Integrated Guidance for Climate-Resilient Infrastructure

Based on the review of over 150 existing publications and tools on climate-resilient infrastructure, the following key actions have been identified to support practitioners in integrating climate resilience into infrastructure development in the Design phase of the infrastructure lifecycle. These actions are summarized in the table below and grouped by theme. Each action is further elaborated on in this section and references and links to key publication and tools are shared.

View all Themes and Actions

Theme 1: Climate Informed Design Criteria

Traditionally, designers will specify parameters and minimum requirements for design that correspond to various climatic factors. For example, drainage systems will be designed to manage a storm of a given return period and structure expansion joints will be sized for an anticipated maximum temperature. These parameters are typically based on historical climate data for existing infrastructure. However, due to rapid climate change these factors may be outdated for new assets and are likely to become increasingly inaccurate over the course of the asset design life, leading to underestimation of climate risks. This may shorten the usable life of the asset or reduce its long-term performance.

Design codes do not presently provide appropriate climate hazard data to inform design. Future-Oriented PlanningFuture-Oriented PlanningFor infrastructure to be climate-resilient, it is therefore essential for designers to consider the best available climate data themselves, a process which should be encouraged and facilitated by owners and operators, to assess how the demands on their designs might during the lifetime of infrastructure assets. Design codes have started to be updated to reflect this new reality and include climate-informed design criteria.

5.1.1 Seek construction codes and design requirement that consider climate change

Building codes and standards, much like other design practices, traditionally base their requirements on historical data which is typically updated on a 10-year. Extreme weather events are more commonly considered in existing codes based on the probability of occurrence within the current climate, with little consistency between countries regarding the annual probability of an extreme event that should be designed for. No building codes from the eight countries surveyed by the Global Resiliency Dialogue (2021) addressed climate risk. However, this is changing. Some building codes are under development to include climate change considerations in future editions. An example is the National Building Code of Canada (NBCC) and the Canadian Highway Bridge Design Code (CHBDC), which are both considering climate change projections for their 2025 editions ^[1].

At present, there are no construction codes or standards with robust consideration of climate change. A survey of civil engineers in the UK found that only 15% always, and 28% very often, considered climate change adaptation in their work ^[2]. The Policies and Plans phase provides guidance on the integration of climate resilience into codes and standards for standard setting bodies. The WFEO ^[3] recommends continual review of and challenge to the traditional standards and tools engineers use in their practice including “procedures, codes of practice, rules of thumb, etc”. Learning and IterationLearning and IterationHowever, infrastructure owners are increasingly asking to adapt their design requirements for future climate above the minimum standards requirements and encourage the adoption of climate-resilient standards by designers when they are produced.

Simple approaches to adapting existing standards include increasing requirements by a given multiplier every few years, for example Australia’s National Wind Code proposes to increase its wind speeds in cyclonic wind regions by 5% in its 2022 code. Approaches based on climate models that address uncertainty to some degree, as is proposed for the Canadian codes among others, are likely to be more valuable in the long-term. The RCP 8.5 climate scenario pathway, which is one of the most severe and high impact scenarios, has been proposed as the likely scenario on which several codes will be based ^[1].

5.1.2 Identify and utilise existing climate data

Evidence-Based Decision MakingEvidence-Based Decision MakingTo effectively address climate change in design criteria, sufficient data on the future climate is required. Global databases provide high level data on future climate. These may be suitable for earlier project phases and to allow appropriate modifications to be made to certain criteria. For example, the estimated peak air temperature encountered during an asset’s lifetime could be altered based on regional or national projections. However, detailed design will usually require higher spatial resolution data with estimates of temperature, wind speeds, humidity, precipitation, and a range of other factors, often necessitating simulated weather profiles. Many organisations have developed publicly available high-resolution climate projections including simulated weather files, typically at a country or regional level. The availability and quality of these more detailed climate projections will vary depending on the project location. Climate risk maps focusing on specific hazards are also often produced, indicating zones or contours of elevated risk.

The links below list examples of climate databases for different countries and regions:

• The World Bank Group’s Climate Change Knowledge Portal, global coverage filterable by country, region or watershed
• Australia’s Bureau of Meteorology climate change datasets
• Copernicus climate data, a range of climate projections and related products, global coverage with a European focus.
• UKCP18 projections for the United Kingdom
• Downscaled climate dataset for East Africa
• Multiple databases covering the United States and parts of Canada
• Regional climate projections for New Zealand

Refer also to Action 1.5.1 and Action 1.5.2 in the Policies and Plans phase for additional climate-related data sources.

Designers should draw from a wide range of climate change projections wherever possible to explore a wide envelope of climate change uncertainties. They should consider both changes in mean climate conditions and extreme climate-related events ^[4]. The selection of specific climate datasets is likely to be limited by national level requirements. The appropriate establishment of these requirements, discussed in the Policies and Plans phase, is therefore key to the effective integration of climate change at the design phase. Section 6.3 of ISO 14091:2021 provides some general guidance on the acquisition and management of data.

The above climate data sources are across a range of scales and resolutions. The resolution of data required will depend on its intended usage. For example, adjustments to the maximum design temperature could be based on an envelope of national projections, whereas detailed hazard modelling will require downscaled, detailed data. Downscaling using computing intensive dynamical techniques or less intensive statistical techniques are well established methods to produce detailed, local climate models from global climate models where necessary ^[5]. The downscaling process is technically difficult and computationally intensive, so infrastructure owners and designers may consider partnering with climate experts in this area.

