Heritage Building Information Modelling Research Articles

Heritage Building Information Modelling (HBIM): A Review of Published Case Studies

Abstract. This paper presents a systematic review of published case studies on Heritage Building Information Modelling (HBIM) since 2018, and identifies research gaps in the subject matter. Building upon the foundational work of Ewart and Zuecco (2019), this research aims to reveal the latest trends in HBIM implementation, identify recent developments of HBIM technologies, changes in the purpose of HBIM programs and stakeholder roles and responsibilities, and uncover knowledge gaps that provide avenues for future research. Utilizing the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) approach, two major academic databases, Scopus and Web of Science (WOS), were searched, resulting in a rich and diverse dataset for analysis. The paper reports findings on the status of reality capture techniques used to acquire data for HBIM development, focusing on terrestrial laser scanning (TLS) technology. The review highlights the benefits and limitations of TLS for data acquisition in HBIM, as well as the integration of TLS with other reality capture technologies, such as Structure from Motion (SfM) and photogrammetry. The paper further outlines the typical workflow for processing TLS scan data and explores the integration of multiple point clouds for comprehensive heritage site modeling. In addition to the state of the art, this systematic review also uncovers several research gaps in the field of HBIM that offer opportunities for future research and innovation, including the lack of guidelines for data acquisition in HBIM programs, the predominantly manual development process of HBIM from TLS point cloud data, and the under-utilized capacity of TLS for long-term monitoring and change detection. This comprehensive review provides valuable insights into the current landscape of HBIM, offering guidance for future research and development in the heritage sector and highlighting areas in need of further investigation to advance the field.

Machine and Deep Learning Implementations for Heritage Building Information Modelling: A Critical Review of Theoretical and Applied Research

Research domain and Problem: HBIM modelling from point cloud data has become a crucial research topic in the last decade since it is potentially considered as the central data model paving the way for the digital heritage practice beyond digitization. Reality Capture technologies such as terrestrial laser scanning, drone-mounted LiDAR sensors and photogrammetry enable the reality capture with a sub-millimetre accurate point cloud file that can be used as a reference file for Heritage Building Information Modelling (HBIM). However, HBIM modelling from the point cloud data of heritage buildings is mainly manual, error-prone, and time-consuming. Furthermore, image processing techniques are insufficient for classification and segmentation of point cloud data to speed up and enhance the current workflow for HBIM modelling. Due to the challenges and bottlenecks in the scan-to-HBIM process, which is commonly criticized as complex with its bespoke requirements, semantic segmentation of point clouds is gaining popularity in the literature. Research Aim and Methodology: Therefore, this paper aims to provide a thorough critical review of Machine Learning and Deep Learning methods for point cloud segmentation, classification, and BIM geometry automation for cultural heritage case study applications. Research findings: This paper files the challenges of HBIM practice and the opportunities for semantic point cloud segmentation found across academic literature in the last decade. Beyond definitions and basic occurrence statistics, this paper discusses the success rates and implementation challenges of machine and deep learning classification methods. Research value and contribution: This paper provides a holistic review of point cloud segmentation and its potential for further development and application in the Cultural Heritage sector. The critical analysis provides insight into the current state-of-the-art methods and advises on their suitability for HBIM projects. The review has identified highly original threads of research, which hold the potential to significantly influence practice and further applied research.

An HBIM Approach for Structural Diagnosis and Intervention Design in Heritage Constructions: The Case of the Certosa di Pisa

In the conservation of monumental heritage, the collection and utilization of information are of primary importance. The Heritage Building Information Modeling (HBIM) procedure harnesses the potential of three-dimensional models, offering significant advantages in accessing documentation, interoperability, multidimensionality of intervention design, cost evaluation, and maintenance management. Our attention here is focused on the Certosa di Pisa (Italy), a large historical complex built in the 14th century as a monastery of the Carthusian Order, currently in a state of deterioration and in need of restoration and re-functionalization. The multifaceted nature of this monumental complex, with its intricate interplay of architectural elements spanning different historical periods and featuring diverse techniques, poses a significant challenge for structural safety assessment. This case study presents an opportunity to explore an HBIM approach to streamline the diagnostic process and facilitate the intervention design phase. The goal is achieved by utilizing an accurate 3D model enriched with data from multiple sources and automating certain operations for a simplified safety assessment of masonry structures under both gravity and seismic loads. The usefulness of the HBIM methodology is highlighted as a valuable tool in the realm of cultural heritage structures for both practitioners and scholars alike.

