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High Speed Two Limited (HS2 Ltd) has identified that there is a strong alignment between the High Speed Two strategic goals and potential circular economy benefits and has therefore adopted a holistic approach to realising these benefits in the delivery of the UK's new high-speed rail network. This paper describes the work undertaken to date, including establishing, embedding and communicating circular economy principles, coordinating the realisation of opportunities and reporting outcomes, as well as providing lessons learnt for other infrastructure projects. [ABSTRACT FROM AUTHOR]

Cement and concrete are essential for global development. However, cement manufacture is responsible for around 7–8% of global greenhouse gas emissions, with significant growth anticipated. Beyond efficiencies in cement manufacturing, other strategies for using less cement in construction through applying the principles of efficient design, circular economy and reuse also have the potential to reduce emissions. A further option is to move towards cements with different compositions and inherently lower embodied carbon dioxide. This paper focuses on these materials and the challenges to their widespread adoption, drawing mainly on applied research, trials and standardisation activities conducted in the UK and the EU. In addition to modification of standards, basic technical and practical information such as strength development curves, durability, site considerations and a shared broad body of evidence are key for specifiers to consider when using any new cement. The paper describes the role of standards and specifications and the underpinning information (applied research, published case studies and experience) essential in getting any new cement adopted. It also shows how a range of evidence from research and application can feed into a simple conceptual model and evidence base. [ABSTRACT FROM AUTHOR]

This paper provides upper- and lower-bound limits of stiffness improvement observed from the treatment of infilled solution features in chalk as part of the Central 1 contract being delivered by the Align JV, which is part of the UK's High Speed 2 Phase 1 rail link. Infilled solution features were treated using rapid impact compaction (RIC) to achieve a sufficiently stiff subgrade beneath a wide range of temporary foundations and reduce the risk of collapse settlement. Improvement by RIC treatment was sufficient to ensure subsequent foundation performance or reduce the extent of compaction grouting subsequently required beneath the most heavily loaded foundations. The depth of improvement observed was up to 10 m and the improvement in elastic modulus observed was up to five times the pre-treatment value. Over 40 cone penetration tests were conducted before and after RIC. Typical lower- and upper-bound improvement curves are presented based on the observed minimum and maximum post-treatment stiffness. The degree of stiffness improvement was observed to generally reduce at greater than 5 m depth. [ABSTRACT FROM AUTHOR]

This paper describes research into the poorly understood axial behaviour of piles driven in chalk. Comprehensive dynamic and monotonic axial testing on 27, mostly instrumented, piles undertaken for the ALPACA joint industry projects is reported and interpreted covering: diameters between 139 mm and 1·8 m; lengths from 3 to 18 m; different pile material types; tip and groundwater conditions; and ages after driving. The experiments show the factors that influence resistance most strongly are: (a) pile end conditions; (b) slenderness ratio and flexibility; (c) shaft material; (d) age after driving; (e) relative water table depth; and (f) whether loading is compressive or tensile. Varying the factors systematically identified a remarkable average long-term shaft resistance range from below 11 kPa to more than 200 kPa for piles driven at the same low- to medium-density chalk test site in Kent (UK). Dynamic and static analyses demonstrate that soil resistances to driving were generally well predicted by the Chalk ICP-18 short-term formulation. Considering the piles' long-term behaviour, the Chalk ICP-18 approach over-predicted capacity, while the widely used CIRIA approach proved over-conservative for most cases. The research enabled the development of a revised 'ALPACA-SNW' long-term capacity assessment method that matches the test outcomes far more faithfully. [ABSTRACT FROM AUTHOR]

Climate change and the need for weather-resilient infrastructure is introducing new safety, performance and financial challenges and opportunities to regulators and those that are regulated. As the safety and economic regulator for railways in Great Britain, the Office of Rail and Road is required to protect the interests of rail users and funders by improving the safety, value and performance of railways, today and in the future. The approach to and understanding of climate change and weather resilience is developing; however, there is an expectation of infrastructure managers to make their asset types more resilient to climate change. This paper explores potential gaps in industry knowledge, what is 'good' practice, how to assess safety and efficiency and how to measure value. Understanding these questions will inform an approach. Regulatory experience suggests that a spectrum of practice exists, from more resilient business as usual to technology adoption. Regional variation has implications for funding, accountability and stakeholders. In this paper, the authors have collected examples across the spectrum; these have been grouped into four themes and an accessible model created to optimise decision making. The authors conclude that proactive value-driven approaches to weather resilience are possible but will require organisational adaptability and recognition that there is no 'one-size-fits-all' approach. [ABSTRACT FROM AUTHOR]

