These seismic principles help agencies make decisions about the seismic resilience of their portfolio and the continued occupation of buildings with low seismic ratings.
Seismic assessments are an important aspect in the management of the government office accommodation portfolio. We help agencies understand their seismic risk ratings, ensure building vulnerabilities are well understood and apply a consistent methodology to unique situations. You should read this guidance alongside 'Seismic Risk Guidance for Buildings' published by the Building Performance team.
The principles provide guidance for managing office buildings leased or owned by government agencies. They are not intended to guide an agency’s decision around operational spaces, such as prisons, hospitals and schools, which fall outside the Government Property Group (GPG) mandate. This guidance does not supersede or replace the seismic advice provided by the Building Performance team or create a separate standard for government tenants.
Seismic Risk Guidance for Buildings [PDF 2.7 MB] – Building Performance
You should understand the benefits and risks of occupying a building, including its seismic resilience before you decide to lease it or renew an existing lease. Questions may arise, for example, when you become aware that a building has a concrete floor structure or other vulnerabilities have been identified.
A decision to commit your agency to a lease requires appropriate due diligence and evaluation of your options.
There are two forms of building seismic assessments in New Zealand:
When carrying out a DSA, engineers assess the vulnerability of all critical elements in the building (eg columns, floors, parapets, heavy exterior cladding etc) that could present a significant life safety hazard during an earthquake. Each of the elements gets a score expressed in terms of percentage of New Building Standard (%NBS) achieved. The lowest score (ie worst performing element) represents the overall earthquake rating (%NBS) for the building.
Unless specified, seismic assessments usually consider only primary and secondary elements of the building structure. They do not usually consider the seismic performance of services (plumbing, electrical, communications, HVAC), internal fitouts or office equipment. You may need to engage an engineer to assist in assessing the performance of these non-structural elements if this is critical to your operations.
If your agency intends to commit to a lengthy lease term for a building not currently within the government property portfolio, a DSA is most appropriate to ensure the seismic rating is well understood. Acquiring a DSA can be a lengthy process, however, some landlords will already have this assessment available for consideration.
The landlord may have already obtained an ISA and/or DSA for their building which may be available to review. In this instance you should still consult with an independent engineer to ensure the assessment is appropriate for the intended lease.
We keep a central record of the seismic ratings of buildings in the government’s office accommodation portfolio. This gives us a holistic view of government office buildings. This information helps to guide our work to enhance the quality and resilience of government property stock over time, and in turn, help agencies identify suitable buildings for long term occupation.
Agencies should understand and report the seismic risk rating of their property portfolio and any potential vulnerabilities of the buildings which they occupy or intend to occupy.
You should record the following information in the Government Property Portal:
The Government Property Portal (GPP)
The Seismic Assessment of Existing Buildings [PDF 307 KB] – EQ-Access
Technical Proposal to Revise C5 [PDF 9.8 MB] – EQ-Access
Deciding to vacate government office space in a co-location environment can significantly impact other agencies co-locating in that space.
Any decision on the impacts of occupancy in a co-location environment as the result of a seismic rating, needs to be taken in conjunction with all occupants of a co-located government site. This ensures a consistent approach and message while balancing a chief executive’s responsibility as a person conducting a business or undertaking (PCBU), as outlined by WorkSafe.
While individual agency chief executives are responsible for their staff when deciding to continue to occupy a building, they may arrive at different decisions. It’s important to be joined up in these decisions so we’re here to help agencies work through this process.
If a building is less than 34%NBS it may be classified as earthquake-prone under the Building (Earthquake-prone buildings) Amendment Act 2016 (EPB). This means the building is more likely to sustain damage following a moderate earthquake and, as a result, there is a higher risk to users than there is in a new building. Over time, the law requires this risk for earthquake-prone buildings to be reduced.
If a building is greater than or equal to 34%NBS but less than 100%NBS, this indicates the building poses a somewhat higher risk to users than a new building does. There is no requirement for an agency to do anything under the Building Act, unless you own the building and the EPB legislation applies.
When you lease a building (particularly for long term leases), you should consider opportunities to encourage your landlord to improve the seismic resilience of your building, particularly if the building is in the 34 to 66%NBS range. In general, a low %NBS rating is not necessarily a need for alarm or immediate action, unless the building element(s) of concern indicate a risk to life safety.