Framework for BIM-Based Repair History Management for Architectural Heritage

This research addresses the challenges faced in collecting and managing repair history information for architectural heritage due to its distribution among different institutions. To overcome this problem, this study proposes a building information modeling (BIM)-based repair history management framework that links non-formal repair details of architectural heritage to BIM. This framework was applied to the case study of the Great Hero Hall of Sudeoksa Temple in Yesan, South Korea. A repair history database in the form of structured data adhering to the historic building information modeling standard was utilized. The proposed framework effectively syncs the repair history database with BIM to preserve architectural heritage and streamline repair history information updates as well as management. Integrated heritage BIM is anticipated to furnish a thorough knowledge base for architectural heritage, comprising non-geometric details and formal information models, thus enhancing building maintenance planning. Ultimately, the benefits and limitations of the suggested framework and methodologies are deliberated for further implementation.

Virtual Reconstruction of the Deconstructed Heritage: The Former Building of the Belo Horizonte School of Medicine

Built between 1911 and 1914 by architect Francisco Izidoro Monteiro, the former neoclassical building of the Belo Horizonte School of Medicine (BHSM) was located in a central area of the city. Its design, inspired by the European precepts at the time, was embedded in the same architectural language that characterized the cityscape of the capital of Minas Gerais, Brazil. The original building was gradually dismantled and completely demolished in 1960 to make way for the present headquarters. Few records of its existence remain. In order to contribute to the construction of the digital heritage of the old BHSM building, this article presents its virtual reconstruction, and demonstrates and analyzes the application of Heritage Building Information Modeling (HBIM) for this purpose. Based on data collection and the organization of numerous references (historical photographs, former students’ recollections, magazine articles, books, minutes, and photogrammetry of the remains), a hypothetical model of the building was developed to represent its condition as built and prior to demolition. Despite the difficulties in modeling, it was possible to perform a virtual historical reconstruction of the building, providing a better understanding of the building that does not currently exist. The preservation of the digital heritage of the demolished building aims to raise public awareness of its memory, which is consistent with the collection of the Memory Center of the UFMG School of Medicine (CEMEMOR).

A METHODOLOGICAL APPROACH FOR AN AUGMENTED HBIM EXPERIENCE THE ARCHITECTURAL THRESHOLDS OF THE MOSTRA D'OLTREMARE

Abstract. Digital survey and parametric-semantic modeling of historical or conventional building artifacts are becoming progressively more oriented toward HBIM (Heritage Building Information Modelling) to XR (Extended Reality) digital fruition projects. This encompasses a wide range of applications, from technical management to historical-scientific popularization of the architectural heritage. In this sense, the research explores the potential of BIM-to-XR virtualization systems concerning the systematization of historiographic documentation and interaction between different types of datasets for managing and disseminating the heritage. In particular, the research presents a prototypal experience conducted on Mostra d'Oltremare in Naples, Italy, a mid-20th-century exhibition center. In particular, the northwest access area had a rationalist layout, while the current configuration strongly differs from the monumental, exedra-shaped one built on a project by Arch. Stefania Filo Speziale, which was largely destroyed by World War II bombing. Thus, to document and facilitate the analysis of the original configurations, the original archival sources have been digitized and cataloged; moreover, reality-based integrated digital survey campaigns have been performed for the acquisition of metric-morphological data of the complex and the segmentation of the characteristic chromatic features of the residual decorative apparatuses. This has enabled the development of a BIM-oriented multi-scale information repository to enrich the real environment with digital content, thus creating an augmented reality experience. The latter has been introduced to create a virtual tool for querying and manipulating BIM databases, using the potential of visual programming languages and traditional scripts to create a two-way flow of data between BIM and AR.