In this paper, a case study is examined in which a bridge structure with fatigue critical details was successfully managed and remediated without extensive traffic closures. Severe theoretical fatigue life shortfalls have been identified at the transverse stiffener frames of the box girder due to distortional effects in the steel box. Gade valley viaduct was the final link in the M25 London orbital motorway, constructed in 1986 at Kings Langley, UK. It is a composite box girder viaduct 440 m long with typical spans of 42 m and carries 180 000 vehicles daily. A series of cracks and original sub-standard weld quality issues were discovered in the transverse stiffener frames of the box girder. The fatigue shortfall that was a significant contributor to the identified fatigue cracking was confirmed by assessment and strain-gauge monitoring. A fatigue enhancement bracing system was deployed at all spans and boxes to provide a full 120 year fatigue life. The use of off-structure testing in a mock-up girder before the application on the live structure was a key feature of this project, where several lessons were learned from weld trials. This case study illustrates how heavily used structures with theoretical fatigue life shortfalls can be successfully rehabilitated to ensure safety. [ABSTRACT FROM AUTHOR]

Saleyard Bridge carries the A465 Heads of the Valleys Road over the River Clydach near Gilwern, Monmouthshire, UK. It comprises a 67 m single-span steel–concrete composite multi-girder superstructure made integral with the abutments. A full-depth precast deck was chosen to tackle site constraints and improve constructability. The alternative precast panel connection detail developed used straight laps to overcome the problems that can arise from using typical U-bar loop type connections between precast deck panels. The successful use of the precast panels proved that a deck design with straight laps was a practical alternative. The ability to increase the multi-beam centres and avoid cantilever edge formwork created a more economical solution with savings estimated at £500 000. The paper examines the detailed design and construction planning needed to realise the savings and speed up construction as well as improving site safety. The lessons learnt are also applicable to the wider use of precast panels as an alternative to in situ concreting. [ABSTRACT FROM AUTHOR]

In the UK, decision makers use hydraulic model outputs to inform funding, connection consent, adoption of new drainage networks and planning application decisions. Current practice requires the application of design storms to calculate sewer catchment performance metrics such as flood volume, discharge rate and flood count. With flooding incidents occurring more frequently than their designs specify, hydraulic modelling outputs required by practice are questionable. The main focus of this paper is the peakedness factor (ratio of maximum to average rainfall intensity) of design storms, adjudging that this is a key contributor to model bias. Hydraulic models of two UK sewer catchments were simulated under historical storms, design storms and design storms with modified peakedness to test bias in modelling outputs and the effectiveness of peakedness modification in reducing bias. Sustainable drainage systems (SuDS) were implemented at catchment scale and the betterment achieved in the modelling outputs was tested. The proposed design storm modification reduced the bias that occurs when driving hydraulic models using design storms in comparison with historical storms. It is concluded that SuDS benefits are underestimated when using design rainfall because the synthetic rainfall shape prevents infiltration. Thus, SuDS interventions cannot accurately be evaluated by design storms, modified or otherwise. [ABSTRACT FROM AUTHOR]

The documents for structural assessment of highway bridges, bridge substructures, retaining structures and buried structures in the UK's Design Manual for Roads and Bridges have been rewritten and updated. In bringing the documents up to date, there have been several technical changes introduced. These include efficiencies in the traffic loading model for bridges, new content on masonry arch assessment and new approaches to the assessment of substructures, retaining structures and buried structures using a Eurocode-aligned basis of assessment. This paper outlines the technical background to the key changes and highlights some of the efficiencies that can be delivered using the new documents. In addition, the paper outlines how the documents connect with related documents, including those on structural review, assessment of abnormal traffic loads, assessment of impact on bridge piers and the management of substandard structures. [ABSTRACT FROM AUTHOR]

From first principles, criteria for the EN 12390-10 outside protected test have been developed and compared with existing practice. These criteria align well with the UK recommendations but are more conservative than the current French and Spanish requirements. The EN 12390-10 outside protected test is unsuitable for classification as this would require anybody using the procedure with identical concrete to get the same result. Unfortunately, current tests that are suitable for classification, whilst safe, do not reflect the real performance of slowly reacting cements. Improving the test for classification purposes will take time and meantime the use of the EN 12390-10 outside protected test and the criteria given in this paper provides a procedure by which both sustainability and durability may be achieved. The downside of this test is its slowness and, therefore, it is only suitable for type testing or the determination of limiting values and other criteria to be used in specifications or production. [ABSTRACT FROM AUTHOR]

