Keywords

1 Introduction

Living in the current built environment is highly impacting both the planet and its inhabitants. Buildings are big consumers of resources and energy, often unable to guarantee minimum environmental quality, and sometimes they badly influence the comfort and well-being of the occupants. If the need to reduce the environmental impacts of buildings is well-known since the energy crisis in the 70s, with the ecology principles entering in the AEC field, this reduction is still an ongoing effort in the climate change era.

Since green challenges in the building sector are as much urgent as complex, digital opportunities can be exploited to manage the building life cycle in a more efficient way, addressing more reliable building processes by supporting a more informed decision-making towards sustainability.

According to the UN Sustainable Development Goals (SDGs), future buildings should rely exclusively on Clean Energy, imperative to contrast climate change, and guarantee Health and Well-being for All in Sustainable Communities and Cities. Foreseeing zero climate impact by 2050, the ambitious EU Green Deal is both a call to update existing buildings in the Renovation Wave strategy and to digitalise the building sector. Moreover, the New European Bauhaus initiative invites to re-think planning and design practices towards creativity and interdisciplinarity, as a basis to envision sustainable, inclusive but also beautiful places.

Notwithstanding both the green and the digital domain have informed AEC research and design practice since decades, the parallel green/digital transition is still moving the first steps, requiring an enlarged interdisciplinary space where digitalisation can support the construction of future sustainable buildings and cities.

2 Experimenting Digital Twins for Building Energy Retrofits

In the context of the green and digital transition, Digital Twins represent the most advanced concept, with the possibility to twin/synchronise existing buildings with digital models by adopting real-virtual data bridges, such as sensors and IoTs (Trombadore et al. 2020). It is easy to capture the potential of such synchronisation, with real-time data deepening the comprehension of buildings for a more appropriate decision-making along the entire life cycle. This appears particularly profitable for the purpose of renovating existing buildings, when the availability of a new amount of reliable digital data can be strategic not only to analyse the existing conditions, but also to predict retrofit scenarios and to drive a more sustainable future use, management and functioning of the public building.

Within the Med-EcoSuRe project (Mediterranean Universities as catalyst of Eco-Sustainable Renovation), the DIDA Department of Architecture of the University of Florence founded beXLab (building environmental eXperience Laboratory), a Living Lab (LL) in the university building site of the retrofit pilot project (Fig. 19.1). Here, the experimentation with Digital Twin is intended both to collectively construct a reliable and shareable image of the existing and to forecast trustable future scenarios (Trombadore and Calcagno 2022).

Fig. 19.1
A photograph of an open plan office room. It has 2 tables, one with a single desktop computer and 4 chairs. Another table has 2 computers and 2 chairs in front of a wall. 2 cubby hole shelves have indoor potted plants placed within them.

Picture of the beXLab inside

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beXLab systematises interdisciplinary competencies and methodologies to innovate the renovation of public buildings, by the means of Digital Twins, especially valorising passive solutions that impact on energy performance and human comfort/wellbeing.

The idea of the LL was born in the field of technology of architecture, and it has immediately involved energy engineering for the common effort to find technological solutions for zero/positive-energy buildings. The LL experience in the university public building under renovation allows to constantly get the pulse on the real challenges, to engage strategic actors involved (decision makers, stakeholders and users), and to take advantage from the local academic community. Working on process innovation to renovate existing buildings, beXLab is in fact enlarging towards information engineering, to tackle the digital side, and user experience design, to valorise the unique human contribution in building energy efficiency and sustainability.

3 The Architectural Point of View

The building environmental experience proposed by the beXLab Living Lab has been conceived on well-rooted principles in the discipline of Technology of Architecture.

Focusing on the appropriateness of the human habitat, the discipline is not limited to formal aspects but considers  to the environmental and socio-cultural dimensions (Schiaffonati et al. 2011). Over the years it  assumed as proper the ecological task of optimisation of buildings’ environmental performance, starting from the design process. Moreover, the consideration of design as a social act (Nardi 2010) nourishes the perspective of engagement and participation of users in the transformation of the built environment.