Digital Twins. HBIM information repositories to centralize knowledge and interdisciplinary management of architectural heritage

It is obvious that the primary document will always be the building itself, but within the field of conservation, restoration or maintenance it is necessary to have a large documentary archive where the interventions are recorded. The older the monument is, the greater the knowledge of the built element must be before any intervention and this requires a lot of time in prior research and which can develop prior studies, in addition to the economic cost that it entails. This is why with the advancement of technology and digital repositories, digital platforms can be created within Heritage Building Information Modeling (HBIM). This article reflects the experience of an eight-century-old monument, San Juan of Hospital of Valencia (Spain), in which a virtual twin has been made with software and specific web platforms in facility management such as Archibus©, EcoDomus©, Zutec© that allow the integration of information from BIM models and data acquired through sensors. With this work, although it is economically expensive and requires a lot of time for people specialized in the required programs, is improving the efficiency of facility management. and maintenance planning for large buildings and infrastructure.

Cost Impact Comparative Analysis via BIM between Heritage Regular Maintenance Projects and Long-Term Restoration Projects—A Case Study

The financial implications of long-term restoration projects for cultural heritage, as compared to regular maintenance efforts, often underscore a flawed decision-making process. This can result from years of neglect versus consistent, organized maintenance. Striking a balance between these strategies is paramount for preserving cultural legacies. This research aims to evaluate the trade-offs between the initial expenditures of restoration initiatives and the consistent costs of maintenance activities. We leverage Building Information Modelling (BIM) and its specialized application for heritage preservation, known as Heritage Building Information Modelling (HBIM). This offers a digital depiction of the heritage building’s conservation state and associated intervention costs. Specifically, this study taps into the fifth dimension of BIM, cost estimation, to draw a comparative analysis between the financial ramifications of regular maintenance and long-term restoration projects. This assessment is exemplified through a case study on the “Aidkeen Al-Bendqdari Dome” located in historic Cairo, Egypt—a component of the Prince Taz Palace. The analysis integrates cost data to generate insights. The ultimate goal is to devise a comparative framework that can guide authorities in budgetary decisions and resource distribution.

Thermal performance improvement for residential heritage building preservation based on digital twins

Excessive temperatures can result in the collapse of structural components, cracking, scaling, and condensation in heritage building structures. Numerous unregenerated residential heritage buildings use portable heaters to adjust the indoor temperature for the comfort of occupants. However, research on the impact of heaters on the preservation of heritage buildings is limited. This paper proposes a novel and systematic approach based on digital twin technology to improve thermal performance effectively in unregenerated heritage buildings by arranging the locations and settings of heaters for improving building preservation. This research extended the functionality of heritage building information modeling (HBIM) to support simulations and decision-making to improve the thermal performance for heritage building preservation. An approach was proposed to address the lack of information by integrating documents, information, and graphics into an HBIM model for heritage building preservation. The digital model process based on HBIM presented in this study can be an effective 3D model for computational fluid dynamics (CFD) simulations. To investigate the impact of the heater on heritage building deformation, a novel method was developed to couple CFD and structural simulation to analyze the thermal performance and building deformation of heritage buildings. The heritage building deformation resulting from the heaters’ power setting and location was identified and quantified. In addition, using the proposed digital twin platform, heaters were controlled automatically. The thermal performance, building cracking and deformation were monitored and recorded automatically along the lifecycle. The improved heater location reduced the maximum total deformation of the heritage building body by at least 62.9 %.

Combination of Terrestrial Laser Scanning and Unmanned Aerial Vehicle Photogrammetry for Heritage Building Information Modeling: A Case Study of Tarsus St. Paul Church

Cultural heritage building information modeling (HBIM) is an emerging process allowing us to reconstruct built heritage virtually. The data of a digitally documented cultural heritage building offers significant advantages as it is accessible and modifiable by all professionals involved in the same or different projects. The most important factor affecting the accuracy and precision of the HBIM model is the ability to collect complete and accurate information about the physical structure. Combining terrestrial laser scanning (TLS) and unmanned aerial vehicle (UAV) photogrammetry point clouds is one of the most efficient ways to capture accurate digital data on the building. This study provides the foundation for creating an HBIM model for cultural heritage the coupling of spatial data with TLS and UAV. This paper aims to generate synergy between TLS and UAV point cloud data and ensure that the spatial database contains sufficient data to model historical objects with HBIM tendencies.