5.1.3 Use or undertake hazard and risk assessments to identify design requirements and solutions on

Designing for climate resilience requires climate modelling data to be translated into locally specific risks ^[6]. Infrastructure practitioners should ideally be able to draw on hazard and risk assessments for known hazards conducted at earlier phases (where they exist) in the project to inform design. These should provide sufficient detail to enable designers to identify and quantify the climatic hazards and disasters of relevance to their projects in order to design the assets to withstand them. For a climate-resilient project, hazard and risk assessments must be able to provide predictions on how the frequency and severity of each hazard might change over the life of the asset. As there remains a level of uncertainty in all climate projections, incorporation of climate change-informed hazard assessments into probabilistic and risk-based approaches can help balance designing for resilience with acceptable costs. It will rarely be feasible or economically viable to design for every worst-case scenario or to eliminate all risks. Many different frameworks to conduct risk assessments exist, one example is the risk assessment from USAID’s framework ^[7], where typical steps include:

• Exposure Analysis – are the proposed assets exposed to the anticipated climate change impacts? Reference should be made to local or regional level hazard maps and climate projections at the design phase (designer should be able to draw on previous stages for this analysis).
• Sensitivity Analysis – To what degree is the asset affected by the climate change impacts? This requires consideration of specific design choices, such as the materials, components and technologies.
• Risk Assessment – What is the probability of the impact occurring and how severe would the associated economic, social or environmental impacts be?
• Risk Evaluation – Is the assessed risk acceptable? If considered unacceptable the design will need to address it.

Asset vulnerability is a factor of both its exposure and sensitivity. Learning and IterationLearning and IterationEven when a risk assessment has been conducted at earlier phases, some degree of review at the design phase to ensure it is still appropriate is required, especially where design decisions may alter the asset’s sensitivity to climate hazards. Consideration should also be given to the possibility of increased risks due to compound hazards. For example, compound flooding caused when multiple drivers, such as tides, storm surges, rainfall runoff and river discharge, coincide to produce a much more severe event than any individual driver. These hazards can be among the most severe but are typically poorly considered in risk assessments ^[8].

5.1.4 Conduct detailed risk assessments and modelling for sensitive and/or critical assets

If a sensitive and/or critical asset is expected to be at risk from more spatially variable climate impacts such as flooding, storm surges, landslides and sea level rise, or a more in depth understanding of the risk posed by the hazard is needed, more detailed modelling may be required by the designers to appropriately assess the risk and how to design against it. The links below list examples of hazard-specific guidance:

• Sea-level rise modelling
• Flood modelling
• Storm surges
• Landslides (overview, technical)
• Extreme heat

5.1.5 Incorporate climate projects into design criteria

Evidence-Based Decision MakingEvidence-Based Decision MakingWith sufficient data to produce probabilistic climate projections, the modification of design parameters and specifications can be done in the same manner as their original definition from historic data. This might be the case for hazards already considered in design but for which the magnitude is expected to increase, for example, an increase in the maximum water levels experienced by a sea defence. The selection of which projections to use for which criterium should be dependent on both the identified risk, the estimated cost of intervention and the asset lifespan, in some cases designing to the worst-case scenario may not be feasible. Designers should work closely with climate and meteorological specialists to ensure their use of climate data is in line with the current scientific consensus. Learning and IterationLearning and IterationIt is important that designers develop a foundational understanding of the climate data they are using and communicate their needs effectively with climate specialists. ASCE ^[9] provides guidance on how to develop flood design criteria informed by climate change, particularly design flood elevations (DFEs). Suggested actions to improve the incorporation of climate data in other design parameters include ^[3]:

• Set out an initial list of the design parameters in codes, standards, and other sources relevant to the work.
• Evaluate how each of these parameters might change with future climate, including extreme cases.
• Engage with climate and weather specialists to derive new values and consider the associated uncertainties, assumptions, data sources, validity, and other considerations.
• Assess the criticality of these values and assumptions on the overall design and function of the system.
• Based on professional judgement, apply updated climate design parameters as deemed appropriate to the safety factors, margins or design values with plans, designs and specifications.

ASCE’s Climate-resilient Infrastructure: Adaptive Design and Risk Management provides guidance on how climate change can be incorporated into design for a range of infrastructure sectors. Although some examples are USA specific, the guidance is mostly globally applicable. Guidance on incorporating climate change into design parameters typically assumes a minimum level of data availability, there is a notable gap in guidance on what to do when climate data is unavailable, limited, or of poor quality which is often the case in Global South contexts.

5.1.6 Consider climate change scenarios and undertake climate stress tests

Future-Oriented PlanningFuture-Oriented PlanningIn addition to affecting the design requirements of infrastructure assets, climate change will also have direct and indirect effects on their ability to perform their intended function, both beneficial and adverse. Service Continuity and ReliabilityService Continuity and ReliabilityAssets that depend directly on climatic factors for their operations, such as many renewable energies and the water sector will be particularly affected. Climate stress testing consists of the generation of possible future climate scenarios and the assessment, typically through simulation or modelling, of their impact on the performance of a system. They are becoming increasingly common practice in the financial sector ^[10].

