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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>BIM Data Content Guiding Takt Production Material Flow: IFC Meets MTS Supply Chain</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Otto Alhava</string-name>
          <email>otto.alhava@fira.fi</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jyrki Oraskari</string-name>
          <email>oraskari@ip.rwth-aachen.de</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Tommi Arola</string-name>
          <email>tommi.arola@rts.fi</email>
          <xref ref-type="aff" rid="aff4">4</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Tero Järvinen</string-name>
          <email>tero.jarvinen@granlund.fi</email>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Markus Järvenpää</string-name>
          <email>markus.jarvenpaa@granlund.fi</email>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Bettina Ruottinen</string-name>
          <email>bettina.ruottinen@aalto.fi</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Aalto University</institution>
          ,
          <addr-line>Otakaari 24, 02150 Espoo</addr-line>
          ,
          <country country="FI">Finland</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Chair of Individualized Production, RWTH Aachen University</institution>
          ,
          <addr-line>Campus-Boulevard 30, 52074 Aachen</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Fira Oy</institution>
          ,
          <addr-line>Teknobulevardi 3, 01530 Vantaa</addr-line>
          ,
          <country country="FI">Finland</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>Granlund Oy</institution>
          ,
          <addr-line>Malminkaari 21, 00701 Helsinki</addr-line>
          ,
          <country country="FI">Finland</country>
        </aff>
        <aff id="aff4">
          <label>4</label>
          <institution>Rakennustietosäätiö RTS sr</institution>
          ,
          <addr-line>Malminkatu 16 A, 00100 Helsinki</addr-line>
          ,
          <country country="FI">Finland</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2025</year>
      </pub-date>
      <fpage>179</fpage>
      <lpage>192</lpage>
      <abstract>
        <p>The stagnation of the construction industry and the lack of productivity growth stem from the separation of design and construction. Although the industry uses various supply chains, it remains largely dependent on manual production and has fallen behind other industries. Inspired by takt production, this study aims to integrate design and manufacturing by streamlining the information flow from BIM/IFC to procurement, supply chain management, and construction. The research focuses on HVAC systems and aims to determine how the design, procurement, manufacturing, and logistics of ventilation products and materials can be integrated as a digital information flow using existing systems and technologies while complying with EU regulatory requirements. The study used a design science approach, modelling and optimising information flows and conducting proof-of-concept testing, which demonstrated the potential of automated data enrichment. In conclusion, the data content of the IFC design models is readily extractable and automated data processing routines can significantly reduce manual work.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;BIM</kwd>
        <kwd>IFC</kwd>
        <kwd>automated data processing</kwd>
        <kwd>Linked Building Data</kwd>
        <kwd>IFCtoLBD</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>The stagnation of the construction industry and its lack of productivity growth stem from the
separation of design and construction [1]. Although the construction sector is part of the
manufacturing industry and relies on various supply chains of the construction product industry [2], [3], [4], [5],
it remains predominantly based on craft production [6]. As a result, it lags significantly behind other
manufacturing industries in terms of developing its production system. This lag is so pronounced
that research has highlighted the need for a dedicated production theory for construction [7]. In
contrast, manufacturing industries have already developed models for different product-specific
production strategies and the corresponding implementation logic for production systems [8]. The
advanced state of manufacturing is further demonstrated by the fact that each type of
manufacturing system has its production theory (or theories) [9]. Since the 1980s, these theories have been
successfully simulated and controlled through computerised real-time systems within various fact
ory layouts [10], [11], [12].</p>
      <p>This study is inspired by the growing adoption of takt production in construction [12], [13] and
the ongoing development of its production system [11]. When implemented as an actual one-piece
flow [14] takt production reveals upstream inefficiencies [15], which becomes more evident as takt
time is reduced [16]. In manufacturing, the successful application of takt production requires
standardised work and flawless material flow management [17]. However, these two aspects cannot be
realised without mastering product design, including all product details [18] and integrating design
for manufacturing (DfM) principles [19].</p>
      <p>Research has shown that building information models do not effectively support downstream
processes beyond the design phase [20]. However, the manufacturing industry successfully
addressed the challenges of integrating product and production design by digitalising information as
early as the 1990s [11]. The models used in manufacturing must also apply to the construction in
dustry, as construction itself is a form of manufacturing, albeit in much more primitive conditions
compared to modern production.</p>
      <p>External pressures, such as CO₂ regulation, labour shortages caused by an ageing population,
climate change, and the adoption of artificial intelligence in other sectors, are driving the
construction industry to adopt new technologies and methods more rapidly. The performance of the
construction sector at the EU level is increasingly monitored through measures such as the Energy
Performance of Buildings Directive (EPBD) and the Construction Products Regulation (CPR).
