so that outage tests include brief reclosing interruptions.

During construction, 100% of critical-system air and water balancing should be verified before functional testing, and generic test scripts are inadequate. The article dates from 2008 and refers to ASHRAE Guideline 0-2005; newer editions and practices need to be checked separately. The article's main contribution is to show with concrete test examples that commissioning is not merely an acceptance test but a quality-assurance process that starts at design and continues through the first year of operation. It therefore concludes that commissioning scope and test depth should be set from the start according to the owner's requirements and the redundancy structure.

Key points

1. Commissioning runs from pre-design through the first 12 months of occupancy to capture four seasons.
2. Electrical distribution, critical-space HVAC, fire detection/suppression and BAS must be commissioned; ancillary systems may be optional.
3. A three-chiller lead/lag plant must be tested staging 1-2-3 and back under all three lead-chiller configurations.
4. Integrated tests use 30 kVA suitcase load banks spread across the raised floor plus infrared scanning.
5. Research the utility recloser scheme so outage tests include brief reclosing interruptions.
6. Verify 100% of critical-system air and water balancing before functional testing.
7. Generic test scripts are inadequate.
8. Reference: ASHRAE Guideline 0-2005.

Using it in design

• Generate a commissioning test matrix from the design: every redundant group should produce test permutations for each lead unit and staging step.
• Add integrated failure scenarios, including utility reclose events, to the matrix.
• Store OPR fields (tier target, redundancy, efficiency) and let them drive commissioning scope.
• Write load bank placement and infrared scanning steps into the integrated test plan.
• Define commissioning scope before design rather than after, and include the first year of operation in the monitoring plan.

Who should read it

Engineers, commissioning authorities and owners preparing data center commissioning, test and acceptance plans.

Related standards

• ASHRAE Guideline 0-2005

Publication details

Authors

Prendergast; Whorton; Riley

Publisher

Consulting-Specifying Engineer

Year

2008

Document language

English

Source type

Expert / community

Access

Free to read

Licence

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

Citation