The International Hydropower Association incorporates a climate stress test into their climate resilience guide ^[11]. This includes the generation of a range of possible climate scenarios and stochastic climate traces representative of the full range of climate change projections. Service Continuity and ReliabilityService Continuity and ReliabilityThe hydropower generation and economic performance of a proposed (or existing) project can then be modelled for each of these scenarios. Similar methods could be employed within any infrastructure sector if specified as design requirements by infrastructure owners. Future-Oriented PlanningFuture-Oriented PlanningOther impacts to be considered include effects on the rate of deterioration of assets, changes in demand or land use.

Learning and IterationLearning and IterationThe results of these assessments should then be used by designers to inform whether the designed infrastructure will be fit for purpose in the future climate. If not, increased capacity or alternative design solutions should be considered.

Theme 2: Systems Thinking

Infrastructure systems are increasingly more complex and interconnected. Systems ThinkingSystems ThinkingIndividual assets within a network will often be dependent on the reliable operation of those that are connected to them, and their failure or disruption will result in cascading failures across the network. Furthermore, interdependencies across networks and sectors can result in substantial, and often unforeseen, cascading impacts when failure occurs. These interdependencies and their consequences will become increasingly important as climate change places additional and new pressures on individual assets, networks and the wider system.

Systems ThinkingSystems ThinkingClimate-resilient infrastructure should therefore account for interdependencies at the design phase through a systems thinking approach. This includes assessing and minimising both the vulnerability of any assets being designed resultant from their interdependencies, and the new vulnerabilities they might introduce in the system. Equity and Social Co-BenefitsEquity and Social Co-BenefitsSystems thinking at this phase will also enable designers to consider how they can maximise the co-benefits delivered by the infrastructure communities and natural systems and minimise negative impacts through the choices they make.

5.2.1 Identify interdependencies within and between systems

There are numerous tools and methodologies available for conducting assessments and modelling of interdependent infrastructure. These methods are “typically more useful for depicting the nature and direction of interdependencies than for accurately quantifying these relationships”^[12]. Nonetheless, Evidence-Based Decision MakingEvidence-Based Decision Makingan awareness of what systems and assets an infrastructure asset is dependent on and what will become dependent on it forms an essential part of a truly climate resilient design and should be incorporated in design requirements. At this phase the ideal goal would be gathering asset-specific interdependency data. However, as a starting point a high-level understanding of the potential interdependencies is required, both within the system and with other infrastructure systems. Creating interdependency maps is a good way to validate and communicate this initial understanding of interdependencies.

C40 Cities describe several distinctions of interdependency:

• Physical interdependencies – when commodities or services offered by one system are required by another to operate.
• Cyber interdependencies – when the state of infrastructure depends on information technology systems.
• Geographic interdependencies – the result of infrastructure systems in close proximity, which are therefore vulnerable to the same hazards and disruptions.
• Logical interdependencies (i.e. cascading consequences) – when disruptions to a system cause second-order impacts through other connections. This category of interdependencies includes the cascading effects on the environment, society, and economy that are triggered by failure in one system.

Inclusive EngagementInclusive EngagementWhere interdependencies between multiple infrastructure systems are poorly understood, stakeholder collaboration activities can be highly valuable as a means for gathering initial information and encouraging systems thinking. This is often conducted through workshops led by city or regional authorities as part of needs identification and planning activities. These activities can provide a foundation on which to build at the design phase, however most examples focus on high-level, primarily conceptual interdependency mapping. The Critical Infrastructures: Relations and Consequences for Life and Environment (Circle) tool is one example designed to facilitate discussions on interdependencies between infrastructure stakeholders. End users should also be included in engagement activities to ensure their needs are appropriately highlighted. Inclusive EngagementInclusive EngagementThis is captured by the UK National Infrastructure Commission design principle to (see page 6) “work with the people who use the infrastructure, the communities who live nearby and the workers who build, maintain and operate in to ensure the design meets their diverse needs”^[13].

5.2.2 Collaborate, benefit from, and contribute to data sharing initiatives

Evidence-Based Decision MakingEvidence-Based Decision MakingData collection is an essential first step in identifying and analysing climate risks to interdependent systems. These data might include infrastructure characteristics, such as the location, condition and interconnectedness of assets; the sensitivity and adaptive capacity of these assets; and the economic, social and environmental context and benefits delivered by the infrastructure. However, access to data concerning other organisations’ assets is often very limited. Inclusive EngagementInclusive EngagementAny approach to interdependencies should engage with a diverse range of organisations from across sectors, containing stakeholders from public, private and community groups. A thorough understanding of the role and composition of each organisation regarding risk management and planning will be required, in addition to recognition that efforts will be most effective if they are viewed as beneficial to all stakeholders and their goals.

Data sharing is best enabled through the creation of a safe platform that allows organisations to be open about their operations while satisfying concerns over potentially sensitive information ^[14]. A number of existing platforms and organisations have been established by local and regional authorities aiming to provide such a space through differing approaches, including Silicon Valley 2.0, the Greater Manchester Open Data Infrastructure Map (GMODIN), the Inner Melbourne Climate Adaptation Network (IMCAN), the City of Bogota’s mapping platform and Virtual Singapore. Inclusive EngagementInclusive EngagementParticipation in these groups could greatly improve infrastructure owners and operators’ ability to facilitate systemic resilience. Learning and IterationLearning and IterationNote that when using data from a shared source, practitioners should regularly evaluate whether the data is suitable, regularly updated, and reliable.