This paper investigates the inherent inaccuracy in the estimation of various extreme response variables (RVs) for different sea defence structures using joint exceedance curve approaches in common use around the UK. Utilising stochastically generated nearshore datasets that include extreme wave and sea-level conditions determined at regular intervals around the English coastline as part of a previous study, and asset information from the Environment Agency's Asset Information Management System database, this paper assesses 592 sea defence structures and their associated extreme response using different joint exceedance curve approaches when compared against the RV approach. This paper highlights that extreme RVs are often underestimated when using a joint exceedance curve approach, which in many cases can be significant. This suggests that the performance of many sea defence structures are incorrectly estimated. As a consequence, joint exceedance curve approaches may under-design sea defence structures to a greater level than previously indicated, or significantly underestimate extreme RVs when assessing the performance of existing structures. [ABSTRACT FROM AUTHOR]

There is currently great interest in the creation of sustainable and liveable cities, both in the UK and globally. While it can be argued that good progress is being made in thinking about the needs of future cities, meeting these needs and aspirations in practice poses major challenges of understanding and measurement (what is meant by these terms and how can progress towards their achievement be measured?), complexity (cities are complex systems of systems with many interacting parts) and resilience (will interventions made today be relevant and effective in the future?). The Liveable Cities research programme created a systematic decision-making method for improving urban sustainability and liveability: the Liveable Cities Method (LCM). The LCM prioritises four criteria – individual and societal well-being, resource security, resource efficiency and carbon dioxide emissions as a proxy for environmental harm – in an interconnected framework and assesses the need for, and the resilience of, interventions designed to move cities towards improved sustainability and liveability. This paper illustrates the LCM through an example intervention made to the city of Birmingham, UK, and highlights how addressing sustainability and liveability in this way offers unique opportunities for the UK civil engineering profession to lead thinking among urban professionals. [ABSTRACT FROM AUTHOR]

Climate projections suggest that the UK will be increasingly affected by climate-induced hazards in the future, exacerbating the potential for multihazard events to occur. This paper explores the extent to which climate resilience is being embedded in current and future rail transport infrastructure projects in London through use of a multihazard approach. It concludes that a multihazard approach is a relatively new concept and is therefore not currently being considered widely. However, opportunities for decision makers to explore its value to mitigate climate risks through collaborative working and further research exist – this paper recommends that two main stages are required to achieve this. Route 1 requires climate/hazard experts to identify and characterise the different hazard interactions that could occur, including their impact on the UK/London. Following this, route 2 involves the creation of multidisciplinary workshops to identify any multihazard vulnerabilities associated with different rail assets – potentially highlighting areas where further research is required. The paper concludes that although a London rail context has been adopted in order to understand the relevance of a multihazard approach, there is opportunity for it to be considered across many different sectors in the UK and the wider civil engineering industry. [ABSTRACT FROM AUTHOR]

Understanding the resilience of transport networks is critical for efficient asset management. This paper takes an innovative approach to studying the operability of the Queensferry Crossing (QFC), UK, including cost–benefit aspects. A key driver for the QFC was to increase the resilience of the A90/M90 link by reducing weather-related closures. The first weather-related closure of the QFC was in February 2020, when ice formed on the superstructure cables and fell on the carriageway and vehicles, creating a safety risk for bridge users. The bridge was closed for 41 h and, in this paper, the estimated monetary losses are compared with those of past Forth Road Bridge (FRB) closures. The costs of potential mitigation measures are then assessed in the context of closure costs, thus improving the resilience of the QFC. Although the QFC has only been open for 3 years, it is already apparent that it is significantly more resilient than the largely replaced FRB, whether this is considered as the number, duration or costs of closures and that this will be substantially improved by the planned use of the FRB during future closures of the QFC. Investment in mitigation measures is a potentially cost-effective solution although the form of any suitable ice prevention or removal system is, as yet, far from clear. [ABSTRACT FROM AUTHOR]

