About the Tool
Regenerate is a freely available tool, created by The University of Sheffield to instil circular economic principles within building design and provoke meaningful discussion across the construction sector.
Following its initial release in 2020 as a prototype spreadsheet, regenerate is now available in its second iteration as a web-based tool. This builds upon earlier work, taking consideration of user feedback to further encourage excellence in circular economy design through an enhanced user experience and improved project management capabilities.
In line with the increasing realisation of its importance in tackling climate change, regenerate’s primary aim is to provide a mechanism by which members of the construction industry are able to engage with the circular economy. This is achieved by assisting design teams in embedding often unknown circular economic principles within their projects, helping drive change across the sector. In doing so, the tool also offers a measure of the circularity of construction projects, addressing to the as-yet-unanswerable question: “how circular is my building?”.
As a result of its development in close consideration of Greater London Authority (GLA) guidance, regenerate can also be used in the preparation of circular economy statements. This results from its provision of achievable and evidencable circularity credits (CC’s) and easy-to-complete form-style versions of commonly required documentation (e.g. GLA table 1/2, Bill of Materials and Recycled Materials).
The tool works to engage design teams; both influencing and assessing proposed, ongoing, and completed construction projects. It adopts a credit-based, self-certification system whereby users are able to record their (intended) attainment of a suite of circular design criteria. These are distributed across 4 circular economic principles and categorised by the key building layers to which they relate. A zone-based approach is also adopted to allow for the analysis of complex projects containing multiple building uses, project types and structural forms. Regenerate has been developed with the iterative nature of design processes in mind, and is intended to be used throughout all design development stages, evolving with projects.
Circular Economy in Building Design
Circular economic principles focus on maintaining materials at their highest value for as long as possible. This means that a circular economy aims to keep materials in circulation, removing the concept of waste and the need for material extraction from primary sources. In a fully circular economy there are no waste outputs from, or external inputs to the system.
If the built environment is thought of in this way, construction materials form the inputs, with waste resulting from renovation and demolition being the output flows. It is these flows which must be minimised in the transition to a circular economy, with reliance instead being placed upon the existing material stock held within our built environment. As well as in material terms, the concept of a circular economy can be extended to embodied carbon.
If demand for new buildings is reduced through retrofit and adaptation, the input flow of embodied emissions falls, and previously expended embodied carbon remains in stock. Another option to reduce flows of new embodied emissions is to channel demolition waste into material inputs. Steel sections, for example, can be extracted from a building at the end of its life and reused, with this element of the circular economy requiring a shift in approach to building deconstruction and material salvage.
Depending on material composition and construction methods, some buildings are better suited to this approach at the end of their lifespan. Adapting the existing building stock and salvaging material at the end of a building’s life will reduce, but not eliminate, the demand for materials and, with it, the addition of embodied carbon to building stocks.
Where new materials are required, strategies such as designing for adaptability and deconstruction should extend building lifespans, and enable component and material reuse at end-of-life. This should enable a reduction in cradle-to-cradle embodied carbon.
Accounts, Teams and Projects
Regenerate users are required to create a personal account using their email address at the point of sign-up. This ensures that they are able to save progress and return to projects throughout design stages. A single account may be used to create a number of projects, allowing design teams to use regenerate to easily work upon and manage multiple projects at the same time.
Owing to regenerate’s aim to engage all members of the design team (and beyond), it incorporates a ‘teams’ function whereby multiple user accounts are able to collaborate on a single project. As well as lending itself to remote working, this allows different sections of regenerate to be completed by the most relevant design team member. A history log is also maintained for each project, detailing when changes have been made to a project, and by whom.
Based upon a modified version of the Greater London Authority’s ‘decision tree’ (see sections 2.5 and 2.5 of the Circular Economy Statement Guidance), the first section of regenerate aids design teams in identifying suitable, project specific, strategic approaches.
Using inputs relating to the viability of recovering existing materials and the permanency of the proposed development, the strategic approach section of the tool makes recommendations on the most pertinent approaches through which a project may maximise the residual value of existing materials and the future value of new materials.
This acts as an ideal first step, indicating which circularity principles should be priorities as designs are developed. The results of this section of the tool may also be used in justifying the adopted strategic approach when preparing circular economy statements (as required by the GLA).
Within regenerate developments are broken up into a number of build zones, with each zone representing areas with a unique development type (new build/refurbishment), building use, and structural form combination. This allows complex developments, which may have differing degrees of circularity, to be assessed within a single project. For example, circularity credits applying to a refurbished, steel-framed section of an existing industrial building are likely to differ greatly from those applicable to the new-build, timber, office space within the same development.
To account for the presence of different building zones, regenerate weights the credit score of each based upon the relative proportion of total gross floor area it represents. This means that if the refurbished industrial building in the example above has twice the gross floor area of the new-build office space, it will represent 2/3 of a given credit, with the office space making up the remaining 1/3 to give a maximum credit score of 1.
