Ceramics as opportunity | by Alfredo Zappa
The construction industry is going through a period of gradual transition in which quantity must be replaced by quality, new build by renovation and urban regeneration, and low-efficiency buildings by structures capable of producing more energy than they consume. National and EU laws, regulatory instruments, subsidies and incentives are all designed with these goals in mind. A less empirical approach is required in which calculations are performed and performance characteristics evaluated to establish design guidelines and parameters that would have been simply unthinkable just a few decades ago. And as new knowledge accumulates, so too new professional figures are emerging. Achieving goals requires an interdisciplinary approach that brings together different skills, where engineering (in its broadest sense) appears to leave less and less room for architectural creativity. This is especially true when architects relinquish their role and fail to explore the new tools (new technologies, new materials, new construction techniques) that are essential for achieving their goals, restoring value to a creative figure that otherwise risks becoming marginalised. As Sicilian writer Leonardo Sciascia wrote in A simple story: “Italian is not Italian: it is a tool for reasoning”. The same applies to architecture.
We can give some useful examples of this in relation to the use of ceramic products and systems in remodelling and energy retrofitting projects on existing buildings. As we all know, the range of offerings is so enormous and varied in terms of both products and installation technologies that there is often a tendency to proceed automatically, thereby failing to make the most of some extraordinary opportunities.
In the field of building envelopes, the most widely adopted solutions (including traditional cementitious adhesive systems, dry ventilated façades mounted on metallic substructures, and insulating layers coupled with an external skin of porcelain panels) might seem to have exhausted their potential for creativity and experimentation in energy recovery interventions, but this is a false impression. For example, far too little is still being done tofully exploit the opportunities offered by ceramic panels according to the orientation of the building. Everyone knows that colour has a big impact on the absorption of sunlight and consequently on the thermal loads placed on building envelopes. Considering the two extremes, the temperature differences between a white and a black façade on a summer day may reach many tens of degrees, and this has a big impact in terms of energy efficiency. With the advent of modern ceramic panels, we can choose products made of the same materials and with identical morphological and performance characteristics while differentiating the colours of the façades according to their orientations and irradiance calculations, bringing good results in terms of both performance and composition. At the same time we can exploit their different degrees of reflectance by choosing from an enormous range of matt, glossy, glazed and metallic surfaces. Not to mention the latest nanometric finishes with self-cleaning characteristics capable of eliminating the main atmospheric pollutants in the urban environment.
Another way of improving passive gain is to use ceramic panels of different thicknesses. In practice, by choosing panels of thicknesses ranging from ultra-thin 3 mm to extra-thick 20 mm, we can create claddings with various degrees of thermal inertia. At the same time, we can model the thermal inertia of a building envelope according to the orientation of the individual façades without altering their technological characteristics or external appearance. At the other extreme, thanks to the considerable experience acquired in the field of dry installation techniques, we can develop systems that enable ceramic surfaces to be juxtaposed with other materials such as aluminium panels, transparent or multicoloured glass sheets and even wooden slats, enabling the most sensitive architects to combine the work of architectural composition with the goal of improving the thermal efficiency of the façade.
Another area where there is still room for exploration is that of adaptive envelopes, in other words building envelopes those that are capable of altering their morphological and performance characteristics according to surrounding conditions thanks to a building automation system. Werner Sobek, head of ILEK (Lightweight Structures and Conceptual Design) at the University of Stuttgart, has made considerable progress in this field based on the use of lightweight materials. But at a more practical level we can easily imagine using portions of dry-set ceramic façade composed of different coloured elements placed back to back and capable of rotating horizontally or vertically to expose the most suitably coloured surface to solar irradiation according to the environmental conditions. In the most extreme situation, this would result in a south-facing façade that is black in winter when passive thermal gain is a benefit and white in summer to reduce overheating.
Ceramic materials offer similar opportunities not just for external cladding but also for interiors. This solution enables the energy efficiency of historic building envelopes to be improved while maintaining the aesthetic qualities of the façade by applying layers of insulating and finishing materials onto the inward facing side. This brings advantages in terms of remodelling of the interior spaces thanks to the enormous range of sizes and surface finishes of ceramic panels (from plain colours to marble, from wood to trowelled plaster effects), as well as the extremely high strength and resistance of the surface (thereby protecting the underlying insulating layers), and durability and ease of cleaning and maintenance. A further benefit derives from the above-mentioned difference in thicknesses of the panels, which allows the mass of the cladding and consequently the thermal inertia of the layers to be varied so as to improve the performance of the entire envelope.
In short, if used effectively and with an original approach, the quality and characteristics of the ceramic materials can in many cases not only help improve the performance of an individual project but also contribute to the emergence of a new architectural language capable of reconciling form with content. It is worth remembering the astute comment made many years ago by the great Cedric Price: “Technology is the answer, but what was the question?”