By leveraging on the need-performance theory, the discipline of technology of architecture adopts a systemic approach that has exceeded the boundaries of the material technologies to evolve into softer ones, towards management and governance (Torricelli 2011), to “lead” the even more diversified contributions occurring in the definition of sustainable projects. For this reason, the discipline focuses both on the material and information transformation in the field of architecture, early recognising the role of ICT to support better design processes (Ciribini 1984).

In the wake of this disciplinary culture, the Med-EcoSuRe pilot project was intended as an occasion to innovate the building retrofit process by engaging its actors (academics, decision makers, stakeholders and users) in a common LL space and place of collaboration.

For the development of the pilot project, a building block hosting functions representative of the university life (teaching, study and research) was selected in the historical complex of Santa Verdiana in the UNESCO World Heritage city centre of Florence. Constructed in the 90s on the design of Arch. Roberto Maestro, the parallelepiped volume with north–south orientation has two floors, with a large room on the first one and other two rooms on the ground floor, separated by a central open/covered corridor (Fig. 19.2).

Fig. 19.2
A side view photograph of a building with rectangular glass windows above the 3 arches. A garden with a tree and bushes is in front of the building.

South façade of the university pilot building in Florence

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Due to the inconsistency of existing data and information, a survey of the building/plant system was conducted for the population of a preliminary BIM asset information model (LOD C - according to UNI 11337-4, 2017). Such information is useful from the earliest stages of the retrofit process for the definition of a reliable knowledge framework on the existing building, for a preliminary energy audit and for an improved communication in the LL (Fig. 19.3). The digital model has been exploited to analyse and simulate the environmental and energy behaviour of the building through different softwares, deepening the identification of the energy and indoor comfort criticalities, as follows:

Fig. 19.3
A computer-generated illustration of a building with rectangular windows above 3 arches. A few people are in the garden in front of the building, which has a tree and bushes. A person sits on a short wall on the left.

Image of the digital model of the pilot building

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  • Environmental analysis: the visualisation of the sun path in the building context highlights that the south façade with large glass surfaces suffers the absence of any type of shading device. Concerning natural ventilation, cross-ventilation cannot occur in the two rooms on the ground floor, due to fixed fixtures (Fig. 19.4);

    Fig. 19.4
    A chart presents top and diagonal views of illustrations of a building, a radar that denotes different wind speeds and 5 wind directions, 6 diagrams of a building with arches, and 2 illustrations that depict winds around the building.

    Preliminary environmental analysis of the existing building

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  • Analysis of the thermo-hygrometric performance of the envelope in dynamic conditions: all the components of the opaque and transparent envelope are characterised by transmittance values that are not fitting the current regulations on building energy performances. The weak behaviour of the envelope overloads the plant system, entailing a high energy demand both for heating and cooling spaces (Fig. 19.5);

    Fig. 19.5
    A chart of transmittance U and transmittance by law values in tables for the roof, external wall, and window, with their respective illustrations. It has multiple frequency graphs at the bottom.

    Preliminary thermo-hygrometer analysis of the opaque and transparent components in dynamic regime

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  • Natural and artificial light analysis: the symmetrical arrangement of the glazed surfaces in the double north–south exposure leads to an uneven indoor distribution of natural light, causing glare phenomena from south and under lighting, especially in the central area of the large room on the upper floor, negatively impacting the visual quality and the energy demand for artificial lighting (Fig. 19.6);

    Fig. 19.6
    A group of illustrations represents illumination calculations with contours of the ground and first floor of a building to analyze daylight for 5, 3, and 1 hour on March 21, June 21, September 21, and December 21.

