Design qualification: catching problems before installation

Design qualification is the documented verification that the proposed design of facilities, equipment or systems is suitable for the intended purpose. It is performed against the URS before installation and often before purchase.

What to check for a storage space

• Refrigeration or HVAC capacity against heat load, including door traffic and lighting.
• Airflow design: will product positions receive circulation? Where are dead zones likely?
• Provision for monitoring sensors and their cabling or wireless coverage.
• Alarm architecture and independence from the control system.
• Door, dock and airlock arrangements against the expected traffic.
• Data handling: logging, retention, access, audit trails.

The output is a DQ report with a traceability matrix from requirement to design element.

Why this stage saves the most money

The cost of fixing a requirement failure rises by roughly an order of magnitude at each stage it survives. A door on the wrong wall is a line on a drawing at DQ, a change order during installation, a rebuild after IQ, and at PQ it is a mapping study that fails and a storage area that cannot be used. The same is true of the less visible ones: no cable route for monitoring sensors becomes surface trunking and a wireless survey; a compressor sized for an empty room becomes a second compressor.

The traceability matrix, which is the actual deliverable

DQ is often described as a review, which undersells it. The output is a matrix with one row per URS requirement, and for each row: the design element that satisfies it, the evidence (drawing number, datasheet, calculation), and a verdict. Anything without a design element is a gap, and a gap at DQ has exactly three resolutions — change the design, change the requirement with approval, or accept a documented deviation with a justification and a compensating control.

The two gaps in that extract are the ones that recur most often in practice, and both are invisible until somebody asks the question in this format. Alarm independence in particular: if the control system fails, a monitoring system that depends on it fails silently at exactly the moment it was needed.

Off-the-shelf equipment

A common objection is that DQ makes no sense for a catalogue freezer nobody designed. Annex 15 expects the design to be verified against requirements regardless of where it came from — and the comparison is still worth making, because catalogue equipment is specified for its own convenience rather than yours. The performance figures on a datasheet are usually empty, at a stated ambient, with the door shut. For standard equipment the DQ may be a two-page comparison of the datasheet against the URS; what matters is that the comparison exists and is signed.

Run DQ before purchase where you can. After the purchase order, every gap is negotiated from a weaker position.