Annex 6: Data for old buildings

Sirje Vares, Jarmo Linjama, Janne Pesu

Introduction

The current focus of building LCA regulation is very much on new buildings, and no country has proposed limit values for renovating existing buildings.

If renovation would require a climate declaration for a building permit, the deconstruction phase would need to be assessed to evaluate the deconstruction, transport, waste management, and disposal of the to-be-removed material. Current construction processes and tools enable good knowledge of the material composition of new buildings, but little data exists on the material content of old buildings.

Our building stock volume, which grows annually through new construction, is very limited. According to Eurostat, 85% of buildings in the EU were built before 2000. It is estimated that 85%–95% of the buildings today will still exist in 2050, and as 75% of buildings are energy inefficient, Member States should set continuous targets and plans for building renovations. Otherwise, fully decarbonising EU building stock by 2050 would be impossible (EC 2021/0426 [COD]).

Renovations and refurbishments will improve the functionality of existing buildings and align them with current requirements. However, this does not apply to all types of buildings. Depending on the building’s condition, demolition may be the best economic and environmental option. In Western countries, buildings are largely assumed to be in good condition, but Estonia, for example, has many Soviet-era buildings whose condition is questionable for refurbishment.

Deciding on demolition or refurbishment requires assessing the building’s condition in advance. In the case of new construction and renovation projects, conducting preliminary CO2 calculation is often necessary to choose the best solution according to the climate impacts or compare proposed solutions. Calculations could be performed, although future construction or a renovation project is not properly designed yet, and there is very little information about the specific case.

In renovations, much can be predicted about the case beforehand; however, the assessment should be based on data or knowledge of historical structures and common practices in the past. An LCA calculation could be performed by using structure types typical for each era (archetypes). A material declaration helps make assessments for renovation (and refurbishment), decide what material will be removed, and choose the best solution for their treatment and utilisation.

The management, renovation, and refurbishment of the building stock will improve our residents’ quality of life, reduce the energy consumption of buildings, and, in the long run, lower the buildings’ environmental impact, but all these activities are having an impact now. Because renovation processes generate much demolition waste, treating demolition materials consumes energy in the dismantling, transporting, treating, landfilling, and even the treatment of utilising demolition materials; all these processes detrimentally impact our environment.

Construction and renovation activities need new materials to replace demolished building parts, and demolished materials turn into waste. It is estimated that of the total waste generated in the EU, up to 32% of that is construction and demolition waste, consisting mainly of inert materials, e.g. bricks, tiles, asphalt, and concrete (> 50%), wood, plastics, and metals (EEA 2012, Figure 3.2). Every demolished structure would require at least as much as was used but usually needs more materials to maintain and improve the quality of buildings, but very often, renovation projects consider expanding the initial construction volume into additional spaces.

Buildings that are relatively new have been built according to the BIM-based design

BIM - Building Information Modelling, creating, and managing information for a built asset using an intelligent model.

, but as the building stock is much older than the BIM-based design, much information about existing buildings is in physical documents or drawings or have been lost.

All information about our old historical buildings, their structure, and their material types promotes organising better waste management and use of materials through material circulation. The information also helps renovation projects compile their work in an environmentally friendly way by enabling environmental calculations for climate- and material declarations. However, knowing the types of structures and the distribution of materials in an existing historical building does not yet tell us about their condition nor directly help us make decisions regarding renovation or demolition. The condition of materials should be assessed using a scenario-based ageing method, and the cost and environmental profitability of the operation should be assessed by comparing life cycle costs and environmental impacts.

Discussion and definition of data needs and use cases

Data sources for old/existing buildings

A building is a separate structure, permanently constructed or erected in its location, with its own entrance, containing covered space intended for different functions and usually bounded by external walls or walls separating it from other structures (buildings) (according to Building classification in Finland)

Luokitukset | Rakennusluokitus 2018 | Tilastokeskus (stat.fi)

Buildings are classified according to their general purpose, e.g. residential and non-residential buildings. Classification is organised according to main building categories, which contain subclasses. When part of the building has a different purpose, a building is classified into the class where most of the building is used. However, building categories might be classified differently in different countries.

Some data on old/existing buildings can be collected from centralised databases (e.g. National Statistics or from the building cadastre). Statistics Finland provides building stock-related data in two separate databases:

A building and dwelling production database contains monthly or quarterly data about building permits by volume, floor area, and dwelling number.
A building and free-time residences database has building stock data according to the building classifications based on the main use purpose. Data that can be retrieved freely is gross m², m³, and the number of buildings in stock by year of construction. Regarding the building materials, statistics are compiled on the material types and quantities of façade- and load-bearing materials, but this information is not freely available.

Another source for collecting information about existing buildings is ‘Building and Dwelling Register’

Statistics Finland: Statistical databases | Statistics Finland (tilastokeskus.fi); Statistics Denmark: www.dst.dk; Statistics Norway: StatBank Norway – SSB; Statistics Sweden: www.scb.se; Statistics Estonia Home | Statistikaamet; Eurostat: Home - Eurostat (europa.eu)

building register related to the single building location, construction year, building size (gross- m²., number of storeys), construction and facade material, method for heating, number of apartments, residents, etc.
dwelling register related to the floor area, tenure status, number and purpose of rooms and spaces (living room, sauna, balcony, etc.), type of kitchen, number of inhabitants, etc.

As these building and dwelling statistics are intended for the statistics of population and housing

Building Stock Register (In Danish): www.bbr.dk; Building Stock Register, Finland: Real estate, building, and spatial information | Digital and population data services agency (dvv.fi)

, these data sources are insufficient for the building stock and material content assessment for the LCA. Thus, other sources of information would be needed.

