1. INTRODUCTION
1.1 IMPROVING RESOURCE EFFICIENCY IN THE BUILT ENVIRONMENT
Societies are facing climate change, biodiversity loss and resource scarcity, and the construction sector is strongly linked to all three through its high material demand, land use and waste generation across the building life-cycles (UNEP 2020; UNEP & Yale Center for Ecosystems + Architecture 2023; Krausmann et al. 2018). Improving resource efficiency in the built environment therefore requires not only the reduction of operational impacts but also the use of strategies that prolong the service life of buildings and their components, and reduce material losses during renovation and at deconstruction.
Design for disassembly (DfD) is one such strategy. By enabling the separation of building components without irreversible damage, DfD supports the reuse, replacement and cascading use of materials across multiple life-cycles. In practical terms, this can reduce demolition waste, extend the service life of products and lower the demand for virgin resources, thereby linking DfD to circular construction and resource-efficiency objectives (Thormark 2007).
However, the disassembly and reuse potential of building components is inherently complex and influenced by a range of technical, organisational and economic factors. These include connection types, accessibility, geometric interdependencies between building layers (Figure 1) and constraints related to dismantling sequences. Consequently, the potential benefits of DfD cannot be derived from design intent alone but depend on how buildings are assembled and disassembled in practice.
Figure 1
Building layers, their average lifespan and weighting factors in the Technical Disassembly Potential of Buildings (TDPB) assessment methodology.
Note: Solid lines depict layers included in the assessment; dashed lines depict building layers that are outside of the scope of this paper.
Source: Building layers are adapted from Brand (1994).
Previous research has therefore described DfD as a systemic issue instead of a set of isolated design solutions, and has emphasised the importance of standardisation, modularity and simplicity in enabling effective disassembly and reuse (Crowther 2018; Ostapska et al. 2024). Studies focusing on reversible and accessible assemblies further show that connection design and interface logic have a key role in enabling disassembly at the building scale (Ottenhaus et al. 2023). In parallel, the recertification of recovered components has been identified as a critical challenge for reuse, requiring reliable documentation and assessment of material properties and structural performance (Räsänen & Lahdensivu 2023; Ottosen et al. 2024). Recent research has also examined DfD and reuse in the context of taller timber buildings from a holistic and interdisciplinary perspective, highlighting the role of system-level design decisions and connection logic (Fink et al. 2025). Related research on demountable and reversible connections has also been conducted for precast concrete structures, with several studies focusing on connection design as a key enabler for disassembly and component reuse (Figueira et al. 2021).
Together, these challenges underline the need for assessment approaches that make technical disassembly potential (TDP) explicit and comparable. Such assessments support design decisions, help to identify disassembly bottlenecks across building layers, and clarify how different design solutions influence the practical realisation of resource-efficient and circular construction.
1.2 ASSESSING THE TECHNICAL DISASSEMBLY POTENTIAL (TDP)
In addition to considering the potential for reuse, it is necessary to examine the TDP of buildings. TDP can be defined as:
the degree to which objects can be disassembled at all scales without compromising the function of the object or surrounding objects.
By enabling the non-destructive separation of components, TDP can prolong the functional lifespan of building elements and support the reuse, repair and replacement strategies (Geldermans 2016).
Disassembly is also closely linked to adaptability, which can be understood as the ability of a building to change or be modified with limited time, effort, cost or disturbance (ISO 2020). Buildings that do not respond to changing user needs are often subject to extensive renovations or premature demolition, particularly when structural and spatial systems are inflexible. Such interventions typically increase material consumption, waste generation, costs and emissions. In contrast, design solutions that support disassembly can enable incremental changes and component-level interventions, thereby improving adaptability and extending building lifespans (Geldermans 2016). While a high level of TDP does not ensure that reuse will occur, it reduces technical barriers and can therefore enable materials and components to remain in use for longer periods.
The relevance of TDP is increasingly recognised in policies and certification frameworks related to circular construction. At the European level, the construction sector is identified as a priority area for achieving more resource-efficient and resilient value chains, with a particular emphasis placed on increasing the availability of reusable products (EC 2023). Despite this strategic emphasis, explicit requirements for assessing or reporting TDP are largely absent from recent regulatory developments, such as the recast Construction Products Regulation (EC 2022) and the recast Energy Performance of Buildings Directive (EC 2024b).
More generally, guidance related to disassembly is often presented at the level of general principles instead of operational assessment frameworks. Standard ISO 20887 (2020) defines the key principles for disassembly, including accessibility, component independence, simplicity, standardisation and safety. These principles provide a useful conceptual basis, but they allow for broad interpretation and by themselves do not enable systematic comparison between buildings or design solutions. As a result, their application in practice can vary significantly.
Previous research has explored different ways of applying disassembly principles, e.g. by analysing connection characteristics, component independence, disassembly speed or element-level properties such as weight or complexity (Guy & Ciarimboli 2008; Pozzi 2019; Casagrande et al. 2021; Yan et al. 2022). Some studies have developed scoring systems to support a more structured evaluation of disassembly potential (Ottenhaus et al. 2025; Grüter et al. 2023; Mañes-Navarrete et al. 2025; Laasonen & Pajunen 2023). However, such approaches are often limited in scope, focus on specific materials or components, or are difficult to extend to building-level assessment.