5.2.3 Evaluate cascading impacts to identify indirect risks

A key requirement to implementing concepts of systems thinking and interdependencies within project design is to assess the potential for cascading impacts within the design system. Evaluation of first-order impacts forms the initial basis of the assessment. Designers will need to be able to draw on maps of the system connections, links, and the nature of interdependent relationships between organisations, assets and operations ^[14]. These may be purely conceptual maps or, if the data is available, spatial maps for use in a GIS environment which will allow for greater evaluation of geographic and physical interdependencies. In the absence of detailed information on every part of the system, proxy data may need to be used ^[14]. For example, public housing or population density data might be employed as a proxy for energy and water demand.

A screening process to review potential climate risks to each part of the system should be conducted. For each element of the system at risk from climate change, the potential impacts of the hazard, consequences of failure and likelihood of the hazard should be considered to produce a preliminary risk rating. This rating can be used as the basis to select hazards to explore in more detail through the development of impact chains, which attempt to evaluate, quantitatively or qualitatively, the impacts of a hazard across an entire system ^[15]. Practitioners should focus on the most important risk factor relationships as it will never be possible to comprehensively capture all aspects. ISO 14091:2021 provides more detailed guidance on the development of impact chains.

Service Continuity and ReliabilityService Continuity and ReliabilityUltimately, system requirements and impacts should be traced back to the end user, ensuring their needs are met, that designs ensure impacts to them are minimised and that they are best able to recover quickly. Where designers may have to prioritise one area of the infrastructure system over another, the impacts to the end user should be the deciding factor.

5.2.4 Use interdependency assessment tools and metrics to prioritise and evaluate design solutions

Quantitative indicators of interdependencies allow for the identification of key focus areas for design and the evaluation of the impact of design and adaptation options. One of the most valuable metrics often calculated as part of an interdependency assessment is criticality. This is an indicator of how critical a particular asset, link or node is to the operation of a wider system and is a useful tool to enable infrastructure owners and operators to appropriately assess the consequences of asset failure. Criticality can be calculated at different levels of complexity, for a small network of connected assets up to cross-sectoral systems on a national or international scale. The EU Science Hub’s open source GRRASP software utilises spatial data on asset locations and connectivity to calculate asset criticality in terms of the level of downstream nodes in a network impacted by disruption at the specified node. It also calculates the vulnerability of a node to disruptions upstream.

Other tools attempt to directly model the cascading impacts resulting from a specific hazard. For example, Fraunhofer EMI’s CAESAR simulates the primary impacts of a natural disaster and propagates the damage caused across the network (such as the loss of power supply of a substation due to damage to a utility pole) and beyond the boundaries of the network (for example, electrical disruptions of mobile phone base stations). This allows the effect of proposed mitigation strategies to be simulated.

The use of these tools and metrics can help practitioners identify vulnerabilities which may require additional mitigation, opportunities for shared resilience building measures and options to manage interdependency. For example, where a critical asset is found to be highly vulnerable to cascading impacts, designers might consider allowing isolation of critical components or employing a modular design ^[16].

5.2.5 Consider how to maximise co-benefits and minimise negative impacts

In addition to the consideration of interdependencies and their inherent risks and opportunities, systems thinking for design should include consideration of the broader impact of the infrastructure on society. Equity and Social Co-BenefitsEquity and Social Co-BenefitsLeverage points and singular interventions to maximise co-benefits which bring added social, environmental, or economic value to the community should be identified wherever possible. Likewise, the negative socio-economic-environmental impacts should be reviewed and minimised where possible.

These principles are embodied within requirements of professional institutions, such as ASCE requirements for engineers to “consider and balance societal, environmental, and economic impacts, along with opportunities for improvement, in their work^[17] and “mitigate adverse societal, environmental, and economic effects^[18]. Social and environmental impacts occur both during construction (for example biodiversity loss from land clearing, the displacement of people or disruption of ordinary activities) and operation (for example, carbon emissions, disrupted ecosystems and habitat connectivity, changes in land use and economic activity, gender discrimination)^[19]. Guidance for the design phase to minimise adverse impacts and enhance co-benefits and natural capital includes:

• Avoiding construction in areas important for biodiversity or high ecosystem service value and prioritisation of brownfield development (UNEP, 2020). The overall project location will generally be selected prior to this phase, but opportunities remain on a smaller scale to influence where construction will take place, particularly for large projects.
• Environmental Co-BenefitsEnvironmental Co-BenefitsEmploying nature-based solutions (NbS) using the services that landscapes and ecosystems provide naturally in place of built infrastructure options (see Theme 5.5) ^[19].
• Equity and Social Co-BenefitsEquity and Social Co-BenefitsSelecting designs with construction and operation methods that optimise employment impacts by increasing the use of labour and local-resource based solutions, and enable the participation of micro, small and medium enterprises ^[19].

Equity and Social Co-BenefitsEquity and Social Co-BenefitsDesign dual-purpose infrastructure and assets that provide additional value to the community. For example, designing flood defence walls have been designed to double as seating-shelters, bike points, shops and recreational facilities among others ^[20] or road drainage that drains into farm ponds for irrigation purposes ^[21].

Equity and Social Co-BenefitsEquity and Social Co-BenefitsCare should be taken not to entrench existing systemic inequalities, as can be the case where design options simply strengthen and enhance the resilience of existing services without wider consideration of their societal impacts ^[22].

Theme 3: Design for Uncertainty

From a climate resilience perspective, the primary sources of uncertainty in the design phase are around climate hazard projections and impacts, such as temperatures, precipitation, and extreme weather events, and this uncertainty is moderately characterised. However, more poorly characterised uncertainty exists surrounding secondary impacts of climate change, such as future demographics and consumption, and uncertainty that cannot be properly characterised around global governance, cooperation and decision-making. There also remains a degree of uncertainty in any system that is yet to be recognised at all ^[9].