In Denmark, the publicly available building stock register (BBR) compiles extensive information on buildings, including their location, size (footprint, floor area, number of floors, etc.), type of use, roof and facade material, construction, latest renovation years, etc.

Sweden does not have a centralised public database; instead, building information is collected and managed primarily at the municipal level.

In assessing existing buildings, the source of the building data could be generic or actual:

generic data is based on the typical building type and its typical components and materials (This case is based on very wide generalisations, making it vulnerable to wrong mapping).
data about actual products and components based on the measurements from the design documents, drawings, specifications, CAD/BIMs, and materials used in construction (as built Wmodel) (This is the most desirable and correct case; however, this is only possible for a few newer building cases).

Existing buildings with BIM based-design

In existing buildings where construction has been carried out based on BIM design, building size, structural solutions, and material types can be found in digital documents – in the ‘as-built model’. This is the best information for calculating the types of materials and their actual weights at the building level.

Existing buildings without BIMs (older, historical buildings)

The only data source for existing buildings without a BIM-based design is the "Building and Dwelling Register". This source also gives information only on the building level but estimates about structural solutions, material types, and the quantities required. Such information must be sought from various sources, e.g. building history books, statistics, publications presenting building solutions, etc.

Historical buildings are built in different eras and consist of different building types; they have typical architectural solutions and historical structures. Typical buildings in the Nordic countries have some similarities but still many differences. There is rarely a detailed material description of those old buildings on a building stock level, so a library of typical structural solutions (archetypes) of old buildings would be very useful.

In Denmark, danskbyggeskik.dk has a multi-storey building library with historical architectural structures. This 3D library applies to the building construction period from 1850 to 2000. Similar solutions would also be needed for existing/old buildings in other Nordic countries.

Use case: Material declaration

A material declaration provides information on the building’s components, the materials used, and the origin of the materials. Such material declaration was drafted for Finnish regulation, but it has later been replaced by a construction product listing. None of the Nordic countries has current regulations on material declaration.

It is assumed that, for the most part, the material description would be created the same way the data would be collected to prepare a climate declaration on the building. Even so, as this material declaration is meant for new construction, it could be produced retroactively, e.g. for renovation and refurbishment projects.

Calculating material weights could be performed using typical building types and their typical structure types (archetypes) according to the construction era.

As an example of structure types, Finnish Construction 2000 classification system (Talo 2000) includes three major building element classes: site, building, and internal space (infilling) (Table 1). The base of this classification is to support BIM-based design, cost estimation, production planning, and control

Finnish construction 2000 classification system (Talo, 2000) The_Finnish_Construction_2000_classification_system.pdf (rakennustieto.fi).

Class	Building element	Justification
Site elements	1.1.1 Ground elements	A significant mass fraction where many recycled materials can be used.
	1.1.2 Soil stabilisation and reinforced elements	A significant site element concerning the impact of climate change.
	1.1.3 Paved and green area	Area coatings, which are known at the design stage (with the necessary accuracy).
	1.1.3.4 Vegetation	Trees to be planted are included because of their impact on carbon sinks and biodiversity.
	1.1.5 Site construction	The technical service life of yard storage or canopies may be shorter than that of the main building. Cataloguing helps later use of materials.
Building elements	1.2.1 Foundation	A mass-significant group that usually causes the highest product-specific environmental and climate impacts. Construction planning covers these elements. Building elements and materials, which are removed from the deconstruction phase, form a base for further utilisation.
	1.2.2 Ground floor
	1.2.3 Structural frame
	1.2.4 Facades
	1.2.5 External decks
	1.2.6 Roof
Internal space elements (infill)	1.3.1 Internal dividers	An important component for the building’s operation. The materials are usually specified when applying for a permit.
	1.3.2 Space surfaces	A wear-prone part whose materials may be changed several times during a building’s lifetime. Cataloguing enables planning for utilisation.
	1.3.3 Internal fixtures	Frequently replaced parts. Cataloguing enables utilisation planning.
	1.3.4.2 Flues and fireplaces	The element necessary for the building’s technical operation. Flues can be significant in weight or contain many usable materials.
	1.3.5 Space unit	May contain a wide variety of materials – an essential part of the recovery design.

Table 1 Building structures according to Finnish Construction 2000 classification (Talo, 2000).

Classification of materials and their origin

The EU’s LCA calculation method level(s) proposes material type classes for materials used in construction. Building material types in level(s):

Concrete, brick, tile, natural stone, ceramic
Wood
Glass
Plastic
Bituminous mixtures
Metals
Insulation materials
Gypsum
Mixed
Electrical and Electronic Equipment

The ‘Material declaration’ can ensure a reliable and harmonised compilation of statistics on building materials, thus creating a uniform basis for assessing the low-carbon performance of buildings.

Since half the raw materials used annually are used in construction, monitoring the total amount of materials and their origin may impact the resource efficiency of construction through an information effect. From the perspective of the sustainable use of natural resources, the resource efficiency of buildings can help curb the consumption of building materials.

EXAMPLE: Utilisation of archetypes in material declaration

In this example, material consumption has been calculated for an external wall structure used in multi-storey residential buildings about 20 years ago (2000). This wall solution has a concrete inner shell as the load-bearing layer and façade, either a concrete layer or brick structure. In both options, glass wool 50+150 mm was used as thermal insulation (MSR 2000 US concrete and MSR 2000 US concrete + brick) (Table 2).

