Manuel Asensio, researcher in construction and renewable energy at AIMPLAS, discusses how the BIO4EEB project seeks to revolutionise insulation in Europe
Insulation in construction is a crucial factor in terms of habitability in homes, as it helps maintain mild temperatures by reducing energy expenditure, especially during periods when temperatures range from 20°C to 25°C, and in regions where temperatures are more extreme throughout the year.
How important is insulation?
In Europe, heating expenditure alone accounts for half of total energy consumption, although depending on the region where a country is located, consumption can be even higher. This is also due to the energy inefficiency of current homes; 80% of homes in Europe have an energy rating of E, F, or G, meaning they are energy inefficient, which generates additional energy expenditure to maintain adequate temperatures inside homes, regardless of the region in which they are located.
On the other hand, the European Commission is studying new regulations for heating with wood, the most traditional and affordable option for the population, especially in rural environments where energy poverty is more prevalent.
In Europe, insulation systems vary according to the climate of each region. In the north, materials such as polyurethane and mineral wool are used to conserve heat, with a focus on exterior insulation and triple-glazed windows. In the south, insulation focuses on preventing overheating and utilising EPS, XPS, and cork.
In the centre, XPS and polyurethane are used, along with ventilated façades and solar solutions. In the west, mineral wool and wood fibre are preferred, with an emphasis on controlled ventilation. In the east, materials such as XPS and ecological solutions are combined, while in the United Kingdom, mineral wool and controlled ventilation are prioritised to prevent humidity.
With all this, it is essential to have efficient, sustainable, and environmentally friendly insulation systems for construction, which can be applied both in new housing and in already built buildings, and which help to increase energy efficiency, maintaining a pleasant temperature inside houses and reducing both the energy and economic costs that this entails.
Understanding BIO4EEB polyurethane foam insulation
The BIO4EEB project, funded by the European Union, has developed polyurethane foam insulation with a 50% bio-based content, thereby improving insulation compared to current commercial systems based on fossil raw materials.
One of the main components used in the developed foams is polylactic acid, PLA, of sustainable origin, which leads to a reduction in the carbon footprint of the foams developed compared to their commercial rivals of fossil origin.
In addition, BIO4EEB has also focused on improving fire resistance, which is very important in materials used in construction, especially in PU insulation, so it has developed the incorporation of DOPO, a flame-retardant additive, in the foam matrix and has evaluated the capacity of these materials to insulate against temperature and resist fire.
In this sense, the incorporation of DOPO into the matrix at different percentages has improved the insulating capacity of the foams, thereby reducing the thermal conductivity of the materials.
As can be seen in the graph above, the materials in which DOPO was incorporated decrease their thermal conductivity, although it should be noted that an increase in DOPO above 10% is counterproductive in terms of the insulating capacity of the material, so using percentages of 15 and/or 20% of DOPO in the matrix decreases the insulating capacity of the foams.
As for the fire resistance of these materials, the values resulting from the calorimetric cone tests, represented in the following graph, reveal a very similar trend to that observed in thermal conductivity.
In general, the values of THR (total heat release), total amount of heat released, HRR (heat rate release), speed at which the material releases heat, and MARHE, the highest value of the average HRR, decrease when using DOPO in the foams, indicating a lower combustibility of the materials compared to not using this type of flame retardant. Similarly to the observed thermal conductivity values, using percentages above 10% of DOPO in the foams reduces fire resistance, since an increase in the values of THR, HRR, and MARHE is observed as we increase the percentage of DOPO from 10% to 15% and 20%.
Scope of the BIO4EEB project
In the BIO4EEB project, the materials developed will be used to enhance the insulation of construction systems, including interior walls, facades, and windows, in buildings located across the European continent, with diverse locations and construction characteristics, such as Spain, Lithuania, and Germany.
In addition to PLA-based insulating foams, BIO4EEB develops another series of sustainable materials for use in the construction sector, such as panels made with Posidonia fibres that possess thermoacoustic insulation properties, or prefabricated elements for facades that integrate bio-based materials, thereby improving the interior insulation of the building and reducing its carbon footprint.
These materials also have a high degree of sustainability, a result of the growing social demand for the increasingly necessary use of materials that are respectful of energy consumption and, ultimately, of the environment.
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