Furthermore, the research team is motivated by findings from a national data flow architecture
developed for the two extremes of supply chain types used in construction: Engineer-to-Order (ETO)
[4] and Make-to-Stock (MTS) [2]. This architecture demonstrates that by standardising the data
content of information models, it is possible to replace 2D drawings and elevate BIM to a systemic
role equivalent to that of Computer-Aided Design (CAD) data in manufacturing industries. The
research team strongly believes that the national data flow architecture [2] will also provide the
means to enhance the construction industry's ability to respond to the new challenges posed by
climate change.</p>
      <sec id="sec-1-1">
        <title>1.1. Research Focus</title>
        <p>This study aims to bridge the gap between the design carried out using Building Information Models
(BIM) and the in-situ installation of HVAC products, employing the same methods applied in the
manufacturing industry. This research focuses on integrating BIM design data with actual in-situ
engineering design and product installation performed by subcontractors. Additionally, the study
aims to establish a continuous data flow for a designer's 3D model and data content, supporting
detailed design, procurement, supply chain management, logistics, and finally, installation. The
objective is to systematically integrate design and detailed design, including product and material
selection and quantity take-off, and transform current construction processes into design and
assembly that align with the manufacturing industry's production logic.</p>
        <p>The study is limited to building services engineering, specifically ventilation systems in
residential buildings, to narrow the scope of data processing to an MTS supply chain and a manageable
amount of design data. The research is based on the Finnish national data flow architecture defined
for the MTS supply chains [2]. The study validates the current data flow through a case study of
apartment-specific ventilation systems, analysing and modelling the design, supply chain and
construction data management processes in two projects.</p>
        <p>This study aims to address the challenges of data flow in the construction industry by answering the
following research questions, thereby complying with EU regulatory requirements.</p>
        <p>How can design, procurement, manufacturing planning and execution, logistics and
installation be implemented as a digital information flow for HVAC installations in construction
using existing systems?
What new methods and technologies are required to implement a digital information flow to
meet EU-level regulatory requirements for HVAC installations?
The following section presents the state of the art. The third section discusses the research
methodology. The fourth section presents the results, and the fifth section provides an analysis of the find
ings. The sixth section discusses the broader applicability of the results. The final section presents
the study’s conclusions regarding the achievement of its objectives and provides a summary of the
findings.</p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>2. State of the Art</title>
      <sec id="sec-2-1">
        <title>2.1. Research Findings on BIM Utilisation in Construction Supply Chains</title>
        <p>Research to develop the national data flow architecture revealed that the data content of HVAC BIM
is not used in procurement, supply management, site logistics, or the actual installation process, i.e.,
construction [2]. This finding is consistent with the results obtained by Revolti and his research
team [19], which showed that BIM is used only during the design phase but not in construction or
facility management. Instead of leveraging BIM, downstream processes rely on 2D PDF drawings,
from which the necessary information is extracted and calculated manually [2].</p>
        <p>The national data flow guidelines propose standardising the design data incorporated in the BIM
model to address this issue. The proposed solution involves exporting the design product data from
the BIM model to a data platform (Engineering Bill of Materials, E-BOM), enriching the data into
purchase items (Manufacturing Bill of Materials, M-BOM), and integrating it into an enterprise
resource planning (ERP) system. Additionally, orders would be processed using the Pan-European
Public Procurement Online (PEPPOL) standard, enabling digital call-offs for construction sites,
electronic material flow management, and creating a digital twin [20].</p>
        <p>However, a significant challenge in practical implementation remains: The national data flow
architecture does not specify the technologies or methods required to enrich the BIM data content
in a format compatible with ERP systems. This gap hinders the real-world adoption of the proposed
digital workflow.</p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. Level of Digitalisation in Construction Processes</title>
        <p>Data transfer in construction processes is still primarily based on manually exchanging files between
different systems and organisations. Existing standards, such as ISO 19650 [21], reinforce this
practice [22], which recommends the use of a Common Data Environment (CDE) as a centralised source
of information [23]. Although the construction industry has been using BIM for 3D design for over
two decades, its level of digitalisation remains significantly underdeveloped compared to the
manufacturing industry [24].</p>
        <p>Manufacturing industries have successfully integrated product design, production planning, and
manufacturing into a coherent model and production system [12], [25], [26]. The construction
industry, which is also a form of manufacturing, has yet to achieve this level of integration. Instead,
design, production planning, and manufacturing have remained separate in terms of organisation,
business operations, and digitalisation. This situation is particularly evident in the way BIM is
utilised in the sector.</p>
        <p>The seven dimensions of design defined for the industry do not address procurement or supply
chain management. These dimensions include geometry (3D), time management (4D), cost
estimation (5D), environmental and sustainability data (6D), and facility management information (7D)
[19].</p>
      </sec>
      <sec id="sec-2-3">
        <title>2.3. Enabling Data Flow in Construction Processes</title>
        <p>This study is based on the hypothesis that construction, as a form of manufacturing, does not
fundamentally differ from other manufacturing industries. However, it has lagged over a century in
developing manufacturing system theories, still relying heavily on craft production. If this hypo
thesis holds, then the construction industry's flow of information and digitalisation can be
implemented using the exact mechanisms currently applied in automated manufacturing.</p>
        <p>Manufacturing and its automation are based on integrating design software with various
industrial-scale machining software, a development that emerged during the Third Industrial Revolution
[27], [28]. At that time, the alignment of digital information systems in manufacturing enabled the
digital control of production lines through CAD/CAM systems and their integration with customer
interfaces, forming what became known as Computer-Integrated Manufacturing (CIM).