    Preliminary analysis on the natural lighting in the pilot building

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  • Simulation of the energy performance: the main energy consumptions for heating and cooling is determined by the need of guaranteeing internal thermal comfort despite the weak envelope behaviour. The main impact on energy consumption for heating in the winter period is attributable to thermal conduction through the vertical components of the envelope, both opaque and transparent. Even more impacting is the energy consumption in the summer period, determined by the negative contribution of solar radiation coming from the south through the large and not shaded windows. Another impacting energy consumption is linked to the presence of lighting bodies with low-energy performance (neon) (Fig. 19.7).

    Fig. 19.7
    A chart has an illustration of a dial to depict kilowatt hours per meter cube, a table lists different energy segments, and another block diagram has texts in a foreign language.

    Preliminary simulation of the existing building energy behaviour

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Addressing the energy targets of the Med-EcoSuRe project, but also considering the specificities of the context of historical and cultural value, the architectural project for the energy retrofit was set up to solve the energy and indoor quality criticalities of the existing building, and formulated to achieve three main objectives:

  • Improvement of indoor comfort (thermal and lighting);

  • Energy efficiency (reduction of energy needs and integration of renewable systems);

  • Architectural constraints (feasibility and reversibility).

Different retrofit scenarios have been integrated in the BIM model, simulated and evaluated by mixing traditional bioclimatic and innovative building technologies, permitting to appreciate the different degrees of improvement in comparison to the current building conditions, in terms of indoor comfort, energy performances and feasibility (Fig. 19.8).

Fig. 19.8
4 computer-generated illustrations of buildings and walls with arched entrances. Clockwise from top left, the first is a brick wall covered with plants. The second is a building with a wooden grid structure around the building. The third and fourth are entranceways covered in hanging plants.

Preliminary architectural design of different retrofit solutions

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It is possible to recognise the opportunities in the adoption of digital building models to address the green objectives in the first phases of the retrofit process:

  • Standardised definition of the knowledge framework of the existing building to start a reliable retrofit process, representing a trustable and interoperable data and information container;

  • Evaluation of the environmental impacts of the existing building through virtual simulations on energy performances and indoor environmental quality, deepening the analysis of criticalities;

  • Definition of predictive retrofit scenarios sustaining the planning and design.

Moreover, digital models can be exploited to innovate the subsequent phases of intervention and post-management of the retrofitted building (operation and maintenance).

Yet, a key factor for the success of the digital modelling towards the definition of feasible scenarios is the validation of the model itself, which can only be achieved through a comparison with real dynamic data. In order to map the main boundary operative conditions, complex monitoring systems are needed together with specific expertise on measurements and data acquisition/post-processing techniques.

4 The Energy Engineering Side

Building technologies are, in most of the cases, well-known and universally standardised. National’s regulations guide the design of new constructions imposing materials’ specs, energy targets and boundary conditions for comfort and well-being (thermo-hygrometric, lighting and acoustic). The major part of recommendations is set on the basis of static calculations and is extrapolated through simplified models.

The concrete challenge is to attest the performance of buildings and comfort status in real dynamic conditions with the influence of user’s occupancy. That aim results even more hard to reach in the existing (buildings of the past decades and historical heritage) where a lack of information is present regarding structures and components such as wall stratigraphy and services. In such a context, it is really important to set up strategies and methodologies which allow acquiring useful data and creating a suitable matrix for the exhaustive description of the living environments. Tools must be configured in a very flexible and modular way in order to be replicable in different sites. The LL is effectively the proper space to configure measurements layouts and test them in operating conditions. Many sensors were installed for real-time monitoring of internal temperature distributions, relative humidity, heat loss flux, lighting levels, air quality as well as external parameters detected through a weather station (see pictures of Fig. 19.9, top). Actually, the amount of data is intentionally large because the setup of redundant data collection lets the cross-correlation, in the research phase, amongst the phenomena acting in the living laboratory involving users. The post-processing of measurement values achieves as a first goal the understanding of the real significance of each sensors’ group and the definition of a compact and plug and play system to install in the next projects. In a second phase, the same collected data would be managed and aggregated to validate the digital model in existing context and set up the Digital Twin.

