Description

Risk analysis involves three interrelated aspects, namely, risk assessment (characterization and estimation of potential adverse effects associated with exposure to hazards), risk management or mitigation (process of controlling risks or reducing their probability of occurrence by weighing alternatives and selecting appropriate action and also by putting in place response and recovery measures should an adverse phenomenon occur), and risk communication to the general public and concerned agencies. The objective of this paper is to propose a conceptual quantitative model for risk assessment in existing buildings that, while being consistent with current financial practice, would allow determination of expected annual monetary cost to recover from various risks. The methodology would thus provide guidance on identifying the specific risks that need to be managed most critically. The proposed methodology allows for the perceived importance with which different stakeholders in a building (for example, a building owner or the tenants) view the interaction between vulnerable risk targets (occupants, property damage, revenue loss) and building elements (such as civil, direct physical, cybernetic, mechanical and electrical system failure, and operation services) that are affected by different hazard categories. Each risk target is further subdivided into several sub-targets, while each hazard category is broken down into hazard events. The analysis involves (1) assigning conditional fuzzy values (with symmetric triangular membership functions) characterizing the perceived importance of different targets and subtargets to the concerned stakeholder, (2) multiplying them with the relevant binary applicability matrix (which is also stakeholder specific), thus, allowing subtargets to be mapped onto hazard categories, (3) multiplying them with historic hazard event probabilities (or absolute annual probability of occurrence of certain hazard events) that depend on such considerations as climate and geographic location of the city, location of building within the city, importance and type of building, and finally, (4) using industry-accepted building specific financial inputs (such as building replacement cost, net return on investment, number of occupants, insurance-related costs, etc.) to compute expected estimates of monetary risk (along with their uncertainty) to various hazards. We adopt a decision tree diagram approach for greater clarity in visualizing the process as well as the ease that it provides in performing the sequential calculations. An illustrative solved example pertinent to a large leased office building is presented and discussed to better illustrate the entire methodology. Logical improvements and extensions are also pointed out. The methodology proposed is of general relevance and is not meant exclusively for assessing risks due to extraordinary incidents.

Units: Dual

Citation: ASHRAE Transactions, vol. 110, pt. 1

Product Details

Published:

2004

Number of Pages:

15

File Size:

1 file , 510 KB

Product Code(s):

D-21900