In light of this uncertainty, the optimal design solution for climate change resilience is not always to attempt to make infrastructure resilient to all potential disruptions and impacts, especially those that cannot be accurately predicted. Furthermore, prohibitive capital expenditure or trade-offs with other socio-economic-environmental objectives may lead decision-makers not to invest in the most extreme physical resilience and to consider alternative options. Additionally, uncertainty that is poorly or entirely uncharacterised cannot be eliminated directly. Methods for managing uncertainty must therefore be developed. This theme requires practitioners to look forward through the lifecycle towards the operation and maintenance phase, as it is during the operational life of the asset that the consequences of uncertainty will come to fruition.

5.3.1 Design redundancy into infrastructure systems

The inclusion of deliberate redundancy in infrastructure is common practice even in traditional design methodologies, often included within planning and construction standards. Diversity and redundancy are inherently resilient by improving the system’s ability to respond to interruptions and providing alternative pathways to mitigate disruptions and facilitate recovery ^[23]. This practice is increasingly essential when confronted with the high level of uncertainty presented by climate change. Service Continuity and ReliabilityService Continuity and ReliabilityRedundancy allows for managed failures while still providing critical services. In creating redundancy, owners, operators, and designers should consider:

• Redundant components so that the loss of a single component does not cause the failure of the asset as a whole. This might also include redundant components for cross-sector dependencies, such as back-up generators for systems reliant on the electricity grid.
• Additional redundant capacity. For example, designing dike walls to be a given height taller than the worst-case flood scenario based on climate change projections discussed in Theme 5.1.
• Interdependencies between assets and components intended to provide redundancy, as discussed in Theme 5.2, which need to be mitigated against. Redundant components in close physical proximity, such as conveyance piping crossing a river on a shared structure, will be vulnerable to the same climate change impact or disasters and should be avoided. Likewise, redundant components that rely on the same electrical grids and communications networks, transport links for their workers, or any other physical, geographic, cyber or logical interdependency may have increased potential for simultaneous failure and therefore reduced efficacy.
• Diversifying technologies to reduce shared vulnerabilities. For example, point-to-point microwave links in mobile backhaul networks are liable to signal scattering by heavy rainfall. Installing fibre optic cables between towers provides additional redundancy.

Network-informed solutions to build redundancy. Closely related to analyses of criticality discussed in Theme 5.2, analysis of the connectivity of links and nodes across a network can identify where additional redundancy is needed. Often, this analysis is more appropriate for regional scale needs identification work, for example to identify where additional road connections are required to provide redundancy in a national road network. However, outputs from these assessments can inform design, such as designing a new asset within a network with sufficient redundancy in capacity to handle rerouted demand from connected nodes after a failure. Both the telecommunications and energy sectors are increasingly employing “ringed” or “meshed” distribution networks at varying scales, which provide multiple supply points and connections to nodes in the network and allow for quick switching of loads ^[12][24].

5.3.2 Employ flexible and adaptable design strategies allowing for future adaptation

Learning and IterationLearning and IterationAdaptable design strategies provide an iterative approach to managing uncertainty. They are engineered with a flexible protection level, initially designed for a portion of their design life, which is then re-evaluated as the risks potentially change. The initial adaptable design then allows improvements to be made comparatively easily. Adaptable design strategies are particularly valuable for large, complex infrastructure projects with long design lives, as they offer effective options to balance uncertainty with cost, especially when confronted with increasingly uncertain climate projections after 30 years or more ^[25]. Common examples of adaptable design include sizing foundations to support larger structures and defences than initially designed or including space for additional connections to increase capacity. Adaptable design strategies can form part of a broader ‘adaptation pathways’ approach, which might combine adaptive design with adaptation at other lifecycle phases. Adaptive management approaches are discussed further in the context of decision-making and prioritisation in Lifecycle Phase 2.

Some of the most comprehensive guidance on the topic of adaptive design is included in ASCE’s Climate-Resilient Infrastructure: Adaptive Design and Risk Management. This guidance outlines the observational method as it would need to be followed by designers, planning out courses of action for the range of possible climate futures, monitoring changes in climate and implementing the planned courses of action. The guidance also offers more advanced approaches to monitoring including the construction of fragility curves and the prediction of failure likelihood to help make adaptation decisions ^[9]. Brown et al. (2020)^[26] outlines a method, intended for water infrastructure but with broader potential applicability, building on traditional cost benefit analyses by incorporating the costs of the fixed design, estimated cost of reactive recovery, proactive recovery, monitoring and detection, and the utility of expected losses. This method is intended to allow planners to value resilience measures under deep uncertainty and indicate when adaptation and transformation is necessary.

Learning and IterationLearning and IterationAdaptive capacity, i.e. the ability for assets to be adapted or modified over time as uncertainties are resolved, can be built through these adaptable design strategies. However, it can also relate to broader concepts of operational efficiencies and flexibility, and the extent to which future changes will be able to affect the finished design^[27].

5.3.3 Include design allowances to improve operations and maintenance

Leveraging design options to allow for improved operations and maintenance practices can help increase the infrastructure system’s capacity to adapt to uncertainty over its lifetime, and in some cases is an essential component of adaptable design.