Several building-level sustainability assessment and certification systems acknowledge disassembly or deconstruction as part of broader circularity objectives. For example, the European Union (EU) Level(s) framework includes Design for Deconstruction as part of Indicator 2.4, which aims to assess circular material life-cycles (Dodd et al. 2020). Similarly, Leadership in Energy and Environmental Design (LEED) and the Building Research Establishment Environmental Assessment Method (BREEAM) acknowledge DfD principles through selected credits or documentation requirements; however, neither provides a building-level, quantitative method for assessing TDP (LEED 2019; BREEAM 2021). The DGNB (2024) framework includes deconstruction planning and introduces a circularity index through the Building Resource Passport, which incorporates an assessment of disassembly potential, although this tool is currently available only in German and remains under development.
Among existing approaches, the DGBC’s (2021) Disassembly Potential Measurement Method Version 2.0, later referred to as the Dutch Green Building Council’s Disassembly Potential 2.0 (DP2) method, represents one of the most comprehensive attempts to assess TDP at the building level (Järvelä et al. 2025; Attia et al. 2024). The method builds on Brand’s (1994) concept of shearing layers and evaluates disassembly using criteria related to connection type, accessibility, component independence and geometry. In DP2, these criteria are combined with weighting based on the environmental cost indicator (ECI), which is a monetised life-cycle-based metric derived from environmental impact databases (Ecochain Technologies 2025). While this allows disassembly to be linked to environmental significance, it also introduces a dependence on external databases, assumptions and weighting choices, which may affect transparency and comparability between assessments (the results vary depending on the external database used, and databases might be proprietary or subscription based).
Other recent methods similarly combine disassembly-related criteria with mass- or environmental impact-based weighting. For example, Järvelä et al. (2025) propose a building-level disassembly potential framework in which accessibility and connection type are weighted using component mass and global warming potential (GWP). Such approaches highlight the close relationship between disassembly and environmental assessment, but they also raise questions about database dependence, parameter variability and the suitability of impact-based weighting for representing TDP. Comprehensive overviews of disassembly and circularity assessment methods at the building level have been provided in recent review studies (Attia et al. 2024).
1.3 AIMS AND SCOPE
A key motivation for this study was the observation that existing assessment methods tend to undervalue the TDP of ecological, lightweight materials—such as sustainably sourced timber or carbon-neutral steel—because they rely on weighting factors such as ECI, GWP or mass, as seen in both DP2 and Järvelä et al.’s (2025) methods. A further limitation of these approaches is their dependence on external databases or environmental product declarations, which reduces comparability across projects. Skaar et al. (2017) demonstrate that emissions from an intermediate floor can vary more than fourfold depending on the selected manufacturers; products with a higher declared GWP result in substantially greater emissions than low-GWP alternatives. Additionally, densities used for mass calculations vary across databases. For example, cross-laminated timber (CLT) densities range from 420 to 470 kg/m3 in Northern Europe (Södra 2026; FEI & MEF n.d.; Boverket n.d.; Stora Enso 2024). While such variations in environmental impacts or densities do not influence the actual TDP, they would affect TDP scores in methods that incorporate environmental impacts or mass as weighting factors. This underscores the need for more objective and material-neutral assessment methods.
The primary objective of this study is to introduce a theoretical material-neutral way to assess TDP by examining and further developing the DP2 method for assessing the TDP of buildings at the building and layer level. To illustrate and evaluate methodological differences, both assessment approaches are applied to a pair of comparable residential case-study buildings, one mainly based on timber structures and the other on concrete structures. The comparison between the buildings is therefore illustrative and supports methodological examination, and it is not intended as a general performance comparison between different construction materials.
The scope of the study is limited to TDP. Although reuse potential is closely related to TDP, actual reuse outcomes depend on additional factors such as regulatory requirements, market demand, economic feasibility and logistical constraints, which are outside the scope of this paper. Accordingly, the study focuses on how different assembly solutions and building layer configurations influence the technical feasibility of disassembly.
The assessment is carried out at the level of entire buildings and their constituent layers (based on Brand’s 1994 shearing layers), which consist of multiple products and connections. First, the TDP of the case study buildings is assessed using the DP2 method, with minor adaptations to support its application outside the Dutch context. Second, based on identified limitations of existing approaches, the DP2 framework is further developed into a new method, referred to as the Technical Disassembly Potential of Buildings (TDPB) method. The TDPB method enables a more transparent and material-neutral assessment of TDP by using quantity- and geometry-based weighting factors instead of environmental or cost indicators or mass. To support this objective, the study examines how different assessment methods represent the TDP of buildings and their layers, and how methodological choices, such as weighting logic and layer definition, influence the interpretation of TDP.
2. MATERIALS AND METHODS
2.1 CASE STUDY BUILDINGS
Both buildings are residential buildings (Figure 2) constructed next to each other in Turku, Finland, in 2022. The buildings are nearly identical: each has four stories, contains 41 apartments with recessed glazed balconies, and shares the same floor plans, apartment layouts and facade opening configurations. They were designed under the same Finnish building regulations and performance requirements, providing a shared regulatory context for the case comparison. Both buildings were constructed using wall and slab elements and employ a shear-wall structural system. The principal distinction between the buildings is the load-bearing material: one uses concrete, whereas the other relies primarily on timber (Table 1). Apart from material choice and minor differences in structural thicknesses, the buildings were intentionally designed to be as similar as possible to enable a direct comparison of timber and concrete construction in practice.
Figure 2
Axonometry and basic floor plan of the case-study buildings.
