ZEMCH 2015 - International Conference Proceedings | Page 582

the energy saving achieved thanks to smart management of demolition waste and hence recycle
and reuse of materials.
The project seeks at investigating, developing and testing a sustainable retrofitting strategy, based
on an innovative integrated design process of new energy-efficient building envelope solutions
for the existing building stock towards nZEBs.
With this aim, the research develops an innovative methodology to manage the whole design and
production process of active components, thanks to the connection between the metric survey
technologies, the parametric computeriz ed CAD-CAM tools for modelling the new surface adaptable to existing morphology, and the CNC machines for the mass customized industrialized
production of different envelope solutions.
The final result of this integrated design process consists in the creation of a continuous envelope
system model, meaning a second skin tailored to the existing shape, constituted of prefabricated panels, linked to the existing façade. This new building envelope model is mainly based on
the dry assembly of prefabricated façade components and on the use of an innovative thermal
insulating material obtained by recycling industrial waste (AAM – Alkali Activated Materials), by
following an architectural bio-mimetic approach.
In order to illustrate the potentiality of the proposed approach, the process is applied to several
case studies united by their typological and constructive envelope solutions, belonging to the
scholastic building stock built after the Second World War, in reinforced concrete and mostly prefabricated.
To demonstrate the effectiveness of the envelope model proposed herein, the paper presents a
specific solution selected among the generable ones in line with it, according to the research
paradigms and the principles of sustainability, meant as modularity, speed of setup, reversibility,
recycling and reuse of materials with low environmental impact.
In particular, the specific innovative solution presented in the paper is characterized by the adoption of prefabricated hexagonal-shaped panels for the tessellation of the new surface, with the
double role of resistant light frame in polymeric composite and stay-in-place structural formwork
for the cast of thermal insulation material.
As demonstrated by the conducted geometrical analysis, the shape of this frame structure composed of hexagonal cells - widely present in nature, e.g. honeycomb (Pearce 1990) - presents a
great potential for the modulation of the façade surfaces: it allows to obtain a surface tiling corresponding to the geometric optimization, according to the principle of the closest packing, and
it permits to reduce both the mechanical connectors to the existent façade and the heat loss
bridges in relation to the discontinuity points.
Regarding the AAM to be used as thermal insulating material for this envelope model, it is produced by using brick waste, combined with an activator solution containing a glass siliceous material (conductivity value λ = 0,045 W.m-1.K-1), therefore obtaining a final product with excellent
thermal properties. It presents a high resistance to chemical agents and good mechanical properties, and it has a great additional value compared to the traditional materials, since it is composed
mainly of raw waste materials, dried at room temperature, with low production of CO2 emissions
(Mazzoli et al. 2013). Further researches are in progress to optimize the investigated AAM in terms
of mechanical and physical properties.
About the chromogenic materials to be used as finishing external coating, tests and measurements demonstrate that photodegradation is a major problem for thermochromic paints when
exposed to outdoor environments (Karlessi et al. 2009). Further prototypes will explore and test
different methods by applying UV absorbers in the coatings, in order to prevent photodegradation and photostabilize the colour-changing effect of the material, according to outdoor temperature and solar radiation levels.
The physical and mechanical properties of these innovative materials have been verified by con-

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ZEMCH 2015 | International Conference | Bari - Lecce, Italy