Manufacturing industries distinguish between the design and production phases in terms of data content. In
assembly-based manufacturing, the BOM is separated between the design and post-procurement
phases, which rely on standardised components sourced from multiple suppliers. During the design
phase, the bill of materials does not specify the supplier but only defines the general component type;
the Engineering Bill of Materials (E-BOM) [29] is used for this purpose. As the designed product
progresses to the production phase, decisions regarding suppliers and materials must be made. At
this stage, the components or materials purchased are identified using supplier-specific part
numbers, forming the Manufacturing Bill of Materials (M-BOM) [29].</p>
      </sec>
      <sec id="sec-2-4">
        <title>2.4. Machine-readable data in construction and opportunities of Linked Building</title>
      </sec>
      <sec id="sec-2-5">
        <title>Data</title>
        <p>Research conducted in the construction sector indicates that design for manufacturing (DfM) is
mainly absent from construction processes [3]. This is evident in the limited use of prefabrication,
which is applied only in specific product categories, such as prefabricated modular bathroom units,
or in special projects, including large-scale, time- and space-constrained projects delivered using
collaborative contracting models.</p>
        <p>Due to increasing environmental requirements and the digitalisation of the construction
orderto-delivery chain, various data contents, types, and formats must be effectively integrated. Some data
are highly standardised, while other data remain unstructured. In construction design, native BIM
software applications are used as desktop tools, each developed for specific design purposes, such as
architectural, mechanical, electrical or structural engineering. These applications adhere to strict
data standards, rendering free-form data enrichment using traditional database methods either
impossible or highly challenging within native BIM software. The varying levels of metadata
definition in BIM content can also be observed in the fragmented implementation of different types of
machine-processing applications. Several tightly scoped solutions have been developed for
machinereadable data processing, such as automatic door annotation [30] and automated verification of
requirements for precast concrete [31]. By using these niche solutions, significant efficiency gains
can be achieved in the design and construction process. In the latter example, the automated veri
fication enables smart services by which stakeholders can assign measurable properties of the precast
concrete modules to the requirements, thus allowing a computerised quality check [31]. The issue
with these solutions lies in their point-by-point nature rather than forming part of a systemic
approach. BIM data should serve as a starting point for enrichment within traditional information
management systems without requiring native BIM software, as many stakeholders in the
construction value chain are unfamiliar with BIM models. This approach would enable non-BIM-based
information systems, such as enterprise resource planning (ERP) systems, to integrate more seam
lessly with BIM-related data. Loading the content of BIM models into a graph database, where design
data can be enriched through database operations linked to product databases, can enhance data
enrichment and interoperability.</p>
        <p>The World Wide Web Consortium (W3C) Linked Building Data group aims to develop
standardised ontologies for the architecture, engineering and construction (AEC) industry and establish
best practices for the sector. One of the key concepts is the modular use of ontologies to facilitate the
publication and accessibility of information. Bonduel et al. demonstrated in 2018 that this applies to
IFC-based building data using building element attributes as examples [32]. Based on this, Linked
Building Data (LBD) emerges as a promising technology that we explore in this study.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Research Methodology</title>
      <p>The study employed the design science method. In the first phase, the research team modelled the
information flows of an apartment-specific HVAC system throughout the design, procurement,
supply chain management, logistics, and installation stages to validate the national data flow
architecture. The research focused on typical new residential construction projects in the Finnish
market.</p>
      <p>This study analysed two completed projects using the MTS (Make-to-Stock) supply chain data
flow architecture as a reference framework for the current and target states [2]. Data from the con
struction phase was gathered through interviews with site managers and HVAC installers,
documentation of installation work, collection of 2D drawings used on site, and video recordings of the
installation process.</p>
      <p>Section 4.1 analyses and documents the results of the first phase. These results are compared with
the MTS product data flow architecture [2], allowing the current state analysis of the HVAC system
information flow to be visualised as a data flow architecture in Figure 1. In the second phase, the
data flow architecture created an optimised data flow for the HVAC components and materials
studied. Standardised design nomenclature enabled machine-readable data processing and
compliance with environmental requirements. Optimisation was carried out by structuring the data content
of the completed projects, which was then used to implement the target state system. The systematic
solution developed in this phase, which facilitates the digitalisation of the entire ventilation system
supply chain—from design to management and execution- was documented as a data flow
architecture in Figure 2. The third phase involved a proof-of-concept test of the data enrichment process
using the IFCtoLBD converter to generate linked building data and enrich it from IFC to M-BOM.