The UK Design Manual for Roads and Bridges (DMRB) document CS 455 for the assessment of concrete highway bridges and structures has been rewritten and updated as part of the project to update the DMRB suite of documents. The key technical changes introduced in the document are outlined in this paper, including: methods for estimating worst credible strength; simplification and improvement in shear resistance near a support where there is a short anchorage length; incorporation of strut-and-tie modelling; serviceability limit state assessment requirements for prestressed concrete; shear resistance of prestressed concrete; and new rules for the effect of cover on bond. The technical background to the key changes is briefly outlined and some of the efficiencies that can be delivered using the new document are highlighted. [ABSTRACT FROM AUTHOR]

The UK's design documents for assessment of steel and composite highway bridges and structures have been updated in line with Highways England's overall plan for modernising the Design Manual for Roads and Bridges. This paper describes the key changes that have been made to the document and their impact on users, providing reassurance that, despite the new format, the methods and requirements are largely unchanged, or changed to facilitate future assessments by allowing more general approaches to be adopted. For steel bridges the key changes are described that affect robustness assessment, notch toughness, bearing stiffeners, cross-girders, stiffened panel buckling and inspection criteria for existing welds. For composite bridges, the changes relate mainly to the serviceability limit state verifications, to fatigue and to the shear connection, as well as the general improvements to remove outdated content and simplify the document. The changes for both documents include greater references to the Eurocodes in general, which will facilitate an easier transition to Eurocode assessment standards when these are published in the future. [ABSTRACT FROM AUTHOR]

Open caisson shafts are a widely adopted solution for a range of geotechnical applications. An external 'cutting shoe' is a common construction feature used to reduce the soil frictional resistance acting on the caisson during sinking. This forms an annular void encircling the caisson which is filled with a support fluid to maintain excavation stability. The primary aim of this paper is to explore the influence of the cutting shoe geometry on the resulting vertical bearing resistance in sand. Finite-element limit analysis is adopted for this purpose. Additional parameters considered in the modelling include the roughness of the caisson cutting face and cutting shoe, and the caisson radius and embedment depth. The results show that the influence of the cutting shoe is highly dependent on the caisson cutting face roughness and the soil friction angle, illustrated using detailed soil failure mechanisms. The roughness of the cutting shoe is also shown to cause a significant increase in the vertical soil reaction for large caisson embedment depths. By way of example, a recent case study in the UK, involving the construction of a 32 m dia. caisson, is used to highlight the potential influence of the cutting shoe on the bearing resistance during caisson sinking. [ABSTRACT FROM AUTHOR]

The UK government's Future Flooding Inquiry called for more integrative methods to respond to flood risk management challenges. The 25-year plan for the environment, A Green Future (published by the UK Department for Environment, Food and Rural Affairs in 2018), has reiterated the requirement for integrated catchment management. There is growing acceptance that natural flood management (NFM) can complement traditional urban flood defence schemes. This paper examines the outcomes of a knowledge transfer partnership (KTP) between Waterco Consultants and the University of Liverpool which explores some of the challenges of implementing what appear to be relative simple NFM measures. Through a multidisciplinary partnership, the KTP project explored multiple delivery challenges. Using case study evidence from north-west England, the paper demonstrates the need for combining partnership working with more traditional hydraulic modelling approaches that can predict the potential flood risk reduction benefits of multiple NFM features, combined with the need to design structurally resilient interventions, so that appropriate permits can be approved. One of the key findings is that while NFM can contribute to flood risk alleviation, with multiple socio-environmental benefits, NFM can only be part of a more holistic approach. Primary evidence for hard and soft engineering measures, combined with use of automated attenuation management, could provide opportunities for more significant integrated flood risk benefits. [ABSTRACT FROM AUTHOR]

With more intense rainfall and sea level rises predicted, an increasing number of people across the UK are vulnerable to flood events. The government has pledged more funding for flood infrastructure planning, design and management. However, schemes tend to focus on technical solutions, with the social impact, including needs and concerns of the local community, seen as secondary. Based on a detailed examination of three case studies in England, this paper identifies the mechanisms through which current processes restrict industry professionals from considering and incorporating the social perspective, often despite seemingly effective community engagement. The paper argues for an approach that incorporates social concerns alongside technical ones. Rather than 'community engagement', it is argued that 'co-production', in which lay communities work alongside technical experts in the design of flood risk alleviation schemes, would enable a final outcome that is both more socially acceptable and more technically successful. [ABSTRACT FROM AUTHOR]