	Structure layer (from outside to inside)	Layer thickness, mm	Material density, kg/m³	Material weight, kg/ m²
MSB, concrete 2000
	External concrete wall	80	2400	192
	Air gap	30		0
	Glass wool wind protection	50	80	4,0
	Glass wool insulation	150	20	3,0
	Load-bearing concrete	100	2400	240
	Steel content in concrete reinforcement			7,6
SUM		410		447
MSB, concrete + brick, 2000
	Clay brick	130		147
	Mortar			71
	Air gap	30
	Mineral wool wind protection (glass wool)	50	80	4,0
	Mineral wool insulation (glass wool)	150	20	3,0
	Load-bearing internal concrete	100	2400	240
	Estimated steel content			4,5
SUM		460		470

Table 2 An example of weight calculation for a concrete wall archetype (a structure from a building built approximately 20 years ago).

Based on this result, the material intensity is 447 kg/wall-m² and 470 kg/wall-m² for the external wall structures under consideration.

For example, in an apartment building with a floor area of 1850 m² and an external wall area of 900 m², the material intensity of the wall structure per floor area of the building is respectively (900 x 447)/1850 = 218 kg/m² and (900x470)/1850=229 kg/m².

All parts used in construction can be assembled by continuing the calculation in the same way for other structural elements. When a library of historical structural solutions already exists, it can be used to calculate different types of houses, where, for example, several façade solutions were used, while house-specific comparisons of houses built in different eras can be made based on material content.

Historical building archetypes could also be used to report material sources (Table 3).

	Concrete, bricks, ceramic, natural stone	Steel	Insulation materials	Non-renewable source	Recycled source
Concrete wall archetype
External concrete wall	192 (44 %)			192 (43 %)
Mineral wool, wind protection			4,0 (57 %)	2 (0,5 %)	2 (18 %)
Mineral wool, insulation			3,0 (43 %)	1,5 (0,3 %)	1,5 (14 %)
Load-bearing concrete, internal	240 (56 %)			240 (54 %)
Seel content estimation		7,6 (100 %)		7,6 (2 %)	7,6 (68%)
Data for material declarations	432	7,6	7	443	11,1
Concrete wall archetype, wall with brick facade
Clay brick	147 (32 %)			147 (32 %)
Mortar	71 (16 %)			71 (15 %)
Mineral wool wind protection (glass wool)			4 (57 %)		2 (25 %)
Mineral wool insulation (glass wool)			3,0 (43 %)		1,5 (19 %)
Load-bearing internal concrete	240 (52 %)			240 (52 %)
Estimated steel content		4,5 (100 %)		4,5 (1 %)	4,5 (56 %)
Data for material declarations	458	4,5	7	463	8

Table 3 An example of a wall structure archetype and use of material weights in material declaration (a structure from the building built approximately 20 years ago).

An assessment of the material types and their quantities may help determine the impact of different spatial planning strategies on the consumption of building materials, demolition waste generation, and related environmental impacts at different territorial levels.

These inventories can also help estimate materials stored in cities, sub-regions, or individual buildings, which can serve as secondary sources of building materials in the circular economy of the future. Such information can be important for public decision-makers as well as circular economy companies, e.g. demolition companies and manufacturers of construction products.

Use case: Building renovation/refurbishment

Renovation is the action that changes previously built construction in the desired direction. Some of the objectives set for renovating structures are quite concrete. For example, the desired U-value can be defined for a new façade, new windows, or roof. Conversely, specifying only desired appearance requirements for maintenance, which is included in the predicted renovation works, is possible.

Renovations can be classified according to the quality level of the building achieved post-renovation:

the quality level of the building does significantly improve (despite the project being a separately financed and implemented complete renovation project)
process that improves the quality level of the building
annual renovation, based on the building’s annual renovation plan, in which the building’s renovation is carried out preventively (maintenance, pipeline renovation, and correction works, according to a 5-year plan)
refurbishment, i.e. renovation carried out as a large-scale modification and functionality improvement project (where changes may concern, e.g. the appearance of the façade, structures, change in the building’s purpose/use, etc.)

A building requires regular maintenance during its service life (use phase) to retain it or an assembled system (part of works) in a state in which it can perform its required functions. Relevant information concerning the building renovation/refurbishment shall be obtained and collected according to the LCA evaluation requirement. Available underlying information shall be reviewed and assessed according to relevant sustainability assessment standards (EN 15978, EN 16309, and EN 16627).

If an existing building is insufficiently documented, deviations in the structures, use, and condition of materials may exist. In such cases, concluding that the documentation is generally insufficient and does not meet current requirements may be appropriate. The results of the analysis can be used to make fundamental decisions on how to deal with existing buildings and, in general, life cycle assessments for refurbishment projects (EN 17680:2023). However, the standard does not say how these decisions should be made.

In the case of renovation projects, the performance of buildings should be assessed against expected requirements and needs, now and going forward, including a comparison of environmental impacts between different options. Each performance level (current and proposed) should be recorded (EN 17680:2023).

The existence of structural types corresponding to the era and construction at hand helps calculate the environmental impact of refurbishment projects. Structural types help calculate the materials used in the building, but conclusions/decisions on what materials are transferred to waste and which parts can be utilised cannot be made before the condition survey. However, calculations can be made on a scenario basis.

Climate impact calculation for the refurbishment project

The life cycle assessment method applies not only to new construction but to existing buildings and their refurbishment projects (EN 15978:11). The standard is being revised, and harmonising it with other sources that have already been updated is its primary purpose.