The outcome of this phase was a digitalisation artefact that demonstrated machine-based data en
richment, presented in Section 4.4.</p>
    </sec>
    <sec id="sec-4">
      <title>4. Case Study</title>
      <sec id="sec-4-1">
        <title>4.1. Current Digital Information Process in Design and Installation of Ventilation</title>
      </sec>
      <sec id="sec-4-2">
        <title>System</title>
        <p>
          In both studied residential construction projects, the main contractor used the design-build pro
ject delivery model to execute the project, and the ventilation design was outsourced to an external
design company. The process followed by the principal contractor, designers, and subcontractors is
illustrated in Figure 4, with references in this section corresponding to the numbered steps. The
national BIM modelling requirements and process for HVAC design are defined in YTV2012 [33].
The YTV2012 requirements (
          <xref ref-type="bibr" rid="ref1">1</xref>
          ) were included in the fixed-term contracts that the main contractor
entered into with the design companies. In both cases, MagiCAD software was used for the
ventilation system design, and Solibri Anywhere was utilised for inspecting the federated model.
According to the study, the main contractor responsible for design coordination during the HVAC design
phase (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ) had approved the HVAC BIM as compliant with YTV2012 based on an inspection of a
representative floor. The YTV2012 does not define metadata requirements for HVAC products and
materials, allowing designers to use their preferred nomenclature. As a result, the HVAC BIM (
          <xref ref-type="bibr" rid="ref3">3</xref>
          )
referenced specific manufacturer products. For the ventilation system, the designer used Lindab
KVDPX silencers and SAFE ducts. By using actual products, the designer used their performance
values as input data for system sizing calculations within MagiCAD (
          <xref ref-type="bibr" rid="ref4">4</xref>
          ). The HVAC IFC model was
used in clash detection (
          <xref ref-type="bibr" rid="ref5">5</xref>
          ) within a federated model (
          <xref ref-type="bibr" rid="ref6">6</xref>
          ) alongside other design disciplines.
Additionally, the designer provided the main contractor with 2D ventilation floor plans (
          <xref ref-type="bibr" rid="ref7">7</xref>
          ) in DWG
format and control diagrams of the ventilation system, as well as equipment lists upon completion
of the design phase. In the procurement phase, the main contractor tendered the ventilation as a
lump sum contract (
          <xref ref-type="bibr" rid="ref8">8</xref>
          ) using 2D PDF drawings and ventilation system documentation in PDF format
(
          <xref ref-type="bibr" rid="ref9">9</xref>
          ). The combined IFC model was included in the tender documentation; however, it was not refer
enced in the document hierarchy for contractual validity.
The HVAC subcontractor's estimator used 2D drawings to perform quantity takeoff for the
ventilation system (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ). The subcontractor separately tendered key components for the ventilation system,
such as the ventilation system for the sample floor, communal areas, and air handling units, to
different suppliers (
          <xref ref-type="bibr" rid="ref11">11</xref>
          ). During the tendering phase, the subcontractor proposed 12 modifications to
the system to the main contractor, aiming to provide a more competitive offer. The ventilation
system’s products at the apartment level were sourced based on standard price lists as a single
package. In both cases, subcontractors used JCAD for processing 2D PDF drawings and Mercus
Broker for performing the quantity takeoff. The subcontractor’s estimator added installation
materials by using the HVAC Installation Material Data Registry (
          <xref ref-type="bibr" rid="ref13">13</xref>
          ) and enriched the ventilation system’s
MBOM manually. The estimator also estimated duct quantities by manually measuring standard
apartment layouts and adding allowances for cutting. The final material quantities were recorded in
an Excel file (
          <xref ref-type="bibr" rid="ref14">14</xref>
          ), with additional comments added at the row level. The file was stored on the sub
contractor’s file server (
          <xref ref-type="bibr" rid="ref15">15</xref>
          ).
        </p>
        <p>
          After the HVAC contract was awarded, the quantity takeoff file was transferred to the produc
tion team, where the project manager initiated the material call-offs (
          <xref ref-type="bibr" rid="ref16">16</xref>
          ) via the supplier’s web portal.
The project manager cross-checked material quantities against any updated plans (
          <xref ref-type="bibr" rid="ref17">17</xref>
          ) following the
contractor’s tendering process. The main contractor and the client utilised a shared project
document management system (18) to store design documentation throughout the construction phase.