Observation is integral to the use of adaptable design strategies. During the initial design, a course of action or design modification must be devised for every foreseeable deviation from the initial design criteria during the infrastructure’s operational life. Evidence-Based Decision MakingEvidence-Based Decision MakingObservations will be necessary to review if any of these predetermined courses of action are required. In many cases this may be possible without site-specific monitoring, for example, if a climate threshold that is already monitored at a regional scale is set, such as sea level rise ^[9]. However, where site-specific thresholds are required, proactive monitoring strategies should be put in place.

Monitoring will naturally occur during the operation and maintenance phase and is discussed in more detail in the Operations and Maintenance phase. Some proactive monitoring techniques will require special measures within the design or must be built-in to the asset itself, for example ground temperature monitoring wells constructed among the piles of a building to monitor the thawing of permafrost ^[9]. In any case, consideration must be given at the design phase of what monitoring, if any, will be necessary to inform the selected adaptation strategies. The use of emerging digital technologies may help in the enhancement of climate preparedness. In the design phase, this might include building information modelling (BIM) and the creation of digital twins to allow for detailed monitoring and analysis of the asset performance ^[28].

Additionally, the embedment of technology to help improve operational processes, such as smart sensors and control systems, should be considered during design. Infrastructure owners and operators should cooperate with designers to ensure requirements to improve operations and maintenance are incorporated into designs

5.3.4 Implement safe-to-fail and disaster management approaches

Business continuity and contingency plans are used by infrastructure owners and operators to identify measures to be taken in the event that an emergency or disruption surpasses all other resilience measures and loss of service occurs, they aim to continue the operations of the business until normal service can be restored. Whereas emergency response plans focus on the protection of life, assets and the environment in an emergency situation. Learning and IterationLearning and IterationThese plans should be in place throughout the operational life of the project and will need to be updated regularly during the operation and maintenance phase. Consideration of the disaster management approaches that will be active in the operations and maintenance phase during design can ensure that the design accommodates these future activities as far as possible. This might include measures such as ensuring access routes for emergency services in any scenario, putting deployable protections in place, or allowing for swapped connections to alternative supplies of water, energy, or any other dependencies.

Service Continuity and ReliabilityService Continuity and ReliabilityAt the design phase, initial contingency plans can be informed by “what-if” worst-case scenarios examining the consequences of failure^[12] Installation of early-warning, monitoring and communications systems can reduce the impact of failure and support recovery. Examples include variable message signs (VMS) on highways which can provide real-time warnings and instructions to road users in the event of an emergency^[29] and advanced metering infrastructure (AMI) in the energy sector, which allows communication between end users and utilities operators and can be used to pinpoint power outages^[12].

Risk mitigation in infrastructure design has traditionally focused on fail-safe design, intended to prevent failures from occurring. In the face of increasing uncertainty it may not always be feasible to design infrastructures to be fail-safe to all possible events. Safe-to-fail approaches can therefore be employed to ensure that the failure of a single asset or area of a system does not result in major disruptions to the wider system. This type of design requires a more systemic approach to understand the societal value of infrastructure and consequences of its failure and relates closely to actions discussed in Theme 5.2. Example efforts to produce safe-to-fail designs have previously employed teams with diverse expertise including social and environmental scientists in addition to engineers^[30].

Theme 4: Building Physical Resilience

Designing physical resilience into infrastructure consists primarily of measures taken to avoid, eliminate or reduce the impacts of hazards on the operation and service delivery of the asset. Total elimination or avoidance is often not an option and is only possible for known hazards that can be accurately characterised, whereas resilient design can reduce the impacts of both known and unknown hazards.

This theme focuses on Service Continuity and ReliabilityService Continuity and Reliabilitymeasures to prevent or reduce climate impacts to the assets for which they are implemented, this is primarily through building robustness, either through strengthening existing designs or adding protective measures. It is important to note that this is not the only approach to building resilience, approaches that focus on delivering redundancy and flexibility, in addition to alternatives to grey infrastructure solutions, are discussed in Theme 5.3 and Theme 5.5 respectively.

5.4.1 Design for the avoidance of known hazards where possible

Infrastructure practitioners should seek to identify and implement opportunities to avoid risk altogether. Designers are unlikely to be responsible for site selection itself; however, comparatively minor changes in the siting of individual aspects of the design can reduce the vulnerability of the project by designing infrastructure so that sensitive assets are located away from a hazard ^[31]. This might include measures such as siting highly flood-sensitive assets, like generators, at higher elevations. Potential siting hazards should be assessed, and serious consideration given to alternative positioning to minimise risk exposure, removing or modifying sensitive structures that will be highly exposed to known hazards ^[32]. The needs of the end user should not be forgotten in this process and care should be taken that the accessibility of the assets is not reduced when designing for avoidance. Attempts to design for the avoidance of hazards are likely to be most effective when implemented at the earlier stages of design, if not in the pre-design phases, as siting, orientation and positioning typically become increasingly locked-in as the project progresses.