A maximum of 6 building zones may be considered for each project (3 new-build and 3 refurbishment/renovation). As well as allowing for the assessment of complex and non-standard projects, by using zoning in this way, regenerate is also able to target specific building areas which require greater attention in terms of an increased consideration of circularity.
Within each zone, the development is broken down further into building layers. As well as for ease of use, this is consistent with the argument put forward by Brand (1997) that, if properly conceived, buildings should comprise several layers of built components that are changed at different rates. This notion of replacement rates is vital in achieving circular design, with each layer representing key elements of a building, namely: site, structure, skin, services, space and stuff (as below).
Excepting ‘stuff’, these have been adopted directly in regenerate, allowing users to specify which layers are to be affected in each building zone. For example, in the refurbished industrial building above, the ‘site’ and ‘structure’ layers may remain unaffected, with ‘services’ and ‘space’ being part of the renovation scheme. By allowing this to be specified, regenerate is able to automatically award the credits associated with a given building layer when it is unaffected by the development.
This is based upon the notion that retaining a building layer in its current form is inherently more circular than replacing it in the most circular manner possible, and ensures that regenerate promotes retention of building layers wherever possible. Unaffected building layers may also be specified for new-build projects, though it is assumed that this will rarely occur, with the occasional exception of ‘site’.
Building layers are also used in the self-certification of circularity criteria, with each circularity principle being split up into the layers listed above. As well as for ease of completion by different members of the deign team (e.g. focus upon ‘structure’ by structural engineers and ‘services’ by M&E engineers), this highlights specific building layers which required greater attention in terms of an increased consideration of circularity.
Please see the resources section for more details regarding building layers
In consideration of existing academic and industrial literature and consistent with common practice, regenerate specifies 4 high-level building design circularity principles: Design for Adaptability, Design for Deconstruction, Circular Materials Selection and Resource Efficiency.
These are presented sequentially within the tool, owing to the preferable order of consideration as outlined below. This suggests that building adaptability is to be prioritised first, being ensured through longevity for permanent structures and consideration of component re-use and re-usability for those with shorter anticipated lifespans. The deconstructability of the building should then be considered, ensuring its end-of-life impacts are minimised as far as possible. Engaging in circular material selection also mitigates this further, promoting the use of materials and components that are not only separable but re-usable at their highest value to promote future material recovery. Following this the building should be optimised for material efficiency, ensuring that the smallest possible amount of resource required to fulfil the requirements of previous principles is consumed.
Further details of each circularity principle may be found within the tool and in turn below.
Design for Adaptability
Adaptability can be thought of as a measure of the ease to which a building can be modified over its lifetime (Webster, 2007). Adaptable buildings have extended lifespans and help to close material loops by ensuring the minimization of waste and new primary resources by designing to accommodate change over different temporal scales. Building longevity should be maximized through ‘loose-fit’ design, whilst durability and resilience provide an innate capacity to adapt to changing societal and environmental needs.
Although adaptability directly addresses long-term material efficiency, it is important to ensure that over-design is limited (e.g. through light-weighting of structural elements after designing for adaptability) to what is likely to be required of the building in the future. This serves to reduces the embodied carbon of the design in the short-term as far as possible, whilst still providing required long-term material efficiency.
Design for Deconstruction
Deconstruction is the method by which a structure is carefully disassembled to salvage as many components as possible (Webster, 2007). In order to improve the reused material supply chain in the future, it is recommended that new buildings are designed for later deconstruction to maximise the quantity of materials that can be recovered with minimal damage (Densley Tingley and Davison, 2011).
Connections across all building layers should enable a high percentage of material recovery. The simplicity and clarity of the construction and the design should be maximised and is an important early design stage consideration. This includes minimising different connections types and employing simple and reversible mechanical connections as opposed to chemical connections to enable components to be separated easily (Densley Tingley, 2013).
To ensure deconstructability, fixings should be durable and easily removable without destroying the structural integrity and finish of the joined construction elements. This means that dry fixing techniques are preferable over recessed or rebated connections involving mixed materials (Cobb, 2015 p.g. 398). Friction connections are also suitable where material recovery is concerned as they do not require holes or notches to be cut into connected members.
Circular Material Selection
Circular material selection encourages a transparent, whole life-cycle approach to material use. This principle should be applied alongside and integrated within other approaches (i.e. designing for adaptability) to ensure that low impact materials with little or no negative impact on human or environmental health are adopted throughout the buildings lifespan.
Sustainable sourcing an a transition from selling products to selling services is important to the circular economy and is promoted in regenerate. This can be accomplished by, for example, reducing on-site waste through payment structures that give customers unlimited access to resources and allow payment only for what is used (UKGBC, 2019).
Resource efficiency aims to reduce material and embodied carbon demand by encouraging efficiency in design and the use of, what would otherwise be, waste products. By encouraging the use of reusable on- or off-site materials, the demand for virgin material is reduced and construction waste is recirculated. In addition, optimisation strategies such as the light-weighting of structural elements should be implemented, but only following the consideration of other circular economic principles (unless the structure is temporary).