The main contractor provided schedule updates and discussed HVAC-related issues in weekly
contractor meetings (19). Upon arrival, the subcontractor’s site team conducted a delivery inspection
(20) by verifying the number of packages against the transport company’s waybill (21). As con
struction progressed, the installer manually collected materials from the floor storage area and the
ground-floor warehouse and transported them (22) to the installation site. The quantities were based
on the installer’s manual takeoff (23) from printed drawings. When the materials ran out, the in
staller restocked from storage.
        </p>
        <p>The installer followed 2D drawings (22) but modified components, materials, installation
sequences and work methods based on experience to improve efficiency. Some changes also resulted
from deviations in previous construction stages. At the beginning of the installation, the main con
tractor collected product documentation, including performance declarations and CE certificates,
from the subcontractor via email. The designer approved the HVAC system products using the
contractor’s product data service (24). Finally, the main contractor submitted the HVAC system
documentation to the client as required (25) and provided paper printouts of the client-specified
HVAC equipment documentation.</p>
      </sec>
      <sec id="sec-4-3">
        <title>4.2. Optimised Information Flow for HVAC Installation</title>
        <p>
          The case study demonstrated that the design, supply chain management, manufacturing, and
handover phases of the HVAC contract are executed entirely by manual data transfer using referenced
2D drawings. Each phase requires manual recalculations of component and material quantities, with
a non-standardised BOM nomenclature used at each stage. Manual data generation and the absence
of a shared metadata definition prevent the reuse of information downstream, rendering data
enrichment impossible. To address the issue of information flow, the application of the design science
research method was based on the data flow architecture for MTS products [2]. This architecture is
suitable for modelling HVAC installations in residential buildings, as all components and materials
required for HVAC installation are MTS products. Apartment-specific HVAC breakdown includes
MTS components (such as fittings, bends, ducts, and silencers), on-site processed materials
(ductwork), and installation materials. The principle of machine-based data enrichment developed in the
study is illustrated in Figure 2, referencing the relevant steps indicated in parentheses. The data flow
architecture defines the E-BOM data as represented by the HVAC product part nomenclature, which
enables naming HVAC components and materials in the HVAC model (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ) using general and
machine-readable design names (
          <xref ref-type="bibr" rid="ref1">1</xref>
          ).
        </p>
        <p>
          Following the data flow architecture, objects in native design software include standardised
design names (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ), which in Finland have been published in a machine-readable format on the na
tional interoperability platform under the name HVAC product part [31]. When a designer uses
standardised design names in BIM modelling, the BIM model can be extracted in the IFC format (
          <xref ref-type="bibr" rid="ref3">3</xref>
          )
as a machine-readable dataset, as it contains objects named with standardised design names and
enriched with technical attributes. The HVAC Design phase generates data on HVAC objects, as
described by designers, along with their technical properties (such as duct lengths), which serve as
technical attributes (
          <xref ref-type="bibr" rid="ref4">4</xref>
          ). The apartment numbers are used as location information (
          <xref ref-type="bibr" rid="ref4">4</xref>
          ). This allows
HVAC products to be extracted from the IFC model into a structured format and assigned to E-BOMs
based on location (
          <xref ref-type="bibr" rid="ref5">5</xref>
          ). This can be implemented, for example, through IFCtoLBD conversion or batch
processing using IfcOpenShell (
          <xref ref-type="bibr" rid="ref6">6</xref>
          ), which are described in more detail in the following sections.
        </p>
        <p>
          In the manufacturing industry, decisions must be made regarding suppliers for individual
components when transitioning from product design to production planning. This is partially automated
in ERP systems, allowing supplier selection based on availability and price using rule-based logic.
Since the procurement of HVAC materials in construction is typically carried out through
projectspecific tenders or seasonal contracts, automation requires that the supplier be preselected in the
ERP system and that the supplier’s product catalogue be available in the ERP (
          <xref ref-type="bibr" rid="ref7">7</xref>
          ). This enables the
enrichment of E-BOM data into M-BOM according to the data flow architecture (
          <xref ref-type="bibr" rid="ref8">8</xref>
          ). For HVAC, the
initial data for M-BOMs related to MTS products must be automatically retrieved from an HVAC
product database, which in Finland is LVI-info (
          <xref ref-type="bibr" rid="ref8">8</xref>
          ). Data are retrieved using the TuoteTieto (TT)
standard for automatic integration with procurement systems or a data platform, making
supplierspecific product catalogues machine-readable. The TT standard and the product database are
compatible with HVAC product parts, as the TT standard requires that each article include information
on its corresponding HVAC product part ID. This means that each physical article in the product
database has a corresponding standardised design name used in HVAC-BIM/IFC (
          <xref ref-type="bibr" rid="ref2">2</xref>
          ). This allows for
the algorithm-based selection of an article for a specific E-BOM component using rule-based logic
(
          <xref ref-type="bibr" rid="ref7">7</xref>
          ).
