Occupied Building Risk Assessments (OBRA)

occupied building risk assessments obra
Occupied Building Risk Assessments OBRA

What is an Occupied Building Risk Assessment (OBRA)?

An Occupied Buildings Risk Assessment (OBRA), is a vital component of process safety risk evaluation. The primary objective of an OBRA is to ascertain whether building occupants are exposed to avoidable risks.  Our team has extensive experience working with COMAH assets and industrial processing sites to create site-wide Occupied Building Strategies to minimise risk and ensure shelter in place facilities are fit for purpose.  This doesn’t just apply to COMAH sites and control buildings – but also to temporary buildings that may sit within the envelope of potential MAH scenarios.

OBRA use a targeted approach to specifically address the impact that Major Accident Hazards (MAHs) pose to building occupants and how these hazards will affect emergency response protocols. The ultimate goal of an OBRA is to ensure that risks are ‘as low as reasonably practicable’ (ALARP). If this threshold is not met, the assessment outlines the necessary actions to further mitigate risks.

OBRAs should be updated and revalidated every 5 years in line with the revision of hazards identified within the site COMAH safety report.

The Chemical Industries Associations (CIA) ‘Guidance for the location and design of occupied buildings on chemical manufacturing and similar major hazard sites’ is considered industry best practice for undertaking OBRAs in the UK and Europe.

IKM’s OBRA Consultants and structural engineering team can assist with strengthening building design, retrofitting, and new blast resistant building designs to withstand predicted blast, thermal and toxic gas releases.

IKM’s Approach to OBRA:  Process & Methodology

  • Risk Assessment:  IKM’s approach is tailored to the unique requirements of the asset/site.  Both hazard-based and risk-based approaches help to ensure a thorough risk assessment is completed.

  • Safety Remediation Design: Our OBRA consultants will define a strategy to enable compliance and reduce the risks to building occupants.

  • Viability & Implementation of Remediation: We can assist in developing Feasibility Studies and Options Appraisals to define and implement strategies to ensure risks are ALARP to building occupants.


OBRA Consultancy Services

  • Physical building surveys identifying vulnerabilities & defects
  • Evaluation & assessment of building fixtures and fittings against hazards
  • Mitigation and improvement studies
  • Design of blast strengthening measures
  • Building siting analysis
  • Cladding system assessments against fire, blast, and toxic gas hazards
  • Single degree of freedom, multi degree of freedom, and non linear time history structural analysis
  • Structural assessment of building response levels using ASCE, PIP, and UFC guidelines
  • Evaluation of temporary buildings
  • Assignment of building vulnerability ratings
  • Consequence-based assessment (PHAST)
  • Risk-based assessment
  • Site-wide strategies & cost-benefit analysis

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