Table 1
Selected case studies and the materials used in the main structures.
| CONCRETE BUILDING | TIMBER BUILDING | |
|---|---|---|
| Net heated floor area (m2) | 2,974 | 3,014 |
| Base floor | In-situ reinforced concrete (RC) | In-situ RC |
| Exterior walls | Concrete sandwich elements | Cross-laminated timber (CLT) |
| Walls between apartments | Prefabricated concrete elements | CLT |
| Intermediate floors | Prefabricated concrete elements | Ribbed laminated veneer lumber (LVL) |
| Roof | Hollow-core concrete plus timber trusses | Timber trusses |
| Plus air raid shelter | In-situ RC | In-situ RC |
The study is based on publicly available documents—floor plans, sections, elevations, technical documents and building type catalogue—retrieved from the building control authority (Building Control Turku n.d.). Additional structural drawings, including structural floor plans, sections and foundation drawings detailing concrete foundations and piling configurations, were incorporated. The assessment was carried out using these documents and supplemented where needed with clarifications from the structural design team, ensuring a complete and accurate understanding of both buildings.
Based on retrieved PDF documents, building information models (BIMs) were made of both buildings using Graphisoft ArchiCAD. Quantities needed for making the assessment were retrieved from the BIMs. The assessment carried out for this study was performed using Microsoft Excel. Table 2 presents the material volumes for each building layer and their respective shares of the total material volume in the case study buildings.
Table 2
Material amounts (m3) and share (%) of the total material volume in selected case studies per building layer.
| CONCRETE BUILDING | TIMBER BUILDING | |||
|---|---|---|---|---|
| Space plan (m3) | 234.1 | 7.1% | 861.4 | 27.6% |
| Skin (m3) | 571.7 | 17.4% | 492.7 | 15.8% |
| Windows and doors (m3) | 41.1 | 1.2% | 41.1 | 1.3% |
| Structure (total) (m3): | 2,442.4 | 74.3% | 1,722.0 | 55.2% |
| Structureelement | 1,598.6 | 48.6% | 1,101.7 | 35.3% |
| Structureon-site | 71.1 | 2.2% | 69.0 | 2.2% |
| Foundation | 772.7 | 23.5% | 551.3 | 17.7% |
| Total (m3) | 3,289.2 | 100% | 3,117.2 | 100% |
2.2 ASSESSMENT METHODS
2.2.1 Fundamentals of the methods
When evaluating the TDP of a building (TDPbuilding), the building is divided into separate layers and, further, separate products. In this context, a product is defined as a building component, which may consist of multiple parts, that arrives at the construction site to be integrated into the building. A window element is considered a product if assembled on-site; however, if it is attached to a wall element in a factory, the entire wall element, including the windows, is regarded as the product. Throughout the TDP assessments, the underlying assumption is that products arriving at the construction site will leave the site as such after disassembly. This study focuses solely on the building, excluding the building site and surrounding areas. Following the DP2 methodology and the layer-concept of Brand (1994), the building is divided into different layers based on function and lifespan, and each identified product is appointed to one layer. In this study, the four main layer categories are internal surfaces and other light constructions (space plan layer), facade and other outer surfaces (skin layer), and the building’s load-bearing frame (structure layer) and windows & doors (Figure 1). To enable more precise evaluation, the structure layer is divided into three subcategories—prefabricated elements, on-site structures and foundations—as these categories generally perform very differently from the disassembly point of view. The division of the building products into various layers is crucial due to the different lifespans of the layers: the space plan-related products are likely replaced many times, while structural products are rarely replaced during the building’s life-cycle. This division is based on, but slightly differs from, Brand’s (1994) and the DP2 method’s layer division, as the structure layer is divided into three sublayers, and windows and doors are introduced as a separate layer. To ease the comparison of methods, the layer division in Figure 1 is used for both methods, as the TDPbuilding score in the DP2 method is independent of the layer division (see equation 4), while this layer division is necessary when using the TDPB method.
Each product in each layer is attached to other building components using certain types of connections. These connections play a key role in the TDP evaluation. Following the basic principles stated in ISO 20887 (2020), the connections TDP can be expressed by the connection type (CT) and connection accessibility (CA), as categorised in general terms in Tables 3 and 4 (DGBC 2021), and based on Durmisevic (2006). When such general definitions are used, it is also well justified to use quasi-linear scale for scoring the different criteria between 0.1 and 1.0 as proposed by DGBC (2021).
Table 3
Definitions of and scores for different connection types (CT).
| CT | SCORE | |
|---|---|---|
| Dry connection | Loose (no fastening material) Click connection Velcro connection Magnetic connection | 1.00 |
| Connections with added elements | Bolt and nut connection Spring connection Corner connections Screw connection Connections with added connection elements | 0.80 |
| Direct integral connection | Pin connections Nail connection | 0.60 |
| Soft chemical connection | Caulking connection Foam connection (polyurethane) | 0.20 |
| Hard chemical connection | Adhesive connection Dump connection Weld connection Cementitious connection Chemical anchors Hard chemical connection | 0.10 |
Table 4
Definitions of and scores for different connection accessibilities (CA).
| CA | SCORE |
|---|---|
| Freely accessible without additional actions to the product or surrounding products | 1.00 |
| Accessible with additional actions that do not cause damage to the product or surrounding products | 0.80 |
| Accessible with additional actions with fully repairable damage to the product or surrounding products | 0.60 |
| Accessible with additional actions with partially repairable damage to the product or surrounding products | 0.40 |
| Not accessible: irreparable damage to the product or surrounding products | 0.10 |
In addition to the connections, the parameters related to the product’s geometry and connectivity to the other products in the same layer, as well as the product’s independence from other layers, also affect the TDP. These parameters, named as geometry of product edge (GPE) and independency (ID), can be defined and judged according to Tables 5 and 6, respectively.
