The documentation of heritage buildings is the preliminary action to deal with any problem related to the built heritage. The procedure of documentation requires a very diverse range of data (quantitative and qualitative) to be obtained and investigated in order to produce an accurate digital representation of the building. This type of work of data capture and interpretation is often conducted in isolation by different stakeholders and for a range of purposes, leading to a lack of communication between different data types, repeated effort and incomplete documentation. Heritage Building Information Modelling (H-BIM) is set to play a key role in the digital documentation of heritage buildings, as it can combine quantitative and qualitative data and facilitate the integration of different stakeholders and specialised data into the digital management of the different phases of dealing with heritage buildings. This paper aims to review the multitude of data types that could be included in the documentation and investigation process of the built heritage, in order to assess the breadth and depth by which heritage buildings can be documented. Four main categories that span the whole documentation data areas are being suggested which vary from outer geometry surveys, to subsurface materials and structural integrity investigations, to data concerning the building performance, as well as the historic records concerning the building’s morphology over time, which can help to create a more in-depth knowledge about the heritage building’s status and performance and can create a solid base for any required restoration and retrofitting processes (Khalil and Stravoravdis 2019a).

Sustainable design is believed to stand on the opposite side of heritage conservation. This view is supported by the fact that sustainable design requires invasive measures to implement new technologies and treatments that challenge the principle of minimum intervention in heritage conservation. Another point of view sees heritage conservation as an already act of sustainable development that protects and preserves social and cultural resources such as heritage buildings and their intangible values. On the other hand, research and practice have proven that heritage buildings can be the subjects of sustainable design projects that achieve outstanding measures of sustainability and energy efficiency while not compromising the authenticity of the heritage value of the building. This sustainable conservation reaches its peak in adaptive-reuse projects of heritage buildings as reusing the building guarantees its ongoing maintenance and promotes its social, cultural and economic values to society, while giving it the ability to withstand modern users’ comfort and energy efficiency standards. This research presents a case study of the adaptive-reuse project of Villa Antoniadis in Alexandria; a heritage building built in the mid-nineteenth century and in the process of a major adaptive-reuse project. The history and significance of the building will be studied as well as the conservation values of the current project, then some proposals for interventions that could achieve more energy efficiency for the project while conserving the building are discussed. The research included a simulation of the building, using building energy modelling software for the current adaptive-reuse project as a base case, and the hypothetical application of different proposed sustainable interventions such as thermal insulation, double glazing, shading, lighting control, natural ventilation, and photovoltaic energy generation, where the energy savings potentials for each proposed intervention were studied. The simulation proved a possible reduction of 36.5% in the cooling, heating and lighting energy consumption as well as generated 74.7% of the energy required for cooling, heating and lighting from renewable energy sources.

Heritage BIM can represent many advantages for heritage building documentation, restoration, retrofitting and management. However, the most complicated challenge concerning H-BIM is the inevitability of starting at an intermediate point in the asset’s life cycle, which can be much more complex than the relatively straightforward cradle-to-grave model that describes new-build construction (Historic England, 2017). This leads to irregular geometry, non-homogeneous materials, variable morphology, not documented changes, damage and various stages of construction. These challenges put more weight on the surveying, documentation, modelling and visualisation phase within the process of HBIM.Many investigation tools can be used and combined to document and investigate the fabric of historic buildings. This paper reviews the literature and the state of art of the different domains of data that could be included in the documentation and investigation process of the built heritage, in order to assess the breadth and depth by which heritage buildings can be documented. These data can vary from outer geometry survey, to sub-surface materials and structural integrity investigations, to data concerning the building performance, as well as the historic records concerning the building`s morphology over time, which can help to create a more in-depth knowledge about the heritage buildings` status and performance and can create a solid base for any required restoration and retrofitting processes.

The AEC industries as well as the heritage sector are facing a number of issues that relate to the management of building digital data. Two of the most prominent ones are the interoperability of data and data longevity. In order to better understand the extent of these issues for the general AEC industry and heritage buildings sectors, an online survey was designed to help quantify them and reveal the opinions of professionals and academics in the field. The online survey highlighted a clear latency in BIM adoption in the heritage sector as only 51% of the heritage participants use BIM in their projects compared to 63% of AEC participants. The reasons for this were further explored in the participants’ comments, as most of the reasons revolved around the issues of BIM data interoperability and longevity, considering the complex and interdisciplinary nature of heritage projects. The survey responses highlighted that data longevity is a crucial challenge for the heritage sector in particular as the need for future re-accessibility of digital data is clear in the results, showing that more than 82% of the heritage participants need to re-access their data in the future. The results also showed the prevalence of BIM interoperability issues and highlighted that the heritage sector is more prone to interoperability issues compared to the general AEC industry as 67% of heritage BIM participants and 50% of AEC BIM participant have faced some issues of BIM interoperability. In total, 72% of the standardised BIM participants agreed that standardised BIM formats could be a promising solution to mitigate the interoperability challenges, while only 57% thought that standardised BIM formats are reliable in their current status. Moreover, the online survey explored the variation in the needs of different disciplinary groups including rates of BIM adoption, use of standardised BIM formats, and needs for access to different heritage buildings data categories. Participants also presented their views on what would be an ideal medium for long-term storage of heritage buildings digital documentation data for future access, with some views being sceptical concerning BIM in its current status. This paper presents the findings of this extensive online survey.

Architectural visualisation has been developing over the year to improve the representation buildings and their contexts to the public. It achieved a long journey from manual drawings to photography to digital 2D and 3D representation, until it reached the era of extended realities (XR), which allowed unprecedented immersive and interactive engagement. Extended reality applications represent a unique opportunity for the visualisation of heritage buildings on many stages; from the early design phase, through the construction and facility management phases, to the education and cultural tourism applications. This paper aims to explore the wide range of state of the art XR applications, investigate their aspects and variations, and study their potentials, challenges and limitations for the built heritage sector.