The Considerate Constructors Scheme (CCS) was introduced in 1997 to improve the image of the UK construction industry and has grown dramatically, with over 6000 construction and infrastructure projects registered valued at £43 billion. While evidence exists that the industry's image is improving, there is little research into the CCS perceptions of those tasked with scheme delivery. It is not clear if contractors engage with CCS willingly as proactive participants or succumb to the requirements of clients to win work simply. The aim of this paper is to gain an insight into contractor perceptions of CCS to aid clients and contractors ultimately in their delivery of the scheme and ensure that the CCS delivers the maximum benefit for stakeholders. A case study of a single infrastructure project registered with the CCS is utilised. All CCS documents were critically analysed, and interviews were conducted with clients, the contractor and residents. The findings contribute to an unexplored area of research and reveal the motivations behind why a contractor engages with the CCS, the advantages and drawbacks in the scheme's current enactment and key lessons on how the CCS could be administered and delivered more effectively for the benefit of all stakeholders. [ABSTRACT FROM AUTHOR]

Malpas Viaduct is a 860m long reinforced concrete structure, located near Newport, Wales carrying the M4 motorway. The structure forms a vital regional link together with the adjacent Brynglas tunnel and River Usk Bridge. A particular feature of the structure is the inclusion of half-joints which are hidden critical elements. The structure was suffering from early signs of structural deterioration as a result of chloride contamination. This paper offers an overall review of the rehabilitation programme, from condition inspection, to structural assessment and finally concrete repairs and corrosion protection. The structural assessment utilised non-linear finite element methods and aimed at firstly assessing the current load carrying capacity of the viaduct and secondly develop a detailed concrete repair sequence which negated the requirement of extensive temporary supports while maintaining full traffic and load carrying capacity on the M4. The rehabilitation strategy incorporated the design and installation of an innovative hybrid corrosion protection electrochemical system to extend the service life of the hidden critical elements by 30 years. The system is the first of its kind in half-joints and offers targeted corrosion protection that passivates the reinforcement from residual chloride contamination and the simplicity and low maintenance of galvanic anodes. [ABSTRACT FROM AUTHOR]

Considerable amounts of data are collected on the UK's stock of bridges. Much of this data is collected to inform the planning and scope of maintenance activities. This paper reports on the results of a series of semi-structured interviews with 17 individuals involved in UK bridge asset management and data-collection activities to explore how such data is used in practice. A wide spectrum of organisations and industrial sectors was represented in this dataset. Hierarchical process modelling was used to characterise the UK's bridge management system and define the processes and sub-processes involved in the management of bridges. Key quotations are used from the interviews to reveal the state of data collection and use in UK bridge infrastructure from the perspective of those directly involved. The study concludes that there is significant variation within the industry regarding the use of visual inspection data and that formal structural health monitoring remains relatively rare. Furthermore, there is a need to develop a new unifying paradigm that will frame the efficient and effective application of emerging artificial intelligence and data science enabled (i.e. 'smart') condition-monitoring techniques to bridge management. [ABSTRACT FROM AUTHOR]

This paper describes the results obtained from a field testing campaign on laterally loaded monopiles conducted at Cowden, UK, where the soil consists principally of a heavily overconsolidated glacial till. These tests formed part of the PISA project on the development of improved design methods for monopile foundations for offshore wind turbines. Results obtained for monotonic loading tests on piles of three different diameters (0·273 m, 0·762 m and 2·0 m) are presented. The piles had length-to-diameter ratios (L/D) of between 3 and 10. The tests included the application of monotonic loading incorporating periods of constant load to investigate creep effects, and investigations on the influence of loading rate. Data are presented on measured bending moments and inclinations induced in the piles. Inferred data on lateral displacements of the embedded section of the piles are determined using an optimised structural model. These field data support the development of a new one-dimensional modelling approach for the design of monopile foundations for offshore wind turbines. They also form a unique database of field measurements in an overconsolidated clay, from lateral loading of piles at a vertical distance above the ground surface. [ABSTRACT FROM AUTHOR]

Many communities around the world are facing increasing flood-induced damage to bridges due to climate change and rising urbanisation. It is thus crucial to understand how different bridge types suffer from flooding and how this may affect surrounding networks. Despite the large body of literature for seismic and hurricane taxonomies, few classifications exist for bridges at flood risk. In this work, existing global bridge classifications were reviewed in order to derive a bridge–flood taxonomy. The review revealed that existing studies mainly classify bridges according to the superstructure material, whereas subclasses consider superstructure and substructure components. A taxonomy of 20 attributes for riverine roadway bridges susceptible to flood hazards is proposed in this paper. Its applicability for three bridge datasets in the UK was verified. The results showed that the considered datasets have data for 13 attributes, which can be used to derive regional bridge classes. In general, the taxonomy is functional for standardising different bridge datasets and applying/developing damage models for given bridge portfolios of flood-prone countries. Future works could apply the taxonomy to additional bridge datasets within a network for risk assessments; the proposed taxonomy could also be extended to allow integration with functionality and restoration models. [ABSTRACT FROM AUTHOR]