Table 5
Definitions of and scores for the geometry of product edge (GPE) parameter.
| GPE | SCORE |
|---|---|
| Open, no obstacle to the (interim) removal of products or elements | 1.00 |
| Overlapping, partial obstruction to the (interim) removal of products or elements | 0.40 |
| Closed, complete obstruction to the (interim) removal of products or elements | 0.10 |
Table 6
Definitions of and scores for the independency (ID) parameter.
| ID | SCORE |
|---|---|
| No interdependency: modular zoning of products or elements from different layers | 1.00 |
| Occasional independency of products or elements from different layers | 0.40 |
| Full integration of products or elements from different layers | 0.10 |
After all the four parameters are evaluated numerically, the total TDP of the product, TDPproduct, can be calculated as the harmonic mean of parameters:
As both methods exclude process and financial aspects, the parameters in equation (1) are defined as per one selected connection in the disassembled product and the number of connections within one product is not counted. The main differences between the methods are highlighted in Table 7 and further discussed in the following subsections. This study applies the same parameter scoring (Tables 3, 4, 5, 6) used in the DP2 method (DGBC 2021). Should updated scoring become available, it can be adopted without modifying the DP2 or TDPB methods.
Table 7
Differences between the two assessment methods.
| METHOD | DP2 | TDPB |
|---|---|---|
| Layers | Division originally into the following layers: space plan, skin, services and structure. Not necessary to assess the technical disassembly potential (TDP) of layers (TDPlayer) to assess the TDP of buildings (TDPbuilding). Thus, a layer division of the TDPB method is also used for the DP2 in this study because it eases the comparison of the methods | Division into the following layers: space plan, skin, structure (prefabricated elements, on-site structures and foundations), and windows and doors. The TDP of the layers (TDPlayer) needs to be reviewed to assess the TDP of buildings (TDPbuilding) |
| CT | Load-bearing connection is used to assess the TDP | The connection most difficult to disassemble is used to assess the TDP |
| Weighting factor | In this paper, the environmental cost indicator (ECI) was replaced by global warming potential (GWP) because insufficient databases make the assessment of ECI difficult outside of the Dutch context | Varies depending on layer: material surface area (m2) for skin and space plan layers; material volume (m3) for on-site structures and foundations; and product amount (pieces) for prefabricated elements and windows and doors |
| CA | Only damage to surrounding products is considered, except when the product is not accessible at all without irreparable damage to the product or the surrounding elements | Damage to the product itself and the surrounding objects are always considered |
| ID | Defines the best-case scenario as ‘No independency [sic]—modular zoning of products or elements from different layers’. It would be more logical if ‘independency’ were replaced with ‘interdependency’. Assessment in this paper was performed with the assumption that ‘independency’ was a typo and ‘interdependency’ is the correct term | Best-case scenario specified as ‘No interdependency—modular zoning of products or elements from different layers’ |
The assessment is two-phased. The first phase can be partly automated because it includes retrieving quantity information from BIMs. In the second phase, the assessors need, in some cases, to separate assemblies into products depending on how they arrive on-site, and to assign products manually to relevant layers and determine their CT, CA, GDE and ID. Thereafter, the rest of the assessment can be automated.
2.2.2 Dutch Green Building Council’s Disassembly Potential 2.0 (DP2) method
When evaluating the TDP of a layer, the TDP of the products is weighted according to their environmental impacts. In the DP2 method, this is done by using the ECI as the product weighting factor. In this case, the TDP of the considered layer TDPlayer is defined as:
where the subscript i is the ith product in the considered layer, and n is the total number of products in the layer. Using the ECI to evaluate buildings is an established practice in the Netherlands, but it is challenging to implement outside the Dutch context due to insufficient databases. Therefore, in this study, ECI is replaced by GWP, which, unlike ECI, considers only greenhouse gas (GHG) emissions, whereas ECI considers a broader spectrum of environmental impacts. However, upon examining the DP2 methodology, it is possible to confirm that the main role of ECI in the assessment of the building’s TDP is to steer the design, particularly ensuring that materials and structural components with severe environmental harms are designed for disassembly. Even though the GWP does not consider as many environmental indicators, using it instead of ECI as part of the assessment promotes designing GHG-intensive building components in a way that enables their reuse. Therefore, the assessment is performed by following the DP2 methodology with the alteration that ECI is replaced by GWP. The GWP is assessed by using the Finnish open emissions database CO2data.fi (FEI & MEF n.d.) and includes the production of components (life-cycle phases A1–A3), their replacements (B4), and reuse, recycling or energy recovery (C3). The TDP of a layer is now rewritten as:
where GWPi is the GWP of the ith product in the considered layer, and GWPlayer is the GWP of the whole layer. Following the DP2 methodology given in DGBC (2021), the whole building’s TDP is obtained by a straightforward summation with no additional weighting factors at the layer level, so that:
where N is the number of products in the building, and the TDP of the considered product i, TDPproduct,i, follows from equation (3).