HBIM-based workflow for the integration of advanced photovoltaic systems in historical buildings

The European Union is pushing towards the adoption of energy production systems from Renewable Energy Sources, in both new and existing buildings. However, integrating photovoltaic (PV) applications into historical heritage context remain challenging due to a number of different barriers, primarily related to social acceptability. This research aims to define a collaborative and interoperable workflow that utilizes Heritage Building Information Modelling (HBIM) tools to facilitate the integration of advanced and customized PV technologies and components in historical buildings refurbishment operations. The workflow combines architectural refurbishment practices with parametric rendering and a best-choice protocol to establish an efficient stakeholder value-chain for a collaborative approach. The methodology includes the following four steps: (i) historical research and on-site survey; (ii) HBIM model construction; (iii) selection of PV interventions and technologies; (iv) modelling of the selected PV components and integration in the HBIM model. The study also demonstrates the output of applying this workflow to a real historical building through a case study. Heritage-compatible building integrated PV (BIPV) interventions are evaluated following a multi-level risk-benefits scheme that considers factors such as aesthetic impact, technological compatibility, theoretical energy performances, economic costs, and environmental issues. Subsequently, selected interventions and advanced customized BIPV elements are modelled in BIM environment. The study highlights the positive implications of this HBIM-based workflow in various aspects, including decision-making (e.g., promoting collaboration and interoperability), modelling (e.g., pre-emptive evaluation and reduction of impacts, PV component customization, and optimization), and data and process management (e.g., creating an all-in-one model for future assessments and operations).

Multi-indicator adaptive HVAC control system for low-energy indoor air quality management of heritage building preservation

Regenerated commercial heritage buildings employ heating, ventilation, and air conditioning (HVAC) systems that significantly increase their energy consumption, necessitating a methodology that supports low-energy operation to achieve a sustainable built environment. Poor indoor air quality (IAQ) management can cause irreversible damage to heritage buildings. However, there are risks of the destruction of inherent heritage values if energy-efficiency approaches are implemented without considering the visual impacts and multiple IAQ parameters in heritage buildings. To preserve heritage buildings, this study developed a multi-indicator adaptive ventilation control system for IAQ management using digital twin technology, which consisted of triggers and feedback. A digital representation of heritage buildings was established using Heritage Building Information Modelling (HBIM) with sensors to trigger adjustments in ventilation system settings. The sensor placement rules for IAQ monitoring and HVAC control of heritage buildings were demonstrated using computational fluid dynamics (CFD) simulations. The relationships among the HVAC inlet velocity, multiple IAQ parameters, and energy consumption were quantified using CFD and energy simulations. Simulation data were used to generate responsive charts for adaptive ventilation control, and the sensor data provided feedback to the ventilation system. The optimal ventilation system control strategy achieved up to 30% energy savings in the illustrative example. The proposed multi-indicator adaptive HVAC control system contributes significantly to the timely reduction of multiple air pollutants, IAQ parameter adjustments for the preservation of heritage buildings with minimal structural and visual impacts, and the need for more autonomous and energy-efficient HVAC systems.

Conservation Digitalization through Heritage Building Information Modelling (HBIM): Online Database Theoretical Review

It is essential in today's world to protect and maintain cultural heritage in the face of threats posed by modernity, development, and climate change, all of which have the potential to shorten the useful lifespan of cultural heritage. On the other hand, the effort involved in conservation is far more challenging since incomplete documentation frequently leads to misunderstandings and incorrect interpretations. Heritage Building Information Modelling (HBIM) is a tool that came into latter part of the 2000s with the intention of assisting in the management of the conservation, rehabilitation, and retrofitting of heritage structures. When it comes to the management and digitization of documents associated with historical buildings and artefacts, HBIM is often regarded as the most trustworthy tools available. The main objective of this paper is to identify theories concerning HBIM based on theoretical review conducted via online database. On 9th October 2022, the search had been made using Scopus online database, 1346 articles and conferences paper were selected in this research, after screening phases, only 65 high quality articles were included. As a result, HBIM digitalization model is proposed.