        </p>
        <p>
          Standardised, product group-specific technical attributes are needed to refine the algorithm's
selection to the correct article, as searching only by design name would return all product sizes for
HVAC ducts. Therefore, retrieving the duct diameter and designed material from the IFC model is
necessary to ensure the selection of the correct product variant and unique identifier, such as the
GTIN code. Since HVAC models do not include support structures for system installation, these
components must be added to the M-BOM using installation materials for standard structures (
          <xref ref-type="bibr" rid="ref9">9</xref>
          ) and
retrieved automatically from a package registry (
          <xref ref-type="bibr" rid="ref10">10</xref>
          ). This automated enrichment process produces
M-BOM by location (
          <xref ref-type="bibr" rid="ref8">8</xref>
          ) without installation waste allowances. The M-BOM, with its quantities and
locations, forms a ready-to-use dataset for procurement (
          <xref ref-type="bibr" rid="ref11">11</xref>
          ) and later for ordering, which is gener
ated in the ERP system and sent to the supplier using PEPPOL standard messages (
          <xref ref-type="bibr" rid="ref12">12</xref>
          ) [34]. This
allows the order to be transferred directly from the ordering system of the main contractor or sub
contractor acting as the client (
          <xref ref-type="bibr" rid="ref13">13</xref>
          ) to the supplier’s system (
          <xref ref-type="bibr" rid="ref14">14</xref>
          ). Orders can also be tendered using
PEPPOL standard order-to-delivery messages (
          <xref ref-type="bibr" rid="ref15">15</xref>
          ) [34]. The location information is part of the
material call-offs (
          <xref ref-type="bibr" rid="ref16">16</xref>
          ), which can be implemented through the PEPPOL message exchange. The
supplier typically manages deliveries using a contract logistics provider (
          <xref ref-type="bibr" rid="ref17">17</xref>
          ) and an electronic
shipping note (18).
The location data extracted from the BIM model is transferred through call-offs to the supplier, who
marks it on packages. This enables site logistics to perform receipt inspection (19) and transport
materials to the correct installation location while updating stock balances (20). Electronically
maintained stock balances enable automatic notifications of installation readiness to the installer
(21). The BOM data flow does not replace the use of 2D drawings during installation, so these must
be provided to the installer along with the material listing (22). Using these data, the principal
contractor can automatically generate the actual CO₂ footprint of the HVAC system by retrieving CO₂
data based on GTIN codes from the LVI-info product database (23) and producing an electronic
handover report for the client (24). Since the bill of materials contains identified articles (GTIN) and
their quantities, the materials used can be submitted electronically to the contractor’s product data
service for product conformity verification (25).
        </p>
      </sec>
      <sec id="sec-4-4">
        <title>4.3. Enhancing the Digital Information Flow with a Machine-Readable Format</title>
        <p>A machine-readable building climate report and material list, combined with the order-to-delivery
chain of a construction project, impose significantly increased requirements on building services
product data and data flow architecture. Product data management is carried out across various
systems, primarily manually, without logical links to the data content of BIM. To address this, BIM
must be converted into a machine-readable format to enable: 1) energy optimisation using different
product and system combinations for the entire building, 2) real-time calculation of the carbon
footprint based on actual products, and 3) integration of the order-to-delivery chain up to
installation, allowing for the calculation of the realised carbon footprint.</p>
        <p>A machine-readable data structure requires data from building services designers. Objects must
be identifiable at the product part level, linked to building services systems, and include the
necessary data content. The data content requirements are defined to ensure that designers understand
the information they produce and can generate it with the correct quality. The IFC standard is
inadequate for precisely identifying building services objects, as many components cannot be distinctly
recognised using IFC alone. As part of the reform of the Finnish Building Act, the Rava3PRO
project [35] implemented national standardisation of building services data, which has also been
incorporated into the buildingSMART Data Dictionary (bSDD) platform [36]. This standardisation covers
building services systems and product parts (more than 800 product parts and more than 300 system
types), enabling machine-readable data for product identification and attributes. Standardising sys
tem types is significant when comparing portfolios across multiple buildings.</p>
        <p>The information model used in this study was an IFC model based on the data content developed
in the Rava3PRO project [35]. In this model, building services objects were modelled using HVAC
product part standards, assigning property values to objects based on design nomenclature, which
can be linked to product data in the next stage. As a result, handling product data within native
modelling software was found to be unnecessary, as these tools are not designed for data manage
ment. The study explored methods for converting the information model into a machine-readable
format. In the new data flow architecture, the E-BOM data content produced by designers is enriched
within data platforms for relevant use cases. It was found that the data from the IFC building
services model could be structured in two ways: 1) by converting part of the IFC model into a graph
database using the IFCtoLBD software as a library, generating an E-BOM for the HVAC ductwork of
the apartment, together with the location and technical attributes of each component in graph
format, and 2) by using the LBD model. In the latter method, each component was enriched through
an algorithm that took technical attributes and HVAC product part information as inputs and added
the corresponding GTIN code and product name to the graph, uniquely identifying the sales article
matching the design nomenclature.</p>
      </sec>
      <sec id="sec-4-5">
        <title>4.4. Enhancing the Digital Information Flow Using Linked Building Product Data</title>
        <p>The IFCtoLBD converter was developed to transform IFC model data (Industry Foundation Classes)
into a more accessible format by representing building information using the W3C Linked Building
Data Community Group (W3C LBD-CG) ontologies. The IFCtoLBD converter was used on the
Jython framework, making it available as a Python library. It operates in three stages (see Figure 6).