According to EN 15978, rebuilding is assessed like a new building (reported in module A1-5). The partial demolition of the existing building is attributed to the rebuilt building, and all reuse of the existing construction is considered sink costs. This approach supports circularity and recovering as much of the existing building as possible when rebuilt.

According to the Finnish Building Act (1.3.2023) a building’s carbon footprint and handprint must be assessed for a new building and for a building undergoing large renovation (refurbishment). This act is being revised, and assessment of renovation will no longer be required.

In Finland, the environmental impacts of renovation projects have been assessed to a limited extent thus far. In most cases, these assessments were made for research purposes, related to improving the level of energy efficiency, and making declaratory assessments based on that research.

In Denmark, Kanafani et al. (2022) developed a model to facilitate an LCA for renovation projects, focusing on typical apartment buildings constructed from 1850 to 1920. Rather than relying on material amounts per m², the model generates a full life cycle inventory based on a few dimension parameters, assuming a typical layout for an apartment building from this period. The model is implemented in the Danish LCA tool LCAbyg. A user working on a renovation project can thus input a few parameters related to the building’s dimensions. LCAbyg generates an approximate LCA model for the existing building, which the user can then edit based on the renovation measures considered. The possible inclusion of mandatory requirements and/or standardised methods for an LCA of renovation projects is under negotiation. Notably, the Danish Strategic Network for Sustainable Construction has recently published recommendations regarding such methods and requirements.

LCA boundaries for the refurbishment

Estimating the renovation project’s carbon footprint is limited to the new materials needed for the repair or building elements and products to be repaired in connection with it. It does not retroactively calculate the effects that occurred before the major correction. The impacts of the construction products manufactured, the construction work phase, and the energy used are part of the previous life cycle of the building are not included in the low-carbon assessment of the renovation (Low carbon building assessment method 2021. Ministry of Environment, Finland 6/21).

Major renovations may affect the building’s layout, structures, components, and technical systems, a change in the building’s intended use, or construction activities by renewing, adapting, or improving the building’s performance. The next table (Table 4) gives the assessment stages for the refurbishment project.

Prior to refurbishment				During refurbishment
C1	Demolition	A1	Raw material acquisition	A4	Transportation of any new materials, products, parts, components, etc., needed for the refurbishment
C2	Waste transportation	A2	Raw material transportation	A5	Construction and installation activities
C3	End-of-life treatment	A3	Material production (any new material, products, parts, etc., needed for the refurbishment)	C2	Transportation of installation wastes and packages to the waste handling plant
C4	Final disposal			C3	End-of-life treatment
C4	Final disposal			C4	Final disposal

Table 4 Life cycle phases, which should be included for assessment of the refurbishment project

Data on the end-of-life phases of building materials are required to calculate an LCA for renovation projects. Such information can be found in the Danish Building Materials Database and partly in the Finnish CO2data.fi database. The Norwegian database EPD Norge contains manufacturer-specific EPD data; when the EPD has been prepared for the entire product life cycle, an estimate of its end-of-life information can also be found. However, in the Swedish Boverket database, this information is completely missing.

The latest account on a national method Denmark for renovation was made by the Strategy Network this year (2024). The network gathers industry representatives and various interest group organisations and is facilitated by Aalborg University. The independent network aims to make recommendations regarding the further development of building carbon regulation in Denmark. It should be highlighted that this proposal does not have an official status.

Proposed method for renovation, Denmark:

Requirements include larger (>1,000 m²) and, later, smaller buildings too.
Larger renovations are divided into simple or deep renovations (refurbishments).
Included: New materials (A1-3, B4, C3-4) and materials removed during renovation (C3-4).
In the case of implementing stages A4 and A5 in the 2025 regulation, construction waste from removed materials will be allocated to A5.
Use stage and end-of-life of existing materials are omitted; no remaining service life is assumed.
Reference unit: Assessment focused on components for which reference values will be developed and against which the assessment will be measured.

EXAMPLE. Utilising archetypes in assessing climate impact from refurbishment

Table 5 gives an example of the climate impact from refurbishment project for a concrete building exterior wall. In this example, it is assumed the concrete element outer layer will be removed with the thermal insulation, and during the refurbishment, a new insulation and outer shell will be installed.

Other assumptions for this case are:

Table 7 shows the life cycle impacts on building materials. The Finnish database on treating (C3) and disposing of construction waste (C4) contains only some results.
The Finnish database (CO2data.fi) provides transport impacts for different load sizes and vehicle loads, assuming the transport distance to the waste treatment plant is 50 km and that the truckload of mixed construction waste is 20%. According to this step, the C2 effect is 0.285 kg CO₂e/tkm. This value is missing in the Danish database.
The Finnish database gives a general impact value for demolition work of different building types (phase C1); this is 7 kg/floor-m² for residential buildings (this total value is allocated to demolishing the wall structure according to the wall/floor ratio). The Danish database does not include any impacts for stage C1.
The assessment was made for a hypothetical 5-storey residential building with a floor area of 1850 m² and a wall area of 900 m².