In the DP2 method, the material layer distribution does not influence the building’s TDP (cf. equations 4 and 6). Therefore, in this study, the layer division developed for the TDPB method is applied to both methods to illustrate how the weighting factors (quantity-based versus environmental impact-based) of the methods assign different significance to building components when assessing TDPbuilding (Tables 8 and 9).
Table 8
Technical disassembly potential (TDP) of the concrete building according to the DP2 and TDPB methods.
| LAYER | DP2 | TDPB | ||||
|---|---|---|---|---|---|---|
| TDPlayer | RELEVANCE (% OF GWPtotal) | TDPbuilding | TDPlayer | RELEVANCE (% OF MATERIAL VOLUMEtotal) | TDPbuilding | |
| Space plan | 0.17 | 13.0% | 0.31 | 7.1% | ||
| Skin | 0.47 | 5.0% | 0.62 | 17.4% | ||
| Windows and doors | 0.94 | 4.0% | 0.94 | 1.2% | ||
| Structure (total): | – | 78.0% | – | 74.3% | ||
| Structureelement | 0.16 | 55.3% | 0.25 | 48.6% | ||
| Structureon-site | 0.13 | 2.0% | 0.13 | 2.2% | ||
| Foundation | 0.13 | 20.7% | 0.13 | 23.5% | ||
| 100% | 0.21 | 100% | 0.29 | |||
Table 9
Technical disassembly potential (TDP) of the timber building according to the DP2 and TDPB methods.
| LAYER | DP2 | TDPB | ||||
|---|---|---|---|---|---|---|
| TDPlayer | RELEVANCE (% OF GWPtotal) | TDPbuilding | TDPlayer | RELEVANCE (% OF MATERIAL VOLUMEtotal) | TDPbuilding | |
| Space plan | 0.36 | 40.5% | 0.65 | 27.6% | ||
| Skin | 0.61 | 6.2% | 0.65 | 15.8% | ||
| Windows and doors | 0.94 | 7.5% | 0.94 | 1.3% | ||
| Structure (total): | – | 45.8% | – | 55.2% | ||
| Structureelement | 0.79 | 18.3% | 0.82 | 35.3% | ||
| Structureon-site | 0.13 | 3.5% | 0.13 | 2.2% | ||
| Foundation | 0.13 | 23.9% | 0.13 | 17.7% | ||
| 100% | 0.42 | 100% | 0.61 | |||
2.2.3 Technical Disassembly Potential of Buildings (TDPB) method
In contrast to the DP2 method presented above in equations (2–4), TDPlayer is defined in the proposed TDPB method as:
where PQi is the quantity of product i in the considered layer. The quantity is measured either as the number of units or surface area or material volume of the product, depending on the layer type (Figure 1).
In the skin and space plan layers, the quantity of the products is measured by surface area. This is because in these layers the products are typically sheet-like (e.g. gypsum boards, acoustic panels) and their thickness has minimal impact on the TDP. The number of fasteners is generally proportional to the surface area rather than to the number of products, as there are typically some predefined intervals for the fasteners. In these layers, some products (e.g. facade renderings, in-situ brick facades, floor screeds) rely on chemical connections rather than fasteners. Still, the surface area remains the most appropriate indicator for assessing the TDP of these products due to the assemblies’ planar nature.
For all prefabricated structures and doors and windows, the significant quantity is the number of products. Rather than the size of the element, it is typically proportional to the number of fasteners needed (e.g., a short beam has the same TDP as a long beam due to both having the same amount of fasteners). In the other structure layers, the TDP of all parts, most of which are built on-site, is assessed based on their volume, as these parts are typically disassembled by demolition.
After layer-level calculations, the TDP of the whole building consisting of N layers is defined as:
where ji is the material volume portion of layer i from the whole building material volume, and TDPlayer,i is calculated by using equation (5). It is worth noting that in equation (6), the relative proportion of different layers can be determined based on their material volumes, because the characteristics of their disassembly have already been considered in the layer-level calculations.
On-site structures, foundations and the relevance of layers are examined based on volume rather than mass, partly because it simplifies the analysis, improves comparability and reduces the risk of undervaluing the TDP of lightweight materials. Calculating volumes requires knowledge of product dimensions, while calculating mass requires both dimensions and density data, and the latter can vary depending on the databases. Additionally, insufficient databases would introduce a more complex dimension to this type of assessment. If using mass instead of volume, in buildings such as the studied timber building, where the structure is lightweight due to CLT, the relevance of the heavy concrete foundations would be over-emphasised (the density of concrete is roughly fivefold that of CLT), which might negatively impact the desire to design the timber frame for disassembly.
3. RESULTS
Figures 3 and 4 show how assessment was performed through example sections from the same part of both studied buildings. They show how the products were sorted into layers and assigned CT, CA, GPE, ID and TDPproduct scores. The following sections present the results of the assessment for both buildings.
Figure 3
Examples of products and their TDPproduct score in the concrete building.
Note: Different colours represent different layers. The connection accessibility (CA) scores altered to perform the sensitivity analysis in Section 3.2 are highlighted with an asterisk (*).
Figure 4
Examples of products and their TDPproduct score in the timber building.
Note: Different colours represent different layers. The connection accessibility (CA) scores altered to do the sensitivity analysis in Section 3.2 are highlighted with an asterisk (*).