Material optimisation strategies enable the use of fewer materials to provide the same service, whereas designing for long life (e.g. adaptability and deconstructability) may result in higher initial material usage with larger life-cycle emissions savings (IEA, 2019). Understanding this balance in material use on a case-by-case basis at the early design stage is important for effective material efficiency over a building’s lifespan.
For structural design checks for example, this could be accomplished by ensuring the utilisation ratio of all elements are as close to unity as possible, whilst adaptability for change of use is provided through large open plan and regular structural grids. In this and all other cases however, a life-cycle analysis of embodied carbon should be balanced against initial savings from optimisation strategies.
Circularity Criteria & Credits
Within each of the circularity principles outlined above, regenerate provides a suite of unique circularity criteria. These each represent a specific, achievable and evidencable actions which may be taken by a design team in order to enhance the circularity of the project under consideration. For ease of completion and to allow for more directed analysis outputs, these are disaggregated further by building layer within each circularity principle.
The (intended) fulfilment of each of these criteria within each building zone is self-certified by the user through a set of drop down response boxes. This allows the specification of whether or not this criteria will be/has been met, or whether this remains to be confirmed, with evidence of the (intended) fulfilment also being requested.
Each criteria has an associated credit score, ranging from 1 (for full attainment), to 0 (for no attainment). To account for the presence of different building zones within a development, the maximum credit score of 1 is apportioned to each zone based upon the relative proportion of total gross floor they represent. This means that a 2-zone development with zone 1 having twice the gross floor area of zone 2 would see credit portions of 0.66 and 0.33 assigned respectively. These credit portions may then be attained independent of each other, dependent upon the fulfilment of the criteria in each building zone.
Though this list of credits its unlikely to be exhaustive in the fast-moving transition to a circular economy within the built environment, they are compiled from an extensive set of academic and industrial sources and are thought to cover all key areas of circular design. As a result, the credit-based self-certification process within regenerate is useful both in prompting the consideration of otherwise unknown circular practices, and in highlighting the need for evidence of specific design actions to support claims of circularity within the construction sector.
For each circularity principle, users must also specify an associated circularity aim. This details the level to which they aim to comply with a principle and are categorised as basic, partial or full (roughly 55%, 80% and 100% of the total attainable circularity credits).The circularity principles to be prioritised by these selected aims are recommended to be informed by the outputs of the strategic approaches section of the tool.
During completion of the self-certification process, the attainment of circularity credits may be measured against these stated aims, with the above percentages being used to generate a circularity rating for each circularity principle/building layer combination in the circularity overview. An aggregated rating for each principle is also provided here.
Circular Economy Statement Preparation (GLA)
Regenerate may also be used in the preparation of circular economy statements such as that required by the upcoming London Plan as a result of its inclusion of populatable and easily outputable versions of key reporting forms. These include Bill of Materials and Recycling and Waste forms, as well as ‘Table 1’ and ‘Table 2’ as required as part of GLA compliant circular economy statements.
To further aid in the completion of these forms, each circularity credit is tagged with the associated GLA principle to which it corresponds, allowing for the rapid evidencing of these as required in ‘Table 2’. Although these sections of regenerate are not mandatory, and credit-based circularity overviews may be outputted in isolation, users are encouraged to complete reporting forms as these help to inform future benchmarking and tool development.
Following completion of the credit-based, self-certification assessment process, regenerate provides users with a circularity overview of their project. Dependent upon the stage at which the assessment is being completed this represents the development’s proposed or actual circularity rating, with output summaries totalling the credits obtained within each circularity principle and building layer as below.
Credit totals for each principle and layer are also represented as percentages of the selected circularity aim and the total available number of credits. This allows both for the assessment of compliance with stated aims, and the comparison of circularity across different layers and principles. In turn, this highlights areas (layers and principles) in which consideration of circularity is lacking, allowing for a more targeted approach in these areas going forward.
Graphical outputs showing awarded and total credit breakdowns by circularity principle are also outputted, along with charts showing the breakdown of credits attained across each building layer (see below).
Following completion of the required assessments, regenerate is capable of generating PDF outputs of the summaries resulting from these. This allows for the rapid generation of documents required to be submitted for evidence of consideration of the circular economy in formal statements or otherwise.
If used across different project stages this allows for the tracking of the evolution of the circularity of a project throughout its development. Such outputs also form suitable documents to be considered when discussing circular economy implications with members of the wider design team.
Regenerate was developed by Dr Danielle Densley Tingley, Will Mihkelson and Charles Gillott from The University of Sheffield, with the assistance of David Cheshire of AECOM.
As well as to those providing feedback on the previously published prototype version of regenerate, the authors would like to thank those listed below for their participation in stakeholder workshops carried out during the early development of this resource.
|Bengt Cousins-Jenvey||(Type Four Projects)|
|Charlie Law||(Sustainable Construction Solutions)|
|Tom Sweet||(Eric Parry Architects)|
|Veronica Ochoa||(Canary Wharf Contractors)|