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 %.

• Automatic airflow intervention was developed by digital twins for facade preservation • A novel atomizer was developed to disperse the airflow for diluting air pollutant • Wind direction effect on air pollutant concentration around the facade was quantified • A novel fresh air curtain wall was developed to preserve facade from air pollutant • The sulfur dioxide concertation at most effective location reduced by 34%

Excessive and fluctuating indoor air quality (IAQ) leads to destruction of historical buildings. Regenerated commercial historic buildings are generally fitted with heating, ventilation, and air conditioning (HVAC) systems for IAQ improvement. There is a time delay in the HVAC system to control environment within the target range after the settings adjustment because of the time required for air conditioners to cool, heat or exchange fresh air. The lack of timely and effective control of traditional HVAC is insufficient to control IAQ for the preservation of historical buildings. This research proposed a novel Multiple Output Gate Recurrent Unit (GRU) - Computational Fluid Dynamics (CFD) integration method and combined it with the automatic control using digital twin technology to improve the effectiveness and efficiency of multiple IAQ management for the preservation of whole indoor spaces. This method considered visual impacts and minimized the external equipment impact. The sequencing order of multiple IAQ enhancements by adjusting HVAC control was investigated based on the priority of multiple IAQ parameters on historic building preservation. The proposed Multiple Output GRU prediction reduced the time by at least 1/3 for training and validation. As heritage buildings restrict the installation of sensors, CFD was used to identify the maximum value and location based on sensed IAQ data for adjustment triggers. The combined method contributed to identifying the predicted maximum value to trigger the 10 min pre-regulation of the HVAC system for dealing with the time delay to maintain multiple IAQ in standard ranges for 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.

The lack of integration between the digital and physical world results in a lower level of efficiency and collaboration in the construction industry. Digital twin technology, which creates a visual and digital model of a corresponding physical object for simulating, monitoring, analyzing, and other actions throughout the whole life cycle, is considered as an effective solution to address these problems. This research proposes a framework to utilize digital twins and extend the existing level of details (LoDs) of building information modeling (BIM) for construction site management. This study analyzes and improves the operation principle and mechanism of digital twins, including the digital representation based on BIM, Internet of Things (IoT), data storage, integration, and analytics, as well as interaction with the physical environment. Questionnaires and interview results verify that the proposed framework can support construction site monitoring and management, enhance quality and efficiency, and improve construction safety. It also acknowledges the contribution of LoDs’ extension to construction site management. The interviews underline the main challenges that BIM, IoT, and data processes face in practical applications.

Underground heritage sites generally experience significant humidity, which results in the destruction of the surfaces and structures. This study establishes an underground heritage site preservation mechanism through a dynamic ventilation system based on digital twin technology. The aim is to control the relative humidity (RH) gradually on the air region near the walls of sites within the standard range and reduce adverse physical equipment effects and energy consumption of the system. Underground heritage site projects have more complex shapes with irregular and nonlinear arcs and height difference distributions. It is challenging to regenerate them. To achieve this objective, a model simplification rule for irregular heritage building information modeling (HBIM) technology was first established via computational fluid dynamics (CFD) simulation. Second, a meth-odology was developed to design a reliable and effective ventilation equipment and its layout based on CFD for irregular heritage sites. Compared with the scheme based on the optimal geometric rule arrangement, the number of pipes can be reduced by up to 25%. Third, a web-based digital twin platform combined with Internet of Things (IoTs) technology was established for achieving real-time control of the overall RH level of under-ground heritage sites within the standard range. The results present new solutions to control the RH of under-ground heritage sites for preservation. The proposed methodology can be used in typical underground heritage sites and illustrated by a real case. The validation encompassed development of digital environment for the real case and development of the ventilation system for its RH optimization.