3.1 COMPARING THE CASE STUDIES
The TDPB method gives higher scores than the DP2 method for both studied buildings. The TDPbuilding score of the concrete building is 0.21 according to the DP2 method and 0.29 according to the TDPB method (Table 8), while for the timber building it is 0.42 according to the DP2 method and 0.61 according to the TDPB method (Table 9). The timber building performs much better from the disassembly point of view compared with the concrete building, regardless of the method used. For both buildings, variations in the TDPlayer score occur in the following layers: space plan, skin and structureelement, depending on the method used. The chosen method has the biggest impact on the TDP of the space plan layers.
When comparing the two buildings, their space plan and structureelement layers perform very differently (Tables 8 and 9). In the concrete building, the space plan layer’s TDPlayer score is 0.17 using the DP2 method, while it is 0.31 using the TDPB method. Similarly, for the timber building, the space plan layer’s TDPlayer score is 0.36 (DP2) and 0.65 (TDPB). For the structureelement layer’s TDPlayer score, the differences between the buildings are greater, as scores for the concrete building are 0.16 (DP2) and 0.25 (TDPB), while scores for the timber building are 0.79 (DP2) and 0.82 (TDPB).
The relevance of the layers varies significantly depending on the method used. According to the TDPB method, the layer most affecting the TDPbuilding score in both buildings is the structureelement layer, while this varies in the DP2 method. According to the DP2 method, the structureelement layer is the one with biggest impact in the concrete building, while the space plan layer has the biggest impact in the timber building. For both methods, main variations in layer relevance are found when studying the space plan (in the concrete building, 13.0% according to DP2 and 7.1% according to TDPB, and 40.5% in the timber building according to DP2 and 27.6% according to TDPB) and structureelement layers (in the concrete building, 55.3% according to DP2 and 48.6% according to TDPB, and 18.3% in the timber building according to DP2 and 35.3% according to TDPB). The variations between the relative impact of most layers are small when comparing the two buildings using the TDPB method.
3.2 SENSITIVITY ANALYSIS
Sensitivity analysis was conducted to evaluate the variations in TDP, focusing on the CA of the prefabricated load-bearing elements. These elements were assessed in greater detail due to their big impact on the TDPbuilding score in both methods and their TDP can cause disagreements (Figure 5).
Figure 5
Sensitivity analysis: TDPbuilding score variations in case studies based on the connection accessibility (CA) adjustments of prefabricated load-bearing elements by one score increase and decrease.
In many cases, removing concrete joints damages the concrete elements. According to Halding (2023), however, prefabricated concrete elements can generally be disassembled without significant cracking if weaker mortars are used in the joints. Disassembly remains challenging and may require special techniques to remove the mortar. Consequently, different evaluators may select varying levels of CA for the concrete elements.
The experiment by Bompa et al. (2024) demonstrates that disassembly and reassembly using screw connections had minimal to no impact on the strength and stiffness of CLT panels, supporting their full reusability. Some reuse approaches involve flipping and interchanging panel sides, while others suggest positioning screws at different points compared with their previous locations. Li et al. (2024) show that while disassembly is achievable, it involves a demanding process of removing fasteners or cutting through the attached timber sections. Other researchers suggest cutting through the wood near the screws may be considered the most practical method for reusing the remaining wooden components (Huuhka et al. 2018). However, in this paper, full TDP is defined as the ability to dismantle components without reducing their size.
Given uncertainties about TDP which enables the reuse of load-bearing products in their original size, the CA for these products is evaluated in the concrete building, with values ranging from 0.1 to 0.6, where 0.4 was the present authors’ choice. For the timber building, CA is assessed with values ranging from 0.4 to 0.8, where 0.6 was the authors’ choice (Figure 5).
Although the TDP of prefabricated load-bearing products was identified by the present authors as the primary factor causing discrepancies in the TDPB method, its overall impact on the building’s TDP is relatively small. Sensitivity analysis shows that the TDPbuilding score is +4% or –9% for the concrete building according to DP2, and +1% or –6% according to the TDPB, and for the timber building the similar values are +3% and –5% (DP2) and +4% and –7% (TDPB), depending on the CA chosen for prefabricated structural products. According to the assessment, the TDPbuilding score for the concrete building is 0.21 using the DP2 method and 0.29 using the TDPB method, while for the timber building, it is 0.42 and 0.61 according to the DP2 and TDPB methods, respectively. However, a pessimistic evaluation of the TDP for load-bearing concrete products yields values of 0.19 (DP2) and 0.28 (TDPB) for the concrete building, while a more optimistic assessment yields values of 0.21 (DP2) and 0.30 (TDPB). A pessimistic evaluation for load-bearing timber products yields values of 0.40 (DP2) and 0.56 (TDPB) for the timber building, while an optimistic assessment results in 0.44 (DP2) and 0.63 (TDPB).