5.4.2 Consider measures to build robustness and protect against climate hazards

Design measures to ensure infrastructure is able to physically withstand the effects of climate hazards consist primarily of those intended to increase the general robustness of the infrastructure itself, its durability and the quality of its construction, to provide a suitable level of protection from hazards and the inclusion of hazard mitigation strategies. The former measures discussed in Theme 5.3 can increase resilience to a number of hazards, including the unforeseen, whereas protection and mitigation strategies generally focus on specific hazards. The actual measures taken will be specific to the infrastructure sector, asset and project types. The table below provides guidance documents for specific sectors which include example measures to build climate change resilience:

The World Bank Resilient Water Infrastructure Design Brief	Examples for drinking and wastewater systems in Appendix B.
The World Bank Urban Rail Development Handbook	Urban rail infrastructure examples on page 673.
PANYNJ Climate Resilience Design Guidelines	Examples for Port infrastructure under Step 4.
The Resilience Shift Electric Utilities Resilience Primer	Examples for electric utilities on page 28.
Resilient Pathways: the adaptation of the ICT sector to climate change	Examples for the telecommunications sector on page 40.
A Guide for USAID Project Managers: Roads	Examples for roads listed in the Appendices.
Guidance on Design and Construction of the Built Environment Against Wildland Urban Interface Fire Hazard: A Review	A discussion of different design and construction approaches to create resilience against wildfire, cross sector in application.

To be economical, the selection of appropriate performance requirements under specific hazard levels should be based on a cost-benefit evaluation looking at the risk posed to the asset (informed by the earlier risk assessments), the consequences of failure, and the financial implications of the design intervention. Future-Oriented PlanningFuture-Oriented PlanningStress testing of a proposed design under future climate conditions can help assess the value of different resilience measures. This can form part of an iterative process of stress testing and adjustment of design until an appropriate solution or combination of solutions is identified ^[33]. Future-Oriented PlanningFuture-Oriented PlanningThe use of life-cycle cost practices that consider all inputs and outputs of acquiring, owning, and disposing of a system also help practitioners appropriately value and select the most appropriate sustainable and resilient practices ^[34].

Service Continuity and ReliabilityService Continuity and ReliabilityOnce appropriate levels of robustness and physical resilience are identified, it is important to ensure these resilience features are maintained throughout the design phase, including during value engineering periods. It is during these cost saving exercises, which attempt to deliver project functionality at the lowest cost, that resilience measures are often the first to be cut^[35].

Multi-hazard approaches should be employed over considering individual hazards individually. As multiple stressors frequently occur at once with complex interactions and cascading consequences. a multi-hazard approach is more realistic ^[36]. Furthermore, considering all potential hazards when selecting resilience measures will help prevent creating resilience against one hazard at the expense of increased vulnerability to another. This might also include non-climate related hazards, for example, the elevation of a structure to protect it from flooding may result in the creation of a seismically vulnerable “soft story” ^[37].

5.4.3 Consider climate change during construction material selection

The selection of appropriate construction materials is integral to building robustness to climate hazards. The physical properties: strength, durability, permeability, thermal sensitivity, colour etc. of construction materials will greatly impact their ability to withstand climate change impacts. Service Continuity and ReliabilityService Continuity and ReliabilityDesigners should evaluate the impacts of increasing heat and other climatic factors on their selected materials using climate projections over the asset lifespan. Material selection might also provide additional benefits. For example, thermally massive, breathable, and light-coloured exterior materials can help provide passive solar cooling and ventilation ^[38]. Some high-level guidance exists on the suitability and durability of different construction materials to climate and natural hazards, from USAID in particular USAID (2015a) A Guide for USAID Project Managers: Bridges^[39], USAID (2015b) A Guide for USAID Project Managers: Roads ^[40] and USAID (2017) Climate Resilient Water Infrastructure^[41]. However, designers should evaluate the specific requirements of their project before selecting materials based on these factors alone.

Material selection provides opportunities for synergy between resilient and sustainable design. For example, timber is increasingly being recognised as a material with the potential for resilient buildings and construction while simultaneously having a lower carbon footprint than most conventional materials and capabilities to support wider sustainability and biodiversity objectives ^[42]). Additionally, the selection of materials which require minimal maintenance, can accommodate adaptation, and can be supplied locally have direct resilience and sustainability benefits ^[43]

5.4.4 Promote adoption of climate-resilient design through qualifications, certifications and tools

Capacity BuildingCapacity BuildingThe embedment of climate-resilient standards in professional practice, accreditation and capacity building will improve the quality of climate-resilient design work among practitioners, strengthening and popularising the role of these individuals (Standards Council of Canada, 2021). Climate resilience is rarely directly addressed in requirements for professional practice and accreditation, however some professional requirements and certifications concerning or related to climate resilience include:

• ASCE policy statement 360 – Climate Change which supports informing engineers and other stakeholders about future climate and developing “a new paradigm” with consideration of climate change.
• The ASCE additionally endorses Envision as a rating tool to evaluate the sustainability of projects, which includes some resilience considerations. Practitioners can also become Envision Sustainability Professionals (ENV SP).
• The UK Institution of Civil Engineers (ICE) has proposed to develop and implement a carbon and climate design literacy programme for all its members and to review carbon literacy as a requirement for membership and fellowship grades ^[44].
• The SuRe® Standard for Sustainable and Resilient Infrastructure is a voluntary standard and certification for infrastructure projects.
• CEEQUAL is a widely adopted rating and awards scheme in the UK and Ireland. It focuses on sustainability but includes requirements around the development of risk assessments and mitigation, including climate change, flood mitigation, and the consideration of future needs ^[45]
• The IS Rating Scheme is a widespread rating scheme in Australia and New Zealand for sustainability across the whole lifecycle, including a design rating phase. Resilience is included as one of the categories assessed in the scheme.
• The RELi Rating System is a certification rating system that combines sustainable and regenerative guidelines with credits for “emergency preparedness, adaptation and community vitality”, it is primarily intended for use in the United States.