CONCRETE BUILDING (1850 floor-m²), concrete exterior wall element (900 m²/building)
Material specification: exterior wall archetype	Replaced outer shell	Saved inner shell

Material specification (kg/wall-m²)
Actual structure: Concrete 432 kg/m² glass wool 7 kg/m² steel 14 kg/m² (used for reinforcement)	Refurbishment waste: Concrete 192 kg/m², mineral wool 7 kg/m², steel 3,8 kg/m² (used for outer shell reinforcement) New materials: Concrete 192 kg/m², mineral wool 7 kg/m², steel 3,8 kg/m² (used for outer shell reinforcement	Life cycle continues: Concrete 240 kg/m²

Table 5 Refurbishment of the exterior wall from the residential multi-storey concrete building (removal of concrete exterior wall shell and insulation and replacement of a new wall shell) (MRB 2000 US concrete)

Building material	Finland, CO2data.fi			Denmark, GENDK + okobau.dat
	A1-A3	C3	C4	A1-A3 kg CO2e/kg	C3	C4
Concrete in wall	0,17 kg CO₂e /kg	0,006 kg CO₂e /kg		282 kg CO₂e /m³	6,72 kg CO₂e / m³	4,97 kg CO₂e / m³
Glass wool	1,2 kg CO₂e /kg		0,57 kg CO₂e /kg for mixed waste	40 kg CO₂e / m³	0,72 kg CO₂e / m³	0,39 kg CO₂e / m³
Reinforcement steel	0,56 kg CO₂e /kg	0,002 kg CO₂e /kg		0,68 kg CO₂e /kg		0,00067 kg CO₂e /kg

Table 6 CO₂e unit values for the building materials used for calculating this renovation project example

	Material type and kg/structure-m²	Finland	Denmark	Building, Finland	Building, Denmark
A1-A5	192 kg concrete	33	23
	7 kg mineral wool	8,4	8
	3,8 kg steel	2,1	2,6
C1	202,8 kg of demolition materials	4,6	not considered
C2	202,8 kg of waste	2,9	not considered
C3	192 kg of concrete	1,2	0,54
	7 kg of insulation		0,14
	3,8 kg steel	0,01	0
C4	concrete		0,40
	mineral wool	0,40	0,08
	steel		0,00066
TOTAL		53 kg/structure-m²	34 kg/structure-m²	50 400 kg/building	30 600 kg/building

Table 7 Climate impact from the refurbishment project of the residential building (removal of concrete exterior wall shell with an insulation layer and replacement of a new wall shell) (MRB 2000 US concrete, Finland)

The previous example was a hypothetical refurbishment case where it was assumed the concrete outer cell had deteriorated so much that repair was impossible. In any case, assessing the actual object requires knowledge of the technical conditions of the structures and an assessment of the service life of the products and materials used.

The existence of historical archetypes does not yet justify conclusions on the condition of the products in any specific case and their remaining service life.

The demolition material and construction waste report shall be updated at the end of the construction or demolition project to include information on the quantities, delivery locations, and treatment of construction and demolition waste leaving the construction site. However, this cannot be based on an estimate but on actual amounts.

Use case: Building stock as a material bank

“Buildings as Material Banks” is a concept that aims to reduce waste and use of virgin resources in the construction industry by increasing the value of building materials. The idea is to design buildings that can be disassembled and the materials reused in other buildings, creating a circular economy where materials sustain their value. The project “BAMB” (Buildings As Material Banks)

BAMB. Grant agreement ID: 642384. European Union’s Horizon 2020 research and innovation program.

developed Materials Passports and introduced Reversible Building Design

About bamb - BAMB (bamb2020.eu)

Over the last few years, initiatives aiming at modelling material amounts in existing buildings with a high level of precision and accuracy to facilitate reuse have been launched in multiple European countries.

Several research projects have investigated material amounts in the existing building stock in Denmark. Lanau and Liu (2020) and later Li et al. (2022) developed an “urban resource cadastre” to identify opportunities for urban mining. At its core, the cadastre uses material intensity coefficients for various archetypes derived from case study buildings. The cases focused on the city of Odense but were later generalised to the entire country.

Information about building archetypes and material amounts are relevant for material stock analyses or for estimating the end-of-life impact of an existing building, but some types of analyses require more detailed data. For instance, estimating the number of reusable materials in a building requires more detailed product-level information. Francart et al. (2023) developed an open-source model to estimate material amounts at the product level in existing buildings

https://github.com/NFrancart/iBuildGreen

. The model delivers more granular estimates, but the total material amounts for the building are less accurate than the ones from Lanau and Liu (2020).

Overall, such building stock models may provide relevant information for strategic planning related to urban mining, but they do not yet reach a high enough level of precision and accuracy to support operational decisions related to reuse. Case by case, detailed assessments of the amounts and properties of materials in existing buildings remain necessary to enable reuse in most cases. Private sector initiatives aimed at facilitating these assessments have also emerged across Europe, e.g. the Dutch company Madaster or the Danish Milva.

Robust classification of building types

Statistics Finland classifies Finland's building stock into 13 main categories

Classification of Buildings 2018, Finland: Classifications | Classification of Buildings 2018 | Tilastokeskus (stat.fi)

according to the purpose of use. There is also one main building class category: a free-time residential building. Free-time residences are treated separately, except for permanent residential second homes, which have been classified as separate small houses in the category of residential buildings.

Meanwhile, the Danish building stock database, BBR, uses a more fine-grained description of building use types, with 104 different building types. However, for comparison purposes, they are reported below in the same categories as in the Finnish statistics (although it should be noted that this mapping is uncertain: the categories might not contain the types of buildings in both countries).

