Keywords

1 Introduction

Cities have always accommodated humans’ needs and their necessity of permanent dwellings. Actively facing new challenges over time, they have always reflected either the stability of the society or the changes of time.

Nowadays, cities are asked to be resilient more than ever: given that ‘resilience’ means the ability of an entity to be able to deal and to overcome a traumatic event or a period of difficulty, cities are called to accommodate and to react to extreme conditions such as the COVID-19 pandemic, the climate change and the severe globalization.

Consequently, with the current fast times, temporary constructions are re-gaining popularity as a practical solution for accommodating the recurring changes dictated by the time. The accelerated speed, due and thanks to which the global society is nowadays moving faster and further, is contributing in making cities quickly obsolete.

Additionally, the continuous birth of new technologies is a double-edged sword, affecting on one hand the progress of the society and their cities but intensifying, on the other hand, the process and the speed of the changes, with a consequent mutual impact on climate change, contributing in parallel to its acceleration and to its slowdown.

Cities and buildings obsolescence is reflected by their need to be more resilient and open to changes, both in terms of aesthetic appearance and technical performances.

The climate change has led to the necessity to diminish the greenhouse gas emissions of the building stock, which is responsible for approximately 40% of the energy consumptions, representing the largest energy consumer and one of the most significant CO2 emission sources in Europe, with a share higher than a third of the total EU emissions (European Commission 2021).

The strategy of the renovation has been continuously spreading in the last years, and new incentives have been launched with the exact purpose of increasing this good practice that contributes in the up-cycle of the building stock and avoids the production of unnecessary waste caused by demolition processes. With the aim to look for fast and average costly solutions in order to encourage building façade renovation processes at different scales of interventions, this paper analyzes innovative solutions on the market for making building façades resilient and adaptable through the application of membranes over façades.

Among the spectrum of lightweight materials, membranes present some inherent properties [such as thinness, easy transportability, fast assembly, etc. (Chilton 2010; Pohl and Pohl 2010)] that make them suitable for both temporary and permanent façade renovations and valuable for overcoming current retrofit constraints. Consequently, taking advantage of membranes potentialities, this analysis aims at comparing current methodologies with innovative membranes retrofit strategies, in order to evaluate the effectiveness and advantages of textile-based products in overcoming existing constraints to façade retrofit and achieving extensive building façade renovations.

2 Methodology

Starting from the assumption that architectural textiles present some inherent properties suitable for retrofit applications, the study focuses on a comparative analysis between current Façade Retrofit Measures (FRMs) and Innovative Membrane Strategies for identifying the current façade retrofit constraints that could be overcome by the application of textile-based solutions.

In order to do so, a qualitative and comparative analysis based on the data acquired through the state of the art has been carried out. The methodology applied for the study consists of two parallel analyses and a sequential investigation aimed at comparing the acquired data: The attention has been drawn, on one hand, on current façade retrofit methodologies and their constraints and, on the other hand, on the analysis of textile potentialities for façade retrofit applications. Successively, the investigation of some textile-based façade retrofit best practices and innovative research contributes in supporting the discussion about the advantages of TFRS.

3 Review of the Current Retrofit Methodologies and Their Constraints

The retrofit practice is globally increasing its popularity due to the necessity to diminish building energy consumptions and to adapt existing buildings to enhanced performances. Aesthetic and functional reasons usually drive the renovation of a building, due to the aging of the components and the lowering of the performances.

Building façade retrofit is an effective measure to reduce global energy consumptions, considering that only façades account for 20–30% of the total (Dall’O’ et al. 2012), being characterized by large thermal transmittance. Therefore, the aim of building façades retrofit is to reduce the use of air-conditioning and heating systems in existing buildings.

The extensive review of Façade Retrofit Measures (FRMs) provided by Sarihi et al. (2021) divides them between Energy Conservation Measures (ECMs), Energy Modulation Measures (EMMs) and Combined Measures (CoMs) (Fig. 66.1), analyzing their effectiveness in different climatic conditions.

Fig. 66.1
A table is titled facade retrofit measures. It has 3 columns that list the energy conservation measures, energy modulation measures, and the combination of both measures.

FRMs classification according to Sarihi et al. (2021)

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The most common FRMs are insulation and shading, respectively, representing the most effective solutions in Heating and Cooling Dominated climates. The main difference between ECMs and EMMs consists in the extension of the measure over time: While ECMs are permanently applied to building façades, EMMs measures modulate energy consumptions only in specific periods.