4. DISCUSSION
The TDPbuilding score of the timber building is significantly higher than of the concrete building, regardless of the assessment method used, and the TDPB method gives both buildings better scores than the DP2 method. The timber building scores a higher TDPbuilding score when using the TDPB method, mainly because the DP2 method undervalues the TDP of products with a low negative environmental impact, in this case the timber frame (cf. the relevance of especially the structureelement layer between methods in Table 9). The timber building performs better than the concrete building regardless of the method used primarily because the structure has a major impact on the TDPbuilding score, and most of the differences stem from the load-bearing structure. In the timber-framed building, load-bearing products are attached with screws that are relatively easy to access. In the concrete-framed building, concrete is poured into the joints of the load-bearing concrete products, complicating access and dismantling. These differences can be identified when comparing the structural (grey) elements’ performance (TDPproduct score, and CT, CA, GPE and ID) in Figure 3 with those of Figure 4. The variations in the relative importance of the structureelement and space plan layers in the studied buildings can be explained by the different ways the buildings are constructed. The timber building is structurally more complex and consists of a greater number of products, especially in the intermediate floors, assembled on-site. The products that are part of the intermediate floors but which are assembled on-site are included in the space plan layer. The structures are simpler in the concrete building and fewer products are assembled on-site, meaning that most materials in the intermediate floors are in the structureelement layer. These differences are visible when comparing Figures 3 and 4. Figure 3 shows that the intermediate floor in the concrete building consists of a prefabricated concrete floor element (grey: structureelement) and a screed and vinyl flooring (purple: space plan layer) which are installed on-site. Figure 4 shows that in the timber building the intermediate floor consists of a prefabricated timber element (grey: structureelement) and gypsum boards, acoustic steel profiles, insulation, screed and vinyl flooring (purple: space plan layer) are installed on-site. It can be concluded that in the case of the timber building, a higher level of prefabrication, especially of the intermediate floors, would have been beneficial for the TDPbuilding score, as the connection determining the TDP of the structure of the floor is easier to disassemble than some of the connections assembled on-site. However, it cannot be generalised that a higher degree of prefabrication always results in a higher TDP. In concrete construction, where the connections of load-bearing structures often use mortars that complicate disassembly, a high level of prefabrication may even have an adverse effect on the TDPbuilding score.
The large discrepancies in the relevance of different building layers when comparing the two methods are due to the methods using different weighting factors to determine layer relevance: DP2 uses GWP, while TDPB uses material volume. The results in Tables 8 and 9 indicate that while both methods rank the buildings in the same order according to their TDPbuilding and TDPlayer scores, and the relevance of the layers reveal substantial differences. As an example, modifying the TDP of windows and doors has a noticeable influence on the TDPbuilding score in the DP2 method, as these elements are emission-intensive, whereas their effect on the TDPB method remains small, since their share of total material use (by volume) is relatively small (cf. the layer relevance for windows and doors between methods in Tables 8 and 9). For someone without prior expertise in construction-related emissions, the building’s TDP score provides a more intuitive indication of its potential to be disassembled if the assessment is based on material quantities rather than on the environmental impacts of those materials.
The TDPB method applied in this study differs from the approach proposed by Järvelä et al. (2025) in scope, complexity and means, though both share similarities with the DP2 method. TDPB assesses disassembly potential at the product and layer levels using the same four parameters as in DP2: CT, CA, GPE and ID, combined through a harmonic mean. It incorporates layer-based weighting based on material quantities (m2, m3 or number of elements), which requires information generally available from the BIM. The aim is a material-neutral score that communicates the building’s TDP and its layers and components. In contrast, the method proposed by Järvelä et al. uses only two disassembly parameters (CT and CA) and weights results by mass or GWP, making the assessment linked to disassembly (only two parameters instead of four) more streamlined, but still making the assessor reliant on databases for materials’ and components’ densities and emissions, which may lead to different results for TDP depending on the databases used. Based on the comparison of these methodologies, the authors suggest a future study to be conducted in which the buildings are assessed using the TDPB methodology with all four disassembly parameters compared with a study of the same buildings using only the two parameters selected by Järvelä et al. This would mean replacing equation (1) with equation (7):
Before material-neutral methods for evaluating TDP become established, assessing TDP only relative to the environmental impacts risks undervaluing sustainable materials. Nevertheless, using such approaches alongside material-neutral methods helps to prioritise the design of, for example, GHG-intensive materials for disassembly. For existing methods that incorporate environmental impacts, it may be beneficial to include additional environmental indicators, such as biogenic carbon storage. This could counterbalance the underestimation of, for example, timber structures, which has been identified as a common bias in some assessment methods.
It is contended here that evaluating the buildings’ TDP is more streamlined and effectively integrated as a standard procedure in life-cycle assessment (LCA) if it utilises easily available data, such as product dimensions and amounts, rather that it being reliant on external databases that might be hard to access or risk comparability. As the calculation of new buildings’ whole-life GHG emissions is a new legal requirement (after 2026 in Finland, and in 2028 in the EU), incorporating data derived for this LCA (such as m2 and m3) into the assessment of TDP further eases the assessment of buildings’ TDP.
To assess the TDPbuilding score, evaluators need to have access to design documents and have a solid understanding of the construction processes, including how products arrive on-site and how they come together to form the final building. Assessing the TDP is considerably easier and less labour intensive for someone who is part of the project’s design team, as they have access to the relevant project information (BIM, drawings, etc.). This situation is also ideal from an evaluation standpoint, since optimally the TDP assessment influences design in a manner that promotes circularity.
In the EU, pre-demolition audits are strongly recommended but not legally obligatory at the EU-wide level. The European Commission (EC), through its Waste Framework Directive and Circular Economy Action Plan, emphasises the importance of selective demolition and encourages pre-demolition audits to support better recycling and material recovery (EC 2020, 2024a). However, each EU member state has its own regulations and enforcement levels regarding these audits. Some countries, such as France and the Netherlands, require pre-demolition audits under specific conditions, particularly if hazardous materials are involved or for buildings over a certain size (Cerema 2011; Overheid.nl 2012). It is expected that pre-demolition audits will also become more common in other countries as the green transition progresses. Clear methods for assessing the TDP of buildings, though completely theoretical, support the creation of these audits, simplify the planning of renovations, transformations and deconstruction, and facilitating the reuse of building products. To facilitate reuse, the end-of-waste procedure needs to be clarified and product approvals for the reused products that are GHG-intensive and/or have demonstrated good TDP should be prioritised.