Organisations might consider upskilling their workforce through higher education. Examples of undergraduate and postgraduate courses with an infrastructure resilience or climate resilience aspect are more common than professional requirements, although it remains an emergent field. The Resilience Shift has produced an ongoing map of opportunities to study infrastructure resilience.

The Cat-I tool, intended to help governments identify gaps in their capacity to plan, deliver and manage infrastructure systems, includes assessment of design phase capacity and could be useful to identify areas of potential development for infrastructure owners and operators.

Theme 5: Nature Based Solutions and Green Infrastructure

Not all climate resilience measures and supply solutions need concern physical infrastructure interventions. Eco-systems have evolved natural resilience, which humans can learn from and promote ^[46]. Often, solutions that work with, or are inspired by nature can be developed, to increase the resilience of the wider system. Three key definitions in this area are:

Nature-based solutions (NbS) – “actions to protect, sustainably manage and restore natural and modified ecosystems in ways that address societal challenges effectively adaptively, to provide both human well-being and biodiversity benefits.” ^[47]

Green infrastructure (GI) – Any restored, new or improved soft, vegetated, natural infrastructure or ecosystem aimed at providing direct or indirect protection from climate hazards. These infrastructures are an essential part of Nature-based Solutions (NbS) ^[48].

Green-grey infrastructure – Solutions that combine green infrastructure with built, engineered, and physical structures (grey infrastructure).

Blue-green infrastructure – A focus on the combined network of natural and semi-natural landscape elements relating to land-based ecosystems (green) and water systems such as ponds, artificial basins, and water courses (blue) ^[49].

5.5.1 Identify opportunities to integrate nature-based solutions into infrastructure design projects

Nature-based solutions (NbS) and green infrastructure (GI) can be used in place of or alongside grey infrastructure measures in a range of applications, from providing natural flood defences to mitigating the risk of wind damage to powerlines ^[50]. Owners and operators, in their role as the client, should include requirements to identify NbS where applicable, and designers should seek opportunities to employ NbS at a range of scales from the project level to minor assets. High level guidance from the Green-Gray Community of Practice walks practitioners through the process of implementing NbS. Key actions from this guidance regarding the design of NbS include ^[51]:

• The assembly of a design team including restoration/conservation specialists with expertise in the relevant ecosystems, community liaison and climate/disaster risk experts, among others, in addition to the normal design team.
• The collection of relevant data, including landscape and ecosystem mapping and assessment.
• Species selection and usage.

To develop these further, EcoShape provides five basic steps for ‘Building with Nature’ design ideas. The US EPA’s guidance on the design and implementation of green infrastructure is primarily focused on urban drainage and stormwater management solutions. The IDB has developed a twelve step guide on the development of NbS for infrastructure resilience. The Port Authority of New York and New Jersey provides detailed guidance on green infrastructure design which has broad applicability despite its port-focused source. The guidance discusses various green infrastructure solutions, their suitability for different sectors and benefits delivered. The Green Infrastructure Flexible Model (GIFMod) provides an open-source conceptual modelling tool for a number of GI water management solution designs.

Environmental Co-BenefitsEnvironmental Co-BenefitsNbS and GI provide an excellent opportunity to build climate resilience while minimising negative impacts to the wider community and maximising positive co-benefits. Additionally, they allow for synergies between climate resilience and sustainability objectives. Designers should consider how their designs might contribute to co-benefits, such as creating or improving healthy ecosystems ^[52], connecting urban systems to the biosphere, and forming a “green fabric” across a city or region of green infrastructure systems ^[53].

Given the long temporal scale and complex, indirect nature of these benefits, they require periodic monitoring to ensure they are delivered. Evidence-Based Decision MakingEvidence-Based Decision MakingNbS actions should therefore be informed by evidence-based assessments of the current state of the ecosystem and should establish clear outcomes, metrics and assessment benchmarks^[54].

5.5.2 Design nature-based solutions with appropriate consideration of the eco-system

Systems ThinkingSystems ThinkingIt is essential that NbS are not designed in isolation, and that wider consideration is given to the broader context surrounding them. A key unifying theme of existing guidance on the implementation of NbS is developing a detailed understanding of the system into which the design will be integrated. Designers must consider NbS holistically at all their scalar dimensions to build an understanding of their full consequences. Eco-systems are generally larger, more complex, sensitive and interconnected than built assets, and as such a systems approach is more essential than ever. NbS therefore require a multi-dimensional and multi-scale approach with particular emphasis on the interdependencies between different dimensions and scales ^[55].

The success of the NbS will in part be dependent on its ability to interact with the economy, society and ecosystems. Synergies across sectors and opportunities to integrate NbS with other measures, such as engineered grey infrastructure, should be sought. A three-scale framework is recommended, considering the parts of the land/seascape (fine scale), the land/seascape itself (local scale) and the environment surrounding the land/seascape (regional scale). This is intended to “encourage NbS designs that recognise the complexity and uncertainty that occur in living dynamic land/seascapes”^[56]. Whereas the designed solutions themselves will in most cases be developed on the fine scale, the design should incorporate risk management options across these scales^[54]. Inclusive EngagementInclusive EngagementThe input of experts on the involved ecosystems, in addition to collaboration with stakeholders primarily focused on earlier phases of the lifecycle, as recommended by the Green-Gray Community of Practice (2020) should help deliver this.