Given that the thermal transmittance of the building envelope represents the main cause of the high energy consumptions, ECMs are being extensively applied in order to stabilize the internal temperature both in summer and winter, minimizing the use of technological appliances for improving interior thermal conditions. The EMMs instead aim at controlling the solar properties by the application of solar thermal-driven heating and cooling technologies. The combination of ECMs and EMMs aims to fully exploit their benefits for reducing the heating and cooling energy demand.

However, each of these strategies implies not only advantages but also various disadvantages (Corrêa et al. 2020) that often prevent tenants and builders from undergoing building renovation processes. The main constraints limiting the extensively application of the practice have been summarized in Fig. 66.2, associating FRMs with each related constraint.

Fig. 66.2
A table of 11 columns and 14 rows. It has columns such as insulation E T I, I T I, C T I, window properties, window-to-wall ratio, double skin glazed facade, opaque ventilated facade, green facade, finish coating, and phase change material.

FRMs and related constraints

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On top of the detailed analysis of each single practice, it should be clarified that most presumably there are some parameters, such as (i) the disturbance for the occupants during the execution of the process, (ii) the high-cost investment requested for the retrofit practice and (iii) the limited durability of the strategy in an optic of LCA, that limit the spread of this practice, representing the crucial barrier that must be overcome for increasing the number and possibilities of application of FRMs.

4 Membranes for Façade Retrofit Strategies

Starting from the most diffused constraints, it follows the clear necessity to exceed them in order to enhance the building façade retrofit practice.

Textile materials are nowadays re-gaining popularity in architecture thanks to their intrinsic characteristics (Chilton 2010; Pohl and Pohl 2010) and the renovated awareness about environmental and sustainability topics (Mendonça 2010; Monticelli and Zanelli 2021; Sandin and Peters 2018). As highlighted by Monticelli (2015a):

the success keys for the textile envelopes in architecture are (1) the reduction of weight and stiff parts of the building elements coupled with ensuring high performances […] and (2) the minimisation of the time of installation and maintenance though allowing an easy replacement of the building elements […].

Indeed, with high performance textiles available on the market, new functions and different architectural applications arise. Membrane applications in façades are mainly recorded as cladding systems for commercial buildings or, sometimes, as the second layer of a double skin (existing) façade. Lately, a new diversified range of products has entered the construction market for being applied either in retrofitting practices of existing buildings, either as sunscreens, or backlit surfaces (Monticelli 2015a).

The main characteristics that make textiles attractive as envelope materials are their lightness, thinness and flexibility, together with the light transportability and the increased durability. Additionally, they present pleasant aesthetic qualities and visual properties given by their translucency and the possibility of sun and light control. They can also comply with the mechanical and thermal requirements of a building façade, being able to face daily and seasonally temperature differences (Mendonça 2010; Paech 2016). Given that textile structures have the advantage to be easy dismantled, it is therefore possible to foresee a second (and even a third) life for these type of structures (Monticelli and Zanelli 2021; Sandin and Peters 2018). The efficient use of the materials and the reduced environmental impact contribute to the diffusion of membranes and their spread especially for temporary structures, taking advantage of the minimization time of installation and maintenance. Starting from the most common characteristics that define and differentiate these materials, it is possible to foresee an extensive use of textiles in the retrofit practice with different applications.

4.1 Membranes in Façade Retrofit Applications

Although nowadays the use of membranes in façade retrofit practice is still limited and it is majorly employed for the purpose of an aesthetic retrofit with the aim to give a new iconic appearance to a building, there are few cases in which it has been used as a sun-shading device or with the aim to improve the energetic efficiency of the building envelope (Mendonça 2010).

The application of textiles and membranes for the purpose of the façade retrofit lays its ground in the exploitation of the intrinsic properties of the materials and the great freedom they leave: Being very lightweight, their application can be taken in consideration even in a second moment, without interfering on the existing structure with additional and excessive weights.

As testified by the Case Studies in Fig. 66.3, the transparency or translucency given by the material used allows for the control of the natural light penetrating inside the building without obstructing the inside-out view. The creation of a textile second-skin has the aim to protect the building components from the atmospheric aging and, defining a buffer zone, allows for natural ventilation. Textiles and membranes can also be employed as exterior sun-shading devices, modulating the sunlight penetration inside the building (Fig. 66.4a) or obstructing it partially or completely through textile curtains, representing at the same time a useful and decorative element of the façade (Fig. 66.4b). A more common application of the material can be detected in Fig. 66.5, where textiles have, respectively, been used as a cladding system for giving a new appearance to the building or as an additional envelope with the aim to define an iconic façade.