4.1 LIMITATIONS
The presented methods provide a theoretical score for the TDPbuilding, which indicates how well a building can be disassembled reversibly without damaging its components. Process-related factors such as time, labour requirements/competence, cost implications and environmental impacts of dismantling were intentionally excluded from the scope. Because these factors strongly influence whether disassembly is practical or economically attractive, the TDP values presented in this study should not be interpreted as indicators of process-related feasibility. This limitation does not affect the technical assessment itself, but it restricts how directly the results can be linked to operational or economic outcomes.
TDP assessments require a substantial number of documents, including detailed technical drawings, which can be difficult to obtain if the assessment is conducted by external assessors after building completion. However, in countries such as Finland, it is generally possible for anyone to obtain a substantial set of design documents from the building control authority. Design documents do not consistently specify which components are installed on-site, which arrive as prefabricated elements, or the degree of prefabrication. When documentation is incomplete, there is a risk that the assessment relies on assumptions or construction-site photographs, which could introduce uncertainty and may lead to products being assigned to the wrong building layers. This, in turn, could affect the relevance (percentage of material volume), thus the layer weightings, and may distort the overall TDPbuilding score. While generalisations can be made in the absence of precise information or in early design phases, such assumptions reduce methodological precision. If the evaluation is based on assumptions, this should be clearly stated when presenting the results.
The current evaluation relies on existing scoring frameworks for CT, CA, GPE and ID that have not been empirically validated through experiments, meaning that these scoring criteria remain theoretical. To strengthen future assessments, improved data are needed for both existing connection types and new solutions that may be introduced in response to circular construction requirements. Ideally, such data should be based on performance under actual disassembly conditions, supported by systematic testing and case studies where various connection types are evaluated. Enhancing the accuracy of CT, CA, GPE and ID scores does not require changes to the proposed method, though bigger updates might make it appropriate to update the TDP assessment of a building even if the building itself remains unchanged.
Finally, the study examines only two case study buildings that were intentionally designed to be as similar as possible in terms of dimensions, with one constructed in concrete and the other in timber. While this strengthens the methodological comparison, it limits the generalisability of the findings. Broader validation would require applying the method across a larger sample of building types, materials, construction methods, structural systems and hybrid structures.
5. CONCLUSIONS
This study investigated the technical disassembly potential (TDP) of two similar four-storey residential buildings by applying two assessment methods: the Dutch Green Building Council’s (DGBC) Disassembly Potential 2.0 (DP2) method and the Technical Disassembly Potential of Buildings (TDPB) method, which was developed as part of this research. The evaluation focused on key technical assembly factors, including connection types, accessibility, geometry and interdependency.
The comparison between the concrete- and timber-framed buildings highlights clear differences in their TDP. The timber building achieved higher TDPbuilding scores than the concrete building in both assessment methods. According to the DP2 method, the timber building scored 0.42 and the concrete building 0.21. According to the TDPB method, the timber building scored 0.61 and the concrete building 0.29. Regardless of the method used, these results indicate that typical timber construction might offer better TDP than typical concrete construction.
The findings highlighted that while both methods rank the buildings in the same order based on their TDPbuilding scores, the underlying layer-level differences were substantial when comparing the methods. The scores were also significantly higher when using the TDPB method. These differences highlight that the TDPB method offers a more objective and transparent basis for evaluating TDP, particularly because its weighting factors are based on quantitative product metrics rather than environmental impact.
The findings of this study show that current knowledge about building disassembly would benefit from more consistent empirical information regarding practical procedures and the performance of different types of connections during dismantling. More uniform data would support more reliable assessments and allow the developed method to be applied with greater accuracy in different building contexts. For long-term evaluation, the TDPbuilding score could be reviewed at key stages (as designed, as constructed, as operated) of a building’s life so that major changes would be captured and relevant information models and assessments could be updated. This would enable more precise assessments of the TDP of existing buildings and support the practical application of the method.
ACKNOWLEDGEMENTS
The authors thank the Turku Building Control Authorities and structural engineers from Sweco Finland Oy for sharing information about the case studies.
AI DECLARATION
The authors used Microsoft 365 Copilot Enterprise to enhance the manuscript’s language and readability, and subsequently reviewed and revised all content. The authors take full responsibility for the final publication.
AUTHOR CONTRIBUTIONS
N.W.: project administration, supervision, conceptualisation, methodology, formal analysis, resources, data curation, writing—original draft, writing—review and editing, visualisation; A.T.: conceptualisation, methodology, resources, data curation, writing—original draft, writing—review and editing, visualisation; S.P.: conceptualisation, methodology, writing—original draft; M.K.: methodology, writing—original draft.
DATA ACCESSIBILITY
The documents used for the assessment are available from the Turku Building Control authorities using the following address information: Pirttivuorenkuja 4, 853-52-22-4, 20900 Turku, FI. Assessment that supports the findings in this study can be retrieved from the corresponding author upon reasonable request.