Greenhouse gas emissions originating from the built environment play a significant role towards climate change. Carefully planning the future of the building sector is key to mitigating these emissions. Addressing this problem by using a predictive approach may miss possible futures that cannot be anticipated. Using explorative scenarios to perform futures analysis helps widen the range of futures taken into account, which minimises this risk. Tools that use scenarios to help study the resilience of sustainable solutions for the UK urban environment are already available. However, they do not facilitate in-depth analysis of future household energy demand. This paper considers how one such tool, 'Designing Resilient Cities' (DRC), could be modified appropriately. It includes (a) a series of indicators representing factors affecting the energy demand in dwellings and (b) their characteristics for each scenario to complement the narratives in DRC. As a case study to validate these additions, the resilience of a recommendation to decrease domestic electricity consumption is evaluated. [ABSTRACT FROM AUTHOR]

Large-diameter open caissons are a widely used construction solution for deep foundations, underground storage and attenuation tanks, pumping stations, and launch and reception shafts for tunnel boring machines. The sinking phase presents a number of challenges during construction, including maintaining caisson verticality, controlling the rate of sinking and minimising soil resistance through the use of lubricating fluids. This paper describes the instrumentation and monitoring of a large-diameter caisson on a UK construction site. The caisson was instrumented for the measurement of settlement and tilt, soil–structure interaction contact stresses and structural performance. A key objective for the monitoring project was to provide real-time feedback to the site engineering team to inform the construction process. The monitored data revealed the occurrence of complex soil–structure interactions during sinking that are not readily captured by existing prescriptive design approaches. This case history provides valuable information for the development of an improved basis for design as well as an important frame of reference for future monitoring projects. [ABSTRACT FROM AUTHOR]

This paper, the second in a series describing the delivery of the Emirates Air Line project in London, UK. It presents the challenges associated with the delivery of the south tower base to the 90 m steel tower, in the tidal Thames, to a tight programme, with an Olympic deadline. The paper presents an appraisal by the team of the given reference design of caisson construction at tender and the decision to develop a different design to meet programme. This is followed by a detailed optioneering of the design of the substructure elements leading to selection of the optimal approach employing large concrete precast elements for site assembly. The elements included a protective silt skirt to avoid erosion of the riverbed. Aesthetic considerations are discussed, including the tower, located offshore on piles that are visible at low tide, which required careful attention to the compositional aspect of its overall substructure. To continue the elegant form of the twisting tower, the piles were fitted with double curved precast concrete sleeves to continue the curvature of the steel ribbons down into the Thames. Finally, construction challenges are outlined and a description is given of the dramatic site delivery of the 200 t precast skirt using river-based shear legs. [ABSTRACT FROM AUTHOR]

An introduction is presented for the journal “Water Management" which focuses on publishing research papers for the benefit of engineers working in water management, and talks about the peer-review process, wastewater treatment and re-use of saline drainage water.

Passive solar systems are often designed primarily with efficiency in mind, and research efforts are concentrated towards gaining an increase in performance. However, due to the multiple materials used, their manufacturing processes, a lifespan that is usually shorter than that of buildings that these systems are applied to and the waste generated when they have reached the end of their useful life, a more holistic approach to the design and performance of these systems should be adopted. This paper reports on the environmental impact of a unique integrated collector–storage solar water heater design, experimentally tested under Scottish weather conditions, considering circular economy and reuse potential. As such, the material flows and components used are mapped against the life-cycle stages of existing European standards while ensuring an optimal efficiency. End-of-life considerations and design for disassembly and reuse are assessed and discussed. Energy payback times of 4·5 and 4·6 years can be realised for a circular and a linear approach, respectively. Operational carbon dioxide savings, which far outstrip the embodied carbon dioxide, demonstrate carbon dioxide payback times of just 7 months, when replacing an electric system. The results show that a holistic design, which promotes circular economy principles, does not compromise efficiency and economic viability. [ABSTRACT FROM AUTHOR]