Heritage Building Information Modelling Implementation First Steps Applied in a Castle Building: Historic Evolution Identity, Data Collection and Stratigraphic Modelling

This research presents an application of the Building Information Modelling (BIM) methodology to the preservation of buildings of historic value. The study of the built heritage encompasses several aspects: namely, the collection of information, the rigorous representation of the building, the identification of the applied traditional construction processes, and the classification of historic eras of construction, conservation or refurbishing. In a BIM context, the topic of old buildings is referred to as Heritage Building Information Modelling (HBIM). In order to illustrate the type of work that needs to be prepared, a building heritage case is presented. The study is focused on the identification of the historic evolution of a castle and the adjacent structural environment. The first step concerns the data collecting: several institutional repositories of old documents were consulted; technical visits to the site were performed; a large photographic survey was undertaken; and photogrammetry technology was applied. Based on the available information, the corresponding stratigraphic HBIM model of the historic complex was generated, which was associated with an accessible and well-organised database. This text aims to contribute positively to the dissemination of the HBIM in the preservation of historic buildings, and it is focused on a mandatory first step: generating a complete stratigraphic HBIM model. The model is intended to be a useful support to professionals to elaborate the preservation project, as it archives relevant data. The description of all processes from the data collection to the stratigraphic model brings an important understanding of the relevance of a primary stage performed with depth and care. This research contemplates, essentially, the topic of collecting data as essential to the performance of heritage studies.

Sustainable management of heritage buildings in long-term perspective (SyMBoL): current knowledge and further research needs

PurposeThis article introduces the Special Issue on Sustainable Management of Heritage Buildings in long-term perspective.Design/methodology/approachIt starts by reviewing the gaps in knowledge and practice which led to the creation and implementation of the research project SyMBoL—Sustainable Management of Heritage Buildings in long-term perspective funded by the Norwegian Research Council over the 2018–2022 period. The SyMBoL project is the motivation at the base of this special issue.FindingsThe editorial paper briefly presents the main outcomes of SyMBoL. It then reviews the contributions to the Special Issue, focussing on the connection or differentiation with SyMBoL and on multidisciplinary findings that address some of the initial referred gaps.Originality/valueThe article shortly summarizes topics related to sustainable preservation of heritage buildings in time of reduced resources, energy crisis and impacts of natural hazards and global warming. Finally, it highlights future research directions targeted to overcome, or partially mitigate, the above-mentioned challenges, for example, taking advantage of no sestructive techniques interoperability, heritage building information modelling and digital twin models, and machine learning and risk assessment algorithms.

An HBIM Integrated Approach Using Non-Destructive Techniques (NDT) to Support Energy and Environmental Improvement of Built Heritage: The Case Study of Palazzo Maffei Borghese in Rome

Built heritage energy and environmental improvement is increasingly being recognised as a key driver in the fight against climate change. This effort necessitates a thorough understanding of the building to guide the selection of technologies and design solutions. To have a picture of the buildings’ characteristics and behaviour that is as complete as possible, in situ studies are essential, although the complexities and heterogeneities of historical buildings make these analyses still challenging, especially in professional practice. To address these issues, the paper describes an integrated approach including the field application of Non-Destructive Techniques (namely, Heat Flow Meter measurements, Infrared thermographies and indoor environmental monitoring) within a Heritage Building Information Modelling process. This interdisciplinary/integrated approach fostered the use of each type of analysis’s results to guide the subsequent analyses and incrementally deepen the knowledge of the building. The methodology was applied to a case study in the historical city centre of Rome in Italy. The analyses will be of service in developing dynamic building performance simulations to support the design of the interventions.

Integration of photogrammetry and laser scanning for enhancing scan-to-HBIM modeling of Al Ula heritage site

The study highlights the significance of combining imaging and laser scanning techniques to enrich point clouds used for reliable documentation and Heritage Building Information Modeling (HBIM). The fusion-based approach was used to document Al Ula Heritage site in Saudi Arabia, a UNESCO World Heritage Site with well-preserved tombs from the first century BC. The HBIM parametric modeling process requires a detailed survey to collect all geometric data. Although terrestrial laser scanners (TLS) are an efficient tool for 3D recording of heritage scenes in a short period of time, the data resolution is insufficient for identifying and evaluating the spatial distribution of surface weathering forms. Furthermore, combining scans collected at different times may pose difficulties in recording the texture. These issues have an impact on the subsequent 3D modeling phase as well as the efficiency of interpreting and tracing surface features in the Scan-to-BIM process. The proposed workflow using imagery data to enhance both the geometry and coloring of laser point clouds. In addition to texture mapping, the high-resolution imagery is used to densify the laser data using dense image matching, allowing for a clear reading of the surface features, and serving as a useful tool to identify the type, extent, and severity of façade damage. TLS and imagery data were collected separately, with images taken at the best time and location for realistically recording of surface details. Finally, the captured images are orthorectified by TLS geometric information and used for HBIM texturing to provide realistic decay mapping. The results showed that the combination of TLS and photogrammetry allowed for the efficient collection of 3D data, which improved tracing and digitizing HBIM with complete mapping information. The research findings will be greatly useful in the management and planning of historic building conservation and restoration projects.