In Estonia, buildings are also classified according to the building’s purpose:

small residential buildings (single-family homes, two-apartment buildings, or terraced houses)
multi-apartment buildings (residential buildings with three or more apartments, including buildings of social welfare institutions and residence halls, except terraced houses)
office buildings, libraries, and research buildings
business buildings (accommodation buildings, food service buildings, service buildings), except office buildings and commercial buildings
public buildings (entertainment buildings, except zoological parks or botanical gardens; sports buildings, except indoor ice rinks and riding halls; museums and library buildings, except libraries and terminal buildings)
commercial buildings and terminal buildings
educational buildings (except preschools)
preschools
healthcare buildings (hospitals and other medical treatment buildings)

Building types	FINLAND m²	DENMARK m²	ESTONIA m²	ICELAND m²
Detached houses	168 649 672	188 901 000		7 154 537
Linked and terraced houses	36 704 988	38 223 000		2 840 715
Residential apartment buildings (multi-storey)	111 616 101	92 953 000		9 626 354
Commercial buildings	31 417 128	25 872 000		8 759 199
Office buildings	20 169 210	26 903 000		1 343 617
Transport buildings	13 816 119	7 364 000		219 710⁺
Buildings for institutional care	11 699 263	9 709 000		415 081
Assembly buildings	11 606 836	reported with ‘industrial building’		1 152 128
Educational buildings	22 747 150	25 980 000		106 371
Industrial buildings	51 952 994	40 701 000		638 948
Warehouses	25 718 735	37 279 000		3 286 194
Agricultural buildings*	22 063 885	97 206 000		3 676 568
Other buildings**	6 668 582	45 096 000		9 626 354
TOTAL	537 816 971	636 187 000	134 244 005	39 219 424
* Class ‘Agricultural buildings’ (Finland) has uncomplete statistics (data from 1995) ** Class ‘Other buildings’ (Finland) include saunas and outbuildings, huts, lodges, ‘Energy supply buildings’ ‘Public utility buildings’, ‘Rescue service buildings’ ⁺In Iceland, only airport buildings ⁺⁺In Iceland, cost category no. 9 applies

Table 8 Building classification and building stock. Statistics Finland based on ‘Building and summer cottage’ database (NOTE: Statistical data until the end of 2020; class detached houses Finland also includes building class: summer cottages, but only habitable) (Statistics Finland data obtained 29.1.2024

Statistics Finland: Rakennukset ja kerrosala muuttujina Vuosi, Alue, Rakennuksen käyttötarkoitus (Rakennusluokitus 2018), Rakennusvuosi ja Tiedot. PxWeb (stat.fi)

and Statistic Denmark).

In Finland, construction was most active from 1970 till 1989 (Figure 1). At the end of 2020, the total floor area of existing buildings in Finland was approximately 516 million square metres. Residential buildings accounted for approximately 60% of the estimated decades (totalling 317 million square metres). Regarding the statistics, most blocks of flats were built in Finland from 1960 to 1979, and most detached, linked, and terraced houses from 1980 to 1999 (Figure 3).

Figure 1 Building Stock, Finland (Statistics Finland, 2020)

Figure 2 Residential and non-residential buildings, Finland (by construction era) (Statistics Finland, 2020)

Figure 3 Example of residential building shares by construction year (Statistics Finland, 2020)

According to Statistics Denmark, residential buildings is the largest building category, accounting for approximately 50% of the total building m² in Denmark. Single-family houses were the largest group of residential building types according to the total built m²; until 1979, they represented the largest era-based constructed -m².

Figure 4 Building stock, Denmark (Building Statistics, 2020)

Figure 5 Building stock, Iceland (Housing and Construction Authority, 2024)

Estonia

In Estonia, apartment buildings comprise 70% of the whole dwelling stock. Most of these apartment buildings (blocks of flats) were constructed during the 1960s, 1970s, and 1980s (over three-fourths of the dwellings) (Statistics Estonia, 2016).

Approximately two-thirds of Estonia’s population lives in apartment buildings (Statistics Estonia, 2016). Apartment buildings are mostly in urban or suburban areas, while detached houses, primarily farmhouses, are the main dwelling type on the outskirts and in rural areas.

Figure 6 shows the Estonian building stock floor area according to the commissioning data (results presented as of the end of 2020).

Figure 6 Building stock (according to commissioning date), Estonia (Building Statistics, 2020) (does not include buildings with an unknown construction date)

Identification of representative structure types and typical material contents

Analysing the existing building stocks aims to create a general/typical base of structural types of buildings, thus avoiding building-specific material analyses when similar information is not publicly available. This information aims to provide a sufficiently reliable model description of the materials used in old buildings.

Finnish Construction Information provider (Rakennustieto Oy) has published a comprehensive series of books that describe apartment buildings from 1880 to 2000, their architecture, structure type, etc. This book series was chosen as the source for material type and amount description (Residential blocks of flats: 1880–1940, 1940–1960, 1960–1975, and 1975–2000, Finnish Architects' Association). Residential apartment buildings were selected for review in the first place because the apartment building type and structure archetypes are more homogeneous and better documented (Figure 7).

Figure 7 Information about used building structure types collected for the multi-storey residential buildings, Finland

Figure 8 Typical load-bearing structure types in multi-storey buildings, Finland (Neuvonen, P., 2006)

Building character
Load-bearing structure type	Wood frame used in a small proportion. Main types were brickwork frame, mixed frame, concrete column/wall frame (bookcase frame type was used from 1960 to 1975).
Material type for wooden houses, example from 1940 to 1960	Log frame recedes; only a few log apartment buildings are being built. A typical wooden multi-storey house was a 2-storey timber frame building (puurangalla).
Material types for ‘stone’ houses	Brick, concrete, and lightweight concrete buildings.
Material share	Buildings from brick frame 40%, concrete 50%, wood 3%.

