A method for prioritizing activities for
the design, maintenance
and renewal of assets.
Criticality is the combined measure
relationship between the probability
of failure (PoF)
of failure (CoF)
of an asset.
Listed below are the key steps in the completion of a criticality
- Identify the inventory of assets.
- Assign a
Probability of Failure (PoF) to each asset based on knowledge of the consumed life along a survivor curve or
- Assign a
Consequence of Failure (CoF) ranking to each asset based on knowledge
of the significance of the failure
- Assign any
weightings to reflect the owners operating
- Rank all the
assets based on their criticality
index (PoF x CoF x weighting).
- Map all the
assets onto a criticality
- Identify the
and the non-critical assets
the intervention practices to manage the risk through an appropriate maintenance mix
- time-based maintenance (TbM) and condition-based
is a process of decomposing product or process into hierarchical
components, followed by study of their failure modes and effects, and
(where appropriate) their causes.
Listed below are some of the merits of the criticality (risk) analysis:
- A necessary
process for the management of bounded
assets and critical
technique for prioritization in a context of budget
constraints and limited resources with competing needs.
- Provides a
compelling business case for resource
Listed below are some of the
limitations of the criticality (risk) analysis:
- Requires a
highly sophisticated asset management team.
Criticality vs. Priority
Simplest possible definition
- Criticality – the level of “importance” (to meet the stakeholders objectives)
- Priority – the level of “urgency” (to satisfy the stakeholders changing needs and changing circumstances)
has a shelf life based on contextual circumstances and proximity to a
need. Criticality has a shelf life based on organizational vision/
mission/ values/ goals/ objectives.
- Criticality applies to objects with intrinsic value: a building, a system, an asset, a component
- Priority applies to activities to realize the value in the objects: a project (to correct/address/meet a need/issue)
There are correlations:
- Consequences of failure – measured by criticality
- Probability of failure – measured by priority (Ie. proximity to a changing circumstances, such as physical degradation)
- We may have a “critical” asset (eg. roof) that is in good condition and therefore not a “priority” at this time.
- We may have a non-critical building (eg. a storage shed) that is in very poor condition and also not a priority
- A fire extinguisher is deemed a “critical asset” because it is regulated by safety standards (external stakeholder)
fire extinguisher becomes a “high-priority asset” when the annual
inspection comes due. Once the inspection is done and the FX is
certified, it is no longer high priority (the project is over)
Application of the analysis:
academic quadrangle is a “critical building” due to factors such as
heritage status, institutional function, etc. (primarily internal
- The academic quadrangle becomes a
“high-priority” building (for a certain period of time) when a bunch of
projects come due (filter to the top of the priority list).
nutshell: Criticality is the backdrop for priority. Defensible
priorities cannot be established without an understanding of
much money will we need over time period x?” – A criticality analysis
to identify the projects that should occur in period n. ie, the
- • “We have
$x, what should we responsibly do with it?” – A criticality analysis to
help identify the projects that float to the top of a rank list.
However, we can only pick the right projects if we know how they ranked
against projects that do not fit into the funding envelope. Otherwise,
we are simply grabbing a bunch of “priority projects” without
consideration of overall criticality.
There are certainly other ways to interpret
criticality-priority. “Critical” is often used to mean that
something has become very “important”. But it has really become a
priority because the probability of failure is now very close and the
consequences of the failure are significant (the criticality backdrop).
Fig. Consequences of Failure (CoF) represented on the vertical (y-axis)
of a criticality matrix (risk matrix).
I. Care is trying to re-align his building’s magnetic north to
geodetic true north and thereby use his building as a sundial to cast a shadow that identifes all the critical assets.
Fig. Risk matrix with tiered consequences of failure.
I. Care is establishing priorities for the different assets but is
fighting the "forces" that necessitate periodic
re-evaluation and re-prioritization.
The relationship between Consequences of Failure
on the vertical (y-axis) and Probability of Failure (PoF) on the
horizontal (x-axis) of a criticality/risk matrix.
Based upon the results of a criticality analysis, I. Care is
allocating the limited resources across a portfolio of buildings