First, the IFC model is converted to RDF format (ifcOWL) using the well-known Express schemas
published by buildingSMART. Second, aggregated value sets (IfcQuantitySet) and property sets
(IfcPropertySet) are compiled from the ifcOWL data—finally, the program processes building
elements, linking them with the collected and IFC standard default values. As depicted in Figure 3,
hierarchical URI naming, simplified property naming, and a Linked Data representation with
minimal complexity level have been adopted to facilitate further processing of property values. The
implemented program uses a library to parse IFC models and directly accesses the model using
SPARQL queries. A key advantage of this approach is that data filtering can be performed at the
query stage, allowing the selection of specific elements and properties of interest. After this, the
program reads the list of elements, creates a list entry for each building entity, and attaches the
corresponding properties. The elements can then be categorised based on their value sets into
product classifications, enabling tasks such as quantity takeoff. The ifcOpenShell [37] Python library
was used as an alternative approach to process the IFC building services model within the software
environment. The desired components were then selected from the IFC standard definitions, which
included pipelines (IFCPipeSegment) and pipeline fittings (IFCPipeFitting).</p>
        <p>All attributes entered into the model are machine-readable. Therefore, the global object identifier,
part name, object type, and standardised design nomenclature were selected for the E-BOM output
(Figure 4). A Python program was developed to recursively search for the required attribute data for
each object in the model and organise them by the floor. The Python program was based on
IfcOpenShell library commands, which allow model objects to be accessed using conventional pro
gramming methods. The final output was structured as a JSON file, which the Python program
generated in the required order. The output format can be adjusted as needed, such as exporting the
data as a CSV file or directly inserting it into an SQL database.</p>
        <p>This process extracted a machine-readable E-BOM from the building services model in the
desired format. This machine-readable E-BOM can now be analysed and enriched with actual product
data to form an M-BOM, using the standardised design nomenclature as a reference. Typically, the
HVAC components of the E-BOM are enriched with precise product details and location data. The
contractor’s procurement team identifies the product components and selects items from the product
databases. The location data for building services components can be generated programmatically
within a data platform if locations have been modelled in the IFC model using IfcSpace object types,
for example.</p>
        <p>Additional stakeholders also contribute to enriching the designer’s E-BOM into an M-BOM. These
include cost estimation and carbon footprint analysis teams, who add supplementary information to
each object within the data platform, such as labour requirements, product costs, and all necessary
installation components, including brackets, bolts, and connectors. The enrichment process was
tested in the IfcOpenShell environment and the LBD graph database. Various product components
in the design model were enriched using an algorithm that took technical attributes and standard
ised HVAC product part data as inputs. This required a separate API request to the HVAC product
database in the IfcOpenShell environment and the LBD graph database. In this case, enrichment
involved an API query within the procurement process to retrieve the GTIN code corresponding to
the design nomenclature, detailed product information (such as carbon footprint), and the corres
ponding sales article for the model objects.</p>
        <p>Seven different component types were tested within an apartment. Additionally, installation
materials such as bracket arms, threaded rods, screws, and nuts had to be manually added to the
MBOM. This was achieved by creating a simple set of rules that accounted for the components of the
apartment, such as silencers and bends, and the total length of straight duct sections. The rule set
was converted into a calculation algorithm that assigned installation materials to components and
ducts within the graph database, completing the M-BOM into an installation-ready format. The
implemented data platform and algorithms demonstrate that the building information model can
play a significantly more meaningful role in design, procurement, logistics and installation processes
than it currently does. Since the data content of IFC design models can be easily extracted into a
machine-readable format using existing programming environments, the automatic data processing
routines could replace the need for manual interpretation of 2D drawings. This requires a clear
understanding of data requirements and the ability to extract information in a format suitable for its
intended use.
Currently, the IFC design data are only minimally processed outside of design software; however,
using a standardised product identifier simplifies further refinement in separate data platforms.