Table 9 Example of historical multi-storey buildings Finland (according to the source: Multi-storey buildings 1940–1960, Rakennustieto Oy).

Estonia
In Estonia, apartment buildings comprise about 70% of the dwelling stock, and the dominant building materials are brick or prefabricated reinforced concrete (large panels), accounting for 37% and 36% of all apartment building floor areas, respectively (Allikmaa, 2013).

Estonian housing stock includes apartment buildings made from aerated autoclaved blocks (12%) and old wooden apartment buildings from the beginning of the 20^th century (8%).

Iceland

According to Statistics Iceland, the most used building material in existing buildings is concrete.

BUILDING STRUCTURE TYPES EXAMPLE, FINLAND:
Following example illustrates material contents of main structures. These are a group of materials with a significant mass (that usually causes the highest product-specific environmental and climate impacts), the building parts included in the central plans of the building, materials that can be used further as other materials are estimated to be of lower significance (materials with small weights like paints, nails connections, etc.). On this basis, the structural elements were divided into six categories:

foundation (P)
ground floor (AP)
intermediate floor
exterior wall (US)
roof (YP)
partition wall (VS)

The next table presents the structures of residential buildings (typical in Finland between 1960 and 1975) according to material types, quantities, and sources (Table 17).

1960–1975	Type of structure	Concrete, bricks, tiles, ceramics	Wood and natural fibres	Glass	Plastics and rubber	Bituminous materials	Metals	Insulation materials	Gypsum	Other	Soil and stones	Total [kg/m²]	Renewable	Non-renewable	Hazardous
Base floor	Slab on grade, concrete, expanded clay	207	0	0	0	0	2	54	0	0	380	643	0	641	0
Base floor	Slab on grade, concrete, cellular polystyrene	207	0	0	0,2	0	2	3	0	0	380	591	0	589	0
Intermediate floor	Cavity slab, mineral wool	253	0	0	0,0	0	2	2	0	18	0	274	0	271	0
Intermediate floor	Solid concrete slab, EPS	486	0	0	0,0	0	6,2	0	0	18	0	511	0	504	0
Exterior wall	Sandwich concrete element (70 + 80) + brick tiles + insulation 160 mm	396	0	0	0	0	8	3	0	0	0	408	0	398	0
Exterior wall	Sandwich concrete element (70 + 150) + brick tiles + insulation 140 mm	564	0	0	0	0	8	2,8	0	0	0	575	0	566	0
Exterior wall	Brick-built, burnt brick (270x130x75 mm) in facade + insulation 120 mm	347	0	0	0	0	0	4	0	0	0	351	0	349	0
Exterior wall	Brick-built, burnt white brick (285x85x75 mm) in facade + insulation 120 mm	285	0	0	0	0	0	4	0	0	0	289	0	287	0

Table 10 Residential buildings: their structure types, material types, weight (kg/structure-m²) used, and material origin (Finland)

BUILDING STRUCTURE TYPES EXAMPLE, DENMARK
Engelmark (2013) has extensively studied the types of structural solutions used over time in Danish multi-family housing buildings. For some elements, he provides an overview of the time periods over which each solution was typically used. The information below is based primarily on Engelmark (2013), but other design manuals have been consulted to provide a rough overview of the Danish construction landscape.

Figure 9 and Table 12 indicate the time periods over which various structural solutions were typically used in Danish housing construction and the typical material amounts for each solution (expressed per m² of wall, floor slab, etc). The actual thickness of insulation depends on the last year of renovation, as it must comply with progressively more ambitious energy regulations.

Figure 9 Typical structural solutions (external walls) in Danish housing construction

External wall type	Material	Amount
Half-timbered wall	Brick	0,138 m³
	Wooden beam	0,052 m³
	Lime gypsum plaster	0,01 m³
	Lime mortar	0,038 m³
Massive brick wall*	Brick	0,263 m³
	Lime gypsum plaster	0,01 m³
	Lime mortar	0,079 m³
Hollow core brick wall	Brick	0,176 m³
	Lime gypsum plaster	0,01 m³
	Lime mortar	0,04 m³
	Mineral wool	0,074 m³
	Steel bars	1,38 kg
Etc.


* Typically, the thickness of brick walls would increase by a half-brick for every second floor above the floor considered. A full brick’s thickness is 228 mm; a half-brick thickness is 108 mm. So, in a five-storey building, the first floor would be one brick thick; the second and third floors one and a half bricks thick; and the fourth and fifth floors one brick thick.