Fig. 66.3
Two photographs of high-rise buildings with glass walls. The building in A has a water body in front and is decorated with lights. The building in B is in the shape of a cruise ship.

a Westraven Office Complex—Utrecht, Netherlands (Credit: Cepezed - picture: Joannes Linders); b ETFE Façade Unilever Building—Hamburg, Germany (Credit: Vector Foiltec)

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Fig. 66.4
Two photographs of a building with glass walls. A. Exterior sunshades are on each floor. B. Curtains hang over the building and leave a few spaces for light.

a King Fahad National Library—Riyadh, Saudi Arabia (Credit: Gerber Architekten - picture: Christian Richters); b Aichinger House—Kronstorf, Austria (Credit: Hertl Architekten - picture: Kurt Hörbst)

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Fig. 66.5
Two photographs of buildings with glass walls. A, depicts a McDonald's building with an elevated roof. B, is a building named Plaza with a tower in the center and a transparent bridge in the front.

a McDonald's – Legnano, Italy (Credit: Canobbio Textile Engineering); b Gotha Cosmetics Headquarter - Lallio, Italy (Credit: iarchitects - picture: Claudia Calegari)

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5 Discussion

The use of textiles in façades for the purpose of the retrofit is increasing its popularity thanks to the different FRMs it matches, especially the ones referring to the EMMs (Fig. 66.6). Some recent studies have been conducted for simulating the application of a textile solution onto an existing façade for improving its energy performances.

Fig. 66.6
A table of facade retrofit measures lists the energy conservation, modulation, and combination of measures. Double-skin glazed facades, opaque ventilated facades, facade finish coatings, and shading are highlighted in the modulation measures.

TFRMs (in green) within the more general spectrum of FRMs edited by Sarihi et al. (2021)

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The tensile second-skin simulation refurbishment (Ciampi et al. 2021) highlighted a yearly heating and cooling energy demand reduction of about 9.8%, while the semi-opaque ventilated façade solution (Cortiços 2020) testified around 23% in heating and 39% in cooling savings in inland areas, with a reduction of 6.45% of CO2 emissions and around €13.5/m2 on the heating and €23.5/m2 on the cooling spending.

Within the spectrum of EMMs, these last two research testify a potential application of TFRS with respect to the first and second strategies. Although there are no studies investigating the energetic behavior of textile sun-shading systems, the numerous applications that can be found and the spread of the practice serve for valuing this measure too.

Given that the analysis of the current FRMs led to the understanding of three main constrains that limit the practice of the retrofit, it is presumable that the application of TFRS could overcome them thanks to their intrinsic characteristics:

  • In terms of disturbance for the occupants, it is possible to claim that a TFRS could diminish it given the reduced amount of time for the installation of the system (Paech 2016; Gezer and Aksu 2021);

  • The cost investment could be lowered by the use of a minor amount of material (Cortiços 2020; Beccarelli and Chilton 2013);

  • The advantage in terms of estimated duration of the practice can be foreseen in an optic of LCA: The use of TFRS could be conceived both for permanent and temporary applications, therefore unveiling new temporary retrofit strategies able to comply with the specific requirements of the time without implying the use of excessive materials, whereas forecasting the re-use of the system (Sandin and Peters 2018; Monticelli and Zanelli 2018).

6 Conclusion

Currently, innovative Façade Retrofit Strategies are being investigated with the aim to disclose easier, faster and lower-cost solutions. TFRS perfectly fit in this scenario, envisaging both permanent and temporary solutions.

The paper has presented some TFRS already accomplished, analyzing their applications and advantages in comparison with current methodologies and the main façade retrofit constraints that limit the spread of the practice. The qualitative analysis has been based on the data acquired through the Literature Review and the investigation of some Best Practices. The outcome highlighted the potentialities of TFRS in overcoming some of the current retrofit constraints, such as the disturbance for the occupants and the cost investment, consequently framing new textile-based products development lines.

Further LCA, Life Cost Analysis and Energy Simulations will be run in order to quantitatively value the thesis. Nevertheless, it is already possible to envisage a wider spread of TFRS by taking advantage of textile intrinsic properties for overcoming current retrofit constraints.