ZEMCH 2015 - International Conference Proceedings | Page 587

energy saving and development of renewable energy”, as amended).
Before implementing any retrofit action, it is appropriate to evaluate it through a detailed analysis
of the cost-effectiveness ratio, in order to estimate, since the phase of the project, the possibility
of not only saving energy but also economic, and time return of the investment.
The research presents a typical case of energy retrofit of a residential apartment located in the
city of Palermo, where outdated construction techniques and uncontrolled economic speculation have produced low-quality buildings with very poor energy performance.
The case of study is exemplary because it allows to demonstrate how it is possible to get a clear
energy saving through simple interventions on the building such as, the thermal insulation of the
external vertical walls.
It was finally compared the result obtainable in different stratification configurations of the wall,
each through different insulation panel, so as to demonstrate the functionality and efficacy of
the innovative panel realized with the waste material of Opuntia ficus-indica plant, compared to
other materials already present in the market since many years.

Innovative materials to the envelope insulation
Insulating the building envelope is the first action to carry out on an existing building. The old
building systems and sometimes the lack of attention to the environmental conditions, determine the increase of the thermal energy demand and the use of air conditioning mechanics in
order to ensure suitable levels of indoor comfort.

Most common insulating materials in the market
Today available in the market there are a lot of different insulating materials. They can be divided
on the basis of the following key requirements:
1. physical-technical: density, thermal conductivity, resistance to water and compression, resistance to fire, etc .;
2. Environmental: impact on human health and on the environment, possibility of recycling, low
(or zero) CO2 emissions;
3. Economic: cost per unit (€/mq);
4. conformity: CE label (for certifying the conformity of the product with the declared performance, but without imposing performance limits) and certification testing laboratory.
On their choice also influence: the shape (panels, foams, etc.), the origin (animal, mineral or synthetic), the hygroscopicity level, the fire resistence and the capacity of heat protection during the
summer.
In the building applications, moreover, it is necessary to classify the insulating materials according to the following scheme:
1. Rigid panels, with the possibility to associate them with other layers of different materials
(wood, plasterboard, laminate, etc.) that confer a greater resistance to the whole system and
that can also serve as finishing;
2. Soft panels (rolls, mats, etc.) which are mostly used in interspaces playing, therefore, the only
function of insulation;
3. Bulk materials (fibers, granules and flakes) for the dry-filling of walls and roofs cavities.
The most common natural insulating materials used in buildings are the wood fiber panels. However, there are other natural products on the market: cotton, cork, lime expanded, cellulose and
even sheep’s wool. The main synthetic insulation materials are the expanded polystyrene or “EPS”,
the extruded polystyrene, and the polyurethane. The insulation of mineral origin, is mainly con-

Eco-friendly materials for the energy retrofit of existing buildings

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