Based on this experiment, enriching the building’s M-BOM within an external data platform is
feasible. However, the study has not yet implemented integration with construction ERP systems
and actual procurement processes. Nevertheless, based on the features of the IfcOpenShell
environment and the flexibility offered by Python programming, this is not expected to be a significant
challenge.</p>
        <p>The results also highlight the extent of unnecessary work caused by using 2D drawings,
particularly in the order-to-delivery process. The proposed automation is likely to have a significant impact
on improving industry productivity as it enables the automated management of material flow using
BIM data as its foundation. The presented solution effectively paves the way for the digitalisation of
the industry, transforming the supply chain one step at a time.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Discussion</title>
      <p>A critical factor for successful data enrichment is the standardisation of the BIM model data content
and the development of a culture of machine-readable data processing. The nationally used HVAC
product part nomenclature enables BIM data to be structured in a format suitable for further use by
various stakeholders. The IFC format, on its own, does not support efficient programming, data
extraction, or integration with ERP or similar systems. Linked Building Data has proven to be an
effective facilitator in this context.</p>
      <p>The process involves two key conversions: the IFC-to-Linked Data Model conversion and the
EBOM to M-BOM conversion. Converting IFC data into a structured format requires filtering, ex
traction, and organisation, but these tasks can be automated through software. Enriching the E-BOM
from standardised design nomenclature into a product-specific list is a complex process, as it requires
defining technical attributes for each product category and refining selection criteria to improve
accuracy in product identification.</p>
      <p>The first significant productivity advantage of software-based IFC model processing is the ability
to perform batch processing and automation, which enables data extraction and enrichment in the
background. Batch processing is already widely used in ERP systems across other industries. The
presented approach allows data processing as batch runs within data platforms and facilitates data
distribution outside native software environments in an unrestricted format. Although IFC model
objects can be accessed conventionally, the ability to automate machine-readable data transfer to
where it is needed eliminates the need for manual data handling. This technical architecture for
machine-readable data is essential for meeting the needs of the construction industry with a
datadriven approach.</p>
      <p>When data enrichment is carried out within a data platform, subsequent stakeholders can benefit
from the information produced in previous phases. For example, scheduling teams can almost
automatically generate an initial schedule version based on cost estimation data. Similarly, carbon
footprint analysis can provide an initial environmental impact assessment by linking generic data to the
machine-readable E-BOM. Once the material selections are finalised and the bill of materials is
enriched with actual product data in an M-BOM, the carbon calculation can be updated to reflect the
exact environmental impact. This provides real-time insights into project costs, scheduling, and
carbon footprints.</p>
      <p>Machine-readable data processing also represents a significant cultural shift that the construction
industry must adapt to. A key starting point is creating the necessary infrastructure and
standardising data content to enable seamless linking between BIM and external data sources. These external
sources often belong to different standard families but are highly relevant to the digitalisation of
construction production. Moving forward, it is essential to continue standardisation efforts, partic
ularly for machine-readable BIM interpretation. The research does not aim to take a stance on where
or in whose systems the enrichment of design data into product data should occur. In any case, the
prevailing file-based data transfer model is set to become obsolete as digitalisation progresses within
the construction industry. Given the significant benefits of automation and the investments required
for its implementation, it is reasonable to assume that automation will fundamentally alter the ex
isting division of labour in the supply chain and disrupt current business models.</p>
    </sec>
    <sec id="sec-6">
      <title>6. Conclusions</title>
      <p>Only a small portion of the potential of building information modelling is used in construction
projects, and BIM models play a secondary role in the projects studied. Projects still rely on 2D
drawings as their primary source of information, as if paper were still the only format for transfer
ring data. Since PDFs are not machine-readable, even with optical character recognition, transferring
data as files can be considered digitisation, but it is not digitalisation. The study demonstrated that
BIM data content can be used similarly to models applied in manufacturing and that information can
be enriched in a structured format. The test confirms that the linked data model is a viable approach
for data enrichment within a data platform and, more importantly, that enrichment can be decoupled
from native software and users. In summary, by using a standardised design nomenclature in the
information model and leveraging IFC as the data source, it becomes possible to enrich the E-BOM
data on a data platform into location-based M-BOM information, supporting both procurement and
installation. In addition to the design nomenclature, enabling technologies such as IFCtoLBD or
IfcOpenShell must be adopted to allow IFC data to be enriched into the data platform's information
model.</p>
      <p>The scope of the study was to test automation in extracting standardised HVAC product and
material design data from BIM/IFC files into a structured format and enriching it from E-BOM to
MBOM. The test confirmed that machine-based data enrichment works for MTS products. Since con
struction widely utilises MTS-type supply chain products, this research finding presents
opportunities for the construction industry to implement CIM architectures, integrate data across different
systems, and automate processes such as manufacturing.</p>
    </sec>
    <sec id="sec-7">
      <title>Declaration on Generative AI</title>
      <p>The authors have not employed any Generative AI tools.
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