DEVELOPMENT OF A VIRTUAL ITINERARY WITH HBIM AND GIS

Abstract. This study explores the potential of Heritage Building Information Modeling (HBIM) and Geographic Information Systems (GIS) for assessing tourist visitation and managing public use of heritage buildings. By integrating these tools, the research aims to improve preventive maintenance and conservation management in culturally significant buildings and urban outdoor spaces. The findings demonstrate the value of HBIM and GIS in handling spatial information and facilitating reliable decision-making for tourist itinerary design and visitor flow management. By examining three buildings of the highest degree of protection as assets of cultural interest, the information obtained can be extrapolated to a municipal management network that encompasses numerous urban models. The integration of databases enables the combination of data at different scales, from the building level to the territorial level, involving all relevant stakeholders from various disciplines. The results highlight the importance of using digital tools in the context of heritage architecture and public use management, promoting more sustainable practices in the preservation and conservation of our cultural heritage.

PRESERVING THE HISTORY OF AFRICAN AMERICAN EDUCATION: DIGITAL DOCUMENTATION OF ROSENWALD SCHOOLS – A CASE STUDY ON THE TANKERSLEY SCHOOL IN HOPE HULL, ALABAMA, USA

Abstract. Established across the American South between 1917 and 1932, Rosenwald Schools were crucial for providing education to African American children during segregation. Now, many of these structures are abandoned and deteriorating, in urgent need of digital documentation and preservation. This paper introduces an innovative approach for using Matterport technology to capture immersive virtual tours and enhance Heritage Building Information Modeling (HBIM) with high-resolution imagery. The Tankersley Rosenwald School in Hope Hull, Alabama serves as the case study. Additionally, this paper features traditional Reality Capture techniques, such as Terrestrial Laser Scanning and aerial photogrammetry, in combination with Matterport technology to create a detailed HBIM model of the historic school. This model enables architectural and structural analysis, informing suitable stabilization, conservation, and restoration strategies. It also acts as a powerful visualization tool, allowing stakeholders to safely examine the school's architectural, structural, and historical aspects. The virtual tour produced through Matterport provides valuable data for developing an accurate HBIM model in Revit, leading to more effective conservation approaches. The integration of these technologies showcases the potential for digital preservation of built heritage and emphasizes the importance of innovative methods in cultural heritage documentation. By digitally preserving these historically significant schools, this research supports the conservation and restoration of a vital aspect of African American educational history and raises awareness of their cultural importance.

COMPARATIVE ANALYSIS OF POINT CLOUDS ACQUIRED FROM A TLS SURVEY AND A 3D VIRTUAL TOUR FOR HBIM DEVELOPMENT

Abstract. This paper presents a comparative analysis of point clouds acquired from a terrestrial laser scanner (TLS) survey and a 3D virtual tour using Matterport technology for heritage building information modeling (HBIM) development. The study uses the Cloister of the Royal College of Corpus Christi Seminary, an important cultural heritage site in Valencia, Spain, as a case study. The point clouds from the TLS survey and Matterport scans were compared both quantitively in CloudCompare software and visually to assess their accuracy and quality. The Matterport point cloud data was found to be slightly lower in quality and accuracy compared to the TLS data, but still sufficient for developing some low-tolerance geometry in the HBIM model. The study shows that Matterport point cloud data has potential to supplement TLS scans, particularly in areas missed during the TLS survey due to range limitations. Matterport technology is accessible, affordable, and easy to use, making it a feasible option for heritage sites with limited resources. Moreover, Matterport technology captures high-quality visual data, including color and texture, providing a detailed representation of the heritage site. Thus, Matterport technology can be a valuable contribution to cultural heritage documentation and preservation, particularly for sites requiring a quick and efficient surveying process. The findings of this research offer insights into the relative advantages and limitations of these two reality capture techniques for cultural heritage documentation and preservation, and could potentially inform decision-making processes for future heritage preservation projects.