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).
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 |
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% |
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 |
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 |
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’ |
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 | |||
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 (*).
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.