Table 11 Typical material amounts for each solution (external walls), Denmark

name	min_year	max_year	min_pitch	amount	unit	prodname
Thatched roof	0	1900	10	37	KG	FASBA e.V. Baustroh 100 kg/mÃ‚Â³
Thatched roof	0	1900	10	0,18	KG	Glass fibre fleece
Thatched roof	0	1900	10	0,02	M3	Timber pine (12% moisture / 10.7% H2O content)
Thatched roof	0	1900	10	0,1	KG	Galvanised steel screws
Clay tiles	1800	2100	25	38	KG	Roof tile
Clay tiles	1800	2100	25	0,006533	M3	Construction wood, pine and spruce (skeleton)
Slate shingles	1800	1930	20	0,006533	M3	Construction wood, pine and spruce (skeleton)
Slate shingles	1800	1930	20	36	KG	Roof slate (thickness 0.011 m)
Zinc	1800	1930	5	0,006533	M3	Construction wood, pine and spruce (skeleton)
Zinc	1800	1930	5	5,7	KG	Zink, patinated
Concrete tiles	1910	2100	20	0,006533	M3	Construction wood, pine and spruce (skeleton)
Concrete tiles	1910	2100	20	36	KG	Roof tiles, concrete
Glass	1920	2100	12	61,8	KG	Glass roof, aluminium
Roofing felt	1930	2100	1	5	KG	Bitumen sheets G 200 S4 (thickness 0.004 m)
Roofing felt	1930	2100	1	5,21	KG	Bitumen sheets PYE PV 200 S5 (non-slated) (thickness 0.004 m)
Eternit tile without asbestos	1930	2100	25	0,006533	M3	Construction wood, pine and spruce (skeleton)
Eternit tile with asbestos	1930	2100	25	0,006533	M3	Construction wood, pine and spruce (skeleton)
Eternit tile without asbestos	1930	2100	25	18	KG	Fibre cement roof tile
Eternit tile with asbestos	1930	2100	25	18	KG	Fibre cement roof tile
Plastic roof	1970	2100	1	2	KG	EPDM roof sheets (thickness 0.0015 m)
Green roof	1970	2100	1	4	KG	Bitumen sheets G 200 S4 (thickness 0.004 m)
Green roof	1970	2100	1	1,13	KG	Foil for green roof (thickness 0.001 m)
Green roof	1970	2100	1	1,66	KG	PE foil (thickness 0.00125 m)
Green roof	1970	2100	1	0,5	KG	PE/PP fleece
Green roof	1970	2100	1	0,04	M3	Mineral wool (partition walls insulation)

Table 12 Example of roof types in existing buildings, Denmark

EXAMPLE ICELAND
Table 13 presents an example of building material amounts (m³ and m²) used in Iceland buildings and their proportional distributions of material types (Iceland buildings from 1950 and 1975 and external wall example.

Building material	Total cubic meters**	Total square meters m²
Concrete	4 789 255	4 510 468	86,6%
Hollow concrete brick	200 965	277 100	5,3%
Brick	6 165	11 693	0,2%
Precast concrete	17 850	26 861	0,5%
Timber/wood	198 460	229 293	4,4%
Steel	1 977	864	0,0%
Concrete + wood	110 587	82 225	1,6%
Concrete/loaded	50 338	64 089	1,2%
Concrete + metal	2 325	4 795	0,1%
		5 207 389

Table 13 Proportional distribution of building materials for housing from 1950 to 1975

Terminology

Building (3.1; EN 15978:2011) construction works that provide shelter for their occupants or contents as one of their primary purposes; are usually enclosed and designed to stand permanently in one place (ISO 6707-1:2020).

Building fabric (3.2; EN 15978:2011) all construction products fixed to the building permanently so that dismantling them changes the building’s performance, and dismantling or replacing them constitutes construction operations.

Deconstruction (3.1.17; prEN 15978:2023) process of selectively and systematically dismantling a building (3.3) to reduce the amount of waste (3.68) created and generate a supply of high-value secondary materials (3.58) suitable for reuse (3.56) and recycling (3.48).

Disassembly (3.1.9; prEN 15978:2023) non-destructive dismantling of construction works (3.14) or constructed assets into constituent materials or components (3.9, 3.10) (ISO 20887:2020).

Design for disassembly (3.20, prEN 15987:2023) approach to designing a product or constructed asset that facilitates disassembly (3.19) at the end of its useful life in such a way that enables its components (3.9, 3.10) and parts to be reused (3.56), recycled (3.47), recovered (3.46) for energy or, in some other way, diverted from the waste stream (ISO 20887:2020).

LCA Life cycle assessment

Recovery (3.23; prEN 15978:2023) operation to turn waste into a useful resource; recovery operations can include material recovery and energy recovery (EN 15643-2:2021).

Recycling (3.47; prEN 15978:2023) recovery (3.46) operation by which waste (3.68) materials are reprocessed into products, materials, or substances for their original purpose or other purposes (EN 15643-2:2021).

Refurbishment, deep renovation, deep retrofit (EN 3.50 prEN 15978:2023) large-scale (substantial) modifications and improvements to existing construction work (3.14) (ISO 6707-1:2020).

Repair (3.28; prEN 15978:2023) action outside planned maintenance (3.42) to return a construction product (3.11), component (3.9), or assembled system (3.10) into an acceptable condition by renewing, replacing, or mending worn, damaged, or degraded parts but not changing its original parameters (ISO 6707-1:2020).

Replacement (3.53; prEN 15978:2023) installation of a new construction product (3.11), component (3.9), or assembled system (3.10), which performs the function of the old product, component, or system (EN 15643-2:2021).

Reuse (3.56; prEN 15978:2023) operation by which products (3.11) or components (3.9), having reached their end-of-life stage, are used again without reprocessing but include preparation for further use (Preparation for reuse means, where required, checking, cleaning, removing connections, trimming, stripping coatings, and/or other recovery operations or repair, by which products or components of products that reached their end of life are prepared so they can be reused without any other reprocessing) (EN 15643-2:2021).

Secondary material (3.32; prEN 15978:2023) material recovered from previous use or waste (3.68), substituting other materials for further use. NOTE 1: Secondary material is measured at the point where it enters the system from another system. NOTE 2: Materials recovered from previous use or waste from one product system and used as input into another are secondary materials. NOTE 3: Examples of secondary materials (to be measured at the system boundary) are recycled metal, crushed concrete, glass cullet, recycled wood chips, and recycled plastic (EN 15804:2012 + A2:2019).

Waste (3.40; EN 15978) substance or object that the holder discards, intends to discard, or is required to discard (EN 15643-2:2021).

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