Fig. 19.9
A photograph of a room with tubes and sensors installed on horizontal bars and a glass panel on the wall. 2 line graphs of p m v and p p d plot a fluctuating line. The top graph has 2 threshold lines, which range from 0.5 to negative 0.5, while the bottom graph has one threshold line at around 10 with respect to the y-axis.

Setup of sensors inside the beXLab (top) and thermo-hygrometric comfort evaluation during January 2022 (bottom)

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From a technical point of view, the environmental monitoring does not represent a critical aspect since the market proposes many solutions that can be easily placed in rooms reducing the impact in the structures, plants and users; the available wireless configurations are in fact very little intrusive, indeed. On the other hand, the elaboration of the huge amount of data that could be collected especially in the long-term periods is a challenging task. Numerical parameters and technical information need to be translated in a simple, clear, educational form to involve the different actors (users, researchers, managers …), to make them aware and to suggest criticalities/opportunities.

For instance, according to national regulations such as UNI EN ISO 7730 (2006), the internal comfort level could be derived and the conduction of the living spaces quantified in terms of predicted mean votes and percentage of dissatisfied as shown in Fig. 19.9, bottom (referred to January 2022). Those objective results would be also compared and validated with the users’ subjective perception, expressed through specific ongoing questionnaires (according to EN ISO 10551 2019).

5 Opening Towards It and Users’ Experience (UX)

Considering the amount and complexity of the row data, currently, one of the pivotal challenges of the LL is the data organisation and visualisation of selected/aggregated information in a smooth, intuitive and pleasant manner.

The idea of experimenting a retrofit project that would be truly accessible and available to all the different kinds of users (managers, students and researchers) requires the customisation of the experience and different levels of data communication. This means that the same incoming information (e.g. from IoT sensors) should be differently addressed to the various users, for example to inform technical offices or disseminate the results to students.

The process of creating info visualisation requires data analysis and a deep understanding of users, of their need and abilities/limitations. The engagement of end-users and UX design in the LL comes with the target of raising the awareness and identifying, analysing and stimulating best human behaviours related to energy, comfort and well-being.

In recent decades, there is a growing phenomenon of translation towards the virtual/digital but also abstract data in visual representation that can easily interact with users and create outstanding quality experiences (Hassenzahl and Tractinsky 2006).

Once the idea of human–computer interaction (HCI) focused just in functional benefits and usability aspects (how to make computers as intuitive as possible), now the concept of UX goes with the idea of interactive technologies, works with a better understanding of knowledge fields, such as emotion graphics, storytelling and linguistics, and takes care of the all contextual aspects.

Despite the growing interest and research on info visualisation and UX in some fields, first of all the cultural one, they are almost undeveloped for the energy efficiency sector, especially concerning retrofitting processes on public buildings. In the age of globalisation and information technology, UX design can encourage the retrofitting process and stimulate the dissemination of contents on energy efficiency and environmental comfort, with innovative and creative solutions to engage people.

6 Conclusions

The interdisciplinary processes described in the present paper have been developed over time, and their implementation is ongoing. However, the objective of an effective green/digital transition in the building sector has immediately revealed the need for synergy amongst working groups from different disciplines and methods.

The system “building-plant-user” is so complex and multi-faceted that it could not be addressed from a single and limited point of view, requiring instead many approaches/languages to dialogue together, contaminating the knowledge and skills from “hard” and “soft” sciences.

Moreover, the complexity of the investigated phenomena needs to be simplified in order to spread the results to the largest number of users, each with their own specific background (from building and energy managers to end-users). beXLab is taking up this challenge, proposing itself as an ideal place where the articulated syntax of the “building-plant-user” system could be understood and codified.

In this context, the human being is placed at the centre not only as a user of the environment, where the maximum efficiency and comfort have to be guaranteed but, above all, as the main responsible for the proper management of the living spaces, of their impact on the health of the planet and its inhabitants.