The diagram shows a colour graded box (blue to amber) indicating the gradual reduction in life safety risk as the %NBS rating increases. The box is divided into thirds vertically, showing risk, approximate %NBS range and recommended mitigation measures for each third.
Understanding the relative vulnerability of different building elements and potential consequences of failure, is more important than the overall %NBS rating for a building. Your engineer can help you understand the vulnerabilities and potential consequences. This is particularly important when making mitigation and occupancy decisions.
When responding to seismic matters, Government agencies should apply a consistent approach, using the 'Seismic Risk Guidance for Buildings' document, along with this guidance. For example, when an agency is considering the occupation of a building not currently within their portfolio, preference should be given to existing buildings that achieve a minimum grade B rating (67 to 79%NBS).
Consider incorporating elements of low damage design in new buildings to assist with resilience planning. Low damage design refers to an approach that seeks to minimise repairs and downtime after an earthquake, while still meeting the life safety requirements of the Building Code.
You should apply a consistent approach and methodology, and understanding of a building’s vulnerabilities, when making decisions that impact on lease commitments or the government’s asset portfolio. This is important as the term of government leases is often lengthy. We can help agencies understand government’s expectations when entering a new lease or renewal.
There are many variables involved in seismic assessments and there can be uncertainty in quantifying risk for a particular building. This means that %NBS should be viewed as indicative of the engineer’s confidence in the expected seismic performance of the building rather than an exact prediction. It also means that buildings perform differently depending on the type of earthquake. So a one-size-fits-all approach to a seismic assessment is not possible.
If you receive an initial seismic assessment (ISA) that identifies areas of concern, you should encourage the building owner to undertake a detailed seismic assessment (DSA). If the landlord isn’t prepared to do a DSA, you should consider obtaining one yourself. You will need the landlord’s cooperation as the engineers will need the building designs and other key materials to assist them with their modelling. It is also worth discussing the potential to share costs with the landlord.
A DSA should be peer reviewed by an independent chartered engineer to provide a higher level of comfort in making decisions about future occupancy.
We recommend that occupancy decisions are not made until you receive a DSA, unless your engineering advice states that your building is not safe to occupy. You should discuss the DSA with your engineer, GPG and other key stakeholders. There are a range of options available to help manage your risk.
Decisions to vacate, or safely continue to occupy a building, will have legal and financial implications for your lease. In some cases, continued occupation requires negotiation with the landlord to undertake remediation works, particularly where seismic rating expectations are not incorporated into your current lease terms.
In case of significant disagreement over the conclusions of a seismic report, Engineering New Zealand offers independent facilitation so that engineers can agree on a narrower assessment rating.
Reconciling differing seismic assessments – Te Ao Rangahau, Engineering New Zealand
Occupation of seismically vulnerable buildings can be an emotive topic. The fear of injury or death, moral obligation toward safety of building users and/or personal liability can weigh heavily on the shoulders of decision-makers.
All buildings should be assessed for seismic risk at various points of a property’s lifecycle. This can be done eg when concerns are identified, a lease is coming up for renewal, or an agency is considering moving to new premises.
There are seven key factors to consider when deciding whether a building is safe to occupy. Each factor contains a different risk rating depending on the circumstances and should be considered in the context of the overall rating. The 'Seismic Risk Guidance for Buildings' has specific information on each of these factors and we can help you work through options.
Ultimately, it is the responsibility of a person conducting a business or undertaking (PCBU) to decide about the suitability of a particular building for occupancy. WorkSafe has information available on the responsibilities of a PCBU.
Who or what is a PCBU? – Mahi Haumaru Aotearoa, WorkSafe
Agencies must understand the seismic profile of a building before entering a lease. Our new lease template will contain seismic provisions and sets out expectations for ongoing seismic performance and warranties for a building. We can help you ensure the appropriate clauses are incorporated to acknowledge government as a long-term tenant.
If you are renewing a lease, you should also make efforts to incorporate these seismic provisions, particularly for longer lease terms. Email the GPG team for the latest lease template.
Decisions regarding the suitability of a building based on its seismic rating are ultimately decisions for an agency to make on behalf of the people who work for it. We recognise the difficulty and complexity in reaching these decisions. We can help you work through this process. We can also help you engage